bluuebunny/crossref_metadata_2025 huggingface dataset:
Do Martian slopes with Recurring Slope Lineae (RSL) have a distinct topographic signature?
Authors: Adam Aharon , Haviv Itai , Blumberg Dan G. , Maman Shimrit , Mushkin Amit
Published: March 2021

Recurring Slope Lineae (RSL) are dynamic, low-albedo, slope-parallel surface features on Mars that occur mainly on steep (>25°) slopes. RSL typically display seasonal dynamics as they appear during late Martian spring, progressively grow during summer, and subsequently fade as summer ends. RSL formation mechanisms remain under debate with proposed mechanisms involving either water/brines (‘wet theories’) vs. dry granular flows within a surficial dust layer (‘dry theories’). In an attempt to distinguish between plausible RSL mechanisms, this study compares the topographic and morphologic characteristics of hillslopes with and without RSL. We suggest that a distinct topographic signature for RSL hillslopes would argue against the ‘dry’ RSL mechanisms, as RSL dynamics within a thin dust layer are not expected to significantly impact the hillslope-scale topography. In contrast, the presence of fluids on RSL hillslopes could conceivably accelerate rock weathering rates, which in turn may impact the hillslope-scale topography. Our analyses are based on HiRISE, CTX and HRSC digital terrain models (DTMs) together with geomorphic mapping using high-resolution orbital images. We focus on inner crater hillslopes and compare the topographic characteristics of RSL vs. non-RSL slopes. In addition, in order to account for the potential influence of aspect-dependent solar irradiation on hillslope processes, we also applied our analysis on adjacent ‘control’ craters that are devoid of RSL activity. Preliminary results from Palikir (-41.6°/ 202.1°E) and Rauna (35.2°/ 328°E) craters reveal that the topographic slope distribution along crater walls with RSL activity is distinct from the slope distribution along crater walls which are devoid of RSL activity. Our results appear to support increased rock-weathering rates on crater walls that presently experience RSL activity.

 

 
Evaluation of SEAS5 Precipitation Forecasts in the Central American Dry Corridor
Authors: Kowal Katherine , Slater Louise , Van Loon Anne
Published: March 2021

Seasonal forecasts provide an opportunity to enhance drought preparedness in the Central American Dry Corridor (CADC). Evaluation of seasonal precipitation predictions within the CADC is important because rainfall affects many local livelihoods, and rainfall predictability in this region may be low due to its complex climate and terrain. In this presentation, SEAS5, a leading seasonal forecasting system produced by the European Centre for Medium-Range Weather Forecasting, is evaluated for the accuracy of its precipitation predictions across the CADC relative to the GPCC gridded precipitation dataset derived from rain-gauge data. A few studies have assessed its predecessor (System 4) in Central America but none have assessed SEAS5 in the CADC. SEAS5 predictions of rainfall mean, variability, and extremes are evaluated using one- to seven- month lead-times over 1981-2016 and for known historical droughts. Results show that SEAS5 precipitation forecasts often perform best during July and August, two important months for crop growth because they occur during the mid-summer dry period, which separates the wet season into distinct phases. Elevation seems to have an influence, although alone it does not explain variations in forecast skill across the region. SEAS5 overpredicts rainfall in greater quantities at high elevation. This analysis showcases promising forecast skill of relevance to agricultural forecasting and could be expanded on in future work by evaluating skill of other drought indicators.
Preprocessing of hydrological models’ input in eWaterCycle with ESMValTool
Authors: Alidoost Fakhereh , Aerts Jerom , Andela Bouwe , Camphuijsen Jaro , van De Giesen Nick , van Den Oord Gijs , Drost Niels , Hut Rolf , Kalverla Peter , Pelupessy Inti , van Werkhoven Ben , Smeets Stef , Verhoeven Stefan
Published: March 2021

Hydrological models exhibit great complexity and diversity in the exact methodologies applied, competing for hypotheses of hydrologic behaviour, technology stacks, and programming languages used in those models. The preprocessing of forcing (meteorological) data is often performed by various sets of scripts that may or may not be included with model source codes, making it hard to reproduce results. Moreover, forcing data can be retrieved from a wide variety of forcing products with discrepant variable names and frequencies, spatial and temporal resolutions, and spatial coverage. Even though there is an infinite amount of preprocessing scripts for different models, these preprocessing scripts use only a limited set of operations, mainly re-gridding, temporal and spatial manipulations, variable derivation, and unit conversion. Also, these exact same preprocessing functions are used in analysis and evaluation of output from Earth system models in climate science.

Within the context of the eWaterCycle II project (https://www.ewatercycle.org/), a common preprocessing system has been created for hydrological modelling based on ESMValTool (Earth System Model Evaluation Tool). ESMValTool is a community-driven diagnostic and performance metrics tool that supports a broad range of preprocessing functions. Using a YAML script called a recipe, instructions are provided to ESMValTool: the datasets which need to be analyzed, the preprocessors that need to be applied, and the model-specific analysis (i.e. diagnostic script) which need to be run on data. ESMValTool is modular and flexible so all preprocessing functions can also be used directly in a Python script and additional analyses can easily be added.

The current preprocessing pipeline of the eWaterCycle using ESMValTool consists of hydrological model-specific scripts and supports ERA5 and ERA-Interim data provided by the ECMWF (European Centre for Medium-Range Weather Forecasts), as well as CMIP5 and CMIP6 climate model data. The pipeline starts with the downloading and CMORization (Climate Model Output Rewriter) of input data. Then a recipe is prepared to find the data and run the preprocessors. When ESMValTool runs a recipe, it produces preprocessed data that can be passed as input to a hydrological model. It will also store provenance and citation information to ensure transparency and reproducibility. This leads to less time spent on building custom preprocessing, more reproducible and comparable hydrological science.

In this presentation, we will give an overview of the current preprocessing pipeline of the eWaterCycle, outline ESMValTool preprocessing functions, and introduce available hydrological recipes and diagnostic scripts for the PCRGLOB, WFLOW, HYPE, MARRMOT and LISFLOOD models.
Mapping mantle flows underneath the North American and Caribbean Plates
Authors: Zhu Hejun
Published: March 2021

In this talk, I will present a new 3-D azimuthally anisotropic tomographic model, namely US32, for the North American and Caribbean Plates. This model is constrained by using seismic data from USArray and full waveform inversion. The inversion uses data from 180 regional earthquakes recorded by 4,516 seismographic stations, resulting in 586,185 frequency-dependent phase measurements. Three-component short-period body waves and long-period surface waves are combined to simultaneously constrain deep and shallow structures. The current azimuthally anisotropic model US32 is the result of 32 pre-conditioned conjugate-gradient iterations. In the current model, I observe a complex depth-dependent pattern for fast axis directions across the North American and Caribbean Plates.  At shallow depths, these fast axis directions delineate local geological provinces, such as the Snake River Plain, Cascadia subduction zone, Rio Grand Rift, etc. At greater depths, the fast axis directions follow the absolute plate motion trajectories at most places. At depths around 700 km, the fast axis directions are perpendicular to the strikes of the mapped Farallon slab, suggesting the presence of 2-D corner flows induced by this ancient subduction underneath the mantle transition zone. In addition, underneath the Cascadia and Cocos subduction zones at depths from 250 to 500 km, the fast axis directions suggest the presence of toroid-mode mantle flows, following the geometry of fast downwelling materials.
Advancing rainfall-induced landslide detection using homogeneous slope units and distributed rainfall thresholds
Authors: Jia Guoqiang , Gariano Stefano Luigi , Tang Qiuhong
Published: March 2021

A better detection of landslide occurrence is critical for disaster prevention and mitigation, and a standing pursuit owing to increasing and widespread impact of slope failures on human activities and natural environment in a changing world. However, the detection of rainfall-induced landslide is limited in some areas by data scarcity and method applicability. In this study, we proposed distributed rainfall thresholds within homogeneous slope units, by considering the interaction of landslide-influencing geo-environmental conditions and landslide-triggering rainfall variables. Homogeneous slope units are extracted based on detailed terrain analysis. Various landforms are identified and used to obtain slope units with homogeneous slope traits. The concept behind the distributed rainfall threshold models is that rainfall threshold for landslide occurrence varies with geo-environmental conditions such as slope gradient. Thus, a link can be established between landslide-influencing geo-environmental conditions and landslide-triggering rainfall variables. We used elevation, slope, plan and profile curvature, mean annual precipitation and temperature, soil texture and land cover as independent variables. Rainfall duration and cumulated rainfall of landslide-triggering rainfall events are automatically calculated and used, the former as one of independent variables, and the latter as the dependent variable. A support vector regression (SVR) and a multiple linear regression (MLR) method are used. The error and correlation coefficient measurement indicate a better performance of SVR method. Compared with grid units, the model scores high accuracy for slope units. The models are implemented at a regional scale (Guangdong, China). The SVR model in slope units ran with error of 0.16 mm and correlation coefficient of 0.93.
Study on the concentration, flux, occurrence and retention processes of total phosphorus in Dahuofang reservoir
Authors: Huang Guoxian , Li Xinghua , Sun Mingdong , Lei Kun
Published: March 2021

Dahuofang reservoir (DHFR) is one of the most important drinking water sources in Liaoning province, China. The processes of total phosphorus (TP) concentration, flux and retention rate are very important to the water quality management and drinking water safety for the reservoir. Based on the monitoring data of meteorology, hydrology, water quality and sediment, etc. at the controlled stations of Dahuofang catchment during 1992-2017, The suspended sediment centration(SSC) and TP concentration variation and differences from upper to lower reach of DHFR  during floods in 2010 and 2013 are analyzed and compared respectively. Based  on the  mass balance equation of TP and the related fluxes formula at the different boundaries, the stocking processes in both the overlying water and the active surface sediment layer are solved. The results revealed the TP accumulation variation in the overlying water and the surface sediment layer, together with the controlling mechanism of TP concentration in overlying water under different floods events. Moreover, the results discovered that the combination of flood and dry hydrological rhythms is very important to maintain the dynamic balance of accumulated sediment and TP in the reservoir. The study does not only provide the effective calculation method forthe TP flux, accumulation and retention rate in the large reservoir, but also partly supply a new eyesight on the sediment nutrient control and related continuable management  for large reservoirs in north China.
Does the Signal-to-Noise Paradox Exist in Subseasonal Predictions?
Authors: Zhang Wei , Xiang Baoqiang , Kirtman Ben , Becker Emily
Published: March 2021

One of the emerging topics in climate prediction is the issue of the so-called “signal-to-noise paradox”, characterized by too small signal-to-noise ratio in current model predictions that cannot reproduce the realistic signal. Recent studies have suggested that seasonal-to-decadal climate can be more predictable than ever expected due to the paradox. But no studies, to the best of our knowledge, have been focused on whether the signal-to-noise paradox exists in subseasonal predictions. The present study seeks to address the existence of the paradox in subseasonal predictions based on (i) coupled model simulations participating in phase 5 and phase 6 of the Coupled Model Intercomparison Project (CMIP5 and CMIP6, respectively), and (ii) subseasonal hindcast outputs from the Subseasonal Experiment (SubX) and the Subseasonal-to-Seasonal Prediction (S2S) projects. Of particular interest is the possible existence of the paradox in the new generation of GFDL SPEAR model, through the diagnosis of which may help identify potential issues in the new forecast system to guide future model development and initialization. Here we investigate the paradox issue using two methods: the ratio of predictable component defined as the ratio of predictable component in the real world to the signal-to-noise ratio in models and the persistence/dispersion characteristics estimated from a Markov model framework. The preliminary results suggest a potentially widespread occurrence of the signal-to-noise paradox in subseasonal predictions, further implying some room for improvement in future ensemble-based subseasonal predictions.
First release of the CMEMS Global coastal OLCI 300 meters Chlorophyll-a Product
Authors: Garnesson Philippe , Mangin Antoine , Demaria Julien , Bretagnon Marine , Hembise Fanton d'Andon Odile
Published: March 2021

The Ocean Colour Instrument (OLCI) on-board the Sentinel-3A and 3B satellites with a 300 m spatial resolution has a major advantage compared to other satellite missions with a typical 1 km spatial resolution. The chlorophyll-a product derived from OLCI’s 300 m measurement facilitates many applications in marine and coastal ecology, from ecosystem modeling, to fisheries management, and monitoring of water quality. The OLCI 300 m chlorophyll-a swath data (Level-2) are operationally disseminated in NRT mode by the EUMETSAT agency. The Copernicus Marine Environment Monitoring Service (CMEMS) eases the usage of these Level-2 (swath data) by providing Level-3 (daily mapped gridded files) at global and regional level.

This study highlights the first release of a 300 m NRT global daily chlorophyll-a product based on the merging of OLCI S3A and S3B. It will be routinely disseminated in the frame of CMEMS in May 2021. Before this date, the resolution of the CMEMS Chlorophyll products was 4km at global level and 1km over some European regional seas This 300 m product will be based on the Copernicus-GlobColour processor already used by CMEMS for the Global chlorophyll-a product and the regional Atlantic daily interpolated product. The daily image will correspond to a large matrix of 32400x64800 pixels with chlorophyll-a data provided along the coastline (200 km). CMEMS provides to the end-user facilities to extract data on his area and period of interest.

This new product will take benefit of a new EUMETSAT’s Level-2 product baseline which should be switched operationally in NRT mode mid-February 2021. This new baseline improves mainly the System Vicarious Calibration (SVC) gains of both S3A and S3B and the associated quality flags. The Chlorophyll-a OC4ME algorithm has been also improved with the use of the Colour Index algorithm for clear water. The assessment of this new OC4ME chlorophyll-a product (based on tandem data) shows a very good correlation between S3A and S3B. A regression between a daily S3A and S3B global product provides a R2 of 0.98 with a respective slope and offset of 1.0 and 0.005. However, some limitations concerning the level-2 upstream products have been identified. Details about the merging procedure, inter-comparison with existing product and illustrations of results will be presented.
Seismic hazard and risks for social and infrastructure exposures adjacent to the Baikal–Amur Mainline
Authors: Kossobokov Vladimir , Nekrasova Anastasia
Published: March 2021

Seismic hazard assessment requires an adequate understanding the earthquake distribution in magnitude, space, and time ranges. Laking data for a period of several thousand years makes probabilistic approach to estimating the recurrence time of hazardous ground shaking unreliable and misleading. In spite of theoretical flaws and actual failures on practice, the probabilistic seismic hazard assessment (PSHA) maps keep being actively used both at global and national scales. In recent decades, alternative methodologies have been developed to improve the reliability and accuracy of reproducible seismic hazard maps that pass intensive testing by historical evidence and realistic modelling of scenario earthquakes. In particular, the neo-deterministic seismic hazard assessment (NDSHA) confirms providing reliable and effective input for mitigating object-oriented earthquake risks. The unified scaling law for earthquakes (USLE) is a basic part of NDSHA that generalizes application of the Gutenberg-Richter law (G-RL). The USLE states that the logarithm of expected annual number of earthquakes of magnitude M in an area of linear size L within the magnitude range [M– , M+] follows the relationship log N(M, L) = A + B×(5 − M) + C×log L, where A, B, and C are constants.  Naturally, A and B are analogous to the classical a- and b-values, while C compliments to G-RL with the estimate of local fractal dimension of earthquake epicentres allowing for realistic rescaling seismic hazard to the size of exposure at risk. USLE implies that the maximum magnitude MX expected with p% chance in T years can be obtained from N(MX, L) = p%, then used for estimating and mapping ground shaking parameters by means of the NDSHA algorithms. So far, the reliable USLE based seismic hazard maps tested by historical evidence have been plotted for a number of regions worldwide. We present the USLE based maps of MX computed at earthquake-prone cells of a regular grid, as well as the adapted NDSHA estimates of seismic hazard and risks for social and infrastructure exposures in the regions adjacent to the Russian Federation Baikal–Amur Mainline. The study supported by the Russian Science Foundation Grant No. 20-17-00180.
The influence of the dust-free zone on F-corona brightness
Authors: Eren Saliha , Mann Ingrid
Published: March 2021

This presentation is related to model calculations of the circumsolar dust brightness that is seen in the F-corona and inner Zodiacal light. We calculate the brightness integral that includes the size distribution of the interplanetary dust, the spatial distribution, and the scattering properties. The scattering properties are estimated with Mie calculations of spherical particles consisting of astronomical silicate. We consider different size distributions of the dust particles with sizes between 1 nanometre - 100 micrometre. It was recently discussed that the extension of the dust-free zone can be inferred from the slope of the F-corona brightness seen in new observations received from the WISPR instrument on the NASA Parker Solar Probe (Stenborg et al., 2020). We, therefore, investigate the influence of the dust-free zone on the brightness and compare it to the influence that the dust size distribution has.

References

1. G. Stenborg, R. A. Howard, P. Hess, B. Gallagher, PSP/WISPR observations of dust density depletion near the Sun I. Remote observations to 8 Rsol from an observer between 0.13-0.35 AU, A&A, Forthcoming article, 2020. DOI: 10.1051/0004-6361/202039284
Modeling the Interaction between Slow Slip Events and Earthquake Ruptures in the Nicoya Peninsula, Costa Rica. 
Authors: Alalouf Lise , Liu Yajing
Published: March 2021

Subduction zones are where the largest earthquakes occur. In the past few decades, scientists have also discovered the presence of episodic aseismic slip, including slow slip events (SSEs), along most of the subduction zones. However, it is still unclear how these SSEs can influence megathrust earthquake ruptures. The Costa Rica subduction zone is a particularly interesting area because a SSE was recorded 6 months before the 2012 Mw7.6 earthquake in the Nicoya Peninsula, suggesting a potential stress transfer from the SSE to the earthquake slip zone. SSEs beneath the Nicoya Peninsula were also recorded both updip and downdip the seismogenic zone, making it a unique area to study the complex interaction between SSEs and earthquakes.

As most of the shallow SSEs were recorded around the Nicoya Peninsula, we chose to start using a 1D planar fault embedded in a homogeneous elastic half-space, with different dipping angles following several geometric profiles of the subduction fault beneath the Nicoya Peninsula section of the Costa Rica margin. This 1D modelling study allows us to better investigate the interaction between shallow and deep SSEs and megathrust earthquakes with high numerical resolution and relatively short computation time. The model provides information on the long-term seismic history by reproducing the different stages of the seismic cycle (interseismic slip, shallow and deep episodic slow slip, and coseismic slip).

We study the influence of the variation of numerical parameters and frictional properties on the recurrence interval, maximum slip velocity and cumulative slip of SSEs (both shallow and deep) and earthquakes and their interaction with each other. We then compare our results with GPS and seismic observations (i.e. cumulative slip, characteristic duration, moment rate, depth and size of the rupture, equivalent magnitude) to identify an optimal set of model parameters to understand the interaction between various modes of subduction fault deformation.
Energetic analysis of succinic acid in water droplets: insight into the size-dependent solubility of atmospheric nanoparticles
Authors: Chen Chuchu , Wang Xiaoxiang , Binder Kurt , Ghahremanpour Mohammad Mehdi , van der Spoel David , Pöschl Ulrich , Su Hang , Cheng Yafang
Published: March 2021

Size-dependent solubility is prevalent in atmospheric nanoparticles, but a molecular level understanding is still insufficient, especially for organic compounds. Here, we performed molecular dynamics simulations to investigate the size dependence of succinic acid solvation on the scale of ~1-4 nm with the potential of mean forces method. Our analyses reveal that the surface preference of succinic acid is stronger for a droplet than the slab of the same size, and the surface propensity is enhanced due to the curvature effect as the droplet becomes smaller. Energetic analyses show that such surface preference is primarily an enthalpic effect in both systems, while the entropic effect further enhances the surface propensity in droplets. On the other hand, with decreasing droplet size, the solubility of succinic acid in the internal bulk volume may decrease, imposing an opposite effect on the size dependence of solubility as compared with the enhanced surface propensity. Meanwhile, structural analyses, however, show that the surface to internal bulk volume ratio increases drastically, especially when considering the surface in respect to succinic acid, e.g., for droplet with radius of 1 nm, the internal bulk volume would be already close to zero for the succinic acid molecule.
Holocene variability of the northeastern Laurentide Ice Sheet in the Clyde Inlet area, western Baffin Bay, from radiogenic isotope records in marine sediments
Authors: Hingst Johanna , Hillaire-Marcel Claude , Lucassen Friedrich , Vogt Christoph , Okuma Emmanuel , Kasemann Simone
Published: March 2021

The reconstruction of late glacial ice sheet fluctuations helps understanding and modelling the local glacio-isostatic adjustment as well as global eustatic changes. From this viewpoint, the large-scale spatial and temporal variations of the Fox Basin-Baffin Island ice dome (NE Laurentide Ice Sheet, Canada) have been well documented. However, high frequency Holocene fluctuations and final decay of it are still poorly documented. We have thus investigated the behaviour of one of its eastern outlet glaciers in the Clyde Inlet fjord, northeastern Baffin Island. The reconstruction of ice sheet margin fluctuation is based on the radiogenic isotope composition (Sr-Pb-Nd) and mineral assemblage of detrital sediments in two marine cores raised within and off the Clyde Inlet (GeoB22346-3, Clyde Inlet head; GeoB22357-3, adjacent continental shelf). Radiogenic isotope ratios and bulk mineral assemblages from such sites are imprints of bedrock erosion along the active ice margin, as well as along ice-streams and subglacial drainage patterns. They may thus be used for the reconstruction of spatial and temporal variations in meltwater discharge into Baffin Bay and of the position of the active margin fluctuations inland. The location of the two sediment cores also informs on the traceability of radiogenic isotope signals from proximal to more distal areas of sediment deposition. Changes in mineralogical and radiogenic isotope compositions at the proximal core site suggest ice margin and drainage fluctuations rather than a constant retreat throughout the Holocene. Shelf sediment provenances are dominated by relatively homogenized Baffin Island inputs during the mid to late Holocene, but record a slightly offshore ice margin position from the late Pleistocene to the early Holocene.
Critical transition to monsoon in outgoing long-wave radiation: prediction of the advance of Indian Summer Monsoon
Authors: George Nitin Babu , Surovyatkina Elena , Krishnan Raghavan , Kurths Jürgen
Published: March 2021

The Indian summer monsoon (ISM) dramatically transforms the weather from hot and dry conditions to abundant precipitation within four months. The high temperature in the summer creates a low-pressure monsoon trough. Subsequently, moist winds from the surrounding seas increase the humidity in the atmosphere. Both the temperature and humidity influence the cloud formation over the monsoon region. Outgoing longwave radiation (OLR) indicates convective activity, which is the basis for cloud formation. Thus, the OLR is a crucial characteristic in meteorology to define monsoon's arrival in the state of Kerala. However, certain values of OLR at monsoon onset for different locations remain unknown. That is a scientific challenge to characterize monsoon onset at every location. This study aims to quantify the advance of monsoon and then make predictions.

Recently, Stolbova et al. 2016 [1] showed temperature and relative humidity exhibit a critical transition from pre-monsoon to monsoon in central India, which allowed making a long-term prediction of monsoon onset and withdrawal in Central India [2].  In the current study, we reveal that OLR exhibits a critical transition from high OLR values during the pre-monsoon state to low OLR values in the rainy season state. We prove the existence of criticality by identifying the OLR-critical threshold. Moreover, we show the appearance of the critical phenomena on the eve of the monsoon onset. In particular, we observe a growth of autocorrelation and variance of fluctuations for different regions in temperature, relative humidity, and OLR.
We find that the abruptness of the transition varies along the direction of advance of the monsoon. More abrupt the transition higher the amount of precipitation. These findings allow us to predict the timing of the monsoon advance from South India to central India. Such a forecast provides crucial information for farmers to sow the appropriate crops before the monsoon begins.

[1] Stolbova, V., E. Surovyatkina, B. Bookhagen, and J. Kurths (2016). GRL 43, 1–9 [doi:10.1002/2016GL068392]
[2] https://www.pik-potsdam.de/en/output/infodesk/forecasting-indian-monsoon

NB acknowledges the financial support of the EPICC project (18_II_149_Global_A_Risikovorhersage) funded by BMU; ES acknowledges the Russian Foundation for Basic Research (RFBR) (No. 20-07-01071)
Potential of sociohydrology for studying natural disasters
Authors: Vanelli Franciele Maria , Kobiyama Masato
Published: March 2021

Natural disasters refer to disruptions of the society’s functioning as result of negative interactions between natural hazards and social organization. Meanwhile, sociohydrology is dedicated to understanding the coupled human-water systems feedbacks. Both natural disaster studies and sociohydrology focus on understanding bidirectional interactions between environmental and social aspects, which is characterized by a dichotomous thinking pattern. In this context, natural disaster studies and sociohydrology have many parallels. In the present research, we conducted an exploratory research from two central arguments: (i) sociohydrology development can contribute to understanding how to disaster risk reduction by converting negative impacts into a harmonious coexistence between natural and social interactions; and (ii) water is relevant to all types of natural disasters in a direct or an indirect manner and is also fundamental in disaster response. Advances in knowledge about bidirectional interactions between environmental and social aspects overcoming dichotomous thinking pattern can update the sociohydrology development and the concepts commonly applied to natural disaster and risk reduction. We propose that any local community should use the school catchment concept that refers to any experimental catchment which serves for scientific researches and environmental education activities. The partnership between natural and social scientists and society is a challenge. Thus, school catchment construction and use can assist to overcome dichotomous thinking such as natural × social aspects, quantitative × qualitative analyses, systematic × non-systematic data, global × local spatial scales, and structural × non-structural measures. Hence, sociohydrology can support the integrated management of water resources and natural disasters and risks, contributing to achieving the Sendai Framework goals and the Sustainable Development Goals of the United Nations Agenda 2030. On the other hand, natural disaster studies can contribute to the interdisciplinary or transdisciplinary development of sociohydrology. Therefore, we conclude that sociohydrology has the potential, not yet explored, for contributing to natural disaster studies and vice and versa.
AvaFrame as a testing and benchmarking environment for avalanche simulations 
Authors: Oesterle Felix , Wirbel Anna , Tonnel Matthias , Fischer Jan-Thomas
Published: March 2021

Testing and benchmarking avalanche models is a crucial step in developing models as well as assessing their applicability. This is not only limited to the representation of physical processes within models, be it via first principles or using empirical relationships, but also concerns their computing environment, including compilers, hardware used, programming language, among others. 

Test, benchmarking, and comparison strategies can aim at different issues, among others: numerics, the implementation thereof, plausibility, verification, or evaluation. However, they always require reference or expected results. References can come from observations, analytical results, comparison to other models, known physical processes or material properties that cannot be changed – e.g., “avalanches cannot fly”. The question is: which characteristics or properties do we test and how to design appropriate tests?  

To facilitate this, as part of the newly developed opensource avalanche framework - AvaFrame -, we started providing commonly accessible tools to make testing and developing easier. This ranges from tools to import data, generate input parameters to automatic analysis and plotting. Not only do we provide the infrastructure for testing, but we also provide a set of test cases complete with all necessary input data, reference results, and run script examples. These tests so far include idealized (generic) topographies, specific test cases for numerical questions, and 6 real world avalanches with distinct characteristics. 

In this contribution we present this freely available set of tests and benchmarks suitable to assess various aspects and properties of a shallow water model solver for a dense flow avalanche model, one of the core computing modules of AvaFrame (com1DFA). We highlight how we utilize the entire range of tests in our continuous model development to assure the quality and applicability / validity of our development. Showing results from comparison to existing models, but also how to extend and apply our strategies to other models or research questions, we invite other researchers and developers to make full use of these tools.
Reconstruction of the surface marine carbonate system at the Western Tropical Atlantic
Authors: Musetti de Assis Carlos Augusto , Cotrim da Cunha Letícia , Queiroz Pinho Luana , de Jesus Affe Helen Michelle , Evangelista Vieira Renan Luis , Veloso Franklin Thiago
Published: March 2021

The Western Tropical Atlantic is a crucial region when it comes to understanding the CO2 dynamics in the tropics, as it is subject to large inputs of freshwater from the Amazon River and the ITCZ rainfall, as well as the input of CO2-rich waters from upwelling of subsurface water. This study aims to reconstruct the surface marine carbonate system from 1998 to 2018 using sea surface temperature (SST) and sea surface salinity (SSS) data from the PIRATA buoy at 8°N 38°W and describe its variability in time. Two empirical models were used to calculate total alkalinity (TA) and dissolved inorganic carbon (DIC) from SSS. From these two parameters and SST data, it was possible to calculate pH and CO2 fugacity (fCO2) values. Only DIC, pH and fCO2 showed a statistically significant trend in time, where DIC showed an increase of 0.717 µmol kg-1 year-1, pH decreased 0.001394 pH units year-1, and fCO2 had an increase of 1.539 µatm year-1. Two different seasons were observed when data were analyzed: a dry season from January to June, when SSTs were lower (around 27°C) and SSS was stable around 36, matching the period when the ITCZ is over the South American continent, Amazon river plume is restricted to western shelf areas and Equatorial upwelling is more active, and a rainy season from July to December, when SSTs were higher (around 28.5°C) and SSS had higher variability (from 31 to 36), matching the period when the ITCZ is at its northern range, the Amazon plume is spread eastwards through the North Brazil Current’s retroflection and the Equatorial upwelling is less intense. Along with that, TA, DIC and pH varied positively with SSS, with higher values (TA around 2350 µmol kg-1, DIC around 2025 µmol kg-1 and pH around 8.060 pH units) during dry season and lower values (TA around 2300 µmol kg-1, DIC around 1990 µmol kg-1 and pH around 8.050 pH units) during rainy season. On the other hand, fCO2 varied positively with SST, with lower values (around 385 µatm) during dry, upwelling season and higher values (around 390 µatm) during rainy season, showing that both SSS and SST variability play an important role in the CO2 solubility in the region.
Investigation of a Coupled Deterministic Inversion for the Interior of the Earth by using Gravity-Anomaly, Acoustic-Wavefield and Geodetic Velocity measurements
Authors: Simons Frederik J. , Reuber Georg S.
Published: March 2021

Conventionally, exploration in geology involves distinct research groups, each looking at a different observable and performing separate inversions for subsurface structure. In this work we discuss the advantages and performance of a combined inversion coupling gravity-anomaly, acoustic-wavefield and surface velocities as observables in one single framework. The gravity potential, which varies across the Earth, is sensitive to density anomalies at depth and can be obtained by solving a Poisson type equation. Its inversion is ill-posed since its solutions are non-unique in the depth and the density of the inverted anomaly. We also consider the surface displacement caused by a compressible wave as a consequence of an earthquake at depth. This inversion results in a wavespeed reconstruction but lacks interpretability, i.e. whether the anomaly is thermal or chemical in origin. The surface velocity, caused by the motion of highly viscous rocks in the subsurface, is the third observable. It can be modelled by the (nonlinear) Stokes equations, which account for the density and viscosity of a subsurface anomaly.

All three equations and their adjoints are implemented in one single Python framework using the finite element library FeNICS. To investigate the shape of the cost function, a grid search in the parameter space for three geological settings is presented. Additionally, the performance of gradient-based inversions for each observable separately or in combination, respectively, is presented. We further investigate the performance of a shape-optimizing inversion method, assuming the material parameters are known, while the shape is unknown.
Spatiotemporal variability of E. coli concentrations in two irrigation ponds
Authors: Stocker Matthew , Hill Robert , Kim Moon , Pachepsky Yakov
Published: March 2021

Escherichia coli is the most commonly assessed indicator of fecal contamination. The presence of elevated levels of E. coli is used to evaluate the microbial water quality in recreational and irrigation water sources.  E. coli concentrations are spatially and temporally variable. Monitoring of the variability inherent in water measurements can help create and implement effective monitoring designs and solutions. The objective of this work is to determine if there exist spatial patterns that are stable in time over years of observations. Two irrigation ponds in Maryland USA were monitored for three years during the growing seasons (June to August). Water samples and in situ measurements were collected in the same 47 locations biweekly for three years. The presence of stable spatial patterns was researched for relative differences between the logarithm of concentrations in specific locations and the average logarithm across the pond for each of observation times. The mean of these relative differences (MRD) over the observation period formed consistent spatial patterns. We found stable patterns of locations across the pond and found higher MRD values near the banks than the pond interiors.  MRDs computed for separate years were more variable and had amplitudes different from the overall average MRD over the three years, although the similarities between patterns across years was apparent. 
Integrating Seafloor Mapping Data with Sediment Transport and Coastal Change Studies:  Preliminary Results from the Southern Gulf of Maine, USA
Authors: Brothers Laura , Ackerman Seth , Foster David , Andrews Brian , Warner John , Himmelstoss Emily , Danforth William , Huntley Emily
Published: March 2021

Coastal erosion, intense storm events and sea-level rise pose threats to coastal communities and infrastructure. Managers and scientists often lack the high-resolution data needed to improve estimates of sediment abundance and movement, shoreline change, substrate heterogeneity and other seabed characteristics that influence coastal vulnerability. To address these and other needs the U.S. Geological Survey is conducting a multi-tiered research initiative consisting of shoreline change characterization, sediment transport numerical modeling and seafloor mapping in Cape Cod Bay, Massachusetts, USA. Here we present the seafloor mapping findings and their applications to an integrated coastal change analysis. Our comprehensive seafloor mapping technique includes the collection of multibeam and phase-discriminating data, seismic-reflection profile data, sediment samples, seabed imagery, as well as the synthesis of regional legacy datasets. A first-order comparison of the interdisciplinary results indicates that the presence of seafloor bedforms and the thickness of Late Holocene sediments correspond to patterns of modeled seabed elevation change and observed relative coastline stability. Analyses of these data are ongoing and may further resolve the relationships among shoreline change, nearshore processes and antecedent geology.
A highly diverse silicic end member of a bimodal magma suite formed in an active continental back arc, Okinawa Trough
Authors: Murch Arran , Tani Kenichiro , Sano Takashi , Yoneda Shigekazu
Published: March 2021

The Okinawa Trough (OT) is an incipient continental back-arc basin that extends from Kyushu in the north to Taiwan in the south. The Okinawa Trough can be split in to three segments, the Northern (NOT), Middle (MOT), and Southern (SOT) with active back-arc volcanism restricted to volcanic centres located in en-echelon grabens the MOT and SOT. Previous studies have shown magmatism in the OT is bimodal (basaltic to rhyolitic), with at least two types of silicic melts inferred to form through pure fractional crystallisation from basalt and by fractional crystallisation along with minor crustal assimilation (Shinjo and Kato, 2000).

Here we present petrological descriptions, along with major, trace element and Sr–Nd isotopic data for 75 silicic end member samples recovered as both lava and pumice, collected during the R/V Sonne HYDROMIN1 and 2 cruises in 1988 and 1990, respectively. Samples were dredged from various seafloor knolls and ridges located in the Io and Iheya grabens and from Izena Hole in the MOT, and from a single volcanic ridge in the Yaeyama graben and a single isolated knoll in the SOT.

Results show a chemically highly diverse silicic end member magmas, with at least four identifiable groups based on differences in the degree of enrichment of incompatible elements (LREE, K, Rb, Ba, etc.). Each group contains at least one dense lava sample suggesting the chemical diversity is a primary feature of magmatism in the Okinawa Trough rather than a result of the floating in of pumiceous material from various locations.

Using petrological descriptions and the chemistry of samples along with MELTS modelling we plan to calculate magma formation conditions and identify any evidence of magma mixing or crustal assimilation. In doing so we hope to provide a model to explain the diversity of silicic magma chemistry in the MOT and SOT.

 

Shinjo, R., and Kato, Y. (2000). Geochemical constraints on the origin of bimodal magmatism at the Okinawa Trough, an incipient back-arc basin. Lithos 54, 117–137. doi:10.1016/S0024-4937(00)00034-7.
Dynamic Coupling of SWAT+ with System Dynamics Models using Tinamït and a Socket Based Protocol
Authors: Harms Joel Z. , Malard Julien J. , Adamowski Jan F.
Published: March 2021

Effective and sustainable decision making in water resources management often requires modelling techniques that are able to account for the inherent complexity of coupled human-water systems. One approach that is used to model coupled human-water systems is to couple physically based models and system dynamics models. However, in many cases, this type of model coupling is labour-intensive and time-consuming, which can hinder its routine use in modeling and decision making.

Tinamït, a Python package, is an application programming interface (API) that provides definitions of functions and objects that simplify, in this case, coupled model building. Tinamït supports automatic SD model wrapping and coupling to specialized physically-based models, which makes it particularly useful for coupled human-water systems modelling. In this research, a connection between SWAT+ (a FORTRAN-based hydrological model) and the Tinamït API is established through model wrapping. This wrapping approach takes advantage of both the agility of sockets and the wide applicability of JavaScript Object Notation (JSON) to transmit data between FORTRAN and Python routines at runtime. Any model that runs in SWAT+ can now be automatically coupled to SD models through the Tinamït API, without the need for extensive programming, therefore facilitating wider application of coupled modelling techniques for integrated policy development and decision making in the field of coupled human-water systems.
Two classes of eruptive events during Solar Minimum
Authors: Bhowmik Prantika , Yeates Anthony
Published: March 2021

During Solar Minimum, the Sun is perceived to be quite inactive with barely any spots emerging on the solar surface. Consequently, we observe a drop in the number of highly energetic events such as solar flares and coronal mass ejections (CMEs), which are often associated with active regions on the photosphere. However, our magnetofrictional simulations during the minimum period suggest that the solar corona could still be significantly dynamic while evolving in response to the large-scale shearing velocities on the solar surface. The non-potential evolution of the corona leads to the accumulation of magnetic free energy and helicity, which is periodically lost through eruptive events. Our study shows that these events can be categorised into two distinct classes. One set of events are caused due to full-scale eruption of low-lying coronal flux ropes and could be associated with occasional filament erupting CMEs observed during Solar Minimum. The other set of events are not driven by destabilisation of low-lying structures but rather by eruption from overlying sheared arcades. These could be linked with streamer blowouts or stealth CMEs. The two classes differ considerably in the amount of magnetic flux and helicity shed through the outer coronal boundary. We additionally investigate how other measurables such as current, open magnetic flux, free energy, coronal holes area, and the horizontal component of the magnetic field on the outer model boundary vary during the two classes of event. This study demonstrates and emphasises the importance and necessity of understanding the dynamics of the coronal magnetic field during Solar Minimum.
Low and middle latitude thermosphere and ionosphere responses to geomagnetic activity
Authors: Wang Wenbin , Wu Qian , Ling Dong
Published: March 2021

Solar wind and its embedded interplanetary magnetic field (IMF) affects Earth’s upper atmosphere by changing high-latitude ionospheric convection patter, producing auroral precipitation and depositing energy and momentum at high latitudes. These processes are greatly enhanced during geomagnetically active periods.  The geomagnetic activity induced changes at high latitudes are then transmitted to middle and low latitudes. In this work we employ the recently developed Multiscale Atmosphere-Geospace Environment (MAGE) model to simulate the non-linear electrodynamic and dynamic processes by which solar wind and IMF affect low and middle latitude thermosphere and ionosphere during geomagnetically active periods, including the stream interaction region event that happened in September 2020.  We examine the changes in ionospheric electric fields caused by penetration electric fields and neutral wind dynamo, as well as changes in neutral winds, temperature, composition  and ionospheric plasma densities. Model results are compared with  data from recent satellite mission, including COSMIC 2, GOLD and ICON to obtain new insight in the physical processes in the global thermosphere ionosphere responses to disturbed solar wind and IMF driving conditions.