WILBERT

Description: Aerosol indirect effects on summer precipitation in a regional climate model for the Euro-Mediterranean region Nicolas Da Silva, Sylvain Mailler, and Philippe Drobinski Ann. Geophys., 36, 321-335, https://doi.org/10.5194/angeo-36-321-2018, 2018 Aerosols affect atmospheric dynamics because they absorb radiations (direct effects) and because they act as cloud condensation nuclei (indirect effects). The present study shows that aerosol indirect effects reduce summer precipitation in the Euro-Mediterranean region through reduction of the radiative heating of the surface and corresponding reductions of surface temperature, resulting in increased atmospheric stability in the presence of high aerosol loads.

Description: Differentiating Diffuse Aurora Based on Phenomenology Eric Grono and Eric Donovan Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-21,2018 Manuscript under review for ANGEO (discussion: open, 0 comments) The solar wind reshapes Earth's magnetic field to create our magnetosphere and powers many dynamic processes in our plasma-filled environment, some of which produce the aurora. Networks of ground-based all-sky cameras are valuable tools that offer a large field-of-view with which to study the aurora. Using sequences of auroral images, this study defines criteria for differentiating an important type of aurora whose subcategories are often conflated.

Description: Mesopause region temperature variability and its trend in southern Brazil Mateus S. Venturini, José V. Bageston, Nattan R. Caetano, Lucas V. Peres, Hassan Bencherif, and Nelson J. Schuch Ann. Geophys., 36, 301-310, https://doi.org/10.5194/angeo-36-301-2018, 2018 In the past years, the study of the temperature trend and its variability in the upper atmosphere has increased. However, most works were conducted in regions of medium and high latitude. Therefore, we aim to analyze a low-latitude region, the south of Brazil and surrounding areas. Using data from the TIMED/SABER instrument and applying the Trend-Run model for temperature trend analyses, no substantial temperature trend was found in the MLT region (80–100 km) from the years 2003 to 2014.

Description: Case study of mesospheric front dissipation observed over the northeast of Brazil Amauri Fragoso Medeiros, Igo Paulino, Cristiano Max Wrasse, Joaquim Fechine, Hisao Takahashi, José Valentin Bageston, Ana Roberta Paulino, and Ricardo Arlen Buriti Ann. Geophys., 36, 311-319, https://doi.org/10.5194/angeo-36-311-2018, 2018 On 3 October 2005, a mesospheric front was observed over São João do Cariri (7.4° S, 36.5° W) propagating to the northeast in the OH airglow images. One and a half hours later, it disappeared completely and ripples were observed in the eastern part of the images. After studying the background atmosphere, the main conclusion of this work was that the instability in the airglow layer did not allow the propagation of the front to the other side of the local zenith.

Description: Latitudinal variation rate of geomagnetic cutoff rigidity in the active Chilean convergent margin Enrique G. Cordaro, Patricio Venegas, and David Laroze Ann. Geophys., 36, 275-285, https://doi.org/10.5194/angeo-36-275-2018, 2018 The interaction between the magnetic field and the particles coming from outer space, which apparently have a relationship with tectonic plates, is studied. The major earthquakes of Maule (2010, 8.8  M w ), Sumatra (2004, 9.2  M w ) and Tohoku (2011, 9.0  M w ) were studied, similar frequencies being found in the vertical component of the magnetic field (microhertz range). The temporal evolution of the magnetic oscillations showed the possible link with the seismic movement of Maule in 2010.

Description: An initial ULF wave index derived from 2 years of Swarm observations Constantinos Papadimitriou, Georgios Balasis, Ioannis A. Daglis, and Omiros Giannakis Ann. Geophys., 36, 287-299, https://doi.org/10.5194/angeo-36-287-2018, 2018 Swarm is the fourth Earth Explorer mission of the European Space Agency (ESA), launched on 23 November 2013. The mission provides an opportunity for better knowledge of the near-Earth electromagnetic environment. This study presents an initial attempt to derive an ultra low-frequency (ULF) wave index from low-Earth orbit satellite data. The technique can be potentially used to define a new product from the mission, the Swarm ULF wave index, which would be suitable for space weather applications.

Description: Intrinsic parameters of periodic waves observed in the OI6300 airglow layer over the Brazilian equatorial region Igo Paulino, Joyrles F. Moraes, Gleuson L. Maranhão, Cristiano M. Wrasse, Ricardo Arlen Buriti, Amauri F. Medeiros, Ana Roberta Paulino, Hisao Takahashi, Jonathan J. Makela, John W. Meriwether, and José André V. Campos Ann. Geophys., 36, 265-273, https://doi.org/10.5194/angeo-36-265-2018, 2018 This article presents characteristics of periodic waves observed in the thermosphere from airglow images collected in the Northeast of Brazil. Using simultaneous measurements of the background wind in the airglow emission altitudes, it was possible to estimate the intrinsic parameters and the role of the wind in the propagation of the waves into the thermosphere. An anisotropy in the propagation direction of the waves was observed and it could be explained by the wind filtering process.

Description: Unknown high-frequency (7–12 kHz) quasi-periodic VLF emissions observed on the ground at L ~ 5.5 Jyrki Manninen, Natalia Kleimenova, Tauno Turunen, and Liudmila Gromova Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2018-18,2018 Manuscript under review for ANGEO (discussion: open, 0 comments) We reveal previously unknown quasi-periodic (QP) VLF emissions at the unusual high-frequency band of ~ 7–11 kHz by applying the digital filtering of strong sferics to the ground-based VLF data recorded at Kannuslehto station (KAN). In one event, the spectral-temporal forms of the emissions looked like a series of giant bullets with the very abrupt cessation. In the second event, the modulation period was about 3 min under the absence of the simultaneous geomagnetic pulsations.

Description: Cross-correlation and cross-wavelet analyses of the solar wind IMF B z and auroral electrojet index AE coupling during HILDCAAs Adriane Marques de Souza, Ezequiel Echer, Mauricio José Alves Bolzan, and Rajkumar Hajra Ann. Geophys., 36, 205-211, https://doi.org/10.5194/angeo-36-205-2018, 2018 Cross-wavelet and classical cross-correlation analyses were used in order to study solar-wind–magnetosphere coupling during HILDCAAs. Cross-correlation analyses results show that the coupling between the solar wind and the magnetosphere during HILDCAAs occurs mainly in the period ≤ 8 h. Classical correlation analysis indicates that the correlation between IMF B z and AE may be classified as moderate (0.4–0.7) and that more than 80 % of the HILDCAAs exhibit a lag of 20–30 min.

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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: Unraveling hydrometeor mixtures in polarimetric radar measurements Nikola Besic, Josué Gehring, Christophe Praz, Jordi Figueras i Ventura, Jacopo Grazioli, Marco Gabella, Urs Germann, and Alexis Berne Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-58,2018 Manuscript under review for AMT (discussion: open, 0 comments) In this paper we propose an innovative approach for hydrometeor de-mixing, i.e. to identify and quantify the presence of mixtures of different hydrometeor types in a radar sampling volume. It is a bin-based approach, inspired by conventional decomposition methods, and evaluated using C and X band radar measurements compared with synchronous ground observations. The paper also investigates the potential influence of incoherency in the backscattering from hydrometeor mixtures in a radar volume.

Description: Field calibration of electrochemical NO 2 sensors in a citizen science context Bas Mijling, Qijun Jiang, Dave de Jonge, and Stefano Bocconi Atmos. Meas. Tech., 11, 1297-1312, https://doi.org/10.5194/amt-11-1297-2018, 2018 Although in many cities the population is exposed to air pollution, real-time air quality is usually only measured at a few locations. New low-cost sensor technology has the potential to extend the monitoring network significantly. We show that citizen science campaigns using the current generations of electrochemical NO 2 sensors may provide useful complementary data on local air quality in an urban setting, provided that experiments are properly set up and the data are carefully analysed.

Description: The SPARC water vapour assessment II: Comparison of stratospheric and lower mesospheric water vapour time series observed from satellites Farahnaz Khosrawi, Stefan Lossow, Gabriele P. Stiller, Karen H. Rosenlof, Joachim Urban, John P. Burrows, Robert P. Damadeo, Patrick Eriksson, Maya García-Comas, John C. Gille, Yasuko Kasai, Michael Kiefer, Gerald E. Nedoluha, Stefan Noël, Piera Raspollini, William G. Read, Alexei Rozanov, Christopher E. Sioris, Kaley A. Walker, and Katja Weigel Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-33,2018 Manuscript under review for AMT (discussion: open, 0 comments) Time series of stratospheric and lower mesospheric water vapour using 33 data sets were compared in the framework of the second SPARC water vapour assessment. We find that all data sets can be considered in observational and modelling studies addressing e.g. stratospheric and lower mesospheric water vapour variability and trends when data set specific characteristics (e.g. a drift) and restrictions (e.g. temporal and spatial coverage) are taken into account.

Description: Shipborne Wind Measurement and Motion-induced Error Correction of a Coherent Doppler Lidar over the Yellow Sea in 2014 Xiaochun Zhai, Songhua Wu, Bingyi Liu, Xiaoquan Song, and Jiaping Yin Atmos. Meas. Tech., 11, 1313-1331, https://doi.org/10.5194/amt-11-1313-2018, 2018 A Doppler wind lidar attitude correction method is presented. This algorithm-based method relaxes the requirements for mechanical stability and active compensation mechanisms. A shipborne wind measurement campaign was carried out in the Yellow Sea, 2014. Comparison between lidar and radiosonde wind measurements shows good consistency, indicating that the method can provide continuous and high spatio-temporal resolution measurement of atmospheric turbulence processes in the marine boundary layer.

Description: Regional uncertainty of GOSAT XCO 2 retrievals in China: quantification and attribution Nian Bie, Liping Lei, ZhaoCheng Zeng, Bofeng Cai, Shaoyuan Yang, Zhonghua He, Changjiang Wu, and Ray Nassar Atmos. Meas. Tech., 11, 1251-1272, https://doi.org/10.5194/amt-11-1251-2018, 2018 The results imply that XCO 2 from satellite observations could be reliably applied in the assessment of atmospheric CO 2 enhancements induced by anthropogenic CO 2 emissions. The large inconsistency among different algorithms presented in western deserts with a high albedo and dust aerosols demonstrates that further improvement is still necessary in such regions, even though many algorithms have endeavored to minimize the effects of aerosols and albedo.

Description: Calibration and field testing of cavity ring-down laser spectrometers measuring CH 4 , CO 2 , and δ 13 CH 4 deployed on towers in the Marcellus Shale region Natasha L. Miles, Douglas K. Martins, Scott J. Richardson, Christopher W. Rella, Caleb Arata, Thomas Lauvaux, Kenneth J. Davis, Zachary R. Barkley, Kathryn McKain, and Colm Sweeney Atmos. Meas. Tech., 11, 1273-1295, https://doi.org/10.5194/amt-11-1273-2018, 2018 Analyzers measuring methane and methane isotopic ratio were deployed at four towers in the Marcellus Shale natural gas extraction region of Pennsylvania. The methane isotopic ratio is helpful for differentiating emissions from natural gas activities from other sources (e.g., landfills). We describe the analyzer calibration. The signals observed in the study region were generally small, but the instrumental performance demonstrated here could be used in regions with stronger enhancements.

Description: Comparisons of the tropospheric specific humidity from GPS radio occultations with ERA-Interim, NASA MERRA, and AIRS data Panagiotis Vergados, Anthony J. Mannucci, Chi O. Ao, Olga Verkhoglyadova, and Byron Iijima Atmos. Meas. Tech., 11, 1193-1206, https://doi.org/10.5194/amt-11-1193-2018, 2018 This study cross-compares the 10-year record of GPS radio occultation (GPS-RO) specific humidity product against independent databases (e.g., AIRS satellite, NASA/MERRA, and ERA-Interim). Our objective is to investigate the suitability of the GPS-RO humidity as a climate variable, which the science community could use in climate research. GPS-RO offers high vertical resolution, low sensitivity to clouds, and long-term stability making GPS-RO humidity a valuable complementary data set.

Description: Information content analysis: the potential for methane isotopologue retrieval from GOSAT-2 Edward Malina, Yukio Yoshida, Tsuneo Matsunaga, and Jan-Peter Muller Atmos. Meas. Tech., 11, 1159-1179, https://doi.org/10.5194/amt-11-1159-2018, 2018 We present an assessment of the predicted information content and retrieval errors for 13 CH 4 retrieval from the planned GOSAT-2 satellite, assuming a wide range of land surface conditions. Retrieval of this quantity may allow for estimation of methane source types (e.g. biological or non-biological) based on the δ 13 C metric. We conclude that GOSAT-2 can be used for this purpose (to an accuracy of 10 ‰) assuming sufficient spatial (regional) and temporal (at least monthly) averaging.

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: Retrieval of health-related UV doses from PAR measurements Marcelo de Paula Corrêa, Sophie Godin-Beekmann, Fabrina Bolzan Martins, Kátia Mendes, Martial Haeffelin, Miguel Rivas, and Elisa Rojas Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2017-466,2018 Manuscript under review for AMT (discussion: open, 0 comments) This paper provides a very simple method for UV index estimation from PAR measurements. These latter are generally performed by cheaper instruments and commonly found in any ordinary meteorological station. A large dataset collected in South America and Europe was used to test this method and thes results are comparable to the instrumental errors. For this reason, the method is a useful tool for UV index evaluations in regions lacking adequate instrumentation.

Description: Potential of INSAT-3D Sounder Derived Total Precipitable Water Product for Weather Forecast Shailesh Parihar, Ashim Kumar Mitra, and Rajiv Bhatla Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-8,2018 Manuscript under review for AMT (discussion: open, 0 comments) Current work is based on operational work carried out at IMD, New Delhi using INSAT-3D satellite derived sounder product TPW for the weather events such as rainfall and thunderstorm. The INSAT-3D TPW is being used by forecasters as well as many user community from last 2 years. This work is mainly bring out the in-depth validation with in-situ ground measurement data as well as GNSS system for its suitability in weather prediction. This paper can be utilized operationally for weather purpose.

Description: Atmospheric QBO and ENSO indices with high vertical resolution from GNSS radio occultation temperature measurements Hallgeir Wilhelmsen, Florian Ladstädter, Barbara Scherllin-Pirscher, and Andrea K. Steiner Atmos. Meas. Tech., 11, 1333-1346, https://doi.org/10.5194/amt-11-1333-2018, 2018 Tropical atmospheric variability is often described using proxy indices of the Quasi-Biennial Oscillation and the El Niño–Southern Oscillation. We introduce new proxies derived from GNSS radio occultation (RO) satellite measurements. Using the high vertical resolution of the RO temperature fields we obtain altitude-resolved indices which can improve the description of atmospheric variability patterns and can be used in climate studies where a detailed knowledge of these patterns is required.

Description: Unraveling hydrometeor mixtures in polarimetric radar measurements Nikola Besic, Josué Gehring, Christophe Praz, Jordi Figueras i Ventura, Jacopo Grazioli, Marco Gabella, Urs Germann, and Alexis Berne Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-58,2018 Manuscript under review for AMT (discussion: open, 0 comments) In this paper we propose an innovative approach for hydrometeor de-mixing, i.e. to identify and quantify the presence of mixtures of different hydrometeor types in a radar sampling volume. It is a bin-based approach, inspired by conventional decomposition methods, and evaluated using C and X band radar measurements compared with synchronous ground observations. The paper also investigates the potential influence of incoherency in the backscattering from hydrometeor mixtures in a radar volume.

Description: Field calibration of electrochemical NO 2 sensors in a citizen science context Bas Mijling, Qijun Jiang, Dave de Jonge, and Stefano Bocconi Atmos. Meas. Tech., 11, 1297-1312, https://doi.org/10.5194/amt-11-1297-2018, 2018 Although in many cities the population is exposed to air pollution, real-time air quality is usually only measured at a few locations. New low-cost sensor technology has the potential to extend the monitoring network significantly. We show that citizen science campaigns using the current generations of electrochemical NO 2 sensors may provide useful complementary data on local air quality in an urban setting, provided that experiments are properly set up and the data are carefully analysed.

Description: Shipborne Wind Measurement and Motion-induced Error Correction of a Coherent Doppler Lidar over the Yellow Sea in 2014 Xiaochun Zhai, Songhua Wu, Bingyi Liu, Xiaoquan Song, and Jiaping Yin Atmos. Meas. Tech., 11, 1313-1331, https://doi.org/10.5194/amt-11-1313-2018, 2018 A Doppler wind lidar attitude correction method is presented. This algorithm-based method relaxes the requirements for mechanical stability and active compensation mechanisms. A shipborne wind measurement campaign was carried out in the Yellow Sea, 2014. Comparison between lidar and radiosonde wind measurements shows good consistency, indicating that the method can provide continuous and high spatio-temporal resolution measurement of atmospheric turbulence processes in the marine boundary layer.

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: 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: 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: 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: How intermittency affects the rate at which rainfall extremes respond to changes in temperature Marc Schleiss Earth Syst. Dynam. Discuss., https//doi.org/10.5194/esd-2018-4,2018 Manuscript under review for ESD (discussion: open, 1 comment) The present study aims at shedding new light on the importance of intermittency and how it modulates the rate at which precipitation extremes (in current climate) depend on temperature. The analysis of 99 stations in the United States reveals that rapid increases or decreases in intermittency cause extremes to respond differently to changes in temperature than expected from Clausius–Clapeyron. A new model is proposed to help better anticipate changes across scales.

Description: An improved and homogeneous altimeter sea level record from the ESA Climate Change Initiative Jean-François Legeais, Michaël Ablain, Lionel Zawadzki, Hao Zuo, Johnny A. Johannessen, Martin G. Scharffenberg, Luciana Fenoglio-Marc, M. Joana Fernandes, Ole Baltazar Andersen, Sergei Rudenko, Paolo Cipollini, Graham D. Quartly, Marcello Passaro, Anny Cazenave, and Jérôme Benveniste Earth Syst. Sci. Data, 10, 281-301, https://doi.org/10.5194/essd-10-281-2018, 2018 Sea level is one of the best indicators of climate change and has been listed as one of the essential climate variables. Sea level measurements have been provided by satellite altimetry for 25 years, and the Climate Change Initiative (CCI) program of the European Space Agency has given the opportunity to provide a long-term, homogeneous and accurate sea level record. It will help scientists to better understand climate change and its variability.

Description: Photosynthesis–irradiance parameters of marine phytoplankton: synthesis of a global data set Heather A. Bouman, Trevor Platt, Martina Doblin, Francisco G. Figueiras, Kristinn Gudmundsson, Hafsteinn G. Gudfinnsson, Bangqin Huang, Anna Hickman, Michael Hiscock, Thomas Jackson, Vivian A. Lutz, Frédéric Mélin, Francisco Rey, Pierre Pepin, Valeria Segura, Gavin H. Tilstone, Virginie van Dongen-Vogels, and Shubha Sathyendranath Earth Syst. Sci. Data, 10, 251-266, https://doi.org/10.5194/essd-10-251-2018, 2018 The photosynthetic response of marine phytoplankton to available irradiance is a central part of satellite-based models of ocean productivity. This study brings together data from a variety of oceanographic campaigns to examine how the parameters of photosynthesis–irradiance response curves vary over the global ocean. This global synthesis reveals biogeographic, latitudinal and depth-dependent patterns in the photosynthetic properties of natural phytoplankton assemblages.

Description: Estimating the thickness of unconsolidated coastal aquifers along the global coastline Daniel Zamrsky, Gualbert H. P. Oude Essink, and Marc F. P. Bierkens Earth Syst. Sci. Data Discuss., https//doi.org/10.5194/essd-2017-110,2018 Manuscript under review for ESSD (discussion: open, 0 comments) An increasing number of coastal areas worldwide is facing a threat of groundwater quality degradation by salt water intrusion. Groundwater flow models help to get a better idea about the volumes of fresh groundwater reserves in these areas. Our research provides information on aquifer thickness which is one of the most important parameters for such models. However, we found that geological complexity of coastal aquifer systems is an at least equally important factor for accurate predictions.

Description: Development and Analysis of Soil Water Infiltration Global Database Mehdi Rahmati, Lutz Weihermüller, Jan Vanderborght, Yakov A. Pachepsky, Lili Mao, Seyed Hamidreza Sadeghi, Niloofar Moosavi, Hossein Kheirfam, Carsten Montzka, Kris Van Looy, Brigitta Toth, Zeinab Hazbavi, Wafa Al Yamani, Ammar A. Albalasmeh, Ma'in Z. Alghzawi, Rafael Angulo-Jaramillo, Antônio Celso Dantas Antonino, George Arampatzis, Robson André Armindo, Hossein Asadi, Yazidhi Bamutaze, Jordi Batlle-Aguilar, Beatrice Bechet, Fabian Becker, Günter Blöschl, Klaus Bohne, Isabelle Braud, Clara Castellano, Artemi Cerdà, Maha Chalhoub, Rogerio Cichota, Milena Císlerová, Brent Clothier, Yves Coquet, Wim Cornelis, Corrado Corradini, Artur Paiva Coutinho, Muriel Bastista de Oliveira, José Ronaldo de Macedo, Matheus Fonseca Durães, Hojat Emami, Iraj Eskandari, Asghar Farajnia, Alessia Flammini, Nándor Fodor, Mamoun Gharaibeh, Mohamad Hossein Ghavimipanah, Teamrat A. Ghezzehei, Simone Giertz, Evangelos G Hatzigiannakis, Rainer Horn, Juan José Jiménez, Diederik Jacques, Saskia Deborah Keesstra, Hamid Kelishadi, Mahboobeh Kiani-Harchegani, Mehdi Kouselou, Madan Kumar Jha, Laurent Lassabatere, Xiaoyan Li, Mark A. Liebig, Lubomír Lichner, María Victoria López, Deepesh Machiwal, Dirk Mallants, Micael Stolben Mallmann, Jean Dalmo de Oliveira Marques, Miles R. Marshall, Jan Mertens, Félicien Meunier, Mohammad Hossein Mohammadi, Binayak P. Mohanty, Mansonia Pulido Moncada, Suzana Montenegro, Renato Morbidelli, David Moret-Fernández, Ali Akbar Moosavi, Mohammad Reza Mosaddeghi, Seyed Bahman Mousavi, Hasan Mozaffari, Kamal Nabiollahi, Mohammad Reza Neyshabouri, Marta Vasconcelos Ottoni, Theophilo Benedicto Ottoni Filho, Mohammad Reza Pahlavan Rad, Andreas Panagopoulos, Stephan Peth, Pierre-Emmanuel Peyneau, Tommaso Picciafuoco, Jean Poesen, Manuel Pulido, Dalvan José Reinert, Sabine Reinsch, Meisam Rezaei, Francis Parry Roberts, David Robinson, Jesús Rodrigo-Comino, Otto Corrêa Rotunno Filho, Tadaomi Saito, Hideki Suganuma, Carla Saltalippi, Renáta Sándor, Brigitta Schütt, Manuel Seeger, Nasrollah Sepehrnia, Ehsan Sharifi Moghaddam, Manoj Shukla, Shiraki Shutaro, Ricardo Sorando, Ajayi Asishana Stanley, Peter Strauss, Zhongbo Su, Ruhollah Taghizadeh-Mehrjardi, Encarnación Taguas, Wenceslau Geraldes Teixeira, Ali Reza Vaezi, Mehdi Vafakhah, Tomas Vogel, Iris Vogeler, Jana Votrubova, Steffen Werner, Thierry Winarski, Deniz Yilmaz, Michael H. Young, Steffen Zacharias, Yijian Zeng, Ying Zhao, Hong Zhao, and Harry Vereecken Earth Syst. Sci. Data Discuss., https//doi.org/10.5194/essd-2018-11,2018 Manuscript under review for ESSD (discussion: open, 0 comments) This paper presents and analyzes a global database of soil infiltration data, the SWIG database, for the first time. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists or they were digitized from published articles. We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models.

Description: seNorge2 daily precipitation, an observational gridded dataset over Norway from 1957 to the present day Cristian Lussana, Tuomo Saloranta, Thomas Skaugen, Jan Magnusson, Ole Einar Tveito, and Jess Andersen Earth Syst. Sci. Data, 10, 235-249, https://doi.org/10.5194/essd-10-235-2018, 2018 The observational gridded climate datasets are among the primary sources of information for climate analysis and monitoring. The seNorge2 high-resolution dataset of daily total precipitation (1957–2017) constitutes a valuable meteorological input for snow and hydrological simulations which are routinely conducted over Norway for research and to support operational applications for civil protection purposes. The dataset and the seNorge2 software are publicly available for download.

Description: Gross and net land cover changes in the main plant functional types derived from the annual ESA CCI land cover maps (1992–2015) Wei Li, Natasha MacBean, Philippe Ciais, Pierre Defourny, Céline Lamarche, Sophie Bontemps, Richard A. Houghton, and Shushi Peng Earth Syst. Sci. Data, 10, 219-234, https://doi.org/10.5194/essd-10-219-2018, 2018 We evaluated the land cover changes based on plant functional types (PFTs) derived from the newly released annual ESA land cover maps. We addressed the geographical distributions and temporal trends of the translated PFT maps and compared with other datasets commonly used by the land surface model community. Different choices of these datasets for the applications in land surface models are proposed depending on the research purposes.

Description: Evaluation oxygen deficiency in the Chesapeake Bay Wencheng L. Slater, James J. Pierson, and Michael R. Roman Earth Syst. Sci. Data Discuss., https//doi.org/10.5194/essd-2017-129,2018 Manuscript under review for ESSD (discussion: open, 1 comment) We conducted six cruises in 2010 and 2011 to understand the effects of low dissolved oxygen to the ecosystem in the Chesapeake Bay, USA. We also estimated the oxygen supply and demand of zooplankton according to the surrounding environment. We found that hypoxia could be underestimated if only using dissolved oxygen, especially under warm and salty conditions. Instead, we recommend that temperature and species-specific metrics also be considered when setting water quality goals for management.

Description: Ship- and island-based soundings from the 2016 El Niño Rapid Response (ENRR) field campaign Leslie M. Hartten, Christopher J. Cox, Paul E. Johnston, Daniel E. Wolfe, Scott Abbott, H. Alex McColl, Xiao-Wei Quan, and Matthew G. Winterkorn Earth Syst. Sci. Data Discuss., https//doi.org/10.5194/essd-2018-7,2018 Manuscript under review for ESSD (discussion: open, 1 comment) Radiosonde data collected during NOAA's El Niño Rapid Response Field Campaign in early 2016 have been reprocessed and lightly quality controlled. Temperature, humidity, and wind soundings from Kiritimati Island and the NOAA Ship Ronald H. Brown capture the repeated advance and retreat of the ITCZ at Kiritimati, a variety of marine tropospheric environments encountered by the ship, and lower-stratospheric features of the 2015–2016 QBO (quasi-biennial oscillation).

Description: Baseline Surface Radiation Network (BSRN): structure and data description (1992–2017) Amelie Driemel, John Augustine, Klaus Behrens, Sergio Colle, Christopher Cox, Emilio Cuevas-Agulló, Fred M. Denn, Thierry Duprat, Masato Fukuda, Hannes Grobe, Martial Haeffelin, Nicole Hyett, Osamu Ijima, Ain Kallis, Wouter Knap, Vasilii Kustov, Charles N. Long, David Longenecker, Angelo Lupi, Marion Maturilli, Mohamed Mimouni, Lucky Ntsangwane, Hiroyuki Ogihara, Xabier Olano, Marc Olefs, Masao Omori, Lance Passamani, Enio Bueno Pereira, Holger Schmithüsen, Stefanie Schumacher, Rainer Sieger, Jonathan Tamlyn, Roland Vogt, Laurent Vuilleumier, Xiangao Xia, Atsumu Ohmura, and Gert König-Langlo Earth Syst. Sci. Data Discuss., https//doi.org/10.5194/essd-2018-8,2018 Manuscript under review for ESSD (discussion: open, 0 comments) The Baseline Surface Radiation Network (BSRN), collects and centrally archives high quality ground-based radiation measurements in 1-minute resolution. More than 10 300 months, i.e. 〉 850 years, of high radiation data in one-minute resolution from the years 1992 to 2017 are available. The network currently comprises 59 stations collectively representing all seven continents as well as island-based stations in the Pacific, Atlantic, Indian and Arctic Oceans.

Description: SM2RAIN-CCI: a new global long-term rainfall data set derived from ESA CCI soil moisture Luca Ciabatta, Christian Massari, Luca Brocca, Alexander Gruber, Christoph Reimer, Sebastian Hahn, Christoph Paulik, Wouter Dorigo, Richard Kidd, and Wolfgang Wagner Earth Syst. Sci. Data, 10, 267-280, https://doi.org/10.5194/essd-10-267-2018, 2018 In this study, rainfall is estimated starting from satellite soil moisture observation on a global scale, using the ESA CCI soil moisture datasets. The new obtained rainfall product has proven to correctly identify rainfall events, showing performance sometimes higher than those obtained by using classical rainfall estimation approaches.

Description: An improved and homogeneous altimeter sea level record from the ESA Climate Change Initiative Jean-François Legeais, Michaël Ablain, Lionel Zawadzki, Hao Zuo, Johnny A. Johannessen, Martin G. Scharffenberg, Luciana Fenoglio-Marc, M. Joana Fernandes, Ole Baltazar Andersen, Sergei Rudenko, Paolo Cipollini, Graham D. Quartly, Marcello Passaro, Anny Cazenave, and Jérôme Benveniste Earth Syst. Sci. Data, 10, 281-301, https://doi.org/10.5194/essd-10-281-2018, 2018 Sea level is one of the best indicators of climate change and has been listed as one of the essential climate variables. Sea level measurements have been provided by satellite altimetry for 25 years, and the Climate Change Initiative (CCI) program of the European Space Agency has given the opportunity to provide a long-term, homogeneous and accurate sea level record. It will help scientists to better understand climate change and its variability.

Description: Historical gridded reconstruction of potential evapotranspiration for the UK Maliko Tanguy, Christel Prudhomme, Katie Smith, and Jamie Hannaford Earth Syst. Sci. Data Discuss., https//doi.org/10.5194/essd-2017-137,2018 Manuscript under review for ESSD (discussion: open, 1 comment) Potential evapotranspiration (PET) is a necessary input data for most hydrological models, used to simulate river flows. To reconstruct PET prior to 1960s, simplified methods are needed because of lack of climate data required for complex methods. We have found that McGuinness-Bordne PET equation, which only needs temperature as input data, works best for the UK provided it is calibrated for local conditions. This method was used to produce a 5 km gridded PET dataset for the UK for 1891–2015.

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: Modeling and clustering water demand patterns from real-world smart meter data Nicolas Cheifetz, Zineb Noumir, Allou Samé, Anne-Claire Sandraz, Cédric Féliers, and Véronique Heim Drink. Water Eng. Sci., 10, 75-82, https://doi.org/10.5194/dwes-10-75-2017, 2017 This paper aims at a better understanding of water consumption usage.

Description: How concave are river channels? Simon M. Mudd, Fiona J. Clubb, Boris Gailleton, and Martin D. Hurst Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-7,2018 Manuscript under review for ESurf (discussion: open, 1 comment) Rivers can reveal information about erosion rates, tectonics, and climate. In order to make meaningful inferences about these influences one must be able to compare headwaters to downstream parts of the river network. We describe new methods for normalizing river steepness for drainage area to better understand how rivers record erosion rates in eroding landscapes.

Description: Scales of collective entrainment and intermittent transport in collision-driven bed load Dylan B. Lee and Doug Jerolmack Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-8,2018 Manuscript under review for ESurf (discussion: open, 3 comments) The transport of pebbles in a river is smooth and continuous under high flow conditions, but under typical flows becomes erratic and unpredictable. We perform experiments to learn more about the origins of this unpredictable, intermittent behavior. Our results show that this unpredictability is similar to how infrequent avalanches occur in a sandpile. Transport events are similar in size but become more infrequent and erratic as the river transports less and less sediment.

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: Statistical modeling of the long-range dependent structure of barrier island framework geology and surface geomorphology Bradley A. Weymer, Phillipe Wernette, Mark E. Everett, and Chris Houser Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-5,2018 Manuscript under review for ESurf (discussion: open, 0 comments) This research presents a new method for quantifying the geologic controls on modern barrier island evolution. We used statistical time series analysis to evaluate the scale-dependent vs. scale-independent behavior of a barrier island in south Texas, USA. By integrating subsurface geophysical with surface geomorphological measurements we show that the island exhibits both free, and forced evolutionary behavior that has important implications for how the island may respond to rising sea levels.

Description: U–Th and 10 Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia Antoine Cogez, Frédéric Herman, Éric Pelt, Thierry Reuschlé, Gilles Morvan, Christopher M. Darvill, Kevin P. Norton, Marcus Christl, Lena Märki, and François Chabaux Earth Surf. Dynam., 6, 121-140, https://doi.org/10.5194/esurf-6-121-2018, 2018 Sediments produced by glaciers are transported by rivers and wind toward the ocean. During their journey, these sediments are weathered, and we know that this has an impact on climate. One key factor is time, but the duration of this journey is largely unknown. We were able to measure the average time that sediment spends only in the glacial area. This time is 100–200 kyr, which is long and allows a lot of processes to act on sediments during their journey.

Description: U–Th and 10 Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia Antoine Cogez, Frédéric Herman, Éric Pelt, Thierry Reuschlé, Gilles Morvan, Christopher M. Darvill, Kevin P. Norton, Marcus Christl, Lena Märki, and François Chabaux Earth Surf. Dynam., 6, 121-140, https://doi.org/10.5194/esurf-6-121-2018, 2018 Sediments produced by glaciers are transported by rivers and wind toward the ocean. During their journey, these sediments are weathered, and we know that this has an impact on climate. One key factor is time, but the duration of this journey is largely unknown. We were able to measure the average time that sediment spends only in the glacial area. This time is 100–200 kyr, which is long and allows a lot of processes to act on sediments during their journey.

Description: Identifying (subsurface) anthropogenic heat sources that influence temperature in the drinking water distribution system Claudia M. Agudelo-Vera, Mirjam Blokker, Henk de Kater, and Rob Lafort Drink. Water Eng. Sci., 10, 83-91, https://doi.org/10.5194/dwes-10-83-2017, 2017 Water temperature in the drinking water distribution system (DWDS) and at the customers' taps approaches the surrounding soil temperature at 1 m in depth. In the Netherlands drinking water is distributed without additional residual disinfectant and drinking water temperature at the customers' tap should not exceed 25 ºC. Some urban infrastructures are heat sources and generate hot-spots. This article describes a method to find anthropogenic heat sources that influence temperature in the DWDS.

Description: Clay mineralogy, strontium and neodymium isotope ratios in the sediments of two High Arctic catchments (Svalbard) Ruth S. Hindshaw, Nicholas J. Tosca, Alexander M. Piotrowski, and Edward T. Tipper Earth Surf. Dynam., 6, 141-161, https://doi.org/10.5194/esurf-6-141-2018, 2018 For many applications in Earth sciences it is important to know where river and ocean sediments have originated. In this study we used geochemical and mineralogical tracers to characterise sediments from Svalbard. We find that the sediments are formed from two sources: old rocks in Greenland and younger rocks in Siberia. Glaciation influences how much of each end-member is present in the river sediments today, implying that the sediment composition can change through time as the climate changes.

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: Tectonic controls of Holocene erosion in a glaciated orogen Byron A. Adams and Todd A. Ehlers Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-9,2018 Manuscript under review for ESurf (discussion: open, 0 comments) Recent work has highlighted a strong, worldwide, glacial impact of orogen erosion rates over the last 2 Ma. While it may be assumed that glaciers increased erosion rates when active, the degree to which past glaciations influence Holocene erosion rates through the adjustment of topography is not known. In this study, we investigate the influence of long-term tectonic and post-glacial topographic controls on erosion in a glaciated orogen, the Olympic Mountains, USA. We present 14 new 10 Be and 26 Al analyses which constrain Holocene erosion rates across the Olympic Mountains. Basin-averaged erosion rates scale with basin-averaged values of 5-km local relief, channel steepness, and hillslope angle throughout the range, similar to observations from non-glaciated orogens. These erosion rates are not related to mean annual precipitation or the marked change in Pleistocene alpine glacier size across the range, implying that glacier modification of topography and modern precipitation parameters do not exert strong controls on these rates. Rather, we find that despite intense spatial variations in glacial modification of topography, patterns of recent erosion are similar to those from estimates of long-term tectonic rock uplift. This is consistent with a tectonic model where erosion and rock uplift patterns are controlled by the deformation of the Cascadia subduction zone.

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 20-year record (1998–2017) of permafrost, active layer and meteorological conditions at a high Arctic permafrost research site (Bayelva, Spitsbergen) Julia Boike, Inge Juszak, Stephan Lange, Sarah Chadburn, Eleanor Burke, Pier Paul Overduin, Kurt Roth, Olaf Ippisch, Niko Bornemann, Lielle Stern, Isabelle Gouttevin, Ernst Hauber, and Sebastian Westermann Earth Syst. Sci. Data, 10, 355-390, https://doi.org/10.5194/essd-10-355-2018, 2018 A 20-year data record from the Bayelva site at Ny-Ålesund, Svalbard, is presented on meteorology, energy balance components, surface and subsurface observations. This paper presents the data set, instrumentation, calibration, processing and data quality control. The data show that mean annual, summer and winter soil temperature data from shallow to deeper depths have been warming over the period of record, indicating the degradation and loss of permafrost at this site.

Description: SM2RAIN-CCI: a new global long-term rainfall data set derived from ESA CCI soil moisture Luca Ciabatta, Christian Massari, Luca Brocca, Alexander Gruber, Christoph Reimer, Sebastian Hahn, Christoph Paulik, Wouter Dorigo, Richard Kidd, and Wolfgang Wagner Earth Syst. Sci. Data, 10, 267-280, https://doi.org/10.5194/essd-10-267-2018, 2018 In this study, rainfall is estimated starting from satellite soil moisture observation on a global scale, using the ESA CCI soil moisture datasets. The new obtained rainfall product has proven to correctly identify rainfall events, showing performance sometimes higher than those obtained by using classical rainfall estimation approaches.

Description: Historical gridded reconstruction of potential evapotranspiration for the UK Maliko Tanguy, Christel Prudhomme, Katie Smith, and Jamie Hannaford Earth Syst. Sci. Data Discuss., https//doi.org/10.5194/essd-2017-137,2018 Manuscript under review for ESSD (discussion: open, 1 comment) Potential evapotranspiration (PET) is a necessary input data for most hydrological models, used to simulate river flows. To reconstruct PET prior to 1960s, simplified methods are needed because of lack of climate data required for complex methods. We have found that McGuinness-Bordne PET equation, which only needs temperature as input data, works best for the UK provided it is calibrated for local conditions. This method was used to produce a 5 km gridded PET dataset for the UK for 1891–2015.

Description: How concave are river channels? Simon M. Mudd, Fiona J. Clubb, Boris Gailleton, and Martin D. Hurst Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-7,2018 Manuscript under review for ESurf (discussion: open, 1 comment) Rivers can reveal information about erosion rates, tectonics, and climate. In order to make meaningful inferences about these influences one must be able to compare headwaters to downstream parts of the river network. We describe new methods for normalizing river steepness for drainage area to better understand how rivers record erosion rates in eroding landscapes.

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.