WILBERT

Description: An evaluation of the potential of Sentinel 1 for improving flash flood predictions via soil moisture–data assimilation Luca Cenci, Luca Pulvirenti, Giorgio Boni, Marco Chini, Patrick Matgen, Simone Gabellani, Giuseppe Squicciarino, and Nazzareno Pierdicca Adv. Geosci., 44, 89-100, https://doi.org/10.5194/adgeo-44-89-2017, 2017 This research aims at improving hydrological modelling skills of flash flood prediction by exploiting earth observation data. To this aim, high spatial/moderate temporal resolution soil moisture maps, derived from Sentinel 1 acquisitions, were used in a data assimilation framework. Findings revealed the potential of Sentinel 1-based soil moisture data assimilation for flash flood risk reduction and improved our understanding of the capabilities of the aforementioned satellite-derived product.

Description: Civil protection and Damaging Hydrogeological Events: comparative analysis of the 2000 and 2015 events in Calabria (southern Italy) Olga Petrucci, Tommaso Caloiero, Angela Aurora Pasqua, Piero Perrotta, Luigi Russo, and Carlo Tansi Adv. Geosci., 44, 101-113, https://doi.org/10.5194/adgeo-44-101-2017, 2017 This work presents a methodological approach to perform the comparative analysis of 2 events affecting the Calabria region (southern Italy), by collecting all the qualitative and quantitative features useful to describe both rain and damage. The first event occurred between 8 and 10 September 2000 while the second event occurred between 30 October and 1 November 2015. We concluded that, in the 2015 event, the management of pre-event phases allowed to reduce the number of victims.

Description: Flood and landslide warning based on rainfall thresholds and soil moisture indexes: the HEWS (Hydrohazards Early Warning System) for Sicily Giuseppina Brigandì, Giuseppe Tito Aronica, Brunella Bonaccorso, Roberto Gueli, and Giuseppe Basile Adv. Geosci., 44, 79-88, https://doi.org/10.5194/adgeo-44-79-2017, 2017 The paper presents the flood and landslide early warning system HEWS developed by the University of Messina for the Integrated Multi-Risk Decentralised Functional Centre of Sicily (Italy). HEWS implements a methodology based on the combined use of rainfall thresholds, soil moisture modelling and quantitative precipitation forecast (QPF) to issue alert bulletins both for floods and landslide. The software Delft-FEWS has been adopted as operation platform to support the implementation of HEWS.

Description: Advanced design and characterization methodologies for memory-aware CMOS power-amplifier implementation Martin Schleyer, Dominic Maurath, Heinrich Klar, and Friedel Gerfers Adv. Radio Sci., 15, 49-54, https://doi.org/10.5194/ars-15-49-2017, 2017 This paper reports on an effective root-cause analysis method of memory effects in power amplifiers, as well as introduces compensation techniques on a circuit design level. Despite conventional memory-effect approaches, the discussed method uses a two-tone scan over a wide operation and modulation range. The approach is demonstrated on a 65-nm CMOS power amplifier with an OIP1 of 27 dBm and a PAE of over 30 % using WCDMA and LTE signals.

Description: A Novel Target-Height Estimation Approach Using Radar-Wave Multipath Propagation for Automotive Applications Amir Laribi, Markus Hahn, Jürgen Dickmann, and Christian Waldschmidt Adv. Radio Sci., 15, 61-67, https://doi.org/10.5194/ars-15-61-2017, 2017 This paper introduces a novel target height estimation approach using a Frequency Modulation Continuous Wave (FMCW) automotive radar. The presented algorithm takes advantage of radar wave multipath propagation to measure the height of objects in the vehicle surroundings. A multipath propagation model is presented first, then a target height is formulated using geometry, based on the presented propagation model. It is then shown from Sensor-Target geometry that height estimation of targets is highly dependent on the radar range resolution, target range and target height. The high resolution algorithm RELAX is discussed and applied to collected raw data to enhance the radar range resolution capability. This enables a more accurate height estimation especially for low targets. Finally, the results of a measurement campaign using corner reflectors at different heights are discussed to show that target heights can be very accurately resolved by the proposed algorithm and that for low targets an average mean height estimation error of 0.03 m has been achieved by the proposed height finding algorithm.

Description: Lithium-ion battery models: a comparative study and a model-based powerline communication Fida Saidani, Franz X. Hutter, Rares-George Scurtu, Wolfgang Braunwarth, and Joachim N. Burghartz Adv. Radio Sci., 15, 83-91, https://doi.org/10.5194/ars-15-83-2017, 2017 This paper presents a comparative overview of models for lithium-ion batteries from an electrical Engineering Point of view. The comparison criteria and the different models are presented. After this comparison, a model is used to establish a new communication concept.

Description: Orthogonal frequency division multiplexing with amplitude shift keying subcarrier modulation as a reliable and efficient transmission scheme for self-mixing receivers Jonas Kornprobst, Thomas J. Mittermaier, and Thomas F. Eibert Adv. Radio Sci., 15, 99-106, https://doi.org/10.5194/ars-15-99-2017, 2017 By analyzing the behavior of a self-mixing receiver, an appropriate model with a squre-law device can be obtained. This model is analyzed and a novel transmission technique with higher spectral efficiency is deduced by the formulation of the signal reconstruction problem as a phase retrival problem. Simulation results show the good performance of the proposed method.

Description: An interoperable research data infrastructure to support climate service development Tiziana De Filippis, Leandro Rocchi, and Elena Rapisardi Adv. Sci. Res., 14, 335-340, https://doi.org/10.5194/asr-14-335-2018, 2018 Accessibility, availability, re-use and re-distribution of scientific data are prerequisites to build climate services across Europe. The proposed architecture uses open-source tools and interoperable standards to ensure sustainability in the development and deployment of Web applications. The availability of structured raw data as customized information paves the way for building climate service purveyors to support adaptation, mitigation and risk management at different scales.

Description: Wind regimes and their relation to synoptic variables using self-organizing maps Sigalit Berkovic Adv. Sci. Res., 15, 1-9, https://doi.org/10.5194/asr-15-1-2018, 2018 This study exemplifies the ability of the self-organizing maps method to directly define well known wind regimes over Israel during the entire year, except summer, period at 12:00 UTC. This procedure may be applied at other hours and is highly relevant to future automatic climatological analysis and applications. The investigation is performed by analysing surface wind measurements. The relation between the synoptic variables and the wind regimes is revealed from composite calculations.

Description: Comparison of digital beamforming algorithms for 3-D terahertz imaging with sparse multistatic line arrays Bessem Baccouche, Patrick Agostini, Falco Schneider, Wolfgang Sauer-Greff, Ralph Urbansky, and Fabian Friederich Adv. Radio Sci., 15, 283-292, https://doi.org/10.5194/ars-15-283-2017, 2017 In this contribution we compare the back-projection algorithm with our recently developed modified range migration algorithm for 3D terahertz imaging using sparse multistatic line arrays. Numerical and experimental investigations show that imaging results from the proposed range migration algorithm approximates very nicely these of the back-projection algorithm, yet with a significant computational saving. These results are appealing for time critical 3D terahertz imaging.

Description: Design of a dual linear polarization antenna using split ring resonators at X-band Sadiq Ahmed and Madhukar Chandra Adv. Radio Sci., 15, 259-267, https://doi.org/10.5194/ars-15-259-2017, 2017 In this paper, a novel approach (using metamaterials) is used to enhance the XPD for a dual linear polarization patch antenna at the frequency of 10 GHz. This improvement is obtained by placing two S-RRs close to the microstrip patch antenna, placing a SRR between two microstrip feed lines, and etching two pairs of CSRRs in the ground plane. An improvement in the XPD by 8.8 dB as compared to the conventional dual linear polarization antenna is noticed.

Description: Experimentelles FMCW-Radar zur hochfrequenten Charakterisierung von Windenergieanlagen Karsten Schubert, Jens Werner, and Fabian Schwartau Adv. Radio Sci., 15, 1-9, https://doi.org/10.5194/ars-15-1-2017, 2017 A cost-effective and universal FMCW radar is developed for the RF characterisation of wind turbine plants. This radar is modular and can be easily adapted for different measurement tasks. A long-term goal is to investigate high-frequency characteristics of wind turbines at different locations by their Doppler spectrum. The results obtained will be used to derive a statistical model.

Description: Chemical characterization of laboratory-generated tar ball particles Ádám Tóth, András Hoffer, Mihály Pósfai, Tibor Ajtai, Zoltán Kónya, Marianne Blazsó, Zsuzsanna Czégény, Gyula Kiss, Zoltán Bozóki, and András Gelencsér Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-132,2018 Manuscript under review for ACP (discussion: open, 0 comments) Atmospheric tar balls are abundant particles in biomass smoke and were shown to be strongly light-absorbing. Being able to synthesize pure tar balls in the laboratory we deployed various analytical techniques to determine the chemical characteristics of tar balls and to compare them with those of other light-absorbing particle types such as soot (black carbon, BC). The results have relevance in better representing these specific smoke particles in global climate models.

Description: Aircraft Observations of Aerosol in the Manaus Urban Plume and Surrounding Tropical Forest during GoAmazon 2014/15 John E. Shilling, Mikhail S. Pekour, Edward C. Fortner, Paulo Artaxo, Suzane de Sá, John M. Hubbe, Karla M. Longo, Luiz A. T. Machado, Scot T. Martin, Stephen R. Springston, Jason Tomlinson, and Jian Wang Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-193,2018 Manuscript under review for ACP (discussion: open, 0 comments) We report aircraft observations of the evolution of organic aerosol in the Manaus urban plume as it ages. We observe dynamic changes in the organic aerosol. The mean carbon oxidation state of the OA increases from −0.6 to −0.45. Hydrocarbon-like organic aerosol (HOA) mass is lost and is balanced out by formation of oxygenated organic aerosol (OOA). Because HOA loss is balanced by OOA formation, we observe little change in the net Δorg/ΔCO values with aging.

Description: Influence of anthropogenic emissions and boundary conditions on multi-model simulations of major air pollutants over Europe and North America in the framework of AQMEII3 Ulas Im, Jesper Heile Christensen, Camilla Geels, Kaj Mantzius Hansen, Jørgen Brandt, Efisio Solazzo, Ummugulsum Alyuz, Alessandra Balzarini, Rocio Baro, Roberto Bellasio, Roberto Bianconi, Johannes Bieser, Augustin Colette, Gabriele Curci, Aidan Farrow, Johannes Flemming, Andrea Fraser, Pedro Jimenez-Guerrero, Nutthida Kitwiroon, Peng Liu, Uarporn Nopmongcol, Laura Palacios-Peña, Guido Pirovano, Luca Pozzoli, Marje Prank, Rebecca Rose, Ranjeet Sokhi, Paolo Tuccella, Alper Unal, Marta G. Vivanco, Greg Yarwood, Christian Hogrefe, and Stefano Galmarini Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2017-1231,2018 Manuscript under review for ACP (discussion: open, 0 comments) We evaluate the impact of global and regional anthropogenic emission reductions on major air pollutant levels over Europe and North America, using a multi-model ensemble of regional chemistry and transport models. Results show that ozone levels are largely driven by long-range transport over both continents while other pollutants such as carbon monoxide or aerosols are mainly controlled by domestic sources. Use of multi model ensembles can help to reduce the uncertainties in individual models.

Description: Ozone impacts of gas–aerosol uptake in global chemistry transport models Scarlet Stadtler, David Simpson, Sabine Schröder, Domenico Taraborrelli, Andreas Bott, and Martin Schultz Atmos. Chem. Phys., 18, 3147-3171, https://doi.org/10.5194/acp-18-3147-2018, 2018 The impact of six heterogeneous gas–aerosol uptake reactions on tropospheric ozone and nitrogen species was studied using two chemical transport models, the Meteorological Synthesizing Centre-West of the European Monitoring and Evaluation Programme (EMEP MSC-W) and the European Centre Hamburg general circulation model combined with versions of the Hamburg Aerosol Model and Model for Ozone and Related chemical Tracers (ECHAM-HAMMOZ). Species undergoing heterogeneous reactions in both models include N 2 O 5 , NO 3 , NO 2 , O 3 , HNO 3 , and HO 2 . Since heterogeneous reactions take place at the aerosol surface area, the modelled surface area density ( S a ) of both models was compared to a satellite product retrieving the surface area. This comparison shows a good agreement in global pattern and especially the capability of both models to capture the extreme aerosol loadings in east Asia. The impact of the heterogeneous reactions was evaluated by the simulation of a reference run containing all heterogeneous reactions and several sensitivity runs. One reaction was turned off in each sensitivity run to compare it with the reference run. The analysis of the sensitivity runs confirms that the globally most important heterogeneous reaction is the one of N 2 O 5 . Nevertheless, NO 2 , HNO 3 , and HO 2 heterogeneous reactions gain relevance particularly in east Asia due to the presence of high NO x concentrations and high S a in the same region. The heterogeneous reaction of O 3 itself on dust is of minor relevance compared to the other heterogeneous reactions. The impacts of the N 2 O 5 reactions show strong seasonal variations, with the biggest impacts on O 3 in springtime when photochemical reactions are active and N 2 O 5 levels still high. Evaluation of the models with northern hemispheric ozone surface observations yields a better agreement of the models with observations in terms of concentration levels, variability, and temporal correlations at most sites when the heterogeneous reactions are incorporated. Our results are loosely consistent with results from earlier studies, although the magnitude of changes induced by N 2 O 5 reaction is at the low end of estimates, which seems to fit a trend, whereby the more recent the study the lower the impacts of these reactions.

Description: Exploring the relationship between surface PM 2.5 and meteorology in Northern India Jordan L. Schnell, Vaishali Naik, Larry W. Horowitz, Fabien Paulot, Jingqiu Mao, Paul Ginoux, Ming Zhao, and Kirpa Ram Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-24,2018 Manuscript under review for ACP (discussion: open, 0 comments) We evaluate the ability of a developmental version of the NOAA GFDL Atmospheric Model, version 4 to simulate observed wintertime pollution and its relationship to weather over Northern India, one of the most densely populated and polluted regions in world. We also compare two emission inventories and find that the newest version dramatically improves our simulation. Observed and modeled pollution is the highest within the Indo-Gangetic Plain, where it is closely related to near-surface weather.

Description: Aerosol–cloud interactions in mixed-phase convective clouds – Part 1: Aerosol perturbations Annette K. Miltenberger, Paul R. Field, Adrian A. Hill, Phil Rosenberg, Ben J. Shipway, Jonathan M. Wilkinson, Robert Scovell, and Alan M. Blyth Atmos. Chem. Phys., 18, 3119-3145, https://doi.org/10.5194/acp-18-3119-2018, 2018 Changes induced by perturbed aerosol conditions in moderately deep mixed-phase convective clouds (cloud top height  ∼  5 km) developing along sea-breeze convergence lines are investigated with high-resolution numerical model simulations. The simulations utilise the newly developed Cloud–AeroSol Interacting Microphysics (CASIM) module for the Unified Model (UM), which allows for the representation of the two-way interaction between cloud and aerosol fields. Simulations are evaluated against observations collected during the COnvective Precipitation Experiment (COPE) field campaign over the southwestern peninsula of the UK in 2013. The simulations compare favourably with observed thermodynamic profiles, cloud base cloud droplet number concentrations (CDNC), cloud depth, and radar reflectivity statistics. Including the modification of aerosol fields by cloud microphysical processes improves the correspondence with observed CDNC values and spatial variability, but reduces the agreement with observations for average cloud size and cloud top height. Accumulated precipitation is suppressed for higher-aerosol conditions before clouds become organised along the sea-breeze convergence lines. Changes in precipitation are smaller in simulations with aerosol processing. The precipitation suppression is due to less efficient precipitation production by warm-phase microphysics, consistent with parcel model predictions. In contrast, after convective cells organise along the sea-breeze convergence zone, accumulated precipitation increases with aerosol concentrations. Condensate production increases with the aerosol concentrations due to higher vertical velocities in the convective cores and higher cloud top heights. However, for the highest-aerosol scenarios, no further increase in the condensate production occurs, as clouds grow into an upper-level stable layer. In these cases, the reduced precipitation efficiency (PE) dominates the precipitation response and no further precipitation enhancement occurs. Previous studies of deep convective clouds have related larger vertical velocities under high-aerosol conditions to enhanced latent heating from freezing. In the presented simulations changes in latent heating above the 0°C are negligible, but latent heating from condensation increases with aerosol concentrations. It is hypothesised that this increase is related to changes in the cloud field structure reducing the mixing of environmental air into the convective core. The precipitation response of the deeper mixed-phase clouds along well-established convergence lines can be the opposite of predictions from parcel models. This occurs when clouds interact with a pre-existing thermodynamic environment and cloud field structural changes occur that are not captured by simple parcel model approaches.

Description: Aerosol optical properties over Europe: an evaluation of the AQMEII Phase 3 simulations against satellite observations Laura Palacios-Peña, Pedro Jiménez-Guerrero, Rocío Baró, Alessandra Balzarini, Roberto Bianconi, Gabriele Curci, Tony Christian Landi, Guido Pirovano, Marje Prank, Angelo Riccio, Paolo Tuccella, and Stefano Galmarini Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2017-1119,2018 Manuscript under review for ACP (discussion: open, 0 comments) The main uncertainties in estimates of changes in the Earth's energy budget are related to the role of atmospheric aerosols. These changes are caused mainly by aerosol-radiation (ARI) and aerosol-cloud interactions (ACI), which heavily depend on aerosol properties. From the 1980s, many international modelling initiatives have studied atmospheric aerosols and their climate effects. Phase 3 of the Air Quality Model Evaluation International Initiative (AQMEII) focuses on evaluating and intercomparing regional and linked global/regional modelling systems by collaborating with the Task Force on the Hemispheric Transport of Air Pollution Phase 2 (HTAP2) initiative. Within this framework, the main aim of this work was to evaluate the representation of aerosol optical depth (AOD) and the Ångström exponent (AE) by the AQMEII Phase 3 simulations over Europe. The evaluation was made using satellite data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on board the Terra and Aqua platforms. The results indicated that the skills of AQMEII simulations in the AOD representation produced fewer errors than in the AE. Regardless of the models and emissions used, models were skilful at representing the low and medium AOD values observed (below 0.5). However, high values (close to 1.0) were underestimated for biomass burning episodes, and were overestimated for desert dust contributions, related mainly to emission and boundary conditions. Despite this behaviour, the spatial and temporal variability of this variable was well-represented by all the models. Generally, the AE evaluation showed more serious errors than the AOD evaluation. Moreover, the observed variability of this parameter was strongly underestimated in all the simulations.

Description: Technical Note: Atmospheric CO 2 inversions on the mesoscale using data-driven prior uncertainties: methodology and system evaluation Panagiotis Kountouris, Christoph Gerbig, Christian Rödenbeck, Ute Karstens, Thomas Frank Koch, and Martin Heimann Atmos. Chem. Phys., 18, 3027-3045, https://doi.org/10.5194/acp-18-3027-2018, 2018 Atmospheric inversions are widely used in the optimization of surface carbon fluxes on a regional scale using information from atmospheric CO 2 dry mole fractions. In many studies the prior flux uncertainty applied to the inversion schemes does not directly reflect the true flux uncertainties but is used to regularize the inverse problem. Here, we aim to implement an inversion scheme using the Jena inversion system and applying a prior flux error structure derived from a model–data residual analysis using high spatial and temporal resolution over a full year period in the European domain. We analyzed the performance of the inversion system with a synthetic experiment, in which the flux constraint is derived following the same residual analysis but applied to the model–model mismatch. The synthetic study showed a quite good agreement between posterior and true fluxes on European, country, annual and monthly scales. Posterior monthly and country-aggregated fluxes improved their correlation coefficient with the known truth by 7 % compared to the prior estimates when compared to the reference, with a mean correlation of 0.92. The ratio of the SD between the posterior and reference and between the prior and reference was also reduced by 33 % with a mean value of 1.15. We identified temporal and spatial scales on which the inversion system maximizes the derived information; monthly temporal scales at around 200 km spatial resolution seem to maximize the information gain.

Description: Extraction of wind and temperature information from hybrid 4D-Var assimilation of stratospheric ozone using NAVGEM Douglas R. Allen, Karl W. Hoppel, and David D. Kuhl Atmos. Chem. Phys., 18, 2999-3026, https://doi.org/10.5194/acp-18-2999-2018, 2018 This study examines whether ozone data in the stratosphere (10–50 km altitude) can be used to benefit weather forecasts. The approach involves creating simulated ozone data and assimilating these into the US Navy's global weather model. Key findings are that assimilation of dense and accurate ozone data markedly benefits winds and temperature. However, the benefit is small when realistic ozone data are assimilated along with currently available microwave and infrared sounding measurements.

Description: Source apportionment of atmospheric aerosol in a marine dusty environment by Ionic/composition Mass Balance (IMB) João Cardoso, Susana M. Almeida, Teresa Nunes, Marina Almeida-Silva, Mário Cerqueira, Célia Alves, Fernando Rocha, Paula Chaves, Miguel Reis, Pedro Salvador, Begoña Artiñano, and Casimiro Pio Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-10,2018 Manuscript under review for ACP (discussion: open, 0 comments) Atmospheric aerosol was sampled in Cape Verde islands and analysed for chemical composition. Very high levels of dust were measured during the winter months, as a result of transport from Africa. Mass Balances were applied to the particulate material, permitting the determination of 7 different source contributions to the aerosol loading. The balance methodology compared well with Standard Source Apportionment methods, showing its capability for the source apportionment of aerosol particles.

Description: Chemical characterization of laboratory-generated tar ball particles Ádám Tóth, András Hoffer, Mihály Pósfai, Tibor Ajtai, Zoltán Kónya, Marianne Blazsó, Zsuzsanna Czégény, Gyula Kiss, Zoltán Bozóki, and András Gelencsér Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-132,2018 Manuscript under review for ACP (discussion: open, 0 comments) Atmospheric tar balls are abundant particles in biomass smoke and were shown to be strongly light-absorbing. Being able to synthesize pure tar balls in the laboratory we deployed various analytical techniques to determine the chemical characteristics of tar balls and to compare them with those of other light-absorbing particle types such as soot (black carbon, BC). The results have relevance in better representing these specific smoke particles in global climate models.

Description: The Effect of Instrumental Stray Light on Brewer and Dobson Total Ozone Measurements Omid Moeini, Zahra Vaziri, C. Thomas McElroy, David W. Tarasick, Robert D. Evans, Irina Petropavlovskikh, and Keh-Harng Feng Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-2,2018 Manuscript under review for AMT (discussion: open, 0 comments) This study documents the error caused by the effect of stray light in the Brewer and Dobson total ozone measurements using a mathematical model for each instrument. The errors caused by stray light are particularly significant at high latitudes in the late winter and early spring when measurements are made at large solar zenith angles and large total ozone column. It is considerable importance if those data are to be used for trend analysis or satellite data validation.

Description: Halo ratio from ground based all-sky imaging Paolo Dandini, Zbigniew Ulanowski, David Campbell, and Richard Kaye Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-3,2018 Manuscript under review for AMT (discussion: open, 0 comments) The halo ratio indicates the strength of the 22° cirrus halo, and gives valuable information on cloud properties. We propose to obtain it from all-sky images by applying a range of transformations and corrections and averaging brightness azimuthally over sun-centred images. The ratio is then taken at two angles from the sun, 20° and 23°, in variance from previous suggestions. While we find ratios 〉 1 to be linked to halos, they can occur under scattered cumuli as artefacts due to cloud edges.

Description: Water vapour retrieval using the Precision Solar Spectroradiometer Panagiotis-Ioannis Raptis, Stelios Kazadzis, Julian Gröbner, Natalia Kouremeti, Lionel Doppler, Ralf Becker, and Constantinos Helmis Atmos. Meas. Tech., 11, 1143-1157, https://doi.org/10.5194/amt-11-1143-2018, 2018 The purpose of this work is to retrieve integrated water vapour using spectral measurements from Precision Solar Spectroradiometer (PSR). Two different approaches were developed one using single-channel direct sun irradiance measurements, and the second one integrating at a certain spectral region. The results of the spectral approach are closer to the retrievals of non-photometric techniques (GPS, microwave radiometer and radiosondes), suggesting this method provide more accurate IWV product.

Description: Increasing persistent haze in Beijing: potential impacts of weakening East Asian winter monsoons associated with northwestern Pacific sea surface temperature trends Lin Pei, Zhongwei Yan, Zhaobin Sun, Shiguang Miao, and Yao Yao Atmos. Chem. Phys., 18, 3173-3183, https://doi.org/10.5194/acp-18-3173-2018, 2018 This paper demonstrates the increasing frequency of persistent haze events (PHE) in Beijing based on updated observations and explores the associated changes in large-scale atmospheric circulations with possible links to the large-scale warming trend. We propose a more concrete observation-based mechanism for explaining how the local PHE in Beijing change with large-scale climate warming via the sea surface temperature anomaly in the northwestern Pacific.

Description: Results from the Fourth WMO Filter Radiometer Comparison for aerosol optical depth measurements Stelios Kazadzis, Natalia Kouremeti, Henri Diémoz, Julian Gröbner, Bruce W. Forgan, Monica Campanelli, Victor Estellés, Kathleen Lantz, Joseph Michalsky, Thomas Carlund, Emilio Cuevas, Carlos Toledano, Ralf Becker, Stephan Nyeki, Panagiotis G. Kosmopoulos, Viktar Tatsiankou, Laurent Vuilleumier, Frederick M. Denn, Nozomu Ohkawara, Osamu Ijima, Philippe Goloub, Panagiotis I. Raptis, Michael Milner, Klaus Behrens, Africa Barreto, Giovanni Martucci, Emiel Hall, James Wendell, Bryan E. Fabbri, and Christoph Wehrli Atmos. Chem. Phys., 18, 3185-3201, https://doi.org/10.5194/acp-18-3185-2018, 2018 Aerosol optical depth measured from ground-based sun photometers is the most important parameter for studying the changes in the Earth's radiation balance due to aerosols. Representatives for various sun photometer types belonging to individual institutions or international aerosol networks gather every 5 years, for 3 weeks, in Davos, Switzerland, in order to compare their aeorosol optical depth retrievals. This work presents the results of the latest (fourth) filter radiometer intercomparison.

Description: Nighttime wind and scalar variability within and above an Amazonian canopy Pablo E. S. Oliveira, Otávio C. Acevedo, Matthias Sörgel, Anywhere Tsokankunku, Stefan Wolff, Alessandro C. Araújo, Rodrigo A. F. Souza, Marta O. Sá, Antônio O. Manzi, and Meinrat O. Andreae Atmos. Chem. Phys., 18, 3083-3099, https://doi.org/10.5194/acp-18-3083-2018, 2018 Carbon dioxide and latent heat fluxes within the canopy are dominated by low-frequency (nonturbulent) processes. There is a striking contrast between fully turbulent and intermittent nights, such that turbulent processes dominate the total nighttime exchange during the former, while nonturbulent processes are more relevant in the latter. In very stable nights, during which intermittent exchange prevails, the stable boundary layer may be shallower than the highest observational level at 80 m.

Description: Lower tropospheric ozone over India and its linkage to the South Asian monsoon Xiao Lu, Lin Zhang, Xiong Liu, Meng Gao, Yuanhong Zhao, and Jingyuan Shao Atmos. Chem. Phys., 18, 3101-3118, https://doi.org/10.5194/acp-18-3101-2018, 2018 Deteriorating tropospheric ozone pollution over India may not only affect local human health and vegetation but also perturb global ozone distribution. This study analyzes the processes controlling lower tropospheric ozone over India using OMI satellite observations (2006–2014) and model simulations (1990–2010). We show that the South Asian monsoon largely controls the seasonal cycle and interannual variability of Indian lower tropospheric ozone via changes in ozone production and transport.

Description: Investigating the yield of H 2 O and H 2 from methane oxidation in the stratosphere Franziska Frank, Patrick Jöckel, Sergey Gromov, and Martin Dameris Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-170,2018 Manuscript under review for ACP (discussion: open, 0 comments) Previously, it was assumed that one molecule of methane produces two water molecules. Applying various modeling concepts, we find that this overestimates the production in some areas of the atmosphere and underestimate it in other. Additionally, the chemical loss of water influences the actual abundance of it, especially in the upper atmosphere. We question the assumption of a vertically constant chemical production of water vapor and rather encourage to apply a sophisticated vertical profile.

Description: Ice-nucleating efficiency of aerosol particles and possible sources at three coastal marine sites Meng Si, Victoria E. Irish, Ryan H. Mason, Jesús Vergara-Temprado, Sarah Hanna, Luis A. Ladino, Jacqueline D. Yakobi-Hancock, Corinne L. Schiller, Jeremy J. B. Wentzell, Jonathan P. D. Abbatt, Ken S. Carslaw, Benjamin J. Murray, and Allan K. Bertram Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-81,2018 Manuscript under review for ACP (discussion: open, 0 comments) Using the concentrations of ice-nucleating particles (INPs) and total aerosol particles measured at three coastal marine sites, the ice-nucleating efficiency of aerosol particles as a function of size was determined. The ice-nucleating efficiency was strongly dependent on size, with larger particles being more efficient. This type of information can help determine or rule out the sources of INPs, and constrain future modeling of INPs and mixed-phase clouds.

Description: A high-resolution inventory of air pollutant emissions from crop residue burning in China Xiaohui Zhang, Yan Lu, Qin'geng Wang, and Xin Qian Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2017-1113,2018 Manuscript under review for ACP (discussion: open, 0 comments) Activity data at prefectural-city level combined with high-resolution land use data were adopted to improve spatial resolution and detailed crop rotations and harvest times in different regions were considered in determining temporal distribution. Also, MODIS fire products were applied to verify the spatial and temporal variations of the emissions. Results showed that high emissions were generally located in Eastern, Central and Northeastern China, and temporally peaking in June and October.

Description: Atmospheric CO 2 inversions on the mesoscale using data-driven prior uncertainties: quantification of the European terrestrial CO 2 fluxes Panagiotis Kountouris, Christoph Gerbig, Christian Rödenbeck, Ute Karstens, Thomas F. Koch, and Martin Heimann Atmos. Chem. Phys., 18, 3047-3064, https://doi.org/10.5194/acp-18-3047-2018, 2018 Optimized biogenic carbon fluxes for Europe were estimated from high-resolution regional-scale inversions, utilizing atmospheric CO 2 measurements at 16 stations for the year 2007. Additional sensitivity tests with different data-driven error structures were performed. As the atmospheric network is rather sparse and consequently contains large spatial gaps, we use a priori biospheric fluxes to further constrain the inversions. The biospheric fluxes were simulated by the Vegetation Photosynthesis and Respiration Model (VPRM) at a resolution of 0.1° and optimized against eddy covariance data. Overall we estimate an a priori uncertainty of 0.54 GtC yr −1 related to the poor spatial representation between the biospheric model and the ecosystem sites. The sink estimated from the atmospheric inversions for the area of Europe (as represented in the model domain) ranges between 0.23 and 0.38 GtC yr −1 (0.39 and 0.71 GtC yr −1 up-scaled to geographical Europe). This is within the range of posterior flux uncertainty estimates of previous studies using ground-based observations.

Description: Contrasting the co-variability of daytime cloud and precipitation over tropical land and ocean Daeho Jin, Lazaros Oreopoulos, Dongmin Lee, Nayeong Cho, and Jackson Tan Atmos. Chem. Phys., 18, 3065-3082, https://doi.org/10.5194/acp-18-3065-2018, 2018 To what degree can precipitation be predicted given information about clouds? Or, conversely, with precipitation information at hand, can we provide good guesses about the clouds responsible? To answer these questions, we performed joint analysis of rainfall and cloud data, which are significantly decoupled. We find that only for the deepest and thickest clouds does cloud amount relate strongly with the intensity of rainfall, and that the details are different over oceans and land.

Description: Establishing the Impact of Model Surfactants on Cloud Condensation Nuclei Activity of Sea Spray Aerosols Sara D. Forestieri, Sean M. Staudt, Thomas M. Kuborn, Katharine Faber, Christopher R. Ruehl, Timothy H. Bertram, and Christopher D. Cappa Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2018-207,2018 Manuscript under review for ACP (discussion: open, 0 comments) Our work establishes how surface tension reduction influences droplet growth and activation of simple sea spray mimics, i.e. NaCl coated with fatty acids. Fatty acids can substantially reduce droplet surface tension near activation, but have limited impact on activation. Coating of NaCl by stearic acid (a wax) impedes water uptake, but this impedance is removed if oleic acid (a liquid) is mixed in. The properties that surface active compounds need to impact activation are theoretically examined.

Description: Increasing persistent haze in Beijing: potential impacts of weakening East Asian winter monsoons associated with northwestern Pacific sea surface temperature trends Lin Pei, Zhongwei Yan, Zhaobin Sun, Shiguang Miao, and Yao Yao Atmos. Chem. Phys., 18, 3173-3183, https://doi.org/10.5194/acp-18-3173-2018, 2018 This paper demonstrates the increasing frequency of persistent haze events (PHE) in Beijing based on updated observations and explores the associated changes in large-scale atmospheric circulations with possible links to the large-scale warming trend. We propose a more concrete observation-based mechanism for explaining how the local PHE in Beijing change with large-scale climate warming via the sea surface temperature anomaly in the northwestern Pacific.

Description: Results from the Fourth WMO Filter Radiometer Comparison for aerosol optical depth measurements Stelios Kazadzis, Natalia Kouremeti, Henri Diémoz, Julian Gröbner, Bruce W. Forgan, Monica Campanelli, Victor Estellés, Kathleen Lantz, Joseph Michalsky, Thomas Carlund, Emilio Cuevas, Carlos Toledano, Ralf Becker, Stephan Nyeki, Panagiotis G. Kosmopoulos, Viktar Tatsiankou, Laurent Vuilleumier, Frederick M. Denn, Nozomu Ohkawara, Osamu Ijima, Philippe Goloub, Panagiotis I. Raptis, Michael Milner, Klaus Behrens, Africa Barreto, Giovanni Martucci, Emiel Hall, James Wendell, Bryan E. Fabbri, and Christoph Wehrli Atmos. Chem. Phys., 18, 3185-3201, https://doi.org/10.5194/acp-18-3185-2018, 2018 Aerosol optical depth measured from ground-based sun photometers is the most important parameter for studying the changes in the Earth's radiation balance due to aerosols. Representatives for various sun photometer types belonging to individual institutions or international aerosol networks gather every 5 years, for 3 weeks, in Davos, Switzerland, in order to compare their aeorosol optical depth retrievals. This work presents the results of the latest (fourth) filter radiometer intercomparison.

Description: Influence of anthropogenic emissions and boundary conditions on multi-model simulations of major air pollutants over Europe and North America in the framework of AQMEII3 Ulas Im, Jesper Heile Christensen, Camilla Geels, Kaj Mantzius Hansen, Jørgen Brandt, Efisio Solazzo, Ummugulsum Alyuz, Alessandra Balzarini, Rocio Baro, Roberto Bellasio, Roberto Bianconi, Johannes Bieser, Augustin Colette, Gabriele Curci, Aidan Farrow, Johannes Flemming, Andrea Fraser, Pedro Jimenez-Guerrero, Nutthida Kitwiroon, Peng Liu, Uarporn Nopmongcol, Laura Palacios-Peña, Guido Pirovano, Luca Pozzoli, Marje Prank, Rebecca Rose, Ranjeet Sokhi, Paolo Tuccella, Alper Unal, Marta G. Vivanco, Greg Yarwood, Christian Hogrefe, and Stefano Galmarini Atmos. Chem. Phys. Discuss., https//doi.org/10.5194/acp-2017-1231,2018 Manuscript under review for ACP (discussion: open, 0 comments) We evaluate the impact of global and regional anthropogenic emission reductions on major air pollutant levels over Europe and North America, using a multi-model ensemble of regional chemistry and transport models. Results show that ozone levels are largely driven by long-range transport over both continents while other pollutants such as carbon monoxide or aerosols are mainly controlled by domestic sources. Use of multi model ensembles can help to reduce the uncertainties in individual models.

Description: The influence of the ocean circulation state on ocean carbon storage and CO 2 drawdown potential in an Earth system model Malin Ödalen, Jonas Nycander, Kevin I. C. Oliver, Laurent Brodeau, and Andy Ridgwell Biogeosciences, 15, 1367-1393, https://doi.org/10.5194/bg-15-1367-2018, 2018 We conclude that different initial states for an ocean model result in different capacities for ocean carbon storage due to differences in the ocean circulation state and the origin of the carbon in the initial ocean carbon reservoir. This could explain why it is difficult to achieve comparable responses of the ocean carbon system in model inter-comparison studies in which the initial states vary between models. We show that this effect of the initial state is quantifiable.

Description: Response of the carbon cycle in an intermediate complexity model to the different climate configurations of the last nine interglacials Nathaelle Bouttes, Didier Swingedouw, Didier M. Roche, Maria F. Sanchez-Goni, and Xavier Crosta Clim. Past, 14, 239-253, https://doi.org/10.5194/cp-14-239-2018, 2018 Atmospheric CO 2 is key for climate change. CO 2 is lower during the oldest warm period of the last million years, the interglacials, than during the most recent ones (since 430 000 years ago). This difference has not been explained yet, but could be due to changes of ocean circulation. We test this hypothesis and the role of vegetation and ice sheets using an intermediate complexity model. We show that only small changes of CO 2 can be obtained, underlying missing feedbacks or mechanisms.

Description: On the mechanisms of warming the mid-Pliocene and the inference of a hierarchy of climate sensitivities with relevance to the understanding of climate futures Deepak Chandan and W. Richard Peltier Clim. Past Discuss., https//doi.org/10.5194/cp-2018-18,2018 Manuscript under review for CP (discussion: open, 0 comments) We infer the physical mechanisms by which the mid-Pliocene could have sustained a warm climate. We also provide a mid-Pliocene perspective on a range of climate sensitivities applicable on several timescales. Warming inferred on the basis of these sensitivity parameters is compared to forecasted levels of warming. This leads us to conclude that projections for 300–500 years into the future underestimate the potential for warming because they do not account for long timescale feedback processes.

Description: Sedproxy: a forward model for sediment archived climate proxies Andrew M. Dolman and Thomas Laepple Clim. Past Discuss., https//doi.org/10.5194/cp-2018-13,2018 Manuscript under review for CP (discussion: open, 0 comments) Climate proxies from marine sediments provide an important record of past temperatures, but contain noise from many sources. These include mixing by burrowing organisms, seasonal and habitat biases, measurement error and small sample size effects. We have created a forward model that simulates the creation of proxy records and provide it as a user-friendly R package. It allows multiple sources of uncertainty to be considered together when interpreting proxy climate records.

Description: Evidence for increased expression of the Amundsen Sea Low over the South Atlantic during the late Holocene Zoë Thomas, Richard T. Jones, Chris Fogwill, Jackie Hatton, Alan Williams, Alan Hogg, Scott Mooney, Philip Jones, David Lister, Paul Mayewski, and Chris Turney Clim. Past Discuss., https//doi.org/10.5194/cp-2018-11,2018 Manuscript under review for CP (discussion: open, 0 comments) We report a high-resolution study of a 5000 year-long peat record from the Falkland Islands, an area sensitive to the dynamics of the Amundsen Sea Low, which plays a major role in modulating the Southern Ocean climate. We find wetter, colder conditions between 5000 and 2500 years ago due to enhanced southerly airflow, with the establishment of drier and warmer conditions from 2500 years to present, implying more westerly airflow and increased projection of the ASL onto the South Atlantic.

Description: Sensitivity of the Eocene climate to CO 2 and orbital variability John S. Keery, Philip B. Holden, and Neil R. Edwards Clim. Past, 14, 215-238, https://doi.org/10.5194/cp-14-215-2018, 2018 In the Eocene (~ 55 million years ago), the Earth had high levels of atmospheric CO 2 , so studies of the Eocene can provide insights into the likely effects of present-day fossil fuel burning. We ran a low-resolution but very fast climate model with 50 combinations of CO 2 and orbital parameters, and an Eocene layout of the oceans and continents. Climatic effects of CO 2 are dominant but precession and obliquity strongly influence monsoon rainfall and ocean–land temperature contrasts, respectively.

Description: The ENSO teleconnections to the Indian summer monsoon climate through the Last Millennium as simulated by the PMIP3 Charan Teja Tejavath, Karumuri Ashok, Supriyo Chakraborty, and Rengaswamy Ramesh Clim. Past Discuss., https//doi.org/10.5194/cp-2018-7,2018 Manuscript under review for CP (discussion: open, 1 comment) Analysing multiple CMIP5/PMIP3 Last Millennium simulations, we find that the Indian region was warmer and wetter during the medieval warm period, and cooler and drier in the little ice age, as compared to the last millennium mean conditions. This supports findings from the few available proxy findings. The Indian summer monsoon-ENSO association is robust through the last millennium, but varied on centennial time scales.

Description: The Ross Sea Dipole – temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 years Nancy A. N. Bertler, Howard Conway, Dorthe Dahl-Jensen, Daniel B. Emanuelsson, Mai Winstrup, Paul T. Vallelonga, James E. Lee, Ed J. Brook, Jeffrey P. Severinghaus, Taylor J. Fudge, Elizabeth D. Keller, W. Troy Baisden, Richard C. A. Hindmarsh, Peter D. Neff, Thomas Blunier, Ross Edwards, Paul A. Mayewski, Sepp Kipfstuhl, Christo Buizert, Silvia Canessa, Ruzica Dadic, Helle A. Kjær, Andrei Kurbatov, Dongqi Zhang, Edwin D. Waddington, Giovanni Baccolo, Thomas Beers, Hannah J. Brightley, Lionel Carter, David Clemens-Sewall, Viorela G. Ciobanu, Barbara Delmonte, Lukas Eling, Aja Ellis, Shruthi Ganesh, Nicholas R. Golledge, Skylar Haines, Michael Handley, Robert L. Hawley, Chad M. Hogan, Katelyn M. Johnson, Elena Korotkikh, Daniel P. Lowry, Darcy Mandeno, Robert M. McKay, James A. Menking, Timothy R. Naish, Caroline Noerling, Agathe Ollive, Anaïs Orsi, Bernadette C. Proemse, Alexander R. Pyne, Rebecca L. Pyne, James Renwick, Reed P. Scherer, Stefanie Semper, Marius Simonsen, Sharon B. Sneed, Eric J. Steig, Andrea Tuohy, Abhijith Ulayottil Venugopal, Fernando Valero-Delgado, Janani Venkatesh, Feitang Wang, Shimeng Wang, Dominic A. Winski, V. Holly L. Winton, Arran Whiteford, Cunde Xiao, Jiao Yang, and Xin Zhang Clim. Past, 14, 193-214, https://doi.org/10.5194/cp-14-193-2018, 2018 Temperature and snow accumulation records from the annually dated Roosevelt Island Climate Evolution (RICE) ice core show that for the past 2 700 years, the eastern Ross Sea warmed, while the western Ross Sea showed no trend and West Antarctica cooled. From the 17th century onwards, this dipole relationship changed. Now all three regions show concurrent warming, with snow accumulation declining in West Antarctica and the eastern Ross Sea.

Description: 300 years of hydrological records and societal responses to droughts and floods on the Pacific coast of Central America Alvaro Guevara-Murua, Caroline A. Williams, Erica J. Hendy, and Pablo Imbach Clim. Past, 14, 175-191, https://doi.org/10.5194/cp-14-175-2018, 2018 This study reconstructs a new semi-quantitative rainfall index for the Pacific coast of Central America using documentary sources for the period 1640 to 1945. In addition, we explore the various mechanisms and processes that may explain inter-annual and inter-decadal rainfall variability over the Pacific coast of Central America.

Description: Insights into Atlantic multidecadal variability using the Last Millennium Reanalysis framework Hansi K. A. Singh, Gregory J. Hakim, Robert Tardif, Julien Emile-Geay, and David C. Noone Clim. Past, 14, 157-174, https://doi.org/10.5194/cp-14-157-2018, 2018 The Atlantic Multidecadal Oscillation (AMO) is prominent in the climate system. We study the AMO over the last 2000 years using a novel proxy framework, the Last Millennium Reanalysis. We find that the AMO is linked to continental warming, Arctic sea ice retreat, and an Atlantic precipitation shift. Low clouds decrease globally. We find no distinct multidecadal spectral peak in the AMO over the last 2 millennia, suggesting that human activities may have enhanced the AMO in the modern era.

Description: Random and externally controlled occurrence of Dansgaard-Oeschger events Johannes Lohmann and Peter D. Ditlevsen Clim. Past Discuss., https//doi.org/10.5194/cp-2018-3,2018 Manuscript under review for CP (discussion: open, 0 comments) The climate of the last glacial period has been frequently interrupted by rapid warming events, the cause of which is still unknown. One open question is whether the occurrence of events is random or externally controlled. We studied the temporal characteristics of warm and cold phases using statistical null models and find that they are well described as random processes modulated by two different external climate factors. This may help distinguish physical mechanisms for rapid climate change.

Description: Glacial Inception on Baffin Island: The Interaction of Ice Flow and Meteorology Leah Birch, Timothy Cronin, and Eli Tziperman Clim. Past Discuss., https//doi.org/10.5194/cp-2018-5,2018 Manuscript under review for CP (discussion: open, 1 comment) Over the past 0.8 million years, 100 kyr ice ages have dominated Earth's climate with geological evidence suggesting the last glacial inception began in the mountains of Baffin Island. Currently, state-of-the-art global climate models (GCMs) have difficulty simulating glacial inception, possibly due in part to their coarse horizontal resolution and the neglect of ice flow dynamics in some models. We attempt to address the initial inception problem on Baffin Island by asynchronously coupling the Weather Research and Forecast model (WRF), configured as a high resolution inner domain over Baffin and an outer domain incorporating much of North America, to an ice flow model using the shallow ice approximation. The mass balance is calculated from WRF simulations, and used to drive the ice model, which updates the ice extent and elevation, that then serve as inputs to the next WRF run. We drive the regional WRF configuration using atmospheric boundary conditions from 1986 that correspond to a relatively cold summer, and with 115 kya insolation. Initially, ice accumulates on mountain glaciers, driving downslope ice flow which expands the size of the ice caps. However, continued iterations of the atmosphere and ice models reveal a stagnation of the ice sheet on Baffin Island, driven by melting due to warmer temperatures at the margins of the ice caps. This warming is caused by changes in the larger-scale circulation that are forced by elevation changes due to the ice growth. A stabilizing feedback between ice elevation and atmospheric circulation thus prevents full inception from occurring.

Description: Signal detection in global mean temperatures after “Paris”: an uncertainty and sensitivity analysis Hans Visser, Sönke Dangendorf, Detlef P. van Vuuren, Bram Bregman, and Arthur C. Petersen Clim. Past, 14, 139-155, https://doi.org/10.5194/cp-14-139-2018, 2018 In December 2015, 195 countries agreed in Paris to hold the increase in global temperature well below 2.0 °C. However, the Paris Agreement is not conclusive as regards methods to calculate it. To find answers to these questions we performed an uncertainty and sensitivity analysis where datasets, model choices, choices for pre-industrial and warming definitions have been varied. Based on these findings we propose an estimate for signal progression in global temperature since pre-industrial time.

Description: Holocene climate aridification trend and human impact interrupted by millennial- and centennial-scale climate fluctuations from a new sedimentary record from Padul (Sierra Nevada, southern Iberian Peninsula) María J. Ramos-Román, Gonzalo Jiménez-Moreno, Jon Camuera, Antonio García-Alix, R. Scott Anderson, Francisco J. Jiménez-Espejo, and José S. Carrión Clim. Past, 14, 117-137, https://doi.org/10.5194/cp-14-117-2018, 2018 In this study we carried out a multiproxy high-resolution analysis on a sediment record from the Padul Basin in the Sierra Nevada (southern Iberian Peninsula). Padul is a classical and very unique site from the Mediterranean area as it contains a very long and continuous Quaternary sedimentary record. However, the uppermost part of the record was never recovered. In this study we focus on the last 4700 cal yr BP of Holocene climate variability and human activity in the Mediterranean area.

Description: Eolian dust dispersal patterns since the last glacial period in eastern Central Asia: insights from a loess-paleosol sequence in the Ili Basin Yue Li, Yougui Song, Kathryn E. Fitzsimmons, Hong Chang, Rustam Orozbaev, and Xinxin Li Clim. Past, 14, 271-286, https://doi.org/10.5194/cp-14-271-2018, 2018 This paper finds a close tie between loess magnetic susceptibility and wind strength in the Ili Basin, eastern Central Asia, and identifies three distinct aerodynamic environments with end-member modeling analysis of grain size. The Siberian High is the dominant influence on wind dynamics, resulting in loess deposition, and acts as a teleconnection between the climatic systems of the North Atlantic and East Asia in the high northern latitudes, but not for the mid-latitude westerlies.

Description: Climate impact on the development of Pre-Classic Maya civilization Kees Nooren, Wim Z. Hoek, Brian J. Dermody, Didier Galop, Sarah Metcalfe, Gerald Islebe, and Hans Middelkoop Clim. Past Discuss., https//doi.org/10.5194/cp-2018-15,2018 Manuscript under review for CP (discussion: open, 0 comments) We present two new palaeoclimatic records for the Central Maya Lowlands, adding valuable new insights into the impact of climate change on the development of Maya civilization. Lake Tuspan's diatom record is indicative of precipitation changes at a local scale, while a beach ridge elevation record from world’s largest late Holocene beach ridge plain provides a regional picture.

Description: Climate information preserved in seasonal water isotope at NEEM: relationships with temperature, circulation and sea ice Minjie Zheng, Jesper Sjolte, Florian Adolphi, Bo Møllesøe Vinther, Hans Christian Steen-Larsen, Trevor James Popp, and Raimund Muscheler Clim. Past Discuss., https//doi.org/10.5194/cp-2018-8,2018 Manuscript under review for CP (discussion: open, 0 comments) Analyzing seasonally resolved δ 18 O ice core data can aid the interpretation of the climate information in ice cores, providing also insights into factors governing the δ 18 O signal that cannot be deciphered by investigating the annual δ 18 O data only. However, the seasonal isotope signal has not yet to be investigated in northern Greenland, e.g. at the NEEM (North Greenland Eemian Ice Drilling) ice core drill site. Here we analyze seasonally resolved δ 18 O data from four shallow NEEM ice cores covering the last 150 years. Based on correlation analysis with observed temperature, we attribute about 70 % and 30 % of annual accumulation to summer and winter respectively. The NEEM summer δ 18 O signal correlates strongly with summer western Greenland coastal temperature and with the first principal component (PC1) of summer δ 18 O from multiple seasonally resolved ice cores from central/southern Greenland. However, there are no significant correlations between NEEM winter δ 18 O data and western Greenland coastal winter temperature, or southern/central Greenland winter δ 18 O PC1. The stronger correlation with temperature during summer and the dominance of summer precipitation skew the annual δ 18 O signal in NEEM. The strong footprint of temperature in NEEM summer δ 18 O record also suggests that the summer δ 18 O record, rather than the winter δ 18 O record, is a better temperature proxy at the NEEM site. Despite dominant signal of North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) in the central-southern ice cores data, both NAO and AMO exert weak influences on NEEM seasonal δ 18 O variations. The NEEM seasonal δ 18 O is found to be highly correlated with Baffin Bay sea ice concentration (SIC) in satellite observation period (1979–2004), suggesting a connection of the sea ice extent with δ 18 O at NEEM. NEEM winter δ 18 O significantly correlates with SIC even for the period prior to satellite observation (1901–1978). The NEEM winter δ 18 O may reflect sea ice variations of Baffin Bay rather than temperature itself. This study shows that seasonally resolved δ 18 O records, especially for sites with seasonal precipitation bias such as NEEM, provide a better understanding of how changing air temperature and circulation patterns are associated with the variability of the δ 18 O records.

Description: The effect of high dust amount on the surface temperature during the Last Glacial Maximum: A modelling study using MIROC-ESM Rumi Ohgaito, Ayako Abe-Ouchi, Ryouta O'ishi, Toshihiko Takemura, Akinori Ito, Tomohiro Hajima, Shingo Watanabe, and Michio Kawamiya Clim. Past Discuss., https//doi.org/10.5194/cp-2018-2,2018 Manuscript under review for CP (discussion: open, 1 comment) The behaviour of dust on climate can be investigated using past climate. The Last Glacial Maximum (LGM, 21 000 years before present) is known to be dustier. We investigated the impact of plausible dust distribution on the climate of the LGM using an Earth System Model and found that the effect of the LGM dust results in less cooling over the polar regions. Main finding is that the radiative perturbation by the high dust loading in the troposphere acts to warm the surface surrounding Antarctica.

Description: Climate impact on the development of Pre-Classic Maya civilization Kees Nooren, Wim Z. Hoek, Brian J. Dermody, Didier Galop, Sarah Metcalfe, Gerald Islebe, and Hans Middelkoop Clim. Past Discuss., https//doi.org/10.5194/cp-2018-15,2018 Manuscript under review for CP (discussion: open, 0 comments) We present two new palaeoclimatic records for the Central Maya Lowlands, adding valuable new insights into the impact of climate change on the development of Maya civilization. Lake Tuspan's diatom record is indicative of precipitation changes at a local scale, while a beach ridge elevation record from world’s largest late Holocene beach ridge plain provides a regional picture.

Description: Astronomical tunings of the Oligocene–Miocene transition from Pacific Ocean Site U1334 and implications for the carbon cycle Helen M. Beddow, Diederik Liebrand, Douglas S. Wilson, Frits J. Hilgen, Appy Sluijs, Bridget S. Wade, and Lucas J. Lourens Clim. Past, 14, 255-270, https://doi.org/10.5194/cp-14-255-2018, 2018 We present two astronomy-based timescales for climate records from the Pacific Ocean. These records range from 24 to 22 million years ago, a time period when Earth was warmer than today and the only land ice was located on Antarctica. We use tectonic plate-pair spreading rates to test the two timescales, which shows that the carbonate record yields the best timescale. In turn, this implies that Earth’s climate system and carbon cycle responded slowly to changes in incoming solar radiation.

Description: Response of the carbon cycle in an intermediate complexity model to the different climate configurations of the last nine interglacials Nathaelle Bouttes, Didier Swingedouw, Didier M. Roche, Maria F. Sanchez-Goni, and Xavier Crosta Clim. Past, 14, 239-253, https://doi.org/10.5194/cp-14-239-2018, 2018 Atmospheric CO 2 is key for climate change. CO 2 is lower during the oldest warm period of the last million years, the interglacials, than during the most recent ones (since 430 000 years ago). This difference has not been explained yet, but could be due to changes of ocean circulation. We test this hypothesis and the role of vegetation and ice sheets using an intermediate complexity model. We show that only small changes of CO 2 can be obtained, underlying missing feedbacks or mechanisms.

Description: On the mechanisms of warming the mid-Pliocene and the inference of a hierarchy of climate sensitivities with relevance to the understanding of climate futures Deepak Chandan and W. Richard Peltier Clim. Past Discuss., https//doi.org/10.5194/cp-2018-18,2018 Manuscript under review for CP (discussion: open, 0 comments) We infer the physical mechanisms by which the mid-Pliocene could have sustained a warm climate. We also provide a mid-Pliocene perspective on a range of climate sensitivities applicable on several timescales. Warming inferred on the basis of these sensitivity parameters is compared to forecasted levels of warming. This leads us to conclude that projections for 300–500 years into the future underestimate the potential for warming because they do not account for long timescale feedback processes.

Description: Sedproxy: a forward model for sediment archived climate proxies Andrew M. Dolman and Thomas Laepple Clim. Past Discuss., https//doi.org/10.5194/cp-2018-13,2018 Manuscript under review for CP (discussion: open, 0 comments) Climate proxies from marine sediments provide an important record of past temperatures, but contain noise from many sources. These include mixing by burrowing organisms, seasonal and habitat biases, measurement error and small sample size effects. We have created a forward model that simulates the creation of proxy records and provide it as a user-friendly R package. It allows multiple sources of uncertainty to be considered together when interpreting proxy climate records.

Description: Evidence for increased expression of the Amundsen Sea Low over the South Atlantic during the late Holocene Zoë Thomas, Richard T. Jones, Chris Fogwill, Jackie Hatton, Alan Williams, Alan Hogg, Scott Mooney, Philip Jones, David Lister, Paul Mayewski, and Chris Turney Clim. Past Discuss., https//doi.org/10.5194/cp-2018-11,2018 Manuscript under review for CP (discussion: open, 0 comments) We report a high-resolution study of a 5000 year-long peat record from the Falkland Islands, an area sensitive to the dynamics of the Amundsen Sea Low, which plays a major role in modulating the Southern Ocean climate. We find wetter, colder conditions between 5000 and 2500 years ago due to enhanced southerly airflow, with the establishment of drier and warmer conditions from 2500 years to present, implying more westerly airflow and increased projection of the ASL onto the South Atlantic.

Description: The ENSO teleconnections to the Indian summer monsoon climate through the Last Millennium as simulated by the PMIP3 Charan Teja Tejavath, Karumuri Ashok, Supriyo Chakraborty, and Rengaswamy Ramesh Clim. Past Discuss., https//doi.org/10.5194/cp-2018-7,2018 Manuscript under review for CP (discussion: open, 1 comment) Analysing multiple CMIP5/PMIP3 Last Millennium simulations, we find that the Indian region was warmer and wetter during the medieval warm period, and cooler and drier in the little ice age, as compared to the last millennium mean conditions. This supports findings from the few available proxy findings. The Indian summer monsoon-ENSO association is robust through the last millennium, but varied on centennial time scales.

Description: Sensitivity of the Eocene climate to CO 2 and orbital variability John S. Keery, Philip B. Holden, and Neil R. Edwards Clim. Past, 14, 215-238, https://doi.org/10.5194/cp-14-215-2018, 2018 In the Eocene (~ 55 million years ago), the Earth had high levels of atmospheric CO 2 , so studies of the Eocene can provide insights into the likely effects of present-day fossil fuel burning. We ran a low-resolution but very fast climate model with 50 combinations of CO 2 and orbital parameters, and an Eocene layout of the oceans and continents. Climatic effects of CO 2 are dominant but precession and obliquity strongly influence monsoon rainfall and ocean–land temperature contrasts, respectively.

Description: The effect of high dust amount on the surface temperature during the Last Glacial Maximum: A modelling study using MIROC-ESM Rumi Ohgaito, Ayako Abe-Ouchi, Ryouta O'ishi, Toshihiko Takemura, Akinori Ito, Tomohiro Hajima, Shingo Watanabe, and Michio Kawamiya Clim. Past Discuss., https//doi.org/10.5194/cp-2018-2,2018 Manuscript under review for CP (discussion: open, 1 comment) The behaviour of dust on climate can be investigated using past climate. The Last Glacial Maximum (LGM, 21 000 years before present) is known to be dustier. We investigated the impact of plausible dust distribution on the climate of the LGM using an Earth System Model and found that the effect of the LGM dust results in less cooling over the polar regions. Main finding is that the radiative perturbation by the high dust loading in the troposphere acts to warm the surface surrounding Antarctica.

Description: 300 years of hydrological records and societal responses to droughts and floods on the Pacific coast of Central America Alvaro Guevara-Murua, Caroline A. Williams, Erica J. Hendy, and Pablo Imbach Clim. Past, 14, 175-191, https://doi.org/10.5194/cp-14-175-2018, 2018 This study reconstructs a new semi-quantitative rainfall index for the Pacific coast of Central America using documentary sources for the period 1640 to 1945. In addition, we explore the various mechanisms and processes that may explain inter-annual and inter-decadal rainfall variability over the Pacific coast of Central America.

Description: The Ross Sea Dipole – temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 years Nancy A. N. Bertler, Howard Conway, Dorthe Dahl-Jensen, Daniel B. Emanuelsson, Mai Winstrup, Paul T. Vallelonga, James E. Lee, Ed J. Brook, Jeffrey P. Severinghaus, Taylor J. Fudge, Elizabeth D. Keller, W. Troy Baisden, Richard C. A. Hindmarsh, Peter D. Neff, Thomas Blunier, Ross Edwards, Paul A. Mayewski, Sepp Kipfstuhl, Christo Buizert, Silvia Canessa, Ruzica Dadic, Helle A. Kjær, Andrei Kurbatov, Dongqi Zhang, Edwin D. Waddington, Giovanni Baccolo, Thomas Beers, Hannah J. Brightley, Lionel Carter, David Clemens-Sewall, Viorela G. Ciobanu, Barbara Delmonte, Lukas Eling, Aja Ellis, Shruthi Ganesh, Nicholas R. Golledge, Skylar Haines, Michael Handley, Robert L. Hawley, Chad M. Hogan, Katelyn M. Johnson, Elena Korotkikh, Daniel P. Lowry, Darcy Mandeno, Robert M. McKay, James A. Menking, Timothy R. Naish, Caroline Noerling, Agathe Ollive, Anaïs Orsi, Bernadette C. Proemse, Alexander R. Pyne, Rebecca L. Pyne, James Renwick, Reed P. Scherer, Stefanie Semper, Marius Simonsen, Sharon B. Sneed, Eric J. Steig, Andrea Tuohy, Abhijith Ulayottil Venugopal, Fernando Valero-Delgado, Janani Venkatesh, Feitang Wang, Shimeng Wang, Dominic A. Winski, V. Holly L. Winton, Arran Whiteford, Cunde Xiao, Jiao Yang, and Xin Zhang Clim. Past, 14, 193-214, https://doi.org/10.5194/cp-14-193-2018, 2018 Temperature and snow accumulation records from the annually dated Roosevelt Island Climate Evolution (RICE) ice core show that for the past 2 700 years, the eastern Ross Sea warmed, while the western Ross Sea showed no trend and West Antarctica cooled. From the 17th century onwards, this dipole relationship changed. Now all three regions show concurrent warming, with snow accumulation declining in West Antarctica and the eastern Ross Sea.

Description: Holocene climate aridification trend and human impact interrupted by millennial- and centennial-scale climate fluctuations from a new sedimentary record from Padul (Sierra Nevada, southern Iberian Peninsula) María J. Ramos-Román, Gonzalo Jiménez-Moreno, Jon Camuera, Antonio García-Alix, R. Scott Anderson, Francisco J. Jiménez-Espejo, and José S. Carrión Clim. Past, 14, 117-137, https://doi.org/10.5194/cp-14-117-2018, 2018 In this study we carried out a multiproxy high-resolution analysis on a sediment record from the Padul Basin in the Sierra Nevada (southern Iberian Peninsula). Padul is a classical and very unique site from the Mediterranean area as it contains a very long and continuous Quaternary sedimentary record. However, the uppermost part of the record was never recovered. In this study we focus on the last 4700 cal yr BP of Holocene climate variability and human activity in the Mediterranean area.

Description: Technical note: Optimizing the utility of combined GPR, OSL, and LiDAR (GOaL) to extract paleoenvironmental records and decipher shoreline evolution Amy J. Dougherty, Jeong-Heon Choi, Chris S. M. Turney, and Anthony Dosseto Clim. Past Discuss., https//doi.org/10.5194/cp-2018-4,2018 Manuscript under review for CP (discussion: open, 2 comments) Records of past sea levels, storms, and their impacts on coastline are crucial in forecasting future changes resulting from anthropogenic global warming. Coastal barriers that have prograded over the Holocene preserve within their accreting sands history of storm erosion and changes in sea level. High-resolution geophysics, geochronology, and remote sensing techniques offer an optimal way to extract these records and decipher shoreline evolution: Light Detection and Ranging (LiDAR) images the lateral extent of relict shoreline dune morphology; Ground Penetrating Radar (GPR) data records paleo-dune, beach and nearshore stratigraphy; Optically Stimulated Luminescence (OSL) dates when sand grains were deposited that form these shorelines. Utilization of these technological advances has recently become more prevalent in coastal research. The resolution and sensitivity of these methods offer unique insights on coastal environments and their relationship to past climate change. However, discrepancies in analysis and presentation of the data can result in erroneous interpretations. When utilized correctly on prograded barriers these methods (independently or in various combinations) have produced storm records, constructed sea-level curves, quantified sediment budgets, and deciphered coastal evolution. Therefore, combining the application of GPR, OSL, and LiDAR (GOaL) on one prograded barrier has the potential to generate detailed records of storms, sea level, and sediment supply for that coastline. Obtaining this GOaL hat-trick can provide valuable insights into how these three factors influenced past and future barrier evolution. Here we argue that systematically achieving GOaL hat-tricks on some of the 300+ prograded barriers worldwide would allow us to disentangle local patterns of sediment supply from regional effects of storms or global changes in sea level, allowing direct comparison to climate proxy records. To fully realize this aim requires standardization of methods to optimize results. The impetus for this initiative is to establish a framework for consistent data analysis that maximizes the potential of GOaL to contribute to climate change research and assist coastal communities in mitigating future impacts of global warming.

Description: Technical note: Optimizing the utility of combined GPR, OSL, and LiDAR (GOaL) to extract paleoenvironmental records and decipher shoreline evolution Amy J. Dougherty, Jeong-Heon Choi, Chris S. M. Turney, and Anthony Dosseto Clim. Past Discuss., https//doi.org/10.5194/cp-2018-4,2018 Manuscript under review for CP (discussion: open, 2 comments) Records of past sea levels, storms, and their impacts on coastline are crucial in forecasting future changes resulting from anthropogenic global warming. Coastal barriers that have prograded over the Holocene preserve within their accreting sands history of storm erosion and changes in sea level. High-resolution geophysics, geochronology, and remote sensing techniques offer an optimal way to extract these records and decipher shoreline evolution: Light Detection and Ranging (LiDAR) images the lateral extent of relict shoreline dune morphology; Ground Penetrating Radar (GPR) data records paleo-dune, beach and nearshore stratigraphy; Optically Stimulated Luminescence (OSL) dates when sand grains were deposited that form these shorelines. Utilization of these technological advances has recently become more prevalent in coastal research. The resolution and sensitivity of these methods offer unique insights on coastal environments and their relationship to past climate change. However, discrepancies in analysis and presentation of the data can result in erroneous interpretations. When utilized correctly on prograded barriers these methods (independently or in various combinations) have produced storm records, constructed sea-level curves, quantified sediment budgets, and deciphered coastal evolution. Therefore, combining the application of GPR, OSL, and LiDAR (GOaL) on one prograded barrier has the potential to generate detailed records of storms, sea level, and sediment supply for that coastline. Obtaining this GOaL hat-trick can provide valuable insights into how these three factors influenced past and future barrier evolution. Here we argue that systematically achieving GOaL hat-tricks on some of the 300+ prograded barriers worldwide would allow us to disentangle local patterns of sediment supply from regional effects of storms or global changes in sea level, allowing direct comparison to climate proxy records. To fully realize this aim requires standardization of methods to optimize results. The impetus for this initiative is to establish a framework for consistent data analysis that maximizes the potential of GOaL to contribute to climate change research and assist coastal communities in mitigating future impacts of global warming.

Description: Towards a cyber-physical era: soft computing framework based multi-sensor array for water quality monitoring Jyotirmoy Bhardwaj, Karunesh K. Gupta, and Rajiv Gupta Drink. Water Eng. Sci., 11, 9-17, https://doi.org/10.5194/dwes-11-9-2018, 2018 Reliable and effective continuous water quality monitoring has always been challenging. To detect water quality, deployment of multiple sensor nodes in a water distribution network generates complex and convoluted data sets. This paper demonstrates the implementation of a cyber-physical system along with soft-computing approaches (Python and fuzzy). The designed system monitors water quality in real time, simplifies the complexity of sensor data and assists water engineers in decision making.

Description: The effect of a loss of model structural detail due to network skeletonization on contamination warning system design: case studies Michael J. Davis and Robert Janke Drink. Water Eng. Sci. Discuss., https//doi.org/10.5194/dwes-2017-39,2018 Manuscript under review for DWES (discussion: final response, 3 comments) Public drinking water distribution systems can be contaminated. Sensors designed to detect contaminants can provide warning through the use of a contamination warning system (CWS). A properly designed CWS may help reduce the consequences associated with contamination events. Various factors can affect the performance of a CWS design, our paper focuses on the accuracy with which the network model of a distribution system represents the actual structural details of the water distribution network.

Description: Use of an external organic carbon source in the removal of nitrates in bio-sand filters (BSFs) Crispen Mutsvangwa and Evans Matope Drink. Water Eng. Sci., 10, 119-127, https://doi.org/10.5194/dwes-10-119-2017, 2017 Low-income countries lack the capacity to remove chemical contaminants like nitrates. Hence, an economical water filtration technology was explored, which is bio-sand filtration. In order to enhance the removal of nitrates through denitrification, a modified bio-sand filter with ethanol as an external carbon source at C / N ratios of 1.1 and 1.8 was investigated. The results of the research showed a removal rate of 53 % at a C / N ratio of 1.8.

Description: Application of advanced composite modified perlite for degradation of particle size and turbidity in treatment of sewage water Ali Reza Taheri Fard Drink. Water Eng. Sci. Discuss., https//doi.org/10.5194/dwes-2017-40,2018 Manuscript under review for DWES (discussion: final response, 4 comments) Water treatment efficiency of several filter media such as perlite, modified (silicated) perlite, zeolite, and sand were studied on sewage water. It was shown that modified perlite removed more than 90 % of turbidity and it functioned more efficient than other materials in case of high turbidity (more than 100 NTU). Filtration through modified perlite significantly decreased the concentration of total nitrogen (from 4 to 1 mg/L), chemical oxygen demand (from 274 to 0.42 MgO/L), concentration and size of particles (from 3870 nm to 56 nm). Filtering device was created with 2 steps syphon, due to having sedimentation part in the bottom part of next part and having two times upward direction in filtration undoubtedly operates better than monolayer filter with mere perlite. The total cost of filtration unit containing whole part of filtration device and advanced composite modified perlite materials as well as evaluates reducing the cost up 12 % compared to ceramic filter.

Description: Alluvial cover controlling the width, slope and sinuosity of bedrock channels Jens Martin Turowski Earth Surf. Dynam., 6, 29-48, https://doi.org/10.5194/esurf-6-29-2018, 2018 Bedrock channels are a key component of mountainous landscapes. Here, a new model of the steady-state morphology, including channel width, slope and sinuosity, is derived from process physics considerations. The model compares favourably to observed scaling relations.

Description: A lattice grain model of hillslope evolution Gregory E. Tucker, Scott W. McCoy, and Daniel E. J. Hobley Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-4,2018 Manuscript under review for ESurf (discussion: open, 0 comments) This article presents a new technique for computer simulation of slope forms. The method provides a way to study how events that disturb soil or turn rock into soil add up over time to produce landforms. The model represents a cross section of a hypothetical landform is represented as a lattice of cells, each of which may represent air, soil, or rock. Despite its simplicity, the model does a good job of simulating a range of common of natural slope forms.

Description: Glacial Isostatic Adjustment modelling: historical perspectives, recent advances, and future directions Pippa L. Whitehouse Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-6,2018 Manuscript under review for ESurf (discussion: open, 2 comments) This article is a contribution to a special issue on “Two centuries of modelling across scales”. It describes the historical observations, evolving hypotheses, and early calculations that led to the development of the field known as Glacial Isostatic Adjustment (GIA) modelling, which seeks to understand feedbacks between ice-sheet change, sea-level change, and solid Earth deformation. Recent advances are discussed. Future research in the field is likely to involve an interdisciplinary approach.

Description: Tracking the 26 Al/ 10 Be source-area signal in sediment-routing systems of arid central Australia Martin Struck, John D. Jansen, Toshiyuki Fujioka, Alexandru T. Codilean, David Fink, Réka-Hajnalka Fülöp, Klaus M. Wilcken, David M. Price, Steven Kotevski, L. Keith Fifield, and John Chappell Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2017-76,2018 Manuscript under review for ESurf (discussion: final response, 3 comments) Measurements of cosmogenic nuclides 10 Be and 26 Al in sediment along central Australian streams show that lithologically-controlled magnitudes of source-area erosion rates (0.2–11 m/m.y.) are preserved downstream despite sediment mixing. Conversely, downstream-increasing sediment burial signals (〉 400 k.y.) indicate sediment incorporation from adjacent, long-exposed storages, which, combined with low sediment supply and discontinuous flux, likely favours source-area 10 Be- 26 Al signal masking.

Description: Topographical change caused by moderate and small floods in a gravel bed ephemeral river – a depth-averaged morphodynamic simulation approach Eliisa S. Lotsari, Mikel Calle, Gerardo Benito, Antero Kukko, Harri Kaartinen, Juha Hyyppä, Hannu Hyyppä, and Petteri Alho Earth Surf. Dynam., 6, 163-185, https://doi.org/10.5194/esurf-6-163-2018, 2018 This paper analyses the timing of topographical changes of a gravel bed ephemeral river channel during consecutive and moderate- and low-magnitude floods by applying a morphodynamic model calibrated with pre- and post-event surveys using RTK-GPS and mobile laser scanning. The channel acted as a braided river during lower flows but as a meandering river during higher flows. The channel changes can be greater during the long-lasting receding phase than during the rising phase of the floods.

Description: Temporal variability in detrital 10 Be concentrations in large Himalayan catchments Elizabeth H. Dingle, Hugh D. Sinclair, Mikael Attal, Ángel Rodés, and Vimal Singh Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2017-73,2018 Manuscript under review for ESurf (discussion: open, 3 comments) Accurately quantifying sediment fluxes in large rivers draining tectonically active landscapes is complicated by the stochastic nature of sediment inputs. Cosmogenic 10 Be concentrations measured in modern river sands have been used to estimate 10 2 –10 4 year sediment fluxes in these types of catchments, where upstream drainage areas are often in excess of 10,000 km 2 . It is commonly assumed that within large catchments, the effects of stochastic sediment inputs are buffered such that 10 Be concentrations at the catchment outlet are relatively stable in time. We present eighteen new 10 Be concentrations of modern river and dated Holocene terrace and floodplain deposits from the Ganga River near to the Himalayan mountain front. We demonstrate that 10 Be concentrations measured in modern Ganga River sediments display a notable degree of variability, with concentrations ranging between ~ 9,000–19,000 atoms g −1 . We propose that this observed variability is driven by two factors. Firstly, by the nature of stochastic inputs of sediment (e.g. the dominant erosional process, surface production rates, depth of landsliding, degree of mixing) and, secondly, by the evacuation timescale of individual sediment deposits which buffer their impact on catchment-averaged concentrations. Despite intensification of the Indian Summer Monsoon and subsequent doubling of sediment delivery to the Bay of Bengal at ~ 11–7 ka, we also find that Holocene sediment 10 Be concentrations documented at the Ganga outlet have remained within the error of modern river concentrations. We demonstrate that in these systems, sediment flux cannot be simply approximated by converting detrital concentration into mean erosion rates and multiplying by catchment area as it is possible to generate considerably larger volumetric sediment fluxes whilst maintaining comparable average 10 Be concentrations.

Description: Optimising 4-D surface change detection: an approach for capturing rockfall magnitude–frequency Jack G. Williams, Nick J. Rosser, Richard J. Hardy, Matthew J. Brain, and Ashraf A. Afana Earth Surf. Dynam., 6, 101-119, https://doi.org/10.5194/esurf-6-101-2018, 2018 We present a method to analyse surface change using 3-D data collected at hourly intervals. This is applied to 9000 surveys of a failing rock slope, acquired over 10 months. A higher proportion and frequency of small rockfall is observed than in less-frequent (e.g. monthly) monitoring. However, quantifying longer-term erosion rates may be more suited to less-frequent data collection, which contains lower accumulative errors due to the number of surveys and the lower proportion of small events.

Description: Effect of changing vegetation on denudation (part 2): Landscape response to transient climate and vegetation cover Manuel Schmid, Todd A. Ehlers, Christian Werner, Thomas Hickler, and Juan-Pablo Fuentes-Espoz Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-13,2018 Manuscript under review for ESurf (discussion: open, 1 comment) We present a numerial modelling investigation into the interactions between transient climate and vegetation cover with hillslope and fluvial processes. We use a state-of-art landscape evolution model library (Landlab) and designed model experiments to investigate the effect of climate change and associated changes in surface vegetation cover on main basin metrics. This paper is a companion paper to Part 1 (this journal) which investigates the effect of climate change to surface vegetation cover.

Description: Numerical modelling of landscape and sediment flux response to precipitation rate change John J. Armitage, Alexander C. Whittaker, Mustapha Zakari, and Benjamin Campforts Earth Surf. Dynam., 6, 77-99, https://doi.org/10.5194/esurf-6-77-2018, 2018 We explore how two landscape evolution models respond to a change in climate. The two models are developed from a divergent assumption on the efficiency of sediment transport. Despite the different resulting mathematics, both numerical models display a similar functional response to a change in precipitation. However, if we model sediment transport rather than assume it is instantaneously removed, the model responds more rapidly, with a response time similar to that observed in nature.

Description: A hydroclimatological approach to predicting regional landslide probability using Landlab Ronda Strauch, Erkan Istanbulluoglu, Sai Siddhartha Nudurupati, Christina Bandaragoda, Nicole M. Gasparini, and Gregory E. Tucker Earth Surf. Dynam., 6, 49-75, https://doi.org/10.5194/esurf-6-49-2018, 2018 We develop a model of annual probability of shallow landslide initiation triggered by soil water from a hydrologic model. Our physically based model accommodates data uncertainty using a Monte Carlo approach. We found elevation-dependent patterns in probability related to the stabilizing effect of forests and soil and slope limitation at high elevations. We demonstrate our model in Washington, USA, but it is designed to run elsewhere with available data for risk planning using the Landlab.

Description: A lattice grain model of hillslope evolution Gregory E. Tucker, Scott W. McCoy, and Daniel E. J. Hobley Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-4,2018 Manuscript under review for ESurf (discussion: open, 0 comments) This article presents a new technique for computer simulation of slope forms. The method provides a way to study how events that disturb soil or turn rock into soil add up over time to produce landforms. The model represents a cross section of a hypothetical landform is represented as a lattice of cells, each of which may represent air, soil, or rock. Despite its simplicity, the model does a good job of simulating a range of common of natural slope forms.