bluuebunny/crossref_metadata_2025 huggingface dataset:
The early 2021 Sudden Stratospheric Warming as observed by ADM-Aeolus
Authors: Wright Corwin , Banyard Timothy , Hall Richard , Hindley Neil , Mitchell Daniel , Seviour William
Published: March 2021

Sudden Stratospheric Warmings (SSWs) are dramatic events where the usually-strong wind vortex around the edge of the polar stratosphere temporarily weakens or reverses, causing the polar temperature to rise by tens of Kelvin in just a few days. These events can trigger extreme winter weather outbreaks in Europe and North America, and are thus of significant scientific and practical interest. However, due to the major technical challenges involved in measuring wind from space, the changes in wind structure involved in an SSW have never been directly observed at the global scale, and our understanding of these changes  has instead been developed through the use of point measurements, localised flight tracks and (primarily) computer models and assimilative analyses. Here, we exploit novel measurements from Aeolus, the first satellite capable of observing wind in the upper troposphere and lower stratosphere, to study this process observationally during the major January 2021 SSW. As the event is still ongoing at time of abstract submission, precise details of the changes seen in Aeolus data over the full event cannot be provided; however, data from the first full week of the SSW shows clear observational evidence in Aeolus data of significant and descending-with-time structural changes to the lower stratospheric flow, including reversal of the mean zonal flow, a clear shifting of the vortex centre to a location over northern Russia,  and perhaps early evidence of a developing split of the vortex into two sub-vortices.
Fluid flow and faulting history of the Iano tectonic window (Southern Tuscany, Italy).
Authors: Fulignati Paolo , Zucchi Martina , Brogi Andrea , Capezzuoli Enrico , Liotta Domenico , Sarti Giovanni , Molli Giancarlo
Published: March 2021

In the Iano area (Southern Tuscany) a small tectonic window of Tuscan metamorphic units is observed. This belongs to the northernmost part of the so-called Mid-Tuscan ridge and, during Pliocene, formed a submarine high, now defining the easternmost shoulder of the Volterra Pliocene basin. The area gives the opportunity to investigate the complete cycle of negative inversion from crustal thickening to crustal thinning, which characterizes Southern Tuscany. Our new data focus on the western margin of the Iano ridge, and in particular on a system of high angle normal faults that represents the youngest structures of the investigated area. These structures, deformed low angle regional detachments locally juxtaposing the uppermost units of contractional nappe stack (the ophiolite-bearing Ligurian units), with the Tuscan metamorphic units, with an almost complete excision of at least 3.5 Km thick Mesozoic to Tertiary Tuscan nappe succession. The high angle normal faults show variable Plio-Quaternary vertical displacements from few meters to about 500 meters, and acted as pathways for the upwelling of hydrothermal fluids, as revealed by Pleistocene travertine deposits, hydrothermal alteration and occurrence of different generations of fluid inclusions in hydrothermal veins associated with these fault systems. Fluid inclusions were studied in quartz veins hosted in the Verrucano metasediments forming the top of the Tuscan metamorphic unit, as well as in some carbonate lithotypes (Cretaceous to Tertiary in age) of the overlying Tuscan Nappe. Two different kinds of fluid inclusions were documented. The Type 1 are multiphase (liquid + vapor + 1 daughter mineral) liquid-rich fluid inclusions whereas the Type 2 are two-phase (liquid + vapor) liquid-rich fluid inclusions. Type 1 fluid inclusions are primary in origin and were found only in quartz veins present in Verrucano metarudites, whereas Type 2 fluid inclusions occur in quartz veins present in both Verrucano phyllites and quartzites and in the carbonate units of the Tuscan Nappe. These are secondary and can be furthermore distinguished in two sub-populations (Type 2a and Type 2b) on the basis of petrographic observation and microthermometric data. Fluid inclusion investigation evidenced an evolution of the hydrothermal fluids from relatively high-T (~265°C) and hypersaline (35 wt.% NaClequiv.) fluids trapped at about 100 MPa, to lower temperature (~195°C) and salinity (~9.5 wt.% NaClequiv.) fluids, having circulated in the high-angle fault system. Based on the new data and a revision of the local tectonic setting a fluid-rock interaction history has been reconstructed with new hints and constraints for the Plio-Quaternary extensional history of the Volterra basin.
Assembling a geoscience information portal from pieces of the open source software jigsaw puzzle
Authors: Fazio Vincent , Friedrich Carsten , Angreani Rini , Golodoniuc Pavel , Hille John , Hunt Alex , Jiang LingBo , Klump Jens , Squire Geoffrey , Warren Peter , Engelke Ulrich , Woodman Stuart , Bradley Sam
Published: March 2021

As open source geospatial mapping toolkits and platforms continue to develop and mature, the developers of web portals using these solutions need to regularly review and revaluate their technology choices in order to stay up to date and provide the best possible experience and functionality to their users. We are currently undergoing such a refresh with our AuScope Discovery Portal, Virtual Geophysics Laboratory, and the AuScope 3D Geological Models Portal. The task of deciding which solutions to utilise as part of the upgrade process is not to be underestimated. Our main evaluation criteria include the ability to support commonly used map layer formats and web service protocols, support for 3D display capabilities, community size and activity, ease of adding custom display and scientific workflow / processing widgets, cost and benefits of integration with existing components and maintainability into the future. We are beginning a journey to update and integrate our portals’ functionality and will outline the decision process and conclusions of our investigations as well as the detailed evaluation of web based geospatial solutions against our functional and operational criteria.
Retooling climate science for risk assessment
Authors: Sanderson Ben , Peatier Saloua , Terray Laurent
Published: March 2021

Over recent years, climate change has become a global issue, leading political agendas and projecting onto almost every economic and development decision made today.  However, the way that we conduct climate science has remained broadly unchanged since the publication of the first IPCC report in 1990 - still relying on an ensemble of opportunity of climate models which doesn't allow for an estimation of high-impact tail risks and a highly idealized scenario framework which fails to test the fundamental technological assumptions which underpin our remaining pathways for achieving the Paris Agreement.  Here, we discuss how our strategy within the Make Our Planet Great Again "RISCCi" project is attempting to reframe the simulation of climate projections such as to provide better guidance for robust decision-making by categorizing the deep uncertainties of climate projections and mitigation pathways.  We present the initial results from an CNRM ensemble project which seeks to explore tail behaviour in climate feedbacks and impacts, and outline in a wider sense how future work and climate assessment needs to respond to the growing and evolving needs of a society as it works to minimise, and adapt to, climate change.
Remotely sensed temperature is a proxy of greenhouse gas emissions in intact and managed peatlands
Authors: Kull Ain , Burdun Iuliia , Veber Gert , Karasov Oleksandr , Maddison Martin , Sagris Valentina , Mander Ülo
Published: March 2021

Besides water table depth, soil temperature is one of the main drivers of greenhouse gas (GHG) emissions in intact and managed peatlands. In this work, we evaluate the performance of remotely sensed land surface temperature (LST) as a proxy of greenhouse gas emissions in intact, drained and extracted peatlands. For this, we used chamber-measured carbon dioxide (CO2) and methane (CH4) data from seven peatlands in Estonia collected during vegetation season in 2017–2020. Additionally, we used temperature and water table depth data measured in situ. We studied relationships between CO2, CH4, in-situ parameters and remotely sensed LST from Landsat 7 and 8, and MODIS Terra. Results of our study suggest that LST has stronger relationships with surface and soil temperature as well as with ecosystem respiration (Reco) over drained and extracted sites than over intact ones. Over the extracted cites the correlation between Reco CO2 and LST is 0.7, and over the drained sites correlation is 0.5. In natural sites, we revealed a moderate positive relationship between LST and CO2 emitted in hollows (correlation is 0.6) while it is weak in hummocks (correlation is 0.3). Our study contributes to the better understanding of relationships between greenhouse gas emissions and their remotely sensed proxies over peatlands with different management status and enables better spatial assessment of GHG emissions in drainage affected northern temperate peatlands.
Intraseasonal variation and future projection of atmospheric diffusion conditions conducive to extreme haze formation over eastern China
Authors: Feng Weiyang , Wang Minghuai , Zhang Yang , Dai Xianglin , Liu Xiaohong , Xu Yangyang
Published: March 2021

    Future projection of diﬀusion conditions associated with extreme haze events over eastern China is of great importance to government emission regulations and public human health. Here, the diﬀusion conditions and their changes under future warming scenarios are examined. The relative strength of haze events in the Northern China Plain region increase from 150% during 2006–15 to 190% during 2090–99 under RCP8.5 scenarios, induced by a stronger and longer-lasting anticyclone anomaly in eastern China. The strengthened anticyclone anomaly is mainly induced by increased northern wave train convergence emanating from the Barents–Kara Sea, and the longer duration of the anticyclone anomaly is mainly induced by stronger local feedback that can extract more energy from the basic state to maintain the anticyclone anomaly in eastern China. Aerosol reduction is found to play a dominant role in strengthening the upstream wave train near the Barents–Kara Sea and the downstream anticyclone in eastern China, while the eﬀects from increased greenhouse gases are small. The results of this study indicate that future aerosol emissions reduction can induce deteriorating diﬀusion conditions, suggesting more stringent regulations on aerosol emissions in China are needed to meet air quality standards.
Regional impacts of electricity system transition in Central Europe until 2035
Authors: Sasse Jan-Philipp , Trutnevyte Evelina
Published: March 2021

Achieving current electricity sector targets in Central Europe (Austria, Denmark, France, Germany, Poland and Switzerland) will redistribute regional benefits and burdens at sub-national level. Limiting emerging regional inequalities would foster the implementation success. We model one hundred scenarios of electricity generation, storage and transmission for 2035 in these countries for 650 regions and quantify associated regional impacts on system costs, employment, greenhouse gas and particulate matter emissions, and land use. We highlight tradeoffs among the scenarios that minimize system costs, maximize regional equality, and maximize renewable electricity generation. Here, we show that these three aims have vastly different implementation pathways as well as associated regional impacts and cannot be optimized simultaneously. Minimizing system costs leads to spatially-concentrated impacts. Maximizing regional equality of system costs has higher, but more evenly distributed impacts. Maximizing renewable electricity generation contributes to minimizing regional inequalities, although comes at higher costs and land use impacts.
Can we improve soil properties and plant biomass using rock powder as soil amendment?
Authors: Reifschneider Lena , Eichinger Vinzenz Franz , Pihlap Evelin , Garcia-Franco Noelia , Kühnel Anna , Bucka Franziska , Kögel-Knabner Ingrid , Vidal Alix
Published: March 2021

The application of rock powder is an option to improve soil fertility while valorising the overburden material produced by industries. The “enhanced weathering” of silicate rock has also gained recent interest in the scientific community for its potential to mitigate climate change. However, the effect of rock powder on the soil physical properties remains unclear, especially under climate change (e.g., increasing drought events). Prior to any large scale application of rock powder, it is crucial to disentangle the potential effects of rock powder application on its environment. In a mesocosm experiment, we explored the effect of three rock powders on plant biomass, soil aggregation and organic carbon (OC) allocation within aggregates, in two soils with clayey and sandy textures, under regular watering or severe drought conditions. We demonstrate that the rock powder was the third factor after drought and soil texture significantly affecting the plant growth, resulting in a significant plant biomass decrease ranging from - 13 % to - 42 % compared with the control. We mainly attribute this effect to the increase of the already neutral soil pH, along with the release of excessive heavy metal amounts at a toxic range for the plant. Yet, we found that adding rock powder to the soil resulted in an increase of the relative amount of microaggregates in the soil by up to + 70 %, along with a re-distribution of OC within the fine fractions of the soil (up to + 32 % of OC in < 250 µm fractions). The new mineral-mineral and organo-mineral interactions promoted by the rock powder addition could potentially favour OC persistence in soil on the long term. With our results, we insist on the potential risks for plant growth associated to the application of rock powder when not handled properly. In addition to the current enthusiasm around the capacity of rock powder to enhance carbon sequestration in the inorganic form, we also encourage scientists to focus their research on its effect on soil structure properties and OC storage.
Tree-soil-water relations in a mature temperate forest under elevated CO2
Authors: Quick Susan , Curioni Giulio , Blaen Phillip J , Krause Stefan , MacKenzie Angus Robert
Published: March 2021

Extreme anthropogenic global change, such as increasing atmospheric carbon dioxide, can challenge long-lived organisms including trees. Carbon uptake by trees, during photosynthesis, is inevitably accompanied by leaf transpiration; elevated atmospheric CO2 is, therefore, expected to reduce daytime plant water usage. The Free-Air Carbon-dioxide Enhancement (FACE) experiment at the Birmingham Institute of Forest Research (BIFoR) UK manipulates atmospheric CO2 in a 150 year old mixed deciduous temperate forest. In the sub-project described here, we compare diurnal and seasonal plant-water dynamics from individual trees under treatment (elevated CO2) and control conditions. Response of Pedunculate oak (Quercus robur), as the dominant tree species, is reported for the initial three years of elevated CO2, enabling us to characterise whether the woodland is starting to adapt. Xylem sap flux measurement reflects tree water usage and has been used as a proxy for transpiration at stand scale in forest experiments. This project explores a modified sap flux analysis approach, enabling individual trees to be compared and responses to be scaled up to treatment patch level. It considers: inputs-outputs (e.g. precipitation, transpiration), water flow (e.g. xylem sap flux), temperature and radiation to see how tree-soil-water interfaces behave and change with increased CO2. Measurement methods include spot observations (phenology, porometry), and data-logged measures (e.g. of soil moisture and xylem flow). Initially sap flux and stomatal conductance are considered in comparison with previous reported studies of tree water use efficiency and estimations of water storage. By considering these key measurements driven by a tree-centred view the results provide valuable data to improve vegetation, soil and landscape models and increase understanding of trees in mature future- forest environments.
Validating GIC modelling in the Spanish power grid by differential magnetometry
Authors: Torta J. Miquel , Marsal Santiago , Curto Juan J. , Cid Oscar , Ibañez Miguel , Canillas Victoria , Marcuello Alex
Published: March 2021

A series of experiences and recommendations are presented concerning the measurement of geomagnetically induced currents (GIC) in the Spanish power transmission grid by use of the method of differential magnetometry under power lines, by which differential observations are made (one below the line and another at a few hundred meters away) using vector magnetometers to capture the magnetic effect of the GIC flowing through them. This indirect technique, aimed at obtaining observations to validate GIC computational models, is an alternative to the more common way of measuring the current flow in the transformer neutrals, as it does not rely on the involved power grid operators. In contrast, the selection of a suitable site devoid of human interferences, the need of power for the magnetometer/acquisition system, and the election of the appropriate instrumentation are difficulties that often require costly solutions. Our methodology includes the settlement of appropriate magnetometers with the correct levelling and orientation placed inside buried water-proof containers. The magnetometers are fed by solar panel-battery systems, and we have also developed low-consumption data-transmission models using Raspberry-Pi with GPRS connection technology. According to our experience, only induced currents above about 1 A give magnetic signatures that exceed the noise threshold. As we started measuring during the solar minimum and Spain is a mid-latitude country, the latter fact limited the significance of available recorded data, but we can already report and analyse the results for a number of minor geomagnetic storms.
New highlights of gamma-ray observations by ASIM
Authors: Ostgaard Nikolai , Mezentsev Andrey , Marisaldi Martino , Kochkin Pavlo , Neubert Torsten , Reglero Victor , Chanrion Olivier , Lehtinen Nikolai , Sarria David , Skeie Chris , Bjørge-Engeland Ingrid , Lindanger Anders , Christiansen Freddy , Ullaland Kjetil , Genov Georgi , Budzt-Jørgensen Carl
Published: March 2021

ASIM has now observed several hundreds of TGFs since the launch in 2018. Highlights and new science from the first ten months of observations were presented in Østgaard et al. (2019) paper. In this presentation we will present observational highlights from the last 1.5 year, when the relative timing accuracy between the TGF observations and the optical measurements is +/- 5 us (compared to +/- 80 us before march 2019). This includes many more simultaneous TGF and Elve observations, high flux TGFs, double TGFs simultaneous with double optical pulses and many TGFs with good radio measurements.  ASIM has also observed several Gamma Ray Bursts. 
Short term tidal variability in stratosphere using ERA-interim and CMAM temperature data and comparison with satellite retrievals
Authors: Debnath Subhajit , Das Uma
Published: March 2021

A short term variability of migrating and non migrating tide is investigated in the stratosphere from the regular Canadian Middle Atmosphere Model (CMAM) and reanalysis ERA-interim temperature and wind dataset during winter of 2006 to 2010. Short term variability of tides is examined by ±10 day’s window size from Earth’s surface to 1hPa pressure level. To examine the short term variability of migrating and non migrating tide in stratosphere, we applied the fast fourier transform method to the CMAM30 and ERA-interim observation. The results reveal that tide changes with amplitude of 1-2K regularly on short timescales (21days) in stratosphere. Similar variability occurs in ERA-interim reanalysis observation. Non-migrating tide DS0 shows strong winter features with finer variation during 2009 and 2010 at 65°N. The short term variability of DE3 tide in stratosphere during 2008 and 2010 may be driven by zonal mean wind and non linear interaction with planetary wave. Amplitude of DW1 shows day to day variabilities clearly during winter of 2006, 2008 and 2009 at 0.7hPa over the equator and mid-latitude while the peak of DW1 is absent at 1hPa and 10hPa from CMAM temperature data set. Short term tidal variability in the stratosphere is not related to a single source. It depends on ozone density, zonal mean wind, and wave-wave non linear interactions. By using smaller window size, short term variabilities and finer variation of non migrating tides and SPW1 are understood. These results will be compared to results from satellite temperature data set, particularly FORMOSAT-3/COMSIC, for investigating short term tidal variability in the stratosphere.
Multi-variate factor separation of numerical simulations
Authors: Lunt Dan , Chandan Deepak , Schmidt Gavin , Rougier Jonty , Lunt George
Published: March 2021

Factor separation is widely used in the analysis of numerical simulations.  It allows changes in properties of a system to be attributed to changes in multiple variables associated with that system.  There are many possible factor separation methods; here we discuss three previously-proposed methods that have been applied in the field of climate modelling: the linear factor separation, the Stein and Alpert (1993) factor separation, and the Lunt et al (2012) factor separation.  We show that, when more than two variables are being considered, none of these three methods possess all four properties of 'uniqueness', 'symmetry', 'completeness', and 'purity'.  Here, we extend each of these methods so that they do possess these properties for any number of variables, resulting in three factor separation methods -- the 'linear-sum' , the 'shared-interaction', and the 'scaled-total'.  We show that the linear-sum method and the shared-interaction method reduce to be identical in the case of four or fewer variables, and we conjecture that this holds for any number of variables.  We present the results of the factor separations in the context of studies that used the previously-proposed methods.  This reveals that only the linear-sum/shared-interaction factor separation method possesses a fifth property -- `boundedness', and as such we recommend the use of this method in applications for which these properties are desirable.   The work described here is in review in Geoscientific Model Development - see https://gmd.copernicus.org/preprints/gmd-2020-69 .
Quantifying how hydrological and geomorphical dynamics in the land-river interface create opportunities and trade-offs for sustainable development
Authors: Vercruysse Kim , Grabowski Bob
Published: March 2021

Hydrological and geomorphological processes within the land-river interface (LRI) can be directly linked to several Sustainable Development Goals (SDG). The transfer of water and material along the LRI provides a range ecosystem services that support environmental, economic and social needs. However, the LRI is also very dynamic from a hydrologic and geomorphic perspective. Benefits can turn into hazards and vice versa, depending on natural and human-induced variations in flow and associated geomorphic activity. This study aimed to identify these critical areas by (i) quantifying the natural and human controlled variation in hydrology and geomorphology, and (ii) mapping associated SDG-related opportunities and trade-offs. The upper reaches of the Himalayan Beas River (India) were used as a case study, where the LRI is characterised by three main sections: (i) a free-flowing confined upper valley, (ii) a heavily regulated confined middle valley, and (iii) and a valley with wide floodplains flowing into the Pong Reservoir. Remote sensing imagery from Sentinel-2 (ESA) (2016-2019) were used to quantify the monthly spatial recurrence of river channels and gravel bars. In addition, data was collected on human and natural infrastructure within the catchment (including road network, urban areas, cropland, national parks, etc.). Combination of both datasets indicated that hydrological and river geomorphological processes in the upper part are the most spatially and temporally variable, leading to fertile soils (SDG 1,2), but also the highest risk of flooding in urban areas and cropland (SDG 11, 13) . The middle part is characterised by stable river channels (i.e. no lateral movement) due to the presence of two dams and confines valleys, leading to limited interaction with the surrounding land, except for the provision of water (SDG 6) and a higher risk of landslides (SDG 1,11). Finally, the lower part is again more dynamic in terms of geomorphological processes, with wide gravel bars and side channels. These dynamics allow larger urban areas and cropland to develop (SDG 1, 11), but also exposes cropland to flooding and erosion (SDG 2, 6). By quantifying the spatiotemporal dimension of hydrological and geomorphological processes and how these relate to LRI characteristics, this study provides a dynamic baseline to identify opportunities and trade-offs in optimising the role of the LRI in driving sustainable development.
A comparison of soil organic carbon concentration maps of Great Britain
Authors: Feeney Christopher , Cosby Jack , Robinson David , Thomas Amy , Emmett Bridget
Published: March 2021

Soil organic carbon (SOC) is the largest reservoir of organic carbon in the terrestrial biosphere and is the main constituent of soil organic matter, which underpins key soil functions such as storage and filtration of water, and nutrient cycling. SOC concentrations are controlled by several dynamic variables, ranging from micro-scale properties like particle aggregation, to larger-scale drivers such as climate and land cover. Hence, soils are vulnerable to climate change and human disturbances, with implications for ecosystem services such as agriculture and global warming mitigation. Recent decades have seen greater efforts to monitor SOC dynamics, such as the UKCEH Countryside Survey, and to predict concentrations of SOC where we have no measurements, using geostatistics or machine learning approaches. Yet, there is still much to be understood about what controls spatial patterns of SOC, and how effectively different modelling approaches can capture this. Here, we compare predictions by nine maps of the spatial distribution of topsoil SOC in Great Britain. We found broad similarities in SOC concentrations predicted by all maps, which each showed right-skewed distributions with similar median values (43 to 97 g kg-1). The greatest differences between maps occur at higher latitudes and are reflected in the upper ends of the SOC distributions. While the maps generally exhibit a sharp rise in SOC concentrations with increasing latitude from ~54oN, values predicted by the ISRIC-2017 and FAO-GSOC maps show weaker increases with increasing latitude, and peak at lower values of 332 g kg-1 and 354 g kg-1, respectively. We demonstrate that most of the maps, regardless of the modelling approach taken or the underlying data used, produced similar estimates of SOC concentration, including broad spatial patterns. This work will form the basis of more detailed future assessments of the sensitivity of SOC mapping to analytical methods versus the data used to drive these methods, and will be used to assess the importance of using stratified random field survey approaches for generating more accurate predictions of areas that cannot be sampled. Exploration of why and where different and coincident SOC predictions occur between maps should shed light on the utility of different modelling techniques and machine-learning meta-analyses of driving variables currently used to map SOC. Understanding how SOC predictions differ across all current national scale GB maps is a first step in improving modelling and assessment of SOC stock and change.
DeepMIP: Model intercomparison of early Eocene climatic optimum (EECO) large-scale climate features and comparison with proxy data
Authors: Lunt Dan ,   DeepMIP  team
Published: March 2021

We present results from an ensemble of eight climate models, each of which has carried out simulations of theearly Eocene climate optimum (EECO, ∼50 million years ago). These simulations have been carried out in the framework of DeepMIP (www.deepmip.org), and as such all models have been configured with the same paleogeographic and vegetation boundary conditions. The results indicate that these non-CO2 boundary conditions contribute between 3 and 5oC to Eocene warmth. Compared to results from previous studies, the DeepMIP simulations show in general reduced spread of global mean surface temperature response across the ensemble for a given atmospheric CO2 concentration, and an increased climate sensitivity on average. An energy balance analysis of the model ensemble indicates that global mean warming in the Eocene compared with preindustrial arises mostly from decreases in emissivity due to the elevated CO2 (and associated water vapour and long-wave cloud feedbacks), whereas in terms of the meridional temperature gradient, the reduction in the Eocene is primarily due to emissivity and albedo changes due to the non-CO2 boundary conditions (i.e. removal of the Antarctic ice sheet and changes in vegetation). Three of the models (CESM, GFDL, and NorESM) show results that are consistent with the proxies in terms of global mean temperature, meridional SST gradient, and CO2, without prescribing changes to model parameters. In addition, many of the models agree well with the first-order spatial patterns in the SST proxies. However, at a more regional scale the models lack skill. In particular, in the southwest Pacific, the modelled anomalies are substantially less than indicated by the proxies; here, modelled continental surface air temperature anomalies are more consistent with surface air temperature proxies, implying a possible inconsistency between marine and terrestrial temperatures in either the proxiesor models in this region. Our aim is that the documentation of the large scale features and model-data comparison presented herein will pave the way to further studies that explore aspects of the model simulations in more detail, for example the ocean circulation, hydrological cycle, and modes of variability; and encourage sensitivity studies to aspects such as paleogeography, orbital configuration, and aerosols
The Density of Reconnecting Structures Downstream of Earth’s Bow Shock
Authors: Gingell Imogen , Kucharek Harald , Schwartz Steven J. , Farrugia Charles , Trattner Karlheinz J. , Ergun Robert E. , Giles Barbara L. , Strangeway Robert J.
Published: March 2021

Actively reconnecting, thin current sheets have been observed both within the transition region of Earth’s bow shock and far downstream into the magnetosheath. Irrespective of whether these structures arise due to shock processes or turbulent dissipation, they are expected to contribute to particle heating and acceleration within their respective regions. In order to assess the integrated impact of the population of thin current sheets on observations of heating and acceleration, we examine shock crossings and extended magnetosheath intervals recorded by the Magnetospheric Multiscale mission (MMS). For each interval we quantify the number density of reconnecting current sheets in the magnetosheath. We estimate the volume associated with each time interval by considering the three-dimensional cone over which Alfvén and magnetoacoustic waves can propagate within the time interval. We then estimate the number of reconnecting sheets within that volume by comparing heating measures observed within individual sheet crossings with the observed change in those properties across the full interval. Given several extended magnetosheath intervals observed by MMS, we perform our analysis for different locations in the magnetosheath and for different solar wind conditions. In this way we determine the dependence of the number density of thin current sheets on shock orientation (i.e. quasi-parallel or quasi-perpendicular), solar wind transients, and incident plasma parameters.
Constraining spectral models of a terrestrial gamma-ray flash from a terrestrial electron beam observation by the Atmosphere-Space Interactions Monitor
Authors: Sarria David , Østgaard Nikolai , Kochkin Pavlo , Lehtinen Nikolai , Mezentsev Andrew , Marisaldi Martino , Lindanger Anders , Maiorana Carolina , Carlson Brant E. , Neubert Torsten , Reglero Victor , Ullaland Kjetil , Yang Shiming , Genov Georgi , Qureshi Bilal Hasan , Budtz-Jørgensen Carl , Kuvvetli Irfan , Christiansen Freddy , Chanrion Olivier , Navarro-Gonzalez Javier ,   Atmosphere-Space Interactions Monitor (ASIM) team
Published: March 2021

Terrestrial Gamma-ray Flashes (TGFs) are short flashes of high energy photons, produced by thunderstorms. When interacting with the atmosphere, they produce relativistic electrons and positrons, and a part gets bounded to geomagnetic field lines and travels large distances in space. This phenomenon is called a Terrestrial Electron Beam (TEB). The Atmosphere-Space Interactions Monitor (ASIM) mounted on-board the International Space Station detected a new TEB event on March 24, 2019, originating from a tropical cyclone, Johanina. Using ASIM's low energy detector, the TEB energy spectrum is resolved down to 50 keV. We provide a new method to contrain the TGF source spectrum based on the detected TEB spectrum. Applied to this event, it shows that only fully developed RREA spectrums are compatible with the observation. More specifically, assuming a TGF spectrum proportional to 1/E exp(-E/ε), the compatible models have ε ≥ 6.5 MeV. We could not exclude models with ε of 8 and 10 MeV. This is the first time the source energy spectrum of a TGF is contrained based on the detection of the associated TEB.
A follow-up for the Soil Moisture and Ocean Salinity mission
Authors: Rodriguez-Fernandez Nemesio , Kerr Yann , Anterrieu Eric , Cabot Francois , Boutin Jacqueline , Picard Ghislain , Pellarin Thierry , Merlin Olivier , Escorihuela Maria José , Albitar Ahmad , Richaume Philippe , Mialon Arnaud , Palacin Baptiste , Rodriguez Suquet Raquel , Amiot Thierry , Costeraste Josiane , Vivier Frederic , Vialard Jerome , Yu Louise , Decoopman Thibaut ,   rest of the SMOS-HR team
Published: March 2021

The Soil Moisture and Ocean Salinity (SMOS) satellite, launched in 2009 by ESA, has provided, for the first time, systematic passive L-band (1.4 GHz) measurements from space with a spatial resolution of ~ 40 km. SMOS data are an essential component of the ESA Climate Change Initiative (CCI) for ocean salinity and soil moisture and they are used by the CCI biomass. A specific SMOS neural network soil moisture product is assimilated operationally at the European Centre for Medium Range Weather Forecasts (ECMWF). L-band surface SM measurements have also been used to estimate root zone soil moisture, to derive drought indices, to enable food security monitoring and to improve satellite precipitation estimates. SMOS data have also been used to detect frozen soils, thin ice-sheets over the ocean and ice melting in Antarctica and Greenland.

Different studies on scientific and operational applications of L-band radiometry have shown the need of the continuity of L-band observations with an increased resolution with respect to the current generation of sensors. Resolutions from 1 km to 10 km would be a breakthrough for many applications over ocean, land and ice. One approach to obtain those resolutions could be downscaling coarse resolution data using an auxiliary dataset with higher resolution. However, using airborne data, we will show that the accuracy of the data downscaled to 1 km decreases significantly when the initial native resolution is 40 km with respect to downscaling from initial resolutions of 5-10 km. We will present two instrumental concepts to reach native resolutions of 5-10 km.

The SMOS-HR mission project, completed the Phase 0 study at the French Centre National d’Etudes Spatiales (CNES) with contributions from Airbus Defence & Space and CESBIO. The goal was to ensure the continuity of L-band measurements while increasing the spatial resolution to ~10 km, which requires a typical antenna size of ~18 meters. Taking into account the difficulty of deploying a real aperture of this size in space and the successful alternative approach used by SMOS, SMOS-HR will perform aperture synthesis using an array of 230 small antennas distributed in a cross with four 12 m arms. During the Phase A study (ongoing at CNES) a mission concept with a central carrier surrounded by a swarm of nanosatellites will also be studied.
Network-based approach to explore basin network comparing observed and satellite dataset
Authors: Gadhawe Mayuri , Guntu Ravi Kumar , Agarwal Ankit
Published: March 2021

Complex network is a relatively young, multidisciplinary field with an objective to unravel the spatiotemporal interaction in natural processes. Though network theory has become a very important paradigm in many fields, the applications in the hydrology field are still at an emerging stage.  In this study, we employed the Pearson correlation coefficient and Spearman correlation coefficient as a similarity measure with varying threshold ranges to construct the precipitation network of the Ganga River Basin (GRB). Ground-based observed dataset (IMD) and satellite precipitation product (TRMM) are used. Different network properties such as node degree, degree distribution, clustering coefficient, and architecture were computed on each resultant precipitation network of GRB. We also ranked influential grid points in the precipitation network by using weighted degree betweenness to identify the importance of each grid station in the network Our results reveal that the choice of correlation method does not significantly affect the network measures and reconfirm that the thresholds significantly influence network construction and network properties in the case of both datasets. The spatial distribution of the clustering coefficient value is high to low from center to boundary and inverse in the case of degree.  In addition, there is a positive correlation between the average neighbor degree and node degree. Again, we analyzed the architecture of precipitation networks and found that the network has a small world with random network behavior.   Our results also indicated that both products have similar network measures and showed similar kinds of spatial patterns.
Modelling thermal lithospheric thickness along the conjugate South Atlantic passive margins implies asymmetric rift initiation
Authors: Haas Peter , Müller R. Dietmar , Ebbing Jörg , Houseman Gregory A. , Finger Nils-Peter , Kaban Mikhail K.
Published: March 2021

In this contribution, we examine the evolution of the South Atlantic passive margins, based on a new thermal lithosphere-asthenosphere-boundary (LAB) model. Our model is calculated by 1D advection and diffusion with rifting time, crustal thickness and stretching factors as input parameters. The initial lithospheric thickness is defined by isostatic equilibrium with laterally variable crustal and mantle density. We simulate the different rifting stages that caused the opening of the South Atlantic Ocean and pick the LAB as the T=1330° C isotherm. The modelled LAB shows a heterogeneous structure with deeper values at equatorial latitudes, as well as a more variable lithosphere along the southern part. This division reflects different stages of the South Atlantic opening: Initial opening of the southern South Atlantic caused substantial lithospheric thinning, followed by the rather oblique-oriented opening of the equatorial South Atlantic accompanied by severe thinning. Compared to global models, our LAB reflects a higher variability associated with tectonic features on a smaller scale. As an example, we identify anomalously high lithospheric thickness in the South American Santos Basin that is only poorly observed in global LAB models. Comparing the LAB of the conjugate South American and African passive margins in a Gondwana framework reveals a variable lithospheric architecture for the southern parts. Strong differences up to 80 km for selected margin segments correlate with strong gradients in margin width for conjugate pairs. This mutual asymmetry suggests highly asymmetric melting and lithospheric thinning prior to rifting.
Critical trigger condition of seabed liquefaction under ocean waves
Authors: Hsu Cheng-Jung , Hung Ching
Published: March 2021

Soil liquefaction in seabed not only drives vertical sediment transportation but also weakens coastal infrastructures such as pipeline or underwater foundation. The damage of seabed liquefaction events had been documented in literature. Due to the threat to lives and environment, it is important to have an exhaustive analysis on the risk assessment of seabed liquefaction subjected to ocean waves. The objective of this study is to assess the critical wave condition triggering seabed liquefaction in oceanic environment through theoretical modelling. Our investigation focused on the wave condition of momentary liquefaction induced by periodic wave loading. The scenario considers a permeable seabed on which a wide range of ocean waves propagates, and the critical wave parameters of wave height and wavelength causing liquefaction are examined. A two-dimensional analytical solution of seabed response based on Biot’s consolidation theory is applied with nonlinear water wave theory to predict the soil response and the consequence of liquefaction.  In contrast to the previous studies of seabed response applying the analytical solutions which only valid for a restricted wave range, we use a numerical approach of finite-amplitude wave to reflect the nonlinearity effect in a wide range of water wave from deep water to shallow water.  The present assessment of liquefaction is compared with the extant solution of seabed response under Stokes wave and cnoidal wave for validation. In additional, the potential of liquefaction instability is performed by a critical curve of wave condition covering the range of ocean waves from deep water to shallow water. Our study provides advanced theoretical framework and robust mathematical model for the assessment of wave-induced seabed instability under water waves, and the detailed analysis sheds insight into the impact of ocean waves on the seabed liquefaction.
Quantifying the Effects of Urbanization on Floods for two adjacent basins in Shenzhen and Hong Kong, China.
Authors: Liu Dandan , Chen Yiheng , Huang Jinhui , Shi Xiaogang
Published: March 2021

With the accelerating urbanization in developing countries, the threats of extreme rainfall and flood events are increasing. The impact of flood disasters severely threatens the safety of cities with a huge population. In order to quantitatively study the impact of urbanization development on urban floods, the hydrological characteristics of two adjacent basins will be analyzed and compared in this study -- Shenzhen, China with rapid urbanization in the past 40 years, and Hong Kong, China that was already urbanized.

The methods of this study mainly include the following two points. Firstly, in order to clarify the urbanization development process of the study regions, the geospatial database of surface impervious area of two adjacent basins from 1986 to 2018 was obtained in this study. In addition, this study intends to predict the impervious area of the study area in the future years through urban planning. The prediction method is based on adaptive cell deep learning analysis method. Secondly, in order to simulate the waterlogging situation in the two regions, this study intends to select specific flood events to establish and calibrate the SWMM model. By changing the impervious area of the two regions, hydrological parameters such as surface runoff and sensitivity under different scenarios can be obtained.

After model simulation, we will finally analyze the simulation results as follows: Firstly, the variation of runoff and flood peak with impervious area will be analyzed; Secondly, by comparing the simulation results of the two regions, the sensitivity of flood events to urbanization development will be evaluated; Finally, according to the predicted simulation results, the flood situation in the study area will be evaluated in the future years, which has a certain guiding significance for urban flood prevention.
Whole-soil warming alters microbial community, but not concentrations of plant-derived soil organic carbon in subsoil
Authors: Zosso Cyrill , Ofiti Nicholas O.E. , Soong Jennifer L. , Solly Emily F. , Torn Margaret S. , Huguet Arnaud , Wiesenberg Guido L.B. , Schmidt Michael W.I.
Published: March 2021

Soils will warm in near synchrony with the air over the whole profiles following global climate change. It is largely unknown how subsoil (below 30 cm) microbial communities will respond to this warming and how plant-derived soil organic carbon (SOC) will be affected. Predictions how climate change will affect the large subsoil carbon pool (>50 % of SOC is below 30 cm soil depth) remain uncertain.

At Blodgett forest (California, USA) a field warming experiment was set up in 2013 warming whole soil profiles to 100 cm soil depth by +4°C compared to control plots. We took samples in 2018, after 4.5 years of continuous warming and investigated how warming has affected the abundance and community structure of microoganisms (using phospholipid fatty acids, PLFAs), and plant litter (using cutin and suberin).

The warmed subsoil (below 30 cm) contained significantly less microbial biomass (28%) compared to control plots, whereas the topsoil remained unchanged. Additionally below 50 cm, the microbial community was different in warmed as compared to control plots. Actinobacteria were relatively more abundant and Gram+ bacteria adapted their cell-membrane structure to warming. The decrease in microbial abundance might be related to lower SOC concentrations in warmed compared to control subsoils. In contrast to smaller SOC concentrations and less fine root mass in the warmed plots, the concentrations of the plant polymers suberin and cutin did not change. Overall our results demonstrate that already four seasons of simulated whole-soil warming caused distinct depth-specific responses of soil biogeochemistry: warming altered the subsoil microbial community, but not concentrations of plant-derived soil organic carbon.