bluuebunny/crossref_metadata_2025 huggingface dataset:
Time-series of GhG emissions estimation for the learning of inverse modeling
Authors: Gómez-Ortiz Carlos , Monteil Guillaume , Scholze Marko
Published: March 2021

Inverse modeling is a commonly used method to infer greenhouse gases (GhGs) sources and sinks based on their observed concentrations in the atmosphere. It is a Bayesian framework and requires a priori fluxes of all the evaluated sources and sinks, atmospheric observations, an atmospheric transport model that relates the observations to the a priori fluxes and the uncertainties of both fluxes and observations. Various techniques exist to solve the inversion.

Atmospheric inverse modeling is and will become even more important in the future quantification of GhGs to monitor the compliance of the Nationally Determined Contributions (NDCs) under the Paris Agreement. Therefore, the scientific and educational communities are becoming more interested in using atmospheric inversions and this has risen a necessity of creating tools that facilitate understanding as well as training in these techniques.

Quantifying anthropogenic GhG emissions, such as CO2 from fossil fuel burning or CH4 from human activities, from atmospheric concentration observations is difficult since the carbon from all sources, both natural and anthropogenic, is mixed in the atmosphere, making it necessary to use other signals or tracers to separate anthropogenic emissions from natural sources. For fossil fuel CO2 emissions radiocarbon (14CO2) is an excellent emission tracer because, due to its radioactive decay (~ 5000 years), it cannot be found in fossil fuels, which have been deposited millions of years ago as organic material. We have developed a Jupyter Notebook based on Python for the quantification of multi-tracer GhGs fossil fuel emissions and its isotopes. The notebook solves for the emissions by applying atmospheric inversions within a practical two-box model. The inverse modeling notebook is based on the analytical maximum a posteriori (MAP) solution of the Bayes’ theorem and allows to assess the error in the state vector and its uncertainty.

This basic but powerful notebook is meant to be an educational and training tool for university students and new researchers in the field as well as for researchers interested in the estimation of long-term (>centennial) time-series of GhG emissions since it is built as a modular algorithm to be easily modified, coupled or expanded to other approaches or models depending on the application. The notebook was initially developed for the inverse modeling of CO2 and 14CO2 simultaneously and it is being expanded for additional GHG such as CH4 and 13CH4.
Airborne and ground-based geophysical evaluation of the surface and englacial hydrological system of the Sørsdal Glacier, East Antarctica, and implications for ice-shelf stability
Authors: Kulessa Bernd , Thompson Sarah , Cook Sue , Jones Glenn , Watson Christopher , Schoof Christian , Lane Victoria
Published: March 2021

Large swathes of the margin of the East Antarctic Ice Sheet experience pronounced surface melting during the austral summer. The nature and temporal evolution of evolving surface hydrological systems are poorly known, however, as are their potential connections with englacial and subglacial water systems and their effects on ice dynamics. We have acquired helicopter-based ground-penetrating radar (GPR), electrical self-potential (SP), broadband passive seismic and GNSS data to delineate the geometry and monitor the temporal evolution of the subsurface hydrological system of the marine-terminating Sørsdal Glacier, Princess Elizabeth Land, East Antarctica, between the austral summers of 2017-18 and 2018-19. Our data reveal the presence of a shallow englacial hydrological system that is connected to surface lakes upstream of the grounding line and, surprisingly, is active not only in the austral summer but also through the Antarctic winter. Here we illustrate the spatial and temporal characteristics of the englacial hydrological system and its susceptibility to tidal forcing through the Antarctic winter. Our observations are consistent with persistent year-round redistribution of mass from grounded to floating portions of at the East Antarctic margin, with far-reaching consequences for ice shelf stability.
Subglacial hydrology modulates basal sliding response to climate forcing of the Antarctic ice sheet
Authors: Kazmierczak Elise , Sun Sainan , Pattyn Frank
Published: March 2021

Sliding laws determine to a large extent the sensitivity of the Antarctic ice sheet on centennial time scales (Pattyn, 2017, Bulthuis et al, 2019, Sun et al, 2020). Especially the contrast between linear and plastic sliding laws makes the latter far more responsive to changes at the grounding line. However, most studies neglect subglacial processes linked to those sliding laws. Subglacial hydrology may also play a role in modulating the amplitude of the reaction of marine ice sheets to forcing. Subglacial processes influence the effective pressure at the base. For a hard bed system, the latter can be defined by the ice overburden pressure minus the subglacial water pressure determined by routing of subglacial meltwater through a thin film. For soft-bed systems, the effective pressure is determined from till properties and physics. Here we investigate a wide range of subglacial processes and hydrology used in ice sheet models and implemented them in one ice sheet model (f.ETISh).

 

The subglacial hydrology models and till deformation models are coupled to different sliding and friction laws (linear, power law, Coulomb), leading to 24 different representations. The Antarctic ice sheet model was then forced by the ISMIP6 forcing in surface mass balance and ocean temperature until 2100 for different RCP scenarios (Seroussi et al., 2020). Furthermore, to sample the intrinsic sensitivity we performed the ABUMIP experiments (Sun et al., 2020) for the full set of subglacial characteristics.  Results demonstrate that the type of sliding law is the most determining factor in the sensitivity of the ice sheet, modulated by the subglacial hydrology.
An integrated model for prediction of shallow landslides at regional scale with the integration of satellite hydrological data
Authors: Bordoni Massimiliano , Vivaldi Valerio , Brocca Luca , Ciabatta Luca , Meisina Claudia
Published: March 2021

Rainfall-induced shallow landslides are dangerous natural hazards, mainly due to their high temporal frequency, which causes fatalities and high economic damage worldwide. Early Warning Systems (EWS), generally based on definition of rainfall thresholds needed for landslides triggering, are useful tools for risks mitigation. Thresholds generally do not take into account soil hydrological conditions, which play an important role both in landslide triggering. Rainfall measures are also uncertain due to the limited spatial representativeness of ground sensors and the low density of currently available measuring networks. Moreover, in the last years, soil moisture data have become available over large areas (basin and regional scales), thanks to their measurement through satellite sensors.

The aim of this research is to develop a new integrated model to predict shallow landslides, based on a multidisciplinary approach involving physical models, data-driven methods and the implementation of satellite soil moisture and rainfall. The model is developing in Oltrepò Pavese (Northern Italy, Southern Lombardy), affected during the last 11 years by numerous events triggered by intense and frequent rainfalls, causing human fatalities, damaging/blocking roads and bridges, destructing cultivations (mainly vineyards).

To define satellite soil moisture (and rainfall) products, different remote sensing platform are investigating. A very new soil moisture product provided by Sentinel-1 images by ESA (European Space Agency) allows a fine spatial resolution (1 km) and a revisit time of ~7 days. Coarse resolution soil moisture products (~20 km) characterized by a daily temporal resolution and higher accuracy (e.g., SMAP–Soil Moisture Active and Passive, SMOS–Soil Moisture Ocean Salinity, ASCAT–Advanced SCATterometer) is used. These are validated through two hydrological monitoring stations already installed in two representative basins.

The prediction of shallow landslides are carried on by means of a model able to integrate spatial probability of occurrence and temporal occurrence, considering also satellite soil moisture and rainfall products. Empirical and physically-based thresholds considering different initial soil hydrological conditions on soil moisture, which seem the best indicators for shallow landslide triggering, are developing.

Predicition model is tested and validated with real cases, assessing its reliability, to build a prototypal Early Warning System for shallow landslide prediction, that will constitute a valuable tool for Civil Protection in attempt to mitigate the risk in the Oltrepò Pavese area. This work was made in the frame of the project ANDROMEDA, funded by Fondazione Cariplo.
Massflow—A software for dynamic modeling and risk evaluation of earth-surfaced flow
Authors: Ouyang Chaojun
Published: March 2021

Massflow is based on the depth-integrated continuum and solved by second-order MacCormack-TVD finite difference method. Shared code and friendly GUI are provided for researchers and engineers. It adopted CPU and GPU accellerated algorithm to improve the efficiency. Now around 1000 people adopted Massflow to do their own research. Based the framework, we have done several insightful simulations of real landslides and debris flows. Meanwhile, we are developing a solution for catchment-based rainfall- flood-debris flow prediction. We will introduce the basic of the software, the mechanism and related model to modeling the real hazards, and the framework and finished work of forecasting of catchment flood or debris flow. 
Enhanced water loss during the Mars Year 34 C storm
Authors: Holmes James , Lewis Stephen , Patel Manish , Chaffin Michael , Cangi Eryn , Deighan Justin , Schneider Nicholas , Aoki Shohei , Fedorova Anna , Kass David , Vandaele Ann Carine
Published: March 2021

We investigate the evolving water vapour and hydrogen distribution in the martian atmosphere and their associated effect on hydrogen escape during the Mars Year (MY) 34 C storm (a late winter regional dust storm that occurs every Mars year). Improved calculation of the integrated loss of water throughout Mars‘ history (that is currently not well constrained) is possible through tracking the water loss through time from global simulations constrained by available observations. Through constraining water loss we can provide better insight into planetary evolution.

The Open University modelling group global circulation model is combined with retrievals from the ExoMars Trace Gas Orbiter (temperature and water vapour profiles from the Atmospheric Chemistry Suite and water vapour profiles from the Nadir and Occultation for Mars Discovery instrument) and the Mars Climate Sounder (temperature profiles and dust column) on the Mars Reconnaissance Orbiter. This multi-spacecraft assimilation provides the best possible replication of the evolving lower atmosphere.

The unusually intense dusty conditions during the MY 34 C storm led to increased amounts of water vapour and hydrogen above 80 km compared to a more typical C storm, which had an important impact on the amount of water escaping Mars’ atmosphere. Modelled hydrogen escape rates during the MY 34 C storm peaked at around 1.4 x 109 cm-2 s-1, three times the escape rate calculated in the MY 30 C storm scenario and equivalent to those found during previous global-scale dust storms. The weak MY 30 C storm and strong MY 34 C storm can be seen as a bracketing pair of events and therefore the calculated escape rates represent the interannual variabiity expected during C storm events.

Our results indicate water loss during the C storm event each year is highly variable, and must be considered when calculating the integrated loss of water through Mars’ history.
Advancing the selection of soil hydraulic property models for soil-crop modelling
Authors: Weber Tobias Karl David , Streck Thilo , Gayler Sebastian , Ingwersen Joachim , Diamantopoulos Efstathios
Published: March 2021

From hypothesis testing to impact assessment, soil-crop models serve a multitude of purposes in researching climate change impact on the water cycle in cropping systems. As such, model complexity undeniably differs amongst approaches and intended purpose but must include the full range of soil-water states. Climate change is predicted to increase prolonged periods of dry conditions, however, soil-crop models, often misrepresented drying of soils, inducing misquantifications in root water uptake, evapotranspiration, and concomitantly, water use efficiency and ground water recharge rates. While in soil hydrology, this has been recognised and effective solutions exist, soil-crop models typically neglect these more comprehensive approaches.

Our study serves two aims: For one, we shed light into the chaotic multitude of soil hydraulic property models, by representing the models in a systematic framework, of sub-models and processes. This model is called the Brunswick Soil Hydraulic Property Model Framework. With this we hope to make soil hydrology more tangible, for non-experts. Secondly, we i) demonstrate that representing soil hydraulic properties over the entire moisture range, i.e. from fully saturated to completely dry soils, changes simulated root water uptake under dry soil conditions, which sensitively affects crop yields. We quantify these effects by simulating root water uptake using the agro-ecosystem models Expert-N and Daisy, comparing the standard as well as oversimplified approach to a comprehensive model (of the Brunswick model framework). This was possible by using new pedotransfer functions to obtain all required model parameters. The framework and pedotransfer functions are available in the R package spsh on CRAN.
Sedimentary signals of fluvial discharge variability under tide and wave influence: Miocene examples in NW Borneo
Authors: Collins Daniel , Johnson Howard
Published: March 2021

The interaction of river and marine processes in the fluvial to marine transition zone (FMTZ) fundamentally impacts sedimentary dynamics and deposition. Heterolithics are important facies within ancient and modern FMTZs but the preserved signal of river flood, wave and tidal variations in heterolithics remains uncertain. This study integrates facies and ichnofacies characteristics of heterolithics in the Lambir Formation (Baram Delta Province, NW Borneo), with information of larger-scale stratigraphic architecture and modern analogue information, to interpret the preserved record of river flood deposits under the influence of tides and waves in an ancient FMTZ. Within the FMTZ of distributary channels, interpreted proximal–distal sedimentological and stratigraphic trends suggest: (1) a proximal fluvial-dominated, tide-influenced subzone; (2) a distal fluvial- to wave-dominated subzone; and (3) a conspicuously absent tide-dominated subzone. During coupled storm and river floods, fluvial processes dominated the FMTZ along major and minor distributary channels and channel mouths, causing significant overprinting of preceding interflood deposits and deposition of thicker, sandier event beds. Intervening interflood deposits are muddier, with increased bioturbation, and may variably preserve sedimentary indicators of tide and wave processes. Despite interpreted fluvial–tidal channel units and mangrove influence implying tidal processes, there is a paucity of unequivocal tidal indicators (e.g. cyclical heterolithic layering). This suggests that process preservation in the FMTZ preserved in the Lambir Formation primarily records episodic (flashy) river discharge, river flood and storm overprinting of tidal processes, and possible backwater dynamics. 
Comparison of the event and seasonal hillslope-stream hydrologic connectivity in an agricultural headwater catchment
Authors: Pavlin Lovrenc , Széles Borbála , Strauss Peter , Blaschke Alfred Paul , Blöschl Günter
Published: March 2021

In agricultural catchments, subsurface runoff is an important process for streamflow generation and the transport of nutrients and pollutants within and out of the catchment. Where and when subsurface runoff occurs is linked to the hydrologic connectivity in the catchment. This study compares spatial patterns of the connectivity between the hillslope and the stream on the event and seasonal scale. We analyse streamflow and groundwater responses to 53 precipitation events and their seasonal dynamics over two years in the Hydrologic Open Air Laboratory (HOAL), a small (66 ha) agricultural headwater catchment in Lower Austria. We quantify the connectivity in terms of Spearman correlation, hysteresis index and peak-to-peak time between streamflow and groundwater dynamics. It shows a clear spatial pattern, i.e. the connectivity is greatest in the riparian zone and diminishes further away from the stream where the groundwater table is deeper. This is reflected in the significant correlation of connectivity to the topographic indices and groundwater depth. Groundwater connectivity to the stream on the seasonal scale is higher than that on the event scale, indicating that groundwater contributes more to the baseflow than event runoff.
Inefficient compaction in small planetary cores -- application to the Moon
Authors: Lasbleis Marine
Published: March 2021

Growth of the solid inner core is generally considered to power the Earth's present geodynamo. Cristallisation of a solid central inner core has also been proposed to drive the lunar dynamo and to generate a magnetic field in smaller bodies. In a previous work, we estimated the compaction of planetary cores for different scenarios of growth (with or without supercooling) and different sizes of the inner core. Our main results indicated that small inner cores are unlikely to compact efficiently the liquid trapped during the first steps of the growth.

This is especially true for small bodies for which the typical size of the core is similar to the compaction length. The light elements are thus trapped during the cristallisation, reducing the release of latent heat and of light elements. We present here a model to include the effect of an inefficient compaction in the energy budget of a planetary core and investigate the implications for the dynamo evolution in small bodies. We apply this model for the evolution of the core of the Moon.
Sensitivity of the hydrological cycle to aerosol type and amount using high-resolution weather research and forecasting model over India
Authors: Santra Sauvik , Verma Shubha , Koll Roxy Mathew , Boucher Olivier
Published: March 2021

The present study is aimed to provide a quantitative prediction of the comparative impact of aerosol types on the changing pattern of the Indian summer monsoon (ISM) rainfall over recent years. Specific regions with contrasting features of aerosol loading and changes in ISM rainfall pattern relationship were identified through the comparative analysis of long-term (2000 to 2019) spatial distribution of observed AOD and rainfall over the Indian subcontinent. The spatial distribution of aerosol species were estimated using constrained aerosol estimation which could well represent the measured values. Spatial concordances were identified between the contrasting spatial features of changes in ISM rainfall pattern and the spatial distribution of pre-monsoon (March, April, May) anthropogenic and dust aerosols. Optical parameters consisting of aerosol optical depth (AOD), single scattering albedo (SSA), angstrom exponent (AE) corresponding to the estimated spatial distribution of aerosol types were simulated using optical simulation (OPTSIM) and further used in an aerosol radiative feedback simulation (ARFS) to evaluate the impact on ISM rainfall. The positive and negative radiative effect at the top of the atmosphere (TOA) were identified over the anthropogenic and dust aerosols dominated areas respectively. Although surface cooling was caused by both anthropogenic and dust aerosols, dust aerosols contributed to significantly higher surface cooling than the anthropogenic aerosols over the northwestern India (NWI) region. However, over the Indo-Gangetic plain (IGP) region, higher surface cooling was caused by the anthropogenic aerosols. A significant increase in rainfall with respect to no aerosol scenario was identified along the western coast of India due to combined aerosols (both anthropogenic and dust), which is notably in line with the current observations of high rainfall incidents over the region. Overall an increase and decrease in the ISM rainfall was observed over the NWI and IGP region respectively, which is strongly correlated to the spatial distribution of aerosol types over the Indian subcontinent. Production of less but heavier cloud droplets, leading to an enhanced condensation and increased rainfall over the NWI region was attributed to the comparative enhancement of regional evaporation rate due to a weaker surface cooling and atmospheric warming effect of dust aerosols than in the case of anthropogenic aerosols. Reduction in the ISM rainfall over the IGP region was attributed to the enhanced surface cooling due to anthropogenic aerosols (mostly dominated by sulphate aerosols), potentially suppressing the effective evaporation from the region.
Ability of Vis-PIR spectroscopy to monitor changes in organic carbon of loamy soils at two depths
Authors: Zayani Hayfa , Fouad Youssef , Michot Didier , Kassouk Zeineb , Lili-Chabaane Zohra , Walter Christian
Published: March 2021

Visible-Near Infrared (Vis-NIR) spectroscopy has proven its efficiency in predicting several soil properties such as soil organic carbon (SOC) content. In this preliminary study, we explored the ability of Vis-NIR to assess the temporal evolution of SOC content. Soil samples were collected in a watershed (ORE AgrHys), located in Brittany (Western France). Two sampling campaigns were carried out 5 years apart: in 2013, 198 soil samples were collected respectively at two depths (0-15 and 15-25 cm) over an area of 1200 ha including different land use and land cover; in 2018, 111 sampling points out of 198 of 2013 were selected and soil samples were collected from the same two depths. Whole samples were analyzed for their SOC content and were scanned for their reflectance spectrum. Spectral information was acquired from samples sieved at 2 mm fraction and oven dried at 40°C, 24h prior to spectra acquisition, with a full range Vis-NIR spectroradiometer ASD Fieldspec®3. Data set of 2013 was used to calibrate the SOC content prediction model by the mean of Partial Least Squares Regression (PLSR). Data set of 2018 was therefore used as test set. Our results showed that the variation ∆SOCobsobtained from observed values in 2013 and 2018 (∆SOCobs = Observed SOC (2018) - Observed SOC (2013)) is ranging from 0.1 to 25.9 g/kg. Moreover, our results showed that the prediction performance of the calibrated model was improved by including 11 spectra of 2018 in the 2013 calibration data set (R²= 0.87, RMSE = 5.1 g/kg and RPD = 1.92). Furthermore, the comparison of predicted and observed ∆SOC between 2018 and 2013 showed that 69% of the variations were of the same sign, either positive or negative. For the remaining 31%, the variations were of opposite signs but concerned mainly samples for which ∆SOCobs is less than 1,5 g/kg. These results reveal that Vis-NIR spectroscopy was potentially appropriate to detect variations of SOC content and are encouraging to further explore Vis-NIR spectroscopy to detect changes in soil carbon stocks.
Geochemical sensitivity of lacustrine ecosystems of Yamal Peninsula (Russian Arctic) to climate change
Authors: Fedorova Irina , Zdorovennov Roman , Kadutskiy Valeriy , Fedorov Grigorii , Shestakova Elena , Zdorovennova Galina , Guzeva Alina , Chernyshova Mariya , Chetverova Antonina , Frolova Larisa , Nigamatzyanova Gulnara
Published: March 2021

Yamal Peninsula is one of the significant region which terrestrial and aquatic landscapes are sensitive to the climate change. Geochemical processes in lakes can show impact of climate variability on hydrochemical and biological specific, trophic and ecological status. During 2012-2013 and 2018-2020 several Yamal lakes were observed during the summer field investigations. Water samples and sediment cores were taken and analyzed. Distribution of hydrochemical data is wide and cover Yamal coastal zone and central part of the peninsula including several anthropogenic chanced ecosystems. Sediment cores were taken in river terraces of Yuribey, Erkuta, Pysedeiyakha rivers, marine terraces of central Yamal (Neitinskie Lakes), and small core from Beliy island (North part of Yamal). Main ions and trace elements in lakes will be presented in a report as well as TOC/TC, grain-size, dating and paleoecological description of sediments. In order to reconstruct recent environmental and ecological changes half-core MSCL logging (physical properties, 0.5 cm spacing) and half-core XRF scanning (chemical composition, 0.1 cm spacing) have been applied for cores from Neitinskie Lakes (central part of Yamal). The first results of scanning and the statistic will be presented in the report. Comparison of aquatic ecosystem geochemistry for different parts of Yamal peninsula allow to explain the climate impact in different landscapes. Studies supported by RFBR 18-05-60291.  MSCL logging and XRF scanning have been done in Shirshov Institute of Oceanology of RAS by Geotek MSCL-XYZ instrument using.
Flood forecasting in small catchments using deep learning LSTM networks
Authors: Morgenstern Tanja , Pahner Sofie , Mietrach Robert , Schütze Niels
Published: March 2021

Long short-term memory (LSTM) networks are able to learn and replicate the relationships of multiple climate and hydrological temporal variables, and therefore are theoretically suitable for data driven modelling and forecasting of rainfall-runoff behavior. However, they inherit some prediction errors occasionally found in data-driven models: phase shift errors, oscillations and total failures. The phase shift error is a particularly significant challenge due to its occurrence when using hourly precipitation and runoff data for catchments with short response times.

In order to detect and eliminate these errors, we investigated four approaches, of which the first two are of structural nature, while the last two modify the input time series by certain transformations:
1. The use of encoder-decoder architectures for LSTM networks.
2. Offsetting the start of the flood forecast to the forecast time step of interest.
3. The inversion of the input time series.
4. Including subsequently observed precipitation data as a “best precipitation forecast”.

We tested the four approaches on five different pilot catchments located in Saxony, Germany with relatively short response times. The results show no advantage of the structural approaches. In contrast, the modification of the input time series shows potential for improving the predictive quality of flood forecasting in a potential operational application.
Early Holocene ocean conditions off the Zachariæ Isstrøm, Northeast Greenland
Authors: Davies Joanna , Møller Mathiasen Anders , Kristensen Kristiane , Pearce Christof , Seidenkrantz Marit-Solveig
Published: March 2021

The polar regions exhibit some of the most visible signs of climate change globally; annual mass loss from the Greenland Ice Sheet (GrIS) has quadrupled in recent decades, from 51 ± 65 Gt yr−1 (1992-2001) to 211 ± 37 Gt yr−1 (2002-2011). This can partly be attributed to the widespread retreat and speed-up of marine-terminating glaciers. The Zachariae Isstrøm (ZI) is an outlet glacier of the Northeast Greenland Ice Steam (NEGIS), one of the largest ice streams of the GrIS (700km), draining approximately 12% of the ice sheet interior. Observations show that the ZI began accelerating in 2000, resulting in the collapse of the floating ice shelf between 2002 and 2003. By 2014, the ice shelf extended over an area of 52km2, a 95% decrease in area since 2002, where it extended over 1040km2. Paleo-reconstructions provide an opportunity to extend observational records in order to understand the oceanic and climatic processes governing the position of the grounding zone of marine terminating glaciers and the extent of floating ice shelves. Such datasets are thus necessary if we are to constrain the impact of future climate change projections on the Arctic cryosphere.

A multi-proxy approach, involving grain size, geochemical, foraminiferal and sedimentary analysis was applied to marine sediment core DA17-NG-ST8-92G, collected offshore of the ZI, on  the Northeast Greenland Shelf. The aim was to reconstruct changes in the extent of the ZI and the palaeoceanographic conditions throughout the Early to Mid Holocene (c.a. 12,500-5,000 cal. yrs. BP). Evidence from the analysis of these datasets indicates that whilst there has been no grounded ice at the site over the last 12,500 years, the ice shelf of the ZI extended as a floating ice shelf over the site between 12,500 and 9,200 cal. yrs. BP, with the grounding line further inland from our study site. This was followed by a retreat in the ice shelf extent during the Holocene Thermal Maximum; this was likely to have been governed, in part, by basal melting driven by Atlantic Water (AW) recirculated from Svalbard or from the Arctic Ocean. Evidence from benthic foraminifera suggest that there was a shift from the dominance of AW to Polar Water at around 7,500 cal. yrs. BP, although the ice shelf did not expand again despite of this cooling of subsurface waters.
Combining SIF, reflectance, and leaf scale measuremnts to assess the effcets of interannual changes in winter rainfall on tree physiology during the following summer drought period in a dry Mediterranean pine forest
Authors: Cochavi Amnon , Rotenberg Eyal , Tatarinov Fyodor , Kӧhler Philipp , Frankenberg Christian , Yakir Dan
Published: March 2021

Dry Mediterranean forests are characterized by a short rainy season followed by a long dry period with high temperatures and radiation levels. These ecosystem are also exposed to large interannual variations in precipitation. Taking advantage of contrasting rainfall years, we investigated the opportunistic nature of pine trees in this region.  In our study site (the Yatir forest) mean annual precipitation is 288 mm, but it was 220 and 420 mm in the hydrological years 2018/19 and 2019/20, respectively. We used fluorescence measurements at the leaf, tower, and satellite scales, together with reflectance indices and eddy covariance measurements to assess the physiological response in the dry stressful season in these contrasting years.

The results showed that following a low rainfall season, soil moisture contes (SWC) reaches the 16% threshold of no traspirable water in spring, followed by larg decrease in carbon uptake and quantum yield of photosynthesis and the activation of protection mechanisms, such as decrease in chlorophyll content, large NPQ, and drop in the chlorophyll to cartenoid ratio (CCI index, obtained from canopy reflectance). Following the high rainfall year, the active season is extended (as indicated also by the satellite data), but even after the SWC threshold is reached, and mid-day VPD reaches ~5 KPa), carbon uptake continues, the amount of energy allocated to photochemistry remains high (high Fv/Fm and Y(II) levels), without the onset of protective mechanisms: No decrease in leaf chlorophyll and in NPQ, or decrease in CCI. We hypothesize that the opportunistic response of the dry-land forest must rely on yet unidentified water storage outside the root zone (e.g. deep soil pockets within the bedrock, or within the plants), which allow the plant to maintain high, with the only apparent adjustment reflected in shift of activity to early morning hours, when VPD is still low but the PAR levels are sufficiently high.
Upscaling of pore-scale mixing and reaction through effective dispersion coefficients
Authors: Puyguiraud Alexandre , Perez Lazaro , Hidalgo Juan J. , Dentz Marco
Published: March 2021

We utilize effective dispersion coefficients to capture the evolution of the mixing interface between two initially segregated species due to the coupled effect of pore-scale heterogeneity and molecular diffusion. These effective dispersion coefficients are defined as the average spatial variance of the solute plume that evolves from a pointlike injection (the transport Green function). We numerically investigate the effective longitudinal dispersion coefficients in two porous media of different structure heterogeneity  and through different Péclet number regimes for each medium. We find that, as distance traveled increases (or time spent), the solute experiences the pore-scale velocity field heterogeneity due to advection and transverse diffusion, resulting in an evolution of the dispersion coefficients. They evolve from the value of molecular diffusion at early time, then undergo an advection dominated regime, to finally reach the value of hydrodynamic dispersion at late times. This means that, at times smaller than the characteristic diffusion time, the effective dispersion coefficients can be notably smaller than the hydrodynamic dispersion coefficient. Therefore, mismatches between pore-scale reaction data from experiment or simulations and Darcy scale predictions based on temporally constant hydrodynamic dispersion can be explained through these differences. We use the effective dispersion coefficients to approximate the transport Green function and to quantify the incomplete mixing occurring at the pore-scale. We evaluate the evolution of two initially segregated species via this methodology. The approach correctly predicts the amount of chemical reaction occuring in reactive bimolecular particle tracking simulations. These results shed light on the upscaling of pore-scale incomplete mixing and demonstrates that the effective dispersion is an accurate measure for the width of the mixing interface between two reactants. 
Impact of soil water potential pattern on root water uptake distribution and leaf water potential
Authors: Mehmandoost Kotlar Ali , Javaux Mathieu
Published: March 2021

Root water uptake is a major process controlling water balance and accounts for about 60% of global terrestrial evapotranspiration. The root system employs different strategies to better exploit available soil water, however, the regulation of water uptake under the spatiotemporal heterogeneous and uneven distribution of soil water is still a major question. To tackle this question, we need to understand how plants cope with this heterogeneity by adjustment of above ground responses to partial rhizosphere drying. Therefore, we use R-SWMS simulating soil water flow, flow towards the roots, and radial and the axial flow inside the root system to perform numerical experiments on a 9-cell gridded rhizotrone (50 cm×50 cm). The water potentials in each cell can be varied and fixed for the period of simulation and no water flow is allowed between cells while roots can pass over the boundaries. Then a static mature maize root architecture to different extents invaded in all cells is subjected to the various arrangements of cells' soil water potentials. R-SWMS allows determining possible hydraulic lift in drier areas. With these simulations, the variation of root water and leaf water potential will be determined and the role of root length density in each cell and corresponding average soil-root water potential will be statistically discussed.
Reconstructions and predictions of the global carbon cycle with an emission-driven Earth System Model
Authors: Li Hongmei , Ilyina Tatiana , Loughran Tammas , Pongratz Julia
Published: March 2021

The global carbon budget including CO2 fluxes among different reservoirs and atmospheric carbon growth rate vary substantially in interannual to decadal time-scales. Reconstructing and predicting the variable global carbon cycle is of essential value of tracing the fate of carbon and the corresponding climate and ecosystem changes. For the first time, we extend our prediction system based on the Max Planck Institute Earth system model (MPI-ESM) from concentration-driven to emission-driven taking into account the interactive carbon cycle and hence enabling prognostic atmospheric carbon increment. 

By assimilating atmospheric and oceanic observational data products into MPI-ESM decadal prediction system, we can reproduce the observed variations of the historical global carbon cycle globally. The reconstruction from the fully coupled model enables quantification of global carbon budget within a close Earth system and therefore avoids the budget imbalance term of budgeting the carbon with standalone models. Our reconstructions of carbon budget provide a novel approach for supporting global carbon budget and understanding the dominating processes. Retrospective predictions based on the  emission-driven hindcasts, which are initiated from the reconstructions, show predictive skill in the atmospheric carbon growth rate, air-sea CO2 fluxes, and air-land CO2 fluxes. The air-sea CO2 fluxes have higher predictive skill up to 5 years, and the air-land CO2 fluxes and atmospheric carbon growth rate show predictive skill of 2 years. Our results also suggest predictions based on Earth system models enable reproducing and further predicting the evolution of atmospheric CO2 concentration changes. The earth system predictions will provide valuable inputs for understanding the global carbon cycle and supporting climate relevant policy development. 
Hydrological controls of DOC export from Nordic headwater catchments. 
Authors: Knutson Jacqueline , Clayer François , Norling Magnus , Lepistö Ahti , Marttila Hannu , Futter Martyn N. , Eklöf Karin , de Wit Heleen
Published: March 2021

Nordic surface waters are currently much browner than during the 1980s due to drivers related to decreased acid deposition, and increased precipitation. While upward trends in concentration of DOC have been well documented, positive trends in the annual export of DOC are not as widespread. The variation in seasonality of DOC export may mask long-term trends in annual export. A large dataset of 30 natural headwater catchments from Finland, Norway, and Sweden contains more than 20 years of discharge and DOC records. We will use these data to better quantify the trends of DOC export and their relationships to seasonality and the effects of climatic changes seen over the last few decades, such as diminished snowpack, less distinct snowmelt events and increases in autumn precipitation. We will investigate both the seasonal and annual relationships between DOC concentration and discharge (C-Q) and test if they relate to time and catchment characteristics such as size, latitude, and landcover.

We explore 3 hypotheses in this data set. First, spring DOC export is decreased due to less distinct snowmelt and runoff events while autumn export of DOC is increased as a consequence of more autumn runoff. Second, we propose that catchments with a longer or more distinct snow cover period are more sensitive than catchments at lower elevation or latitude due to the length of inactivity caused by low temperatures and a more defined snowmelt runoff event. Third, we hypothesize the negative C-Q relationship in winter and spring is likely due to source limitation and dilution while hydrologic controls in summer and autumn are associated with positive C-Q relationships.

Climate change is promoting enhanced export of DOC from soils towards surface waters, leading to more carbon processed and transported along the aquatic continuum from headwaters to coast. This data set gives us an opportunity to look at a diverse set of headwater catchments in the Nordic region, an area disproportionally affected by climate change, to clarify the hydrologic components and how this will affect overall carbon transport. 
Inter-comparison of wind vectors derived from geostationary satellites with the Aeolus/ALADIN
Authors: Shin Hyemin , Ahn Myoung-Hwan , Kim Jisoo , Kim Jae-Gwan , Choi Joon-Tae
Published: March 2021

Wind information obtained from various means ​​play an important role in data assimilation of numerical weather prediction. Atmospheric Motion Vector (AMV) obtained from the geostationary satellites provide a high spatio-temporal resolution wind information over the whole glove. An accurate quality control is one of the key factor that needs for a better utilization of AMV. Here, we use Aeolus/Atmospheric Laser Doppler Instrument (ALADIN) data to analyze the error characteristics of AMV derived from a newly commissioned geostationary satellite, Geostationary Korea Multi Purpose Satellite-2A (GK2A), stationed over 128.2o E. As majority of the GK2A AMV data are obtained over the ocean where the radiosonde data (used for the reference wind measurement for the error analysis of AMV) is sparse, the ALADIN data could play an important contribution. Data obtained from December 2019 to February 2020 (northern hemisphere winter) are collocated with time, space, and altitude criteria of ±15 min, 0.9 o, and 50hPa. For the quality control data, only AMV data with a Quality Index (QI) of 0.85 or higher are used. In case of the ALADIN data, quality control is performed using the observation type (clear and cloudy) and error estimation value of the ALADIN data. The total number of collocated data for the AMV (using IR channel) and Mie channel ALADIN data is 39971 which gives the root mean square difference (RMSD) of 3.88 m/s. The lower layer (lower than 700 hPa altitude) RMSD shows slightly better comparison, 3.35 m/s vs. 4.17 m/s, while the correlation coefficient is better for the upper and middle layers of 0.98 compared to the 0.94 of the lower layer. In the conference, detailed analysis of the comparison results and additional AMV data, including visible channel and water vapor channel along with the extended time period are going to be presented.
How does the timing of the tide influence thermal stresses experienced by the blue mussel Mytilus edulis?
Authors: Wilmes Sophie-Berenice , Perks Emily , Winterbourn Ben , Malham Shelagh , Robins Peter
Published: March 2021

Rising air and water temperatures are expected to increase the thermal stresses which intertidal organisms experience. Intertidal organisms living close to their thermal tolerances are exposed to thermal extremes that can affect their health, growth, development and survival – ultimately influencing the functioning and structure of ecological communities, resulting in species loss and devasting the shellfish industry. The large tidal range of the eastern Irish Sea has extensive intertidal zones that are exposed at varying times of the day over the springs-neaps cycle. Large differences in tidal phasing occur across small geographic distances: Along the coast of South Wales spring low tides occur in the middle of the day, whereas in North Wales (< 160 km distance) spring low tides occur in the morning and the evening. To determine how these tidal patterns influence the thermal stresses experienced by intertidal organisms, the blue mussel, Mytilus edulis was used as a representative species. Biomimetic loggers (robomussels) which estimate mussel body temperatures were deployed across the intertidal zone at a site in North Wales and South Wales, respectively. For both sites, the warmest robomussel temperatures were recorded during lunchtime exposures with lunchtime spring lows generally resulting in greater heat stresses. This suggests that heat stresses for intertidal organisms may be more severe in intertidal zones which have frequent or long duration aerial exposures, particularly during the middle of the day. These conclusions may be used to identify shellfish cultures at greater risk of mortalities from heat exposure on a greater geographic range.
Assessment interaction of climate change and aquifer recharge in different periods: an article review
Authors: Cárdenas-Castillero Gustavo , Kuráž Michal
Published: March 2021

Groundwater represents 98% of the world's freshwater resource. This resource is strongly impacted by the increase in temperature and variation in precipitation. Therefore, the relationship between climate change and the dynamics of aquifer recharge is still poorly understood. It was not until the 1980s when investigations in this field were improved. This research aims to evaluate the studies carried out on the impact of climate change-related to the recharge of aquifers. The applied methodology is strictly based on the bibliographic review. Bibliographic references were selected from citation database Scopus. This database was studied from a quantitative analysis using the Bibliometric package in RStudio. This investigation evaluates growth performance research on aquifer recharge on climate change from the 1980s to 2020.

 

The results show an average growth of 14.38% and a significant increase in research from 2009. This study identifies 52 countries, just over 26% of total countries; the highest contribution has been made by Australia, the United States and Spain. The journals with the most increased contributions are Water Journal, Journal of Hydrology, Water Resources Research, Science of the Total Environment, and Hydrology and Earth System Sciences. According to the impact of climate change, the worst projections related to the decrease in recharge were identified in arid and desert areas. While the highest recharges were placed in the northern regions and at high altitudes where the recharge capacity is maintained or increases due to rapid thaw and increasing rain. More studies should be extended to analyse groundwater assessment in other latitudes to achieve a complete and comprehensive understanding. This understanding should be one of the priorities of water and governments' scientific society to safeguard this precious resource.

Key words: Climate change, aquifer recharge, climate models, precipitation, and temperature.
13C signatures of aerosol organic and elemental carbon from major combustion sources in China and worldwide
Authors: Yao Peng , Ni Haiyan , Kairys Norbertas , Yang Lu , Huang Ru-Jin , A.J. Meijer Harro , Dusek Ulrike
Published: March 2021

Isotopic source apportionment is commonly used to gain insight into sources and atmospheric processing of carbonaceous aerosols. Since elemental carbon (EC) is chemically stable, it is possible to apportion the main sources of EC (coal/biomass burning and traffic emissions) using a dual 14C-13C isotope approach. However, dual-isotope source apportionment crucially relies on accurate knowledge of the 13C source signatures, which are seldom measured directly for EC. In this work, we present extensive measurements of organic carbon (OC) and EC 13C signatures for relevant sources in China. The EC 13C source signatures are provided first time using the optical split point in a thermal-optical analyzer to isolate EC, which can greatly reduce the influence of pyrolyzed organic carbon (pOC). A series of sensitivity studies (pOC/EC separation) were conducted to investigate the reliability of our method and its relation to other EC isolation methods. Meanwhile, we summarized and compared the literature 13C signatures in detail of raw source materials, total carbon (TC) and EC using a variety of thermal methods. Finally, we recommend composite EC 13C source signatures with uncertainties and detailed application conditions. There are two points worth noting. First, the traffic 13C signatures of raw materials and EC are separated into three groups according to geographical distribution. Second, the EC 13C signature of C4 plant combustion can be influenced greatly if pOC and EC are not well separated, so the thermal-optical method is necessary. Using these EC 13C source signatures in an exemplary dual-isotope source apportionment study shows improvement in precision. In addition, some interesting distinct and repeatable patterns were discovered in 13C source signatures of semi-volatile, low-volatile, and non-volatile primary OC fractions.