WILBERT

Description: Generalized nonlinear height–diameter models for a  Cryptomeria fortunei plantation in the Pingba region of Guizhou Province, China Zongzheng Chai, Wei Tan, Yuanyuan Li, Lan Yan, Hongbo Yuan, and Zhaojun Li Web Ecol., 18, 29-35, https://doi.org/10.5194/we-18-29-2018, 2018 Many years of forestry practice have confirmed that Cryptomeria fortunei can be cultivated in central Guizhou Province of China on a large scale, and this will continue due to its good growth performance and excellent development potential. The generalized height–diameter models proposed in the current paper will help forest managers to reduce costs and save time during the inventory, monitoring, and management for these forests.

Description: Modelling plant invasion pathways in protected areas under climate change: implication for invasion management Chun-Jing Wang, Ji-Zhong Wan, Hong Qu, and Zhi-Xiang Zhang Web Ecol., 17, 69-77, https://doi.org/10.5194/we-17-69-2017, 2017 We used an original global approach to explore the potential relationship between PAs and the intentional movement of IPS based on climate change. Climate change developed the potential pathways for IPS in PAs, and the ability of natural dispersal encourages IPS to invade non-native habitats in the potential movement pathways in PAs. This study shows the importance of the development of global conservation planning for PAs and biological invasion.

Description: Effects of native biodiversity on grape loss of four castes: testing the biotic resistance hypothesis Mauro Nereu, Ruben H. Heleno, Francisco Lopez-Núñez, Mário Agostinho, and Jaime A. Ramos Web Ecol., 18, 15-27, https://doi.org/10.5194/we-18-15-2018, 2018 Management of agricultural landscapes can influence the biodiversity and the ecological services provided by these ecosystems, such as natural biological pest control. Viticulture is a very important economic activity in most countries with Mediterranean climate, often shaping their landscapes and culture. Grape production is affected by a number of pests and diseases, and farmers use prophylactic and response-driven pesticides to control these pests. Here we quantified the main biotic causes of crop losses in four grape castes, two red (Touriga Nacional and Baga) and two white (Arinto and Chardonnay), and evaluated the potential effect of native biodiversity to provide biotic resistance to pest outbreaks and grape losses. Specifically, the diversity and abundance of bird and insect communities in these vineyards were quantified and divided into functional guilds (pest, neutral or auxiliary), to test whether these natural communities hold the potential to naturally control grape pests (biotic resistance hypothesis) under normal vineyard management (including pesticide application regimes). A potential association between distance to the vineyard edge and grape losses was also evaluated. We recorded a very small proportion of grape losses (mean  =  0.6 %; max  =  7.5 %), with insect pests showing a preference for the castes Baga (red) and Chardonnay (white), while bird pests avoided the caste Arinto (white). Grape color did not influence losses caused by insect pests, but birds showed a preference for red castes. The caste Baga was also more vulnerable to losses caused by fungi. Despite their low impact on grape production, most insects and birds detected in the six vineyards were pests, which entails a potentially low level of biotic resistance in this highly managed agricultural ecosystem. Further research is necessary to fully evaluate the role of functional biodiversity in vineyards, particularly if alternative production processes, such as organic farming, can increase the potential of native biodiversity to protect against grape losses from pests under lower regimes of chemical spraying.

Description: Could disruptive technologies also reform academia? Casparus J. Crous Web Ecol., 17, 47-50, https://doi.org/10.5194/we-17-47-2017, 2017 A thriving future science community could depend on disruptive technologies to shake up outmoded academic practices.

Description: Species richness and phylogenetic structure in plant communities: 20 years of succession Jutta Stadler, Stefan Klotz, Roland Brandl, and Sonja Knapp Web Ecol., 17, 37-46, https://doi.org/10.5194/we-17-37-2017, 2017 During early succession plant communities show a decrease in the initial species richness and a change in the phylogenetic structure from random or clustered to overdispersion. We tested this general model in two regional distinct sites. In one region we found the expected trajectory of species richness while phylogenetic structure did not follow the expected trend. In the other region species richness did not follow the expected trajectory and phylogenetic structure remained clustered.

Description: Near-surface temperature inversion during summer at Summit, Greenland, and its relation to MODIS-derived surface temperatures Alden C. Adolph, Mary R. Albert, and Dorothy K. Hall The Cryosphere, 12, 907-920, https://doi.org/10.5194/tc-12-907-2018, 2018 In our studies of surface temperature in Greenland, we found that there can be differences between the temperature of the snow surface and the air directly above, depending on wind speed and incoming solar radiation. We also found that temperature measurements of the snow surface from remote sensing instruments may be more accurate than previously thought. Our results are relevant to studies of climate change in the remote sensing community and in studies of the atmospheric boundary layer.

Description: Inflation Method for Ensemble Kalman Filter in Soil Hydrology Hannes H. Bauser, Daniel Berg, Ole Klein, and Kurt Roth Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-74,2018 Manuscript under review for HESS (discussion: open, 0 comments) Data assimilation methods like the ensemble Kalman filter (EnKF) can combine models and measurements to estimate states and parameters, but require a proper representation of uncertainties. In soil hydrology, model errors typically vary rapidly in space and time, which is difficult to represent. Inflation methods can account for unrepresented model errors. To improve estimations in soil hydrology, we designed a method that can adjust the inflation of states and parameters to fast varying errors.

Description: Using hydraulic head, chloride and electrical conductivity data to distinguish between mountain-front and mountain-block recharge to basin aquifers Etienne Bresciani, Roger H. Cranswick, Eddie W. Banks, Jordi Batlle-Aguilar, Peter G. Cook, and Okke Batelaan Hydrol. Earth Syst. Sci., 22, 1629-1648, https://doi.org/10.5194/hess-22-1629-2018, 2018 This article tackles the problem of finding the origin of groundwater in basin aquifers adjacent to mountains. In particular, we aim to determine whether the recharge occurs predominantly through stream infiltration along the mountain front or through subsurface flow from the mountain. To this end, we discuss the use of routinely measured variables: hydraulic head, chloride and electrical conductivity. A case study from Australia demonstrates the approach.

Description: A Bayesian modelling method for post-processing daily sub-seasonal to seasonal rainfall forecasts from global climate models and evaluation for 12 Australian catchments Andrew Schepen, Tongtiegang Zhao, Quan J. Wang, and David E. Robertson Hydrol. Earth Syst. Sci., 22, 1615-1628, https://doi.org/10.5194/hess-22-1615-2018, 2018 Rainfall forecasts from dynamical global climate models (GCMs) require post-processing before use in hydrological models. Existing methods generally lack the sophistication to achieve calibrated forecasts of both daily amounts and seasonal accumulated totals. We develop a new statistical method to post-process Australian GCM rainfall forecasts for 12 perennial and ephemeral catchments. Our method produces reliable forecasts and outperforms the most commonly used statistical method.

Description: Projected cryospheric and hydrological impacts of 21st century climate change in the Ötztal Alps (Austria) simulated using a physically based approach Florian Hanzer, Kristian Förster, Johanna Nemec, and Ulrich Strasser Hydrol. Earth Syst. Sci., 22, 1593-1614, https://doi.org/10.5194/hess-22-1593-2018, 2018 Climate change effects on snow, glaciers, and hydrology are investigated for the Ötztal Alps region (Austria) using a hydroclimatological model driven by climate projections for the RCP2.6, RCP4.5, and RCP8.5 scenarios. The results show declining snow amounts and strongly retreating glaciers with moderate effects on catchment runoff until the mid-21st century, whereas annual runoff volumes decrease strongly towards the end of the century.

Description: Imaging groundwater infiltration dynamics in the karst vadose zone with long-term ERT monitoring Arnaud Watlet, Olivier Kaufmann, Antoine Triantafyllou, Amaël Poulain, Jonathan E. Chambers, Philip I. Meldrum, Paul B. Wilkinson, Vincent Hallet, Yves Quinif, Michel Van Ruymbeke, and Michel Van Camp Hydrol. Earth Syst. Sci., 22, 1563-1592, https://doi.org/10.5194/hess-22-1563-2018, 2018 Understanding water infiltration in karst regions is crucial as the aquifers they host provide drinkable water for a quarter of the world's population. We present a non-invasive tool to image hydrological processes in karst systems. At our field site, the injection of electrical current in the ground, repeated daily over a 3-year period, allowed imaging changes in the groundwater content. We show that specific geological layers control seasonal to rainfall-triggered water infiltration dynamics.

Description: The Probability Distribution of Daily Precipitation at the Point and Catchment Scales in the United States Lei Ye, Lars S. Hanson, Pengqi Ding, Dingbao Wang, and Richard M. Vogel Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-85,2018 Manuscript under review for HESS (discussion: open, 0 comments) Choosing a probability distribution to represent daily precipitation depths is important for precipitation frequency analysis, stochastic precipitation modeling and in climate trend assessments. Early studies identified the 2-parameter Gamma (G2) distribution as a suitable distribution for wet-day precipitation based on traditional goodness of fit tests. Here, probability plot correlation coefficients and L-moment diagrams are used to examine distributional alternatives for the full-record and wet-day series of daily precipitation at the point and catchment scales in the United States. Importantly, the G2 distribution performs poorly in comparison to either the Pearson Type-III (P3) or Kappa (KAP) distributions. The analysis indicates that the P3 distribution fits the full record of daily precipitation at both the point and catchment scales remarkably well; while the KAP distribution best describes the distribution of wet-day precipitation at the point scale, and the performance of KAP and P3 distributions is comparable for wet-day precipitation at the catchment scale.

Description: Effectiveness of distributed temperature measurements for early detection of piping in river embankments Silvia Bersan, André R. Koelewijn, and Paolo Simonini Hydrol. Earth Syst. Sci., 22, 1491-1508, https://doi.org/10.5194/hess-22-1491-2018, 2018 Backward erosion piping is the cause of a significant percentage of failures and incidents involving dams and river embankments. In the past 20 years fibre-optic Distributed Temperature Sensing (DTS) has proved to be effective for the detection of leakages and internal erosion in dams. This work investigates the effectiveness of DTS for monitoring backward erosion piping in river embankments. Data from a large-scale piping test performed on an instrumented dike are presented and discussed.

Description: Multiple causes of nonstationarity in the Weihe annual low-flow series Bin Xiong, Lihua Xiong, Jie Chen, Chong-Yu Xu, and Lingqi Li Hydrol. Earth Syst. Sci., 22, 1525-1542, https://doi.org/10.5194/hess-22-1525-2018, 2018 In changing environments, extreme low-flow events are expected to increase. Frequency analysis of low-flow events considering the impacts of changing environments has attracted increasing attention. This study developed a frequency analysis framework by applying 11 indices to trace the main causes of the change in the annual extreme low-flow events of the Weihe River. We showed that the fluctuation in annual low-flow series was affected by climate, streamflow recession and irrigation area.

Description: Calibrating electromagnetic induction conductivities with time-domain reflectometry measurements Giovanna Dragonetti, Alessandro Comegna, Ali Ajeel, Gian Piero Deidda, Nicola Lamaddalena, Giuseppe Rodriguez, Giulio Vignoli, and Antonio Coppola Hydrol. Earth Syst. Sci., 22, 1509-1523, https://doi.org/10.5194/hess-22-1509-2018, 2018 The paper aims to infer the bulk electrical conductivity distribution in the root zone from EMI readings. TDR measurements were used as ground-truth data to evaluate the goodness of the estimations by EMI inversion. The approach is based on the mean and standard deviation of the EMI and TDR series. It looks for the physical reasons for the differences between EMI- and TDR-based electrical conductivity and provides a correction of the bias based on the statistical sources of the discrepancies.

Description: Citizen observations contributing to flood modelling: opportunities and challenges Thaine H. Assumpção, Ioana Popescu, Andreja Jonoski, and Dimitri P. Solomatine Hydrol. Earth Syst. Sci., 22, 1473-1489, https://doi.org/10.5194/hess-22-1473-2018, 2018 Citizens can contribute to science by providing data, analysing them and as such contributing to decision-making processes. For example, citizens have collected water levels from gauges, which are important when simulating/forecasting floods, where data are usually scarce. This study reviewed such contributions and concluded that integration of citizen data may not be easy due to their spatio-temporal characteristics but that citizen data still proved valuable and can be used in flood modelling.

Description: Quantification of surface water volume changes in the Mackenzie Delta using satellite multi-mission data Cassandra Normandin, Frédéric Frappart, Bertrand Lubac, Simon Bélanger, Vincent Marieu, Fabien Blarel, Arthur Robinet, and Léa Guiastrennec-Faugas Hydrol. Earth Syst. Sci., 22, 1543-1561, https://doi.org/10.5194/hess-22-1543-2018, 2018 Quantification of surface water storage in extensive floodplains and their dynamics are crucial for a better understanding of global hydrological and biogeochemical cycles. In this study, we present estimates of both surface water extent and storage combining multi-mission remotely sensed observations and their temporal evolution over more than 15 years in the Mackenzie Delta. The Mackenzie Delta is located in the northwest of Canada and is the second largest delta in the Arctic Ocean. The delta is frozen from October to May and the recurrent ice break-up provokes an increase in the river's flows. Thus, this phenomenon causes intensive floods along the delta every year, with dramatic environmental impacts. In this study, the dynamics of surface water extent and volume are analysed from 2000 to 2015 by combining multi-satellite information from MODIS multispectral images at 500 m spatial resolution and river stages derived from ERS-2 (1995–2003), ENVISAT (2002–2010) and SARAL (since 2013) altimetry data. The surface water extent (permanent water and flooded area) peaked in June with an area of 9600 km 2 (±200 km 2 ) on average, representing approximately 70 % of the delta's total surface. Altimetry-based water levels exhibit annual amplitudes ranging from 4 m in the downstream part to more than 10 m in the upstream part of the Mackenzie Delta. A high overall correlation between the satellite-derived and in situ water heights ( R  〉 0.84) is found for the three altimetry missions. Finally, using altimetry-based water levels and MODIS-derived surface water extents, maps of interpolated water heights over the surface water extents are produced. Results indicate a high variability of the water height magnitude that can reach 10 m compared to the lowest water height in the upstream part of the delta during the flood peak in June. Furthermore, the total surface water volume is estimated and shows an annual variation of approximately 8.5 km 3 during the whole study period, with a maximum of 14.4 km 3 observed in 2006. The good agreement between the total surface water volume retrievals and in situ river discharges ( R  =  0.66) allows for validation of this innovative multi-mission approach and highlights the high potential to study the surface water extent dynamics.

Description: Practical experience and framework for sensitivity analysis of hydrological models: six methods, three models, three criteria Anqi Wang and Dimitri P. Solomatine Hydrol. Earth Syst. Sci. Discuss., https//doi.org/10.5194/hess-2018-78,2018 Manuscript under review for HESS (discussion: open, 1 comment) This paper presents a brief review and classification of sensitivity analysis (SA) methods. Six different global SA methods: Sobol, FAST, Morris, LH-OAT, RSA and PAWN are tested on the three conceptual rainfall-runoff models with varying complexity: (GR4J, Hymod and HBV), with respect to effectiveness, efficiency and convergence. Practical framework of selecting and using the SA methods is presented, which may be of assistance for practitioners assessing reliability of their models.

Description: Testing and development of transfer functions for weighing precipitation gauges in WMO-SPICE John Kochendorfer, Rodica Nitu, Mareile Wolff, Eva Mekis, Roy Rasmussen, Bruce Baker, Michael E. Earle, Audrey Reverdin, Kai Wong, Craig D. Smith, Daqing Yang, Yves-Alain Roulet, Tilden Meyers, Samuel Buisan, Ketil Isaksen, Ragnar Brækkan, Scott Landolt, and Al Jachcik Hydrol. Earth Syst. Sci., 22, 1437-1452, https://doi.org/10.5194/hess-22-1437-2018, 2018 Due to the effects of wind, precipitation gauges typically underestimate the amount of precipitation that occurs as snow. Measurements recorded during a World Meteorological Organization intercomparison of precipitation gauges were used to evaluate and improve the adjustments that are available to address this issue. Adjustments for specific types of precipitation gauges and wind shields were tested and recommended.

Description: Land-use change may exacerbate climate change impacts on water resources in the Ganges basin Gina Tsarouchi and Wouter Buytaert Hydrol. Earth Syst. Sci., 22, 1411-1435, https://doi.org/10.5194/hess-22-1411-2018, 2018 This work quantifies how future land-use and climate change may affect the hydrology of the Upper Ganges basin. Three sets of modelling experiments are run for the period 2000–2035, considering (1) only climate change, (2) only land-use change and (3) both climate and land-use change. Results point towards a severe increase in high flows. The changes are greater in the combined land-use and climate change experiment. We also show that future winter water demands in the region may not be met.

Description: Informing a hydrological model of the Ogooué with multi-mission remote sensing data Cecile M. M. Kittel, Karina Nielsen, Christian Tøttrup, and Peter Bauer-Gottwein Hydrol. Earth Syst. Sci., 22, 1453-1472, https://doi.org/10.5194/hess-22-1453-2018, 2018 In this study, we integrate free, global Earth observations in a user-friendly and flexible model to reliably characterize an otherwise unmonitored river basin. The proposed model is the best baseline characterization of the Ogooué basin in light of available observations. Furthermore, the study shows the potential of using new, publicly available Earth observations and a suitable model structure to obtain new information in poorly monitored or remote areas and to support user requirements.

Description: Scenario approach for the seasonal forecast of Kharif flows from the Upper Indus Basin Muhammad Fraz Ismail and Wolfgang Bogacki Hydrol. Earth Syst. Sci., 22, 1391-1409, https://doi.org/10.5194/hess-22-1391-2018, 2018 Snow and glacial melt runoff are the major sources of water contribution from the high mountainous terrain of the Indus River upstream of the Tarbela reservoir. A reliable forecast of seasonal water availability for the Kharif cropping season (April–September) can pave the way towards better water management and a subsequent boost in the agro-economy of Pakistan. The use of degree-day models in conjunction with satellite-based remote-sensing data for the forecasting of seasonal snow and ice melt runoff has proved to be a suitable approach for data-scarce regions. In the present research, the Snowmelt Runoff Model (SRM) has not only been enhanced by incorporating the glacier (G) component but also applied for the forecast of seasonal water availability from the Upper Indus Basin (UIB). Excel-based SRM+G takes account of separate degree-day factors for snow and glacier melt processes. All-year simulation runs with SRM+G for the period 2003–2014 result in an average flow component distribution of 53, 21, and 26 % for snow, glacier, and rain, respectively. The UIB has been divided into Upper and Lower parts because of the different climatic conditions in the Tibetan Plateau. The scenario approach for seasonal forecasting, which like the Ensemble Streamflow Prediction method uses historic meteorology as model forcings, has proven to be adequate for long-term water availability forecasts. The accuracy of the forecast with a mean absolute percentage error (MAPE) of 9.5 % could be slightly improved compared to two existing operational forecasts for the UIB, and the bias could be reduced to −2.0 %. However, the association between forecasts and observations as well as the skill in predicting extreme conditions is rather weak for all three models, which motivates further research on the selection of a subset of ensemble members according to forecasted seasonal anomalies.

Description: IO-Link Wireless enhanced factory automation communication for Industry 4.0 applications Ralf Heynicke, Dmytro Krush, Christoph Cammin, Gerd Scholl, Bernd Kaercher, Jochen Ritter, Pascal Gaggero, and Markus Rentschler J. Sens. Sens. Syst., 7, 131-142, https://doi.org/10.5194/jsss-7-131-2018, 2018 In the context of the Industry 4.0 initiative, Cyber-Physical Production Systems (CPPS) or Cyber Manufacturing Systems (CMS) can be characterized as advanced networked mechatronic production systems gaining their added value by interaction with the ambient Industrial Internet of Things (IIoT). In this context IO-Link is one of the actual communication standards. This article presents IO-Link Wireless as the wireless extension to IO-Link.

Description: The influence of intraocular pressure on the damping of a coupled speaker–air–eye system Jan Osmers, Ágnes Patzkó, Oskar Hoppe, Michael Sorg, Axel von Freyberg, and Andreas Fischer J. Sens. Sens. Syst., 7, 123-130, https://doi.org/10.5194/jsss-7-123-2018, 2018 Glaucoma is the leading cause of irreversible blindness worldwide. The laboratory results of a novel measurement approach for the internal eye pressure are presented, with an uncertainty of less than 1 mmHg. A physical model explaining the relation between eye pressure and the damping ratio of a coupled mechanical system is defined. This provides design parameters for a handheld self-tonometer for Glaucoma diagnosis and therapeutic follow-up, with high application potential in ophthalmology.

Description: Combined distributed Raman and Bragg fiber temperature sensing using incoherent optical frequency domain reflectometry Max Koeppel, Stefan Werzinger, Thomas Ringel, Peter Bechtold, Torsten Thiel, Rainer Engelbrecht, Thomas Bosselmann, and Bernhard Schmauss J. Sens. Sens. Syst., 7, 91-100, https://doi.org/10.5194/jsss-7-91-2018, 2018 Optical temperature sensors offer unique features which make them indispensable for key industries such as the energy sector. However, commercially available systems are designed to perform either distributed or hot spot temperature measurements. We have combined two measurement concepts to overcome this limitation, which allow distributed temperature measurements to be performed simultaneously with read-outs of optical hot spot temperature sensors at distinct positions along a fiber.

Description: A pathway to eliminate the gas flow dependency of a hydrocarbon sensor for automotive exhaust applications Gunter Hagen, Antonia Harsch, and Ralf Moos J. Sens. Sens. Syst., 7, 79-84, https://doi.org/10.5194/jsss-7-79-2018, 2018 Monitoring hydrocarbon concentrations in automotive exhausts is affected by flow rate changes. The signal of thermoelectric gas sensors is a thermovoltage. Its origin is a temperature difference that depends on the flow rate. To avoid this noise effect, the sensor can be installed in a defined bypass position. As shown by simulation and experiments, the gas flow around the sensor is almost turbulence-free and the signal only depends on the hydrocarbon concentration and not on the flow rate.

Description: An SQP method for Chebyshev and hole-pattern fitting with geometrical elements Daniel Hutzschenreuter, Frank Härtig, and Markus Schmidt J. Sens. Sens. Syst., 7, 57-67, https://doi.org/10.5194/jsss-7-57-2018, 2018 The work proposes a fast and accurate algorithm for the calculation of geometrical shapes and fits in three-dimensional product measurement applications. The algorithm is presented in detail. Furthermore, test calculations are made for an assembly simulation with a flange ring. The research was founded by the federal agency of economic affairs and energy of Germany within the scope of the technology transfer program MNPQ-Transfer.

Description: Novel thermocouples for automotive applications Paul Gierth, Lars Rebenklau, Klaus Augsburg, Eric Bachmann, and Lars Niedermeyer J. Sens. Sens. Syst., 7, 43-49, https://doi.org/10.5194/jsss-7-43-2018, 2018 Temperature measurement in engine and exhaust systems is necessary for thermal protection of parts and optimizing the combustion process. The basic idea of this novel sensor concept is to use thick-film technology on component surfaces. Different standardized and especially nonstandard material combinations have been produced for validation of this concept. Application-oriented measurements took place in the exhaust system of a test vehicle and were compared to standard laboratory conditions.

Description: Temperature reconstruction of infrared images with motion deblurring Beate Oswald-Tranta J. Sens. Sens. Syst., 7, 13-20, https://doi.org/10.5194/jsss-7-13-2018, 2018 Images of an infrared camera show blurring effects while recording a moving object. Not only the contrast is corrupted by the motion but also the object temperature seems to be lower. It is shown how such images and the true temperature with a good approximation can be restored. Since the detection mechanism of an infrared camera is different from usual digital cameras, also the restoration is different. Examples are presented for motion deblurring used to restore images with different motions.

Description: Module-based structure design of wheeled mobile robot Zirong Luo, Jianzhong Shang, Guowu Wei, and Lei Ren Mech. Sci., 9, 103-121, https://doi.org/10.5194/ms-9-103-2018, 2018 A systematic method was proposed for the synthesis and creative design of novel structures that can be used to build wheeled mobile robot. The proposed method has led to 236 new design schemes. Mathematical models and a software platform were developed to provide appropriate and intuitive tools for simulating and evaluating performance of the wheeled robots. Physical prototypes of sample wheeled robots were developed and tested, proving and validating the principle and methodology presented.

Description: Modelling, simulation and experiment of the spherical flexible joint stiffness Songyu Li, Liquan Wang, Shaoming Yao, Peng Jia, Feihong Yun, Wenxue Jin, and Dong Lv Mech. Sci., 9, 81-89, https://doi.org/10.5194/ms-9-81-2018, 2018 The spherical flexible joint is used to connect the Tension Leg Platform to the seabed. It can provide low shear stiffness while bearing high compression force. So the research on the stiffness of flexible joint is necessary. The linear rotational stiffness of the flexible joint is formulated and FEM is used to verify the analytical solution. The increase of Poisson's ratio of the rubber layers will enhance the vertical compression stiffness but barely have effect on the rotational stiffness.

Description: Heat transfer and MHD flow of non-newtonian Maxwell fluid through a parallel plate channel: analytical and numerical solution Alireza Rahbari, Morteza Abbasi, Iman Rahimipetroudi, Bengt Sundén, Davood Domiri Ganji, and Mehdi Gholami Mech. Sci., 9, 61-70, https://doi.org/10.5194/ms-9-61-2018, 2018 Analytical and numerical analyses have been performed to study the problem of magneto-hydrodynamic (MHD) flow and heat transfer of an upper-convected Maxwell fluid in a parallel plate channel. The Homotopy Analysis Method (HAM), Homotopy Perturbation Method (HPM) and fourth-order Runge-Kutta numerical method (NUM) are used to solve this problem. Also, velocity and temperature fields have been computed and shown graphically for various values of the important physical parameters.

Description: A self-adjusting stiffness center design for large stroke compliant XY nanomanipulators Zhiqing Liu, Zhen Zhang, and Peng Yan Mech. Sci., 9, 41-50, https://doi.org/10.5194/ms-9-41-2018, 2018 It is proposed a novel design method for large stroke XY compliant mechanisms. An important feature of the design lies in it restricts the parasitic rotation by reducing the moment of force instead of increasing the rotational stiffness widely utilized in the literature. It is presented a millimeter stroke XY nanomanipulator with the proposed design based redundant constraint in a case study. The proposed design provides an alternative to reduce the parasitic rotation of XY compliant mechanism.

Description: Prediction of surface location error in milling considering the effects of uncertain factors Xianzhen Huang, Fangjun Jia, Yimin Zhang, and Jinhua Lian Mech. Sci., 8, 385-392, https://doi.org/10.5194/ms-8-385-2017, 2017 Machining accuracy of a milled surface is influenced by process dynamics. Surface location error (SLE) in milling determines final dimensional accuracy of the finished surface. Therefore, it is critical to predict, control, and minimize SLE. In traditional methods, the effects of uncertain factors are usually ignored during prediction of SLE, and this would tend to generate estimation errors. In order to solve this problem, this paper presents methods for probabilistic analysis of SLE in milling. A dynamic model for milling process is built to determine relationship between SLE and cutting parameters using full-discretization method (FDM). Monte-Carlo simulation (MCS) method and artificial neural network (ANN) based MCS method are proposed for predicting reliability of the milling process. Finally, a numerical example is used to evaluate the accuracy and efficiency of the proposed method.

Description: A modified pseudo-rigid-body modeling approach for compliant mechanisms with fixed-guided beam flexures Pengbo Liu and Peng Yan Mech. Sci., 8, 359-368, https://doi.org/10.5194/ms-8-359-2017, 2017 In the present paper, we investigate a modified pseudo-rigid-body (MPRB) modeling approach for compliant mechanisms with fixed-guided beam flexures by considering the load-dependent property. The proposed MPRB model provides a more analytical and accurate method to predict the performance characteristics such as deformation capability, stiffness variation, as well as error motions of complaint mechanisms and offers a new look into the design and optimization of beam-based compliant mechanisms.

Description: Design and evaluation of a new exoskeleton for gait rehabilitation Ionut Daniel Geonea and Daniela Tarnita Mech. Sci., 8, 307-321, https://doi.org/10.5194/ms-8-307-2017, 2017 A new exoskeleton for human gait motion assistance and rehabilitation is proposed, to investigate motion capabilities and feasibility. Human gait analysis on healthy and disabled subjects is performed to obtain references motion laws for normal gait. A dynamic simulation model of exoskeleton is achieved in ADAMS computational environment. The exoskeleton prototype motion laws, resulted from motion analysis based on ultra speed video cameras are compared with human subject motion laws.

Description: Brief communication: Electron pair donors and Earth's energy generation Frederick Mayer Nonlin. Processes Geophys. Discuss., https//doi.org/10.5194/npg-2018-13,2018 Manuscript under review for NPG (discussion: open, 0 comments) This paper presents a comparison of two processes that start the generation of energy from the Earth. It does this by using a sequence of equations to provide the level of either process by using previously determined from geophysical measurements far from active volcanic sites and a few hundred years after the activity. This work is necessary in order for us and other geophysicists to examine the various nuclei present in this energy generating process after the reactions are completed.

Description: Accelerating assimilation development for new observing systems using EFSO Guo-Yuan Lien, Daisuke Hotta, Eugenia Kalnay, Takemasa Miyoshi, and Tse-Chun Chen Nonlin. Processes Geophys., 25, 129-143, https://doi.org/10.5194/npg-25-129-2018, 2018 The ensemble forecast sensitivity to observation (EFSO) method can efficiently clarify under what conditions observations are beneficial or detrimental for assimilation. Based on EFSO, an offline assimilation method is proposed to accelerate the development of data selection strategies for new observing systems. The usefulness of this method is demonstrated with the assimilation of global satellite precipitation data.

Description: Stratified Kelvin-Helmholtz turbulence of compressible shear flows Romit Maulik and Omer San Nonlin. Processes Geophys. Discuss., https//doi.org/10.5194/npg-2017-67,2018 Manuscript under review for NPG (discussion: open, 7 comments) We study the scaling laws and structure functions of stratified shear flows by performing high-resolution numerical simulations of inviscid compressible turbulence induced by Kelvin-Helmholtz instability.

Description: Ensemble Kalman filter for the reconstruction of the Earth's mantle circulation Marie Bocher, Alexandre Fournier, and Nicolas Coltice Nonlin. Processes Geophys., 25, 99-123, https://doi.org/10.5194/npg-25-99-2018, 2018 We propose a new method to reconstruct the circulation in the Earth's mantle for the last 300 Myr. This method is based on the sequential assimilation of plate layouts obtained from plate tectonic reconstructions into mantle convection models. This method allows us to take into account uncertainties in plate tectonic reconstructions, and provides an estimation of the uncertainties in the final result. We test and validate this method in a controlled environment by using synthetic experiments.

Description: Preface: Current perspectives in modelling, monitoring, and predicting geophysical fluid dynamics Ana M. Mancho, Emilio Hernández-García, Cristóbal López, Antonio Turiel, Stephen Wiggins, and Vicente Pérez-Muñuzuri Nonlin. Processes Geophys., 25, 125-127, https://doi.org/10.5194/npg-25-125-2018, 2018 The third edition of the international workshop Nonlinear Processes in Oceanic and Atmospheric Flows was held at the Institute of Mathematical Sciences (ICMAT) in Madrid from 6 to 8 July 2016. The event gathered oceanographers, atmospheric scientists, physicists, and applied mathematicians sharing a common interest in the nonlinear dynamics of geophysical fluid flows. The philosophy of this meeting was to bring together researchers from a variety of backgrounds into an environment that favoured a vigorous discussion of concepts across different disciplines. The present Special Issue on Current perspectives in modelling, monitoring, and predicting geophysical fluid dynamics contains selected contributions, mainly from attendants of the workshop, providing an updated perspective on modelling aspects of geophysical flows as well as issues on prediction and assimilation of observational data and novel tools for describing transport and mixing processes in these contexts. More details on these aspects are discussed in this preface.

Description: Exceedance frequency of appearance of extreme internal waves in the World Ocean Tatyana Talipova, Efim Pelinovsky, Oxana Kurkina, Ayrat Giniyatullin, and Andrey Kurkin Nonlin. Processes Geophys. Discuss., https//doi.org/10.5194/npg-2018-12,2018 Manuscript under review for NPG (discussion: open, 2 comments) Strong internal waves have a significant influence on underwater marine environment and off-shore engineering facilities. They induce noticeable currents and take part in the processes of mixing of water layers, suspending and transport of sediment particles and formation of sea bottom relief. We consider probability of emergence of large-amplitude internal waves on a base of instrumental measurements of internal wave field in five different regions of the world ocean.

Description: Chaotic dynamics and the role of covariance inflation for reduced rank Kalman filters with model error Colin Grudzien, Alberto Carrassi, and Marc Bocquet Nonlin. Processes Geophys. Discuss., https//doi.org/10.5194/npg-2018-4,2018 Manuscript under review for NPG (discussion: open, 1 comment) While the butterfly effect renders the forecasting problem in chaotic physical applications inherently volatile, chaotic dynamics also put strong constraints on the evolution of prediction errors. Using the framework of chaotic dynamical systems, we analyze the asymptotic properties of ensemble based Kalman filters, and how these are influenced by the dynamical constraints in the model, especially in the context of random model errors and small ensemble sizes.

Description: Parametric covariance dynamics for the nonlinear diffusive Burgers' equation Olivier Pannekoucke, Marc Bocquet, and Richard Ménard Nonlin. Processes Geophys. Discuss., https//doi.org/10.5194/npg-2018-10,2018 Manuscript under review for NPG (discussion: open, 0 comments) The parametric Kalman filter (PKF) is a computationally efficient alternative method to the ensemble Kalman filter (EnKF). The PKF relies on an approximation of the error covariance matrix by a covariance model with space-time evolving set of parameters. This study extends the PKF to nonlinear dynamics using the diffusive Burgers' equation as an application, focusing on the forecast step of the assimilation cycle. The covariance model considered is based on the diffusion equation, with the diffusion tensor and the error variance as evolving parameter. An analytical derivation of the parameter dynamics highlights a closure issue. Therefore, a closure model is proposed based on the so-called kurtosis of the local correlation functions. Numerical experiments compare the PKF forecast with the statistics obtained from an large ensemble of nonlinear forecasts. These experiments strengthen the closure model and demonstrate the ability of the PKF to reproduce the tangent-linear covariance dynamics, at a low numerical cost.

Description: Derivation of the entropic formula for the statistical mechanics of space plasmas George Livadiotis Nonlin. Processes Geophys., 25, 77-88, https://doi.org/10.5194/npg-25-77-2018, 2018 Kappa distributions are frequently used for modeling space plasmas, but their physical origin remains unknown. Recently we realized that the statistical origin of these distributions is not the classical Boltzmann entropy, but the Tsallis q entropy. Thereafter, the question was about the physical origin of this entropic formula. Here we show that the q entropy can be derived under first principles, i.e., by considering that the energy and entropy are additive quantities under certain conditions.

Description: Optimal transport for variational data assimilation Nelson Feyeux, Arthur Vidard, and Maëlle Nodet Nonlin. Processes Geophys., 25, 55-66, https://doi.org/10.5194/npg-25-55-2018, 2018 In geophysics, numerical models are generally initialized through so-called data assimilation methods. They require computation of a distance between model fields and physical observations. The most common choice is the Euclidian distance. However, due to its local nature it is not well suited for capturing position errors. This papers investigates theoretical aspects of the use of the optimal transport-based Wasserstein distance in this context and shows that it is able to capture such errors.

Description: Tipping point analysis of ocean acoustic noise Valerie N. Livina, Albert Brouwer, Peter Harris, Lian Wang, Kostas Sotirakopoulos, and Stephen Robinson Nonlin. Processes Geophys., 25, 89-97, https://doi.org/10.5194/npg-25-89-2018, 2018 We have applied tipping point analysis to a large record of ocean acoustic data to identify the main components of the acoustic dynamical system: long-term and seasonal trends, system states and fluctuations. We reconstructed a one-dimensional stochastic model equation to approximate the acoustic dynamical system. We have found a signature of El Niño events in the deep ocean acoustic data near the southwest Australian coast, which proves the investigative power of the tipping point methodology.

Description: Sensitivity analysis with respect to observations in variational data assimilation Victor Shutyaev, Francois-Xavier Le Dimet, and Eugene Parmuzin Nonlin. Processes Geophys. Discuss., https//doi.org/10.5194/npg-2018-8,2018 Manuscript under review for NPG (discussion: open, 0 comments) The problem of variational data assimilation for a nonlinear evolution model is formulated as an optimal control problem to find unknown parameters of the model. The observation data, and hence the optimal solution, may contain uncertainties. A response function is considered as a functional of the optimal solution after assimilation. Based on the second-order adjoint techniques, the sensitivity of the response function to the observation data is studied. The gradient of the response function is related to the solution of a non-standard problem involving the coupled system of direct and adjoint equations. The non-standard problem is studied, based on the Hessian of the original cost function. An algorithm to compute the gradient of the response function with respect to observations is presented. Numerical example is given for variational data assimilation problem related to sea surface temperature for the Baltic Sea thermodynamics model.

Description: A correlation study regarding the AE index and ACE solar wind data for Alfvénic intervals using wavelet decomposition and reconstruction Fernando L. Guarnieri, Bruce T. Tsurutani, Luis E. A. Vieira, Rajkumar Hajra, Ezequiel Echer, Anthony J. Mannucci, and Walter D. Gonzalez Nonlin. Processes Geophys., 25, 67-76, https://doi.org/10.5194/npg-25-67-2018, 2018 In this work we developed a method to obtain a time series named as AE* which is well correlated with the geomagnetic AE index. In this process, wavelet filtering is applied to interplanetary solar wind data from spacecrafts around the L1 libration point. This geomagnetic indicator AE* can be obtained well before the AE index release in its final form, and it can be used to feed models for geomagnetic effects, such as the relativistic electrons, giving forecasts ~ 1 to 2 days in advance.

Description: Intermittent turbulence in the heliosheath and the magnetosheath plasmas based on Voyager and THEMIS data Wiesław M. Macek, Anna Wawrzaszek, and Beata Kucharuk Nonlin. Processes Geophys., 25, 39-54, https://doi.org/10.5194/npg-25-39-2018, 2018 The aim of this review is a comparison of intermittency in the heliosphere and the magnetosphere. We show that turbulence in the heliosheath and even at the heliospheric boundaries is intermittent. Moreover, analysis of turbulence in the magnetosheath shows that for very high Alfvénic Mach numbers and high plasma beta we have non-Gaussian statistics in the transverse directions. However, for directions parallel to the magnetic fields, the plasma is close to equilibrium.

Description: On the intrinsic timescales of temporal variability in measurements of the surface solar radiation Marc Bengulescu, Philippe Blanc, and Lucien Wald Nonlin. Processes Geophys., 25, 19-37, https://doi.org/10.5194/npg-25-19-2018, 2018 We employ the Hilbert–Huang transform to study the temporal variability in time series of daily means of the surface solar irradiance (SSI) at different locations around the world. The data have a significant spectral peak corresponding to the yearly variability cycle and feature quasi-stochastic high-frequency "weather noise", irrespective of the geographical location or of the local climate. Our findings can improve models for estimating SSI from satellite images or forecasts of the SSI.

Description: Decorrelation scales for Arctic Ocean hydrography – Part I: Amerasian Basin Hiroshi Sumata, Frank Kauker, Michael Karcher, Benjamin Rabe, Mary-Louise Timmermans, Axel Behrendt, Rüdiger Gerdes, Ursula Schauer, Koji Shimada, Kyoung-Ho Cho, and Takashi Kikuchi Ocean Sci., 14, 161-185, https://doi.org/10.5194/os-14-161-2018, 2018 We estimated spatial and temporal decorrelation scales of temperature and salinity in the Amerasian Basin in the Arctic Ocean. The estimated scales can be applied to representation error assessment in the ocean data assimilation system for the Arctic Ocean.

Description: Wind induced variability in the Northern Current (North-Western Mediterranean Sea) as depicted by a multi-platform observing system Maristella Berta, Lucio Bellomo, Annalisa Griffa, Marcello Magaldi, Anne Molcard, Carlo Mantovani, Gian Pietro Gasparini, Julien Marmain, Anna Vetrano, Laurent Béguery, Mireno Borghini, Yves Barbin, Joel Gaggelli, and Céline Quentin Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-20,2018 Manuscript under review for OS (discussion: open, 0 comments) The variability of the Northern Current (NC) in the NW Med Sea is studied using data from observations and models. The NC variability is dominated by a synoptic response to wind events, even though a seasonal trend is also observed. The combination of autonomous observing platforms with classical marine surveys provides high resolution datasets useful for specific scientific purposes but also for practical applications such as the management of marine shared resources in the Mediterranean Sea.

Description: Electromagnetic characteristics of ENSO Johannes Petereit, Jan Saynisch, Christopher Irrgang, Tobias Weber, and Maik Thomas Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-4,2018 Manuscript under review for OS (discussion: open, 0 comments) The study finds that changes of seawater temperature due to El Nino and La Nina, anomalous warm and cold events, are in principle detectable by means of the oceanic tidal induced magnetic field. Furthermore, subsurface processes in the onset of those anomalous events lead the surface processes by several month. These effect cause a lead in the oceanic tidal induced magnetic field signals over seasurface temperature signals.

Description: Effect of winds and waves on salt intrusion in the Pearl River estuary Wenping Gong, Zhongyuan Lin, Yunzhen Chen, Zhaoyun Chen, and Heng Zhang Ocean Sci., 14, 139-159, https://doi.org/10.5194/os-14-139-2018, 2018 Salt intrusion in the Pearl River Estuary is a dynamic process that is influenced by a range of factors, and few studies have examined the effects of winds and waves. Therefore, we investigate these effects using the Coupled Ocean-Atmosphere-Wave-Sediment Transport modeling system in this region. It was found that enhancement of the salt intrusion is comparable between the remote and local winds. Waves decrease the salt intrusion by increasing the water mixing.

Description: Observations of brine plumes below melting Arctic sea ice Algot K. Peterson Ocean Sci., 14, 127-138, https://doi.org/10.5194/os-14-127-2018, 2018 This study presents observations of brine descending from melting Arctic sea ice. The brine passed an under-ice turbulence instrument in plumes and was associated with very high heat fluxes. The salt flux indicates that the melting sea ice lost most of its salt content during the observations. The observations provide evidence of a desalination process not previously reported from drifting Arctic sea ice and is an important contribution to understanding ice–ocean interaction during melt.

Description: Numerical modeling of surface wave development under the action of wind Dmitry Chalikov Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-11,2018 Manuscript under review for OS (discussion: open, 0 comments) Waves obtain the energy from wind; they grow, increase their size and the speed of propagation. The structure of wave field becomes complicated due to appearance of the new wave components. Finally, the sea surface looks as a poorly organized motion consisting of quickly running large hills and hollows covered with smaller waves. This process can be successfully simulated at computers. Such investigations allow us to understand the physics of sea waves, which is important for practice.

Description: Wind induced variability in the Northern Current (North-Western Mediterranean Sea) as depicted by a multi-platform observing system Maristella Berta, Lucio Bellomo, Annalisa Griffa, Marcello Magaldi, Anne Molcard, Carlo Mantovani, Gian Pietro Gasparini, Julien Marmain, Anna Vetrano, Laurent Béguery, Mireno Borghini, Yves Barbin, Joel Gaggelli, and Céline Quentin Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-20,2018 Manuscript under review for OS (discussion: open, 0 comments) The variability of the Northern Current (NC) in the NW Med Sea is studied using data from observations and models. The NC variability is dominated by a synoptic response to wind events, even though a seasonal trend is also observed. The combination of autonomous observing platforms with classical marine surveys provides high resolution datasets useful for specific scientific purposes but also for practical applications such as the management of marine shared resources in the Mediterranean Sea.

Description: Numerical modeling of surface wave development under the action of wind Dmitry Chalikov Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-11,2018 Manuscript under review for OS (discussion: open, 0 comments) Waves obtain the energy from wind; they grow, increase their size and the speed of propagation. The structure of wave field becomes complicated due to appearance of the new wave components. Finally, the sea surface looks as a poorly organized motion consisting of quickly running large hills and hollows covered with smaller waves. This process can be successfully simulated at computers. Such investigations allow us to understand the physics of sea waves, which is important for practice.

Description: Mixed layer depth variability in the Red Sea Cheriyeri P. Abdulla, Mohammed A. Alsaafani, Turki M. Alraddadi, and Alaa M. Albarakati Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-6,2018 Manuscript under review for OS (discussion: open, 0 comments) For the first time in the Red Sea, a monthly climatology of mixed layer depth (MLD) has been derived based on in-situ temperature profiles. The Red Sea MLD pattern displays significant spatial and temporal variability with exceptional features. The MLD variability is dominantly driven by the wind stress in the southern part while heat exchange plays a major role in the remaining parts. The eddies and the Tokar gap summer jet winds are significantly changing the MLD of the localized regions.

Description: An analytical study of M 2 tidal waves in the Taiwan Strait using an extended Taylor method Di Wu, Guohong Fang, Xinmei Cui, and Fei Teng Ocean Sci., 14, 117-126, https://doi.org/10.5194/os-14-117-2018, 2018 Taylor's problem is a classical tidal dynamic problem and in its previous applications all of the studied basins had a closed end. In this study, the Taylor's method is extended so that it can also provide an analytical model for the M 2 tide in the Taiwan Strait (TS), which shows that the reflection of the southward wave at the abruptly deepened topography south of the TS is a major contribution to the formation of the northward propagating wave in the strait.

Description: Dynamics of North Balearic Front during an autumn Tramontane and Mistral storm: air–sea coupling processes and stratification budget diagnostic Léo Seyfried, Claude Estournel, Patrick Marsaleix, and Evelyne Richard Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-14,2018 Manuscript under review for OS (discussion: open, 0 comments) The north Balearic front forms the southern branch of the cyclonic gyre in the North Western Mediterranean Sea. Its dynamics exhibits significant seasonal variability. During autumn, the front spreads northward during the calm wind periods and rapidly moves back southward when it is exposed to strong northerly wind events such as the Tramontane and Mistral. These strong winds considerably enhance the air–sea exchanges. To investigate the role of air–sea exchanges on the dynamics of the North Balearic front, we used observations and a high-resolution air–sea coupled modelling system, and focused on a strong wind event observed in late October 2012, which was well-documented during the Hydrological Cycle Mediterranean Experiment. The coupled model was able to correctly reproduce the 4 °C sea surface temperature drop recorded in the frontal zone together with the observed southwestward displacement of the front. The comparison between the weak wind period preceding the event and the strong wind event itself highlighted the impact of the wind regime on the air–sea coupling, with both thermal and dynamical couplings during the low wind period and mainly thermal coupling during the strong wind period. The effect of air–sea exchanges on the stratification variations in the frontal zone was investigated with a stratification budget diagnosis. The stratification variations are controlled by diabatic air–sea buoyancy flux, adiabatic Ekman buoyancy flux, and advective processes. During the strong wind period, the Ekman buoyancy flux was found to be three times greater than the air–sea buoyancy flux and thus played a major role in the destratification of the frontal zone. The role of Ekman pumping and inertial wave on the advective processes is also discussed.

Description: Assimilating High-resolution Sea Surface Temperature Data Improves the Ocean Forecast in the Baltic Sea Ye Liu and Weiwei Fu Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-8,2018 Manuscript under review for OS (discussion: open, 0 comments) We assess the impact of assimilating the SST data on the Baltic forecast by comparing with both independent and dependent observations. we find that the quality of SST forecast is considerably enhanced by data assimilation. To the Baltic forecast, the temperature in the water above 100 m and salinity in the deep layers have been largely and slightly improved by the SST assimilation, respectively. Besides, the forecasts of both SLA and sea ice are improved in the Baltic Sea by assimilating SST.

Description: ADCP observations of migration patterns of zooplankton in the Cretan Sea Emmanuel Potiris, Constantin Frangoulis, Alkiviadis Kalampokis, Manolis Ntoumas, Manos Pettas, George Petihakis, and Vassilis Zervakis Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-10,2018 Manuscript under review for OS (discussion: open, 0 comments) Zooplankton and fishes living deeper than 200 m, may perform a vertical migration to the surface waters. The migration patterns, from 400 m depth to the surface, of four groups of organisms were studied in the deep (1500 m) Eastern Mediterranean (Cretan Sea) for 2.5 years. The lunar cycle, daylight duration, cloudiness, the presence of prey and predators explains their migration variability. This phenomenon is important as it constitutes an active transport of organic matter over large distances.

Description: Some aspects of the deep abyssal overflow between the middle and southern basins of the Caspian Sea Javad Babagoli Matikolaei, Abbasali Aliakbari Bidokhti, and Maryam Shiea Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-13,2018 Manuscript under review for OS (discussion: open, 0 comments) This study investigates the deep gravity current between the middle and southern Caspian Sea basins, caused by density difference of deep waters. Oceanographic data, numerical model and dynamic models are used to consider the structure of this Caspian Sea abyssal overflow. The CTD data are obtained from UNESCO, and the three-dimensional ocean model COHERENS results are used to study the abyssal currents in the southern basin of the Caspian Sea. The deep overflow is driven by the density difference mainly due to the temperature difference between the middle and southern basins especially in winter. For this reason, water sinks in high latitudes and after filling the middle basin it overflows into the southern basin. As the current passes through the Absheron Strait (or sill), we use an analytic model for the overflow gravity current with inertial effects, bottom friction and entrainment, to consider its structure. The dynamical characteristics of this deep baroclinic flow are investigated with different initial and boundary conditions. The results show that after time passes, the flow adjusts itself, moving as a deepening gravity driven topographically trapped current. This flow is considered for different seasons and its velocity and width are obtained. Because of the topography of the Southern Caspian basin, the flow is trapped after the sill; thus, another simple dynamical model of the overflow, based on potential vorticity similar to that of Bidokhti and Ezam (2009) but with the bottom friction and entrainment included, is used to find the horizontal extent of the outflow from the western coast. To estimate the changes of vorticity and potential vorticity of the flow over the Absheron sill, we use the method of Falcini and Salusti (2015), in this work, the effects of entrainment and friction are considered. Because of the importance of the overflow in deep water ventilation, a simple dynamical model of the boundary currents based on the shape of strait is used to estimate typical mass transport and flushing time which is found to be about 15 to 20 years for the southern basin of the Caspian Sea. This time scale is important for the possible effects on the ecosystem here of pollution due to oil exploration.

Description: Using kinetic energy measurements from altimetry to detect shifts in the positions of fronts in the Southern Ocean Don P. Chambers Ocean Sci., 14, 105-116, https://doi.org/10.5194/os-14-105-2018, 2018 A novel analysis is performed utilizing ocean current kinetic energy computed from from along-track satellite altimetry data from 1993 to 2015. The position of enhanced kinetic energy is used to detect shifts in frontal positions in the Southern Ocean. Results indicate no significant shift in the front positions across the Southern Ocean, on average, although there are some localized, large movements, both north and south.

Description: Numerical study of hydrodynamic and salinity transport process in Pink Beach wetlands of Liao River Estuary, China Huiting Qiao, Mingliang Zhang, Hengzhi Jiang, Tianping Xu, and Hongxing Zhang Ocean Sci. Discuss., https//doi.org/10.5194/os-2017-102,2018 Manuscript under review for OS (discussion: open, 1 comment) Suaeda heteroptera is a dominant species in the wetland of Liao River estuary and a typical saline-alkaline indicator plant, which is distributed in coastal tidal flat, forming a rare natural landscape pink beach . The MIKE 21 model is used to simulate the hydrodynamic characteristics and salinity transport process in Pink Beach wetlands of Liao River estuary. The results are important to understand the suitable circumstances for the vegetation growth in Pink Beach.

Description: Dissolved organic matter and its optical characteristics in the Laptev and East Siberian seas: spatial distribution and interannual variability (2003–2011) Svetlana P. Pugach, Irina I. Pipko, Natalia E. Shakhova, Evgeny A. Shirshin, Irina V. Perminova, Örjan Gustafsson, Valery G. Bondur, Alexey S. Ruban, and Igor P. Semiletov Ocean Sci., 14, 87-103, https://doi.org/10.5194/os-14-87-2018, 2018 This paper explores the possibility of using CDOM and its spectral parameters to identify the different biogeochemical regimes on the ESAS. The strong correlation between DOC and CDOM values in the surface shelf waters influenced by terrigenous discharge indicates that it is feasible to estimate DOC content from CDOM fluorescence assessed in situ. The direct estimation of DOM optical parameters in the surface ESAS waters provided by this study will be useful for validating remote sensing data.

Description: An integrated open-coastal biogeochemistry, ecosystem and biodiversity observatory of the Eastern Mediterranean. The Cretan Sea component of POSEIDON system George Petihakis, Leonidas Perivoliotis, Gerasimos Korres, Dionysis Ballas, Constantin Frangoulis, Paris Pagonis, Manolis Ntoumas, Manos Pettas, Antonis Chalkiopoulos, Maria Sotiropoulou, Margarita Bekiari, Alkiviadis Kalampokis, Michalis Ravdas, Evi Bourma, Sylvia Christodoulaki, Anna Zacharioudaki, Dimitris Kassis, Emmanuel Potiris, George Triantafyllou, Kostas Tsiaras, Evangelia Krasakopoulou, Spyros Velanas, and Nikos Zisis Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-3,2018 Manuscript under review for OS (discussion: open, 2 comments) Oceanic observations that examine several processes including biogeochemical ones are scarce. In the Eastern Mediterranean (Cretan Sea) the spatiotemporal coverage of such observations has increased with the expansion of the POSEIDON observatory. The observatory addresses scientific questions, provides services to policy-makers and society and serves as a technological test bed. It plays a key role in European and international observing programs, in harmonization procedures and data handling.

Description: South Atlantic meridional transports from NEMO-based simulations and reanalyses Davi Mignac, David Ferreira, and Keith Haines Ocean Sci., 14, 53-68, https://doi.org/10.5194/os-14-53-2018, 2018 Four ocean reanalyses and two free-running models are compared to study the meridional transports in the South Atlantic. We analyse the underlying causes of the product differences in an attempt to understand the potential impact (and limitations) of the data assimilation (DA) in improving the simulated ocean states. The DA schemes can consistently constrain the basin interior transports, but not the overturning circulation dominated by the narrow South Atlantic western boundary currents.

Description: Response of O 2 and pH to ENSO in the California Current System in a high-resolution global climate model Giuliana Turi, Michael Alexander, Nicole S. Lovenduski, Antonietta Capotondi, James Scott, Charles Stock, John Dunne, Jasmin John, and Michael Jacox Ocean Sci., 14, 69-86, https://doi.org/10.5194/os-14-69-2018, 2018 A high-resolution global model was used to study the influence of El Niño/La Niña events on the California Current System (CalCS). The mean surface oxygen (O 2 ) response extends well offshore, where the pH response occurs within ~ 100 km of the coast. The surface O 2 (pH) is primarily driven by temperature (upwelling) changes. Below 100 m, anomalously low O 2 and low pH occurred during La Niña events near the coast, potentially stressing the ecosystem, but there are large variations between events.

Description: Impact of mesoscale eddies on water mass and oxygen distribution in the eastern tropical South Pacific Rena Czeschel, Florian Schütte, Robert A. Weller, and Lothar Stramma Ocean Sci. Discuss., https//doi.org/10.5194/os-2018-5,2018 Manuscript under review for OS (discussion: open, 1 comment) The mean circulation on the poleward side of the Oxygen Minimum Zone is overlain by eddy activity playing an important role in the distribution of water masses and oxygen within the OMZ. The activity of different types of eddies was investigated during their westward propagation from the formation area off Peru/Chile into the open ocean. The focus was on the development of eddies, seasonal conditions during their formation and the change of water mass properties transported within the eddies.

Description: Spatial and temporal analysis of fatal off-piste and backcountry avalanche accidents in Austria with a comparison of results in Switzerland, France, Italy and the US Christian Pfeifer, Peter Höller, and Achim Zeileis Nat. Hazards Earth Syst. Sci., 18, 571-582, https://doi.org/10.5194/nhess-18-571-2018, 2018 In this article we analyzed spatial and temporal patterns of fatal Austrian avalanche accidents caused by backcountry and off-piste skiers and snowboarders within the winter periods 1967/1968–2015/2016. As a result of the trend analysis, we noticed an increasing trend of backcountry and off-piste avalanche fatalities within the winter periods 1967/1968–2015/2016. As a result of the spatial analysis, we noticed two hot spots of avalanche fatalities ( Arlberg–Silvretta and Sölden ).

Description: Modelling the water energy nexus: should variability in water supply impact on decision making for future energy supply options? James D. S. Cullis, Nicholas J. Walker, Fadiel Ahjum, and Diego Juan Rodriguez Proc. IAHS, 376, 3-8, https://doi.org/10.5194/piahs-376-3-2018, 2018 This study describes a model for incorporating regional variability in water supply costs into an energy planning model and the impacts of this on the most sustainable future energy mix for a country as well as the potential impact that energy related policies can have on the future of water supply availability in different regions. Modeling of the water-energy nexus is particularly relevant as water supply becomes more variable due to climate change and a potential constraint on development.

Description: Water impacts and water-climate goal conflicts of local energy choices – notes from a Swedish perspective Rebecka Ericsdotter Engström, Mark Howells, and Georgia Destouni Proc. IAHS, 376, 25-33, https://doi.org/10.5194/piahs-376-25-2018, 2018 To meet the global goals (SDGs) on energy and climate, local communities must move towards sustainable energy systems. Our study explores the indirect water uses linked to the supply of energy in 21 counties of Sweden – the country considered to be most advanced towards meeting the SDGs. Results show that the quantity and geography of energy-related water use vary greatly between counties. Further, local inventories of CO 2 -emissions or direct water use poorly correlate with these variation.

Description: An integrated approach to improving rural livelihoods: examples from India and Bangladesh Barry Croke, Wendy Merritt, Peter Cornish, Geoffrey J. Syme, and Christian H. Roth Proc. IAHS, 376, 45-50, https://doi.org/10.5194/piahs-376-45-2018, 2018 Water and food security are vital for improving livelihoods in disadvantaged rural areas. Understanding the water cycle is central to the design of watershed development works intended to improve water security. Better farming practices can help improve food security. It is also vital for social constraints and equity to be considered. Finally, a participatory learning approach is useful for ensuring that watershed development work is effective in producing long-term improvement in livelihoods.

Description: Supporting better decisions across the nexus of water, energy and food through earth observation data: case of the Zambezi basin Fortune Faith Gomo, Christopher Macleod, John Rowan, Jagadeesh Yeluripati, and Kairsty Topp Proc. IAHS, 376, 15-23, https://doi.org/10.5194/piahs-376-15-2018, 2018 The water–energy–food (WEF) nexus has been promoted in recent years as an intersectional concept designed to improve planning and regulatory decision-making across the three sectors. The production and consumption of water, energy and food resources are inextricably linked across multiple spatial scales (from the global to the local), but a common feature is competition for land which through different land management practices mediates provisioning ecosystem services. The nexus perspective seeks to understand the interlinkages and use systems-based thinking to frame management options for the present and the future. It aims to highlight advantage and minimise damaging and unsustainable outcomes through informed decisions regarding trade-offs inclusive of economic, ecological and equity considerations. Operationalizing the WEF approach is difficult because of the lack of complete data, knowledge and observability – and the nature of the challenge also depends on the scale of the investigation. Transboundary river basins are particularly challenging because whilst the basin unit defines the hydrological system this is not necessarily coincident with flows of food and energy. There are multiple national jurisdictions and geopolitical relations to consider. Land use changes have a profound influence on hydrological, agricultural, energy provisioning and regulating ecosystem services. Future policy decisions in the water, energy and food sectors could have profound effects, with different demands for land and water resources, intensifying competition for these resources in the future. In this study, we used Google Earth Engine (GEE) to analyse the land cover changes in the Zambezi river basin (1.4 million km 2 ) from 1992 to 2015 using the European Space Agency annual global land cover dataset. Early results indicate transformative processes are underway with significant shifts from tree cover to cropland, with a 4.6 % loss in tree cover and a 16 % gain in cropland during the study period. The changes were found to be occurring mainly in the eastern (Malawi and Mozambique) and southern (Zimbabwe and southern Zambia) parts of the basin. The area under urban land uses was found to have more than doubled during the study period gearing urban centres increasingly as the foci for resource consumption. These preliminary findings are the first step in understanding the spatial and temporal interlinkages of water, energy and food by providing reliable and consistent evidence spanning the local, regional, national and whole transboundary basin scale.

Description: A half-baked solution: drivers of water crises in Mexico Jonatan Godinez Madrigal, Pieter van der Zaag, and Nora van Cauwenbergh Proc. IAHS, 376, 57-62, https://doi.org/10.5194/piahs-376-57-2018, 2018 A part of the population of Mexico is undergoing severe water crises vis-a-vis with the quantity and quality of water. The water authority's strategy dwells solely in infrastructure development to tackle the symptoms, not the causes. The paper summarizes how the causes of crises lie not in the lack of infrastructure but in a deficient management and governance. I did the research because I'd to influence on policy, and I did it through fieldwork and critical literature review.

Description: Conceptual framework to ensure water security in Ukraine Yaroslav Gadzalo, Mykhailo Romashchenko, and Mykhailo Yatsiuk Proc. IAHS, 376, 63-68, https://doi.org/10.5194/piahs-376-63-2018, 2018 As a result of global climate change nowadays Ukraine is facing the problem of environmental degradation of river basins. Thus, achieving an acceptable level of water security in Ukraine should be defined as the strategic objective of national water policy. The basic principles of a new water policy are supposed to be represented in Water Strategy of Ukraine. Integrated water management by the basin principle should serve as a main tool for achieving the objectives of country's water security.

Description: Modelling the impact of mulching the soil with plant remains on water regime formation, crop yield and energy costs in agricultural ecosystems Yeugeniy M. Gusev, Larisa Y. Dzhogan, and Olga N. Nasonova Proc. IAHS, 376, 77-82, https://doi.org/10.5194/piahs-376-77-2018, 2018 It is shown that in agriculture technologies soil mulching with plant remains leads to increase in the ratio of actual transpiration to potential one and to increase in the yield of crops. Soil mulching with plant remains in combination with subsurface cultivation is the most efficient agricultural mode for the regions of the steppe and forest-steppe zones of the East-European (Russian) plain. This technology is most promising for development of agriculture in these regions.

Description: Comment on Soil organic stocks are systematically overestimated by misuse of the parameters bulk density and rock fragment content (Poeplau et al., 2017, SOIL, 3, 61–66) Eleanor U. Hobley, Brian Murphy, and Aaron Simmons SOIL Discuss., https//doi.org/10.5194/soil-2017-23,2018 Manuscript under review for SOIL (discussion: open, 1 comment) This research is evaluates equations to calculate soil organic carbon (SOC) stocks. Although various equations exist for SOC stock calculations, we recommend using the simplest equation with lowest associated errors. Adjusting SOC stock calculations for rock content is essential. Using the mass proportion of rocks to do so minimises error.

Description: Physical, chemical and mineralogical attributes of a representative group of soils from the Eastern Amazon, Brazil Edna Santos de Souza, Antonio Rodrigues Fernandes, Anderson Martins de Souza Braz, Fábio Júnior de Oliveira, Luís Reynaldo Ferracciú Alleoni, and Milton César Costa Campos SOIL Discuss., https//doi.org/10.5194/soil-2018-3,2018 Manuscript under review for SOIL (discussion: open, 0 comments) The study refers to a survey of the attributes of the main soils classes of the state of Pará, Eastern Brazilian Amazon. These soils have a good potential for agricultural use under natural conditions. In the study we observed that the soils are predominantely kaolinitic, but have relatively low aluminum and organic matter contents, with huge textural variability. The results enable a better understanding of Eastern Amazonian soils, whose extention reaches more than 1.2 million km 2 .

Description: Local soil quality assessment of north-central Namibia: integrating farmers' and technical knowledge Brice Prudat, Lena Bloemertz, and Nikolaus J. Kuhn SOIL, 4, 47-62, https://doi.org/10.5194/soil-4-47-2018, 2018 Soil degradation is a major threat for farmers of semi-arid north-central Namibia. Having tools to assess soil quality is important to evaluate soil conditions and helps targeting important issues. We developed a soil evaluation toolbox that integrates farmers' field experiences and technical knowledge. The combination of local soil descriptions, field soil texture evaluation and soil colour provides locally meaningful information that reveals soil quality improvement potentials.

Description: Saturated and unsaturated salt transport in peat from a constructed fen Reuven B. Simhayov, Tobias K. D. Weber, and Jonathan S. Price SOIL, 4, 63-81, https://doi.org/10.5194/soil-4-63-2018, 2018 Lab experiments were performed to understand solute transport in peat from an experimental fen. Transport was analyzed under saturated and unsaturated conditions using NaCl (salt). We tested the applicability of a physical-based model which finds a wide consensus vs. alternative models. Evidence indicated that Cl transport can be explained using a simple transport model. Hence, use of the physical transport mechanism in peat should be evidence based and not automatically assumed.

Description: How serious a problem is subsoil compaction in the Netherlands? A survey based on probability sampling Dick J. Brus and Jan J. H. van den Akker SOIL, 4, 37-45, https://doi.org/10.5194/soil-4-37-2018, 2018 Subsoil compaction is an important soil threat. It is caused by heavy machines used in agriculture. The aim of this study was to estimate how large the area with overcompacted subsoils is in the Netherlands. This was done by selecting locations randomly and determining the porosity and bulk density of the soil at these locations. It appeared that 43 % of the soils in the Netherlands is overcompacted, and so we conclude that subsoil compaction is indeed a serious problem in the Netherlands.

Description: Uncertainty indication in soil function maps – Transparent and easy-to-use information to support sustainable use of soil resources Lucie Greiner, Madlene Nussbaum, Andreas Papritz, Stephan Zimmermann, Andreas Gubler, Adrienne Grêt-Regamey, and Armin Keller SOIL Discuss., https//doi.org/10.5194/soil-2017-41,2018 Manuscript under review for SOIL (discussion: open, 3 comments) To maintain the soil resource, spatial information on soil multi-functionality is key. Soil function (SF) maps rate soils potentials to fulfill a certain function, e.g. nutrient regulation. We show how uncertainties in predictions of soil properties generated by digital soil mapping propagate into soil function maps, present possibilities to display this uncertainty information and show that otherwise comparable SF assessment methods differ in their behaviour in view of uncertainty propagation.

Description: Proximal sensing for soil carbon accounting Jacqueline R. England and Raphael Armando Viscarra Rossel SOIL Discuss., https//doi.org/10.5194/soil-2017-36,2018 Manuscript under review for SOIL (discussion: open, 2 comments) Proximal sensing can be used for soil C accounting, but the methods need to be standardised and procedural guidelines developed to ensure proficient measurement and accurate reporting. This is particularly important if there are financial incentives for landholders to adopt practices to sequester C. We review sensing for C accounting and discuss the requirements for the development of new soil C accounting methods based on sensing, including requirements for