bluuebunny/crossref_metadata_2025 huggingface dataset:
Continental Hotspots Tracks from Analysis of GOCE Gravity Gradients Data
Authors: Greff-Lefftz Marianne , Panet Isabelle , Besse Jean
Published: March 2021

Hotspots are thermal instabilities that originate in the mantle and manifest themselves on the surface by volcanism, continental breaks or "traces" observed in the oceans. Theirs effects under the continents are still debated: in addition to a phase of activity associated with surface volcanism, a residual thermal anomaly could persist durably under the lithosphere along the trajectory of the hotspot.
For a simple model of thermal anomaly (parallelogram aligned in a fixed direction), we compute the perturbations of the geoid, of the gravity vector and of the associated gravity gradients. We show that in a coordinate system aligned with the parallelogram, gravity gradients have a characteristic signal with an order of magnitude of a few hundred mEotvos, well above the current data detection level. Thus for four real cases: in North Africa (with the Hoggar, Tibesti, Darfur and Cameroon hotspots), in Greenland (Iceland and Jan Mayen), in Australia (Cosgrove) and in Europe (Eifel), we calculate the paleo-positions of the hotspots during the last 100 Ma in a reference frame linked to the lithospheric plates, and we build maps of gravity gradients at different altitudes filtered at the spatial scale of a few hundred kilometers (scale of the hotspot) and oriented along the direction of the trajectory.
We clearly find signals aligned in the direction of the movement of the plates on spatial scales of a few hundred kilometers.
This signal is sometimes correlated with the topography and it is difficult to separate the sources resulting from volcanic edifices and their associated isostatic crustal roots from that induced by residual thermal anomaly. These results show that gradiometric data are able to detect and follow the tracks of hotspots in the continental lithosphere, during at least a few tens of millions of years, providing new clues to constrain their trajectory and improve reference frame tied to the mantle.
Application of deformation–induced topographic effect in interpretation of 2013–2016 spatiotemporal gravity changes at Laguna del Maule (Chile)
Authors: Vajda Peter , Zahorec Pavol , Miller Craig A. , Le Mével Hélène , Papčo Juraj , Camacho Antonio G.
Published: March 2021

The accurate deformation-induced topographic effect (DITE) should be used to account for the gravitational effect of surface deformation when analyzing residual spatiotemporal (time-lapse) gravity changes in volcano gravimetric or 4D micro-gravimetric studies, in general. Numerical realization of DITE requires the deformation field available in grid form. We compute the accurate DITE correction for gravity changes observed at the Laguna del Maule volcanic field in Chile over three nearly annual periods spanning 2013–2016 and compare it numerically with the previously used free-air effect (FAE) correction. We assess the impact of replacing the FAE by DITE on the model source parameters of analytic inversion solutions and apply a new inversion approach based on model exploration and growing source bodies. The new inversion results based on the DITE correction shift the position of the mass intrusion upwards by a few hundred meters and lower the total mass of the migrated fluids to roughly a half, compared to the inversion results based on the local-FAE correction. Our new Growth inversion results indicate that vertical dip-slip faults beneath the lake, as well as the Troncoso fault play active roles in hosting migrating liquid. We also show that for the study period, the DITE at Laguna del Maule can be accurately evaluated by the planar Bouguer approximation, which only requires the availability of elevation changes at gravity network benchmarks. We hypothesize that this finding may be generalized to all volcanic areas with flatter or less rugged terrain and may alter interpretations based on the commonly used FAE corrections.
A new Python package to estimate hydraulic and poroelastic groundwater properties using standard pressure records
Authors: Rau Gabriel , Schweizer Daniel , Turnadge Chris , Blum Philipp , Rasmussen Todd
Published: March 2021

Determining subsurface hydraulic and geomechanical properties crucially underpins groundwater resource investigation and management. While standard practice relies on active testing, passive approaches require less effort and cost but are underutilised. We present the new Python package named HydroGeoSines (HGS) which quantifies hydraulic and poroelastic subsurface properties using the groundwater response to natural forces (such as Earth tides and atmospheric pressure changes) embedded in standard measurements. All implemented methods are drawn from the peer-reviewed literature. The package includes basic handling of time series, such as joining and aligning records and handling gaps. HGS uses standard atmospheric and groundwater pressure records to estimate the Barometric Response Function (BRF) groundwater state of confinement, hydraulic conductivity, specific storage, barometric efficiency (BE) and porosity. If Earth tides are required, they can be calculated on-the-fly using the PyGTide package which is based on ETERNA and included. HGS allows easy compensation and correction of pressure or hydraulic heads from barometric pressure or Earth tide influences. Further, HGS includes import from and export to common data formats as well as visualisation of data and results. We demonstrate the use of HGS using example datasets from around the world. Since HGS unlocks sophisticated methods for use by anyone with Python skills, we anticipate that it will support subsurface investigations and add value to standard monitoring practice.
Terrestrial hydroclimatic variability in basins of Southern Siberia driven by different states of permafrost degradation
Authors: Han Li , Menzel Lucas
Published: March 2021

Changes in the cryosphere caused by global warming are expected to alter the hydrologic system, with inevitable consequences for freshwater availability to humans and ecosystems. Quantitative understandings of the historical hydrologic changes in response to permafrost degradation is essential for projecting future changes with respect to the continuing and possibly intensifying warming. Here we investigate past hydro-climatic changes over three southern Siberian basins with diverse permafrost properties: in the Selenga catchment, all three permafrost types occur, i.e., discontinuous, sporadic and isolated permafrost; the Lena Basin (at gauge Tabaga) is mostly underlain by discontinuous permafrost, while the Aldan is dominated by continuous permafrost.

Based on the reconstruction of terrestrial water storage changes (TWS) from the GRACE satellite mission and hydro-climatic time series over the period 1984-2013, our results show very different change patterns in the TWS among these three basins. There is an unprecedented reduction of TWS (-9.8 km3) in the Selenga basin, but remarkable increases (14.4 km3 and 13.1 km3) in the Lena-Tabaga and Aldan basins, respectively. The diverse changes in TWS, runoff and precipitation over each basin suggest different hydrologic response mechanisms to permafrost degradation under a warming climate. The Selenga, dominated by lateral degradation (i.e., decreasing permafrost extent), suffers severe water loss via deep infiltration of water that was previously stored close to the surface, which induces a drier surface and subsurface drainage system. In contrast, in the Aldan basin, determined by vertical degradation, thicker active layers develop which sustain a water-rich surface and subsurface environment. In the Lena-Tabaga basin finally, which is characterized by both lateral and vertical degradations, the further development of lateral degradation has led to a stronger increase in groundwater storage in comparison to surface runoff during the increased precipitation states, suggesting a potentially groundwater-dominated hydrologic system in this basin. Our findings are of great importance for the regional water management in permafrost-affected regions under ongoing warming.
Communicating Climate Change to broad public through Educations - Project KlimaAlps
Authors: Baumann Cornelia , Beck Inga
Published: March 2021

Education is key in order to create a generation that thinks and acts sustainable and that considers nature as one of the most important good.Within the three years Interreg Project ‘KlimaAlps’ (www.klimaalps.eu) – making climate change visible - one major task is the establishment of a training for educators, to become a certified ‘Climate-Pedagogue’ for the alpine region. The ‘Climate-Pedagogue’-training contains background information of climate change in the Alps and a variety of innovative educational tools and methods. It covers aspects of the high mountain areas, rivers and lakes, human beings, agriculture as well as moors.  The project is managed by the ‘Energiewende Oberland’; five additional partners from Austria and Bavaria are responsible for e. g. a high quality of the taught scientific information (Environmental Research Station Schneefernerhaus), the didactical input (University of Innsbruck, Department of Geography), the outreach activities and the implementation (Naturpark Karwendel, Klimabündnis Oberösterreich, Landratsamt Garmisch-Partenkirchen). During the last one and half years, the concept for the ‘Climate-Pedagogue’- training was worked out in cooperation with other environmental facilities and in March 2021 the first lectures of a pilot run with over 30 selected participants were held. In total there will be two runs in 2021 in order to evaluate the recent version of the training as good as possible. The next and long-term steps will be the firm establishment of a chargeable ‘Climate-Pedagogue’ – Training for every interested person for at least the coming ten years, as well as the strengthening and growing of the network. The presentation will give a short overview about the entire project as well as details about the ‘Climate-Pedagogue’ – Training and some first impressions of the already hold lectures in 2021.
Unifying the sedaDNA scientific community
Authors: Capo Eric ,   sedaDNA scientific community
Published: March 2021

Since the seminal paper in 1998 (Coolen and Overmann), sedimentary ancient DNA (sedaDNA) has become a powerful tool in paleoecology to reconstruct past changes in terrestrial and aquatic biodiversity. Still, sedaDNA is an emerging tool and there is a need for calibrations and validations to ensure the reliability of sedaDNA as a proxy to reconstruct past biota. One way to pursue this goal is by unifying the sedaDNA scientific community. Here, we present a few initiatives taken over the last years to transmit information, augment our knowledge about best practices and method standardisation related to sedaDNA analysis and strengthen collaborations between research groups. Also, we discuss tools and ideas that could be used to increase the visibility of sedaDNA research by the scientific community. Finally, we would like to use this opportunity to discuss with the audience about new strategies to unify experts from different research fields - including paleoecology, paleolimnology, paleoceanography, molecular ecology, aquatic ecology, terrestrial ecology, microbial ecology - around the use of sedaDNA.
Monitoring of water table dynamics in peatlands with OPTRAM: Towards globally applicable algorithms in Google Earth Engine using Landsat and Sentinel-2
Authors: Burdun Iuliia , Bechtold Michel , Komisarenko Viacheslav , Lohila Annalea , Humphreys Elyn , Desai Ankur R. , Nilsson Mats B. , Sagris Valentina , Mander Ülo , De Lannoy Gabrielle
Published: March 2021

Fluctuations of water table depth (WTD) affect many processes in peatlands, such as vegetation development and emissions of greenhouse gases. Here, we present the OPtical TRApezoid Model (OPTRAM) as a new method for satellite-based monitoring of the temporal variation of WTD in peatlands. OPTRAM is based on the response of short-wave infrared reflectance to the vegetation water status. For five northern peatlands with long-term in-situ WTD records, and with diverse vegetation cover and hydrological regimes, we generate a suite of OPTRAM index time series using (a) different procedures to parametrise OPTRAM (peatland-specific manual vs. globally applicable automatic parametrisation in Google Earth Engine), and (b) different satellite input data (Landsat vs. Sentinel-2). The results based on the manual parametrisation of OPTRAM indicate a high correlation with in-situ WTD time-series for pixels with most suitable vegetation for OPTRAM application (mean Pearson correlation of 0.7 across sites), and we will present the performance differences when moving from a manual to an automatic procedure. Furthermore, for the overlap period of Landsat and Sentinel-2, which have different ranges and widths of short-wave infrared bands used for OPTRAM calculation, the impact of the satellite input data to OPTRAM will be analysed. Eventually, the challenge of merging different satellite missions in the derivation of OPTRAM time series will be explored as an important step towards a global application of OPTRAM for the monitoring of WTD dynamics in northern peatlands.
Modelling soil carbon sequestration with biochar using RothC
Authors: Pulcher Roberta , Balugani Enrico , Ventura Maurizio , Greggio Nicolas , Marazza Diego
Published: March 2021

In the context of climate change mitigation, technologies for removing the CO2 from the atmosphere are key challenges. Most recent scenarios from integrated assessment models require large-scale deployment of negative emissions technologies (NETs) to reach the 2 °C target. Among them, technologies for increasing organic carbon content in soils (SOC) have been developed. In the 15th IPCC special report on Global Warming of 1.5 °C, biochar and pyrogenic carbon capture and storage have been credited as promising negative emission technology. In fact, soil carbon sequestration (SCS) and biochar have a large negative emission potential (each 0.7 GtCeq. yr-1) and they are expected to have lower impact on land, water use, nutrients, albedo, energy requirement and cost, and thus fewer disadvantages than many other NETs.

SCS can be assessed using soil carbon dynamic models, such as RothC, as suggested by IPCC. However, studies on the inclusion of biochar in RothC are still scarce. Furthermore, most of these studies are based on the results of laboratory experiments and do not account for the effects of biochar on SOC degradation (the priming effect). The use of laboratory data can be problematic, since they may not adequately represent field conditions, especially due to the lack of long-term field studies.

The aim of this work was to assess and predict how biochar influences the soil C dynamics, by modifying the RothC model to simulate the findings of a long-term field experiment on biochar application to a short coppice rotation in Italy. We first modified the model to include two stocks of C input into the soil: the labile and the recalcitrant biochar pools. We also included a parametrized function to account for the priming effect on SOC dynamics in the soil. Secondly, we calibrated the model parameters with the data obtained from the field experiment. Finally, we validated the model results by estimating the remaining biochar amount in the site after 10 years from application, using an isotopic mass balance.

The results confirm that biochar degradation can be faster in field conditions in comparison to laboratory experiments; nevertheless, it can contribute to substantially increase the C stock in the long-term. Moreover, the modified RothC model allowed to assess the SCS potential of biochar application in soils, at least in the specific conditions examined, and could represent a flexible tool to assess the effect biochar as a SCS strategy in the long-term. We are exploring the possibility to use data from other long-term field experiment to move in that direction. The results of this study could be added to the Italian biochar database, providing new knowledge about a topic that needs to be explored.
The NICAM 3.5km-1024 ensemble simulation: Performance optimization and scalability of NICAM-LETKF on supercomputer Fugaku
Authors: Yashiro Hisashi , Terasaki Koji , Kawai Yuta , Kudo Shuhei , Miyoshi Takemasa , Imamura Toshiyuki , Minami Kazuo , Nakano Masuo , Kodama Chihiro , Satoh Masaki , Tomita Hirofumi
Published: March 2021

In parallel with the new Japanese flagship supercomputer, Fugaku, we have continued improving a nonhydrostatic icosahedral atmospheric model (NICAM). Here, we introduce the results of our system-application co-design since 2014. Fugaku's CPU (A64FX) is based on the Arm instruction-set architecture. This 48-core many-core CPU is equipped with 32GB of HBM2 memory, showing data transfer performance comparable to GPUs. We have implemented kernel-level optimizations to take advantage of Fugaku's high memory performance. Among them, we recognized trade-offs related to ensuring memory locality and parallelism, and register allocation. We improved the application's average arithmetic intensity through detailed loop-by-loop performance measurements and reduced memory pressure by actively using single-precision operations. We also redesigned the data layout and the file I/O component of the ensemble data assimilation (DA) system and achieved good scalability in the atmospheric simulation and DA. We performed a global 3.5km mesh, 1024-member ensemble simulation, and DA using 82% of the Fugaku system (131,072 nodes, 6,291,456 cores). In this world's most massive ensemble DA benchmark experiment, the simulation and the DA achieved 29 PFLOPS and 79 PFLOPS of effective performance.
Seismo-acoustic characterization of the 2019 Stromboli volcano paroxysm events
Authors: Le Pichon Alexis , Marchetti Emanuele , Pilger Christoph , Ceranna Lars , Souty Viviane , Hernandez Bruno , Listowski Constantino
Published: March 2021

Stromboli volcano is well known for its persistent explosive activity, with hundreds of explosions every day ejecting ash and scoria up to heights of several tens/few hundreds of meters. Such a mild activity is however punctuated by lava flows and major/paroxysmal explosions, that represent a much larger hazard. On July 3rd and August 28th 2019, two paroxysmal explosions occurred at Stromboli, generating an eruptive column that quickly raised up to 5 km above the sea level. The Toulouse Volcanic Ash Advisory Center (VAAC) emitted an advisory to the civil aviation with a two-hour delay. The various processes of this event were monitored near and far field by infrasonic arrays up to distance of 3,500 km and by the Italian national seismic network at range of hundreds of kilometres. Using state-of-the-art propagation modeling, we aim at identifying the various seismic and infrasound phases of the event to better characterize the volcanic source. We highlight the need for the integration of the global infrasound International Monitoring System (IMS) network with local and regional infrasound arrays capable of providing a timely early warning to VAACs. This study opens new perspectives in volcano monitoring for hazard assessment and could represent, in the future, an efficient tool in supporting VAACs activity.
Aerosol Assimilation of lidar data from Satellite (AEOLUS) and Ground-based (EARLINET) instruments in COMPO-IFS.
Authors: Letertre-Danczak Julie , Benedetti Angela , Vasiljevic Drasko , Dabas Alain , Flament Thomas , Trapon Dimitri , Mona Lucia
Published: March 2021

Since several years, the number of aerosol data coming from lidar has grown and improved in quality. These new datasets are providing a valuable information on the vertical distribution of aerosols which is missing in the AOD (Aerosol Optical Depth), which has been used so far in aerosols analysis. The launch of AEOLUS in 2018 has increased the interest in the assimilation of the aerosol lidar information. In parallel, the ground-based network EARLINET (European Aerosol Research LIdar NETwork) has grown to cover the Europe with good quality data. Assimilation of these data in the ECMWF/CAMS (European Centre for Medium-range Weather Forecasts / Copernicus Atmosphere Monitoring Service) system is expected to provide improvements in the aerosol analyses and forecasts.

Three preliminary studies have been done in the past four years using AEOLUS data (A3S-ESA funded) and EARLINET data (ACTRIS-2 and EUNADIC-AV, EU-funded). These studies have allowed the full development of the tangent linear and adjoint code for lidar backscatter in the ECMWF's 4D-VAR system. These developments are now in the operational model version in research mode. The first results are promising and open the path to more intake of aerosol lidar data for assimilation purposes. The future launch of EARTHCARE (Earth-Cloud Aerosol and Radiation Explorer) and later ACCP (Aerosol Cloud, Convention and Precipitation) might even upgrade the use of aerosol lidar data in COMPO-IFS (Composition-Integrated Forecast system).

The most recent results using AEOLUS data (for October 2019 and April 2020) and using EARLINET data (October 2020) will be shown in this presentation. The output will be compared to the CAMS operational aerosol forecast as well as to independent data from AERONET (AErosol Robotic NETwork).
Towards the removal of model bias from ESA CCI SM by using an L-band scaling reference
Authors: Madelon Rémi , Rodriguez-Fernandez Nemesio , Van Der Shalie Robin , Kerr Yann , Scalon Tracy , De Jeu Richard , Dorigo Wouter
Published: March 2021

Merging data from different instruments is required to construct long time data records of soil moisture (SM). This is the goal of projects such as the ESA Climate Change Initiative (CCI) for SM (Gruber et al., 2019), which uses both active and passive microwave sensors. Currently, the GLDAS v2.1 model is used as reference to re-scale active and passive time series by matching their Cumulative Density Function (CDF) to that of the model. Removing the dependency on models is important, in particular for data assimilation applications into hydrological or climate models, and it has been proposed (Van der Schalie et al., 2018) to use L-band data from one of the two instruments specifically designed to measure SM, ESA Soil Moisture and Ocean Salinity (SMOS) and NASA Soil Moisture Active Passive (SMAP) satellites, as reference to re-scale other time series.
To investigate this approach, AMSR-2 SM time series obtained from C1-, C2- and X-band observations using LPRM (Land Parameter Retrieval Model) were re-scaled by CDF-matching (Brocca et al., 2011) using different SMAP and SMOS official (SMAP L2 V005, SMOS L3 V300, SMOS NRT V100&V200) and research (SMOS IC V103) SM products as well as the SMAP and SMOS LPRM v6 SM data used by the ESA CCI. The time series re-scaled using L-band remote sensing data were compared to those re-scaled using GLDAS and were evaluated against in situ measurements at several hundred sites retrieved from the International Soil Moisture Network (Dorigo et al., 2011). The results were analyzed as a function of the land cover class and the Koppen-Geiger climate classification.
Overall, AMSR-2 time series re-scaled using SMAP L2, SMAP LPRM and SMOS IC data sets as reference gave the best correlations with respect to in situ measurements, similar to those obtained by the time series re-scaled using GLDAS and slightly better than those of the original AMSR-2 time series. These results imply that different SMAP and SMOS products could actually be used to replace GLDAS as reference for the re-scaling of other sensors time series within the ESA CCI. However, one must bear in mind that this study is limited to the re-scaling of AMSR-2 data at a few hundred sites.
For a more detailed assessment of the L-band data set to be used for a global re-scaling, it is necessary to investigate other effects such as the spatial coverage or the time series length. SMAP spatial coverage is better than that of SMOS in regions affected by radio frequency interference. In contrast, the length of SMAP time series can be too short to capture the long term SM variability for climate applications in some regions. The CDF of SMOS time series computed from the date of SMAP launch is significantly different to those of the full length SMOS time series in some regions of the Globe. Possible ways of using a coherent SMAP/SMOS L-band data set will be discussed.
Abiotic drivers of CO2 fluxes in the transition from the winter-to-spring in coniferous forest and bog in central Siberia
Authors: Park Sung-Bin
Published: March 2021

The transition winter-to-spring is essential for understanding the seasonal dynamics of CO2 flux in high northern latitudes. However, the latest CO2 flux measurements in the two dominant boreal ecosystems, i.e. coniferous forests and bogs are still insufficient. We investigated interannual variability of CO2 fluxes and their major drivers measured in a coniferous forest and a bog from 2013-2017 in Zotino, Russia. To better understand the controlling factors, we utilized the  Multivariate Adaptive Regression Splines (MARS) model. The two ecosystems showed clear differences in the timing of the start of CO2 uptake and CO2 flux rates before and after snowmelt. Both ecosystems started the net CO2 uptake even the snowmelt was incompleted. CO2 flux variations of coniferous forest were more sensitive to changes in air temperature than soil temperature than that of the bog. It is likely that intermittent frost events can reduce the magnitude of CO2 uptake rates of both ecosystems, however, CO2 uptake rates increased with a similar level as pre-frost within a few days. In 2015, both ecosystems reached the highest cumulative net ecosystem exchange of CO2 because of the unusually warm temperature in May compared to the study period. Our findings reveal that continuous and long-term monitoring of the effects of air and soil temperatures on vegetation productivity as well as their legacy effect in subarctic ecosystems required further to be studied.
Determining sedimentation rates by accounting for past compaction in the Mekong Delta as input for 3D delta evolution modelling
Authors: Baldan Selena , Minderhoud Philip S.J. , Zoccarato Claudia , Teatini Pietro
Published: March 2021

The Vietnamese Mekong River Delta has been formed by the deposition of soft, fine-grained sediments during the last thousands of years. Natural compaction of these unconsolidated deposits over time and with increased overburden load is one of the main drivers of subsidence in this delta. High rates of natural compaction may have a considerable increased flood vulnerability of the lowly elevated delta plain and ultimately result in permanent inundation.

Following the loading history of accumulating sediments during the Holocene delta evolution, it is possible to estimate delta-wide present-day natural compaction rates. The ultimate goal of this study is to provide reliable input data on Holocene sedimentation rate throughout the Mekong Delta for a novel 3D numerical model to simulate delta formation and its dynamic evolution during the late Holocene. In order to achieve this, it is fundamental to first take into account previous compaction that already happened to the sediments in the past to estimate the original sedimentation rate of Holocene sediments.

We employed a 1D decompaction module to compute the original, uncompacted thickness of Holocene delta sequences from lithological borelogs to estimate the amount of virgin sediment that has been deposited in time. The original thickness of Holocene sediments was determined after investigating geomechanical properties of Holocene deposits and decompaction of lithological boreholes spread over the delta. To determine the sedimentation rate for the borelogs with missing dating information, the age was estimated by using a linear distance interpolation of age isochrones starting from a limited number of boreholes, where both stratigraphy and sediment ages are available.

As a final step, the estimated sedimentation rates from each of the borelogs are interpolated to arrive at delta-wide sedimentation rates and lithology during the Late Holocene. This provides the required input data for the 3D model to simulate natural consolidation during the delta evolution and accurately assess present natural compaction rates.
Impact of Clouds on Broadband Radiation Profiles in the Summer Arctic Measured by a Tethered Balloon During MOSAiC: First Results
Authors: Lonardi Michael , Pilz Christian , Egerer Ulrike , Ehrlich André , Shupe Matthew D. , Siebert Holger , Wendisch Manfred
Published: March 2021

Arctic boundary layer clouds play an important role in the Arctic amplification due to their impact on the radiative energy budget, e. g., local cooling at cloud top which strongly affects boundary-layer dynamics. High resolution in-situ data characterizing the irradiance profile in clouds over the Arctic sea ice are rare due to the accessibility of this region, the challenges posed by icing and the limited resolution of airborne measurements.

The tethered balloon system BELUGA (Balloon-bornE moduLar Utility for profilinG the lower Atmosphere) was deployed from the ice camp of the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC) in July 2020. BELUGA consists of a 90 m³ helium-filled tethered balloon with maximum flight altitude of 1500 m and an adaptable scientific payload to characterize radiation, cloud, aerosol and turbulence properties which was specifically developed for Arctic tethered balloon operations.

Here a first analysis of vertical profiles of upwards and downwards solar and terrestrial irradiances in cloudy and cloud-free conditions is presented. Profiles of radiative heating were calculated and compared for different cloud covers. The case studies were evaluated by radiative transfer simulations  to quantify the impact of different cloud and atmospheric properties on the heating rate profiles. In combination with surface-based measurements, the cloud radiative forcing in the summer Arctic was assessed.
Soil moisture simulation with the WRF-Hydro modeling system by involving a more precise infiltration process module
Authors: Wang Wei , Liu Jia , Li Chuanzhe , Yu Fuliang , Liu Yuchen
Published: March 2021

Soil moisture is an important factor affecting atmospheric processes as well as land surface hydrological processes. The description of the infiltration process greatly influences the accuracy of the soil moisture simulation, but there is still a lack of a consistent theoretical framework for predicting the effective fluxes and parameters that control infiltration in the atmospheric-hydrological modeling system. A coupled simulation study of the Weather Research and Forecasting model (WRF) and its terrestrial hydrologic component WRF-Hydro is carried out in two mesoscale watersheds of northern China. An infiltration module that is suitable for convective rainfall with large intensity and mixed runoff generation mechanism is added in WRF-Hydro to replace the original infiltration description. The main principle of the new module is: 1) The grid-based topographic index is used as an indication for the infiltration capacity and the soil water storage capacity across the watersheds; and 2) the infiltration is controlled by the variation of the surface soil moisture during the process of the rain, i.e., the infiltration is in an exponential decline as the increase of the surface soil moisture. Three long-duration rainfall-runoff events during the flood season are selected for this study. WRF runs to provide appropriate meteorological inputs to WRF-Hydro, and the simulated soil moisture results are compared with data from the Global Land Data Assimilation System (GLDAS). The results show that the added infiltration module, compared to the original, produces more consistent simulations with the observations regarding the spatial replication of the soil moisture and thus overall results in a higher simulation accuracy.

Keywords: soil moisture, infiltration, WRF-Hydro, topographic index
A regionally explicit, global SWI calibration based on ISMN observations
Authors: Grillakis Manolis G.
Published: March 2021

Remote sensing has proven to be an irreplaceable tool for monitoring soil moisture. The European Space Agency (ESA), through the Climate Change Initiative (CCI), has provided one of the most substantial contributions in the soil water monitoring, with almost 4 decades of global satellite derived and homogenized soil moisture data for the uppermost soil layer. Yet, due to the inherent limitations of many of the remote sensors, only a limited soil depth can be monitored. To enable the assessment of the deeper soil layer moisture from surface remotely sensed products, the Soil Water Index (SWI) has been established as a convolutive transformation of the surface soil moisture estimation, under the assumption of uniform hydraulic conductivity and the absence of transpiration. The SWI uses a single calibration parameter, the T-value, to modify its response over time.

Here the Soil Water Index (SWI) is calibrated using ESA CCI soil moisture against in situ observations from the International Soil Moisture Network and then use Artificial Neural Networks (ANNs) to find the best physical soil, climate, and vegetation descriptors at a global scale to regionalize the calibration of the T-value. The calibration is then used to assess a root zone related soil moisture for the period 2001 – 2018.

The results are compared against the European Centre for Medium-Range Weather Forecasts, ERA5 Land reanalysis soil moisture dataset, showing a good agreement, mainly over mid-latitudes. The results indicate that there is added value to the results of the machine learning calibration, comparing to the uniform T-value. This work contributes to the exploitation of ESA CCI soil moisture data, while the produced data can support large scale soil moisture related studies.
MOPGA/Make Air Quality Great Again: AfriqAir and solution-oriented approaches to improving air quality in the Global South
Authors: Giordano Michael R , Bahino Julien , Beekmann Matthias , Subramanian Ramachandran ,   AfriqAir/MAQGA Team
Published: March 2021

Air pollution is responsible for seven million premature deaths each year, linked to numerous cardiovascular and other diseases. Both monitoring pollution levels and identifying sources is necessary to reduce overall exposure. Many parts of Africa suffer from extreme pollution levels, but the cost of traditional air quality monitoring leads to a significant data gap, which also hinders the development of local capacity to do these tasks. In order to overcome these obstacles, the “Make Air Quality Great Again” (MAQGA) project was funded by the French Agence nationale de la recherché (ANR) under the MOPGA program. The MAQGA project in turn set up the AfriqAir consortium, a global organization that brings together air quality scientists and researchers interested in using air quality data to tackle air quality problems in Africa. Now entering its third year of existence, the consortium has made real strides in increasing the number of air quality monitors in Africa as well as building capacity with local researchers and partners across the continent. This presentation will provide a recap of what the consortium has achieved with ANR and MOPGA support, how we have persevered through the COVID-19 pandemic, and our plans for the immediate and long-term futures. This presentation will cover the scientific gains made by connecting African air quality researchers as well as the successes aided by the network building that AfriqAir has facilitated. 
Evaluation of a high resolution regional atmospheric chemistry model using MAX-DOAS and in situ NO2 measurements
Authors: Kumar Vinod , Remmers Julia , Beirle Steffen , Kerkweg Astrid , Lelieveld Jos , Mertens Mariano , Pozzer Andrea , Steil Benedikt , Wagner Thomas
Published: March 2021

Regional atmospheric chemistry models are adopted for simulating concentrations of atmospheric components at high resolution and quantifying the impact of localized emissions (e.g. industrial and urban clusters) on the non-linear chemical processes, e.g. ozone production. However, their evaluation is challenging due to the limited availability of high spatiotemporally resolved reference datasets. For the same reason, the vertical distribution of pollutants simulated by the model is especially arduous to assess.

Here, we present regional atmospheric chemistry model studies with spatial resolution up to 2.2 × 2.2 km2 focused around Germany for May 2018 using the MECO(n) model system. Using a network of surface concentration measurements at background, near traffic and industrial locations, we evaluate the spatial distribution of NO2 simulated by the model. The highly resolved model together with a comparable resolution and up-to-date input emissions inventory, was found to perform best in reproducing the spatial distribution of NO2 surface volume mixing ratios (VMRs). We propose a computationally efficient approach to account for the diurnal and day of the week variability of input anthropogenic emissions (e.g. from road transport), which proved to be crucial for resolving the temporal variability of NO2 surface VMRs.

The simulated NO2 tropospheric vertical column densities were evaluated by employing the measurements of a 4-azimuth MAX-DOAS instrument in Mainz. Generally, such comparisons do not account for the spatial sensitivity volume of the MAX-DOAS measurements, the change of sensitivity within this volume and the spatial heterogeneity of NO2. We therefore apply a consistent approach of comparison of the differential slant column densities (dSCDs), which overcomes these limitations. Moreover, the dSCDs are obtained for several elevation and azimuth angles, which are characterized by distinctive sensitivity for different vertical levels within the boundary layer and different horizontal representativeness. Hence, also an evaluation of the model in simulating the vertical distribution of NO2 can be performed with this approach using continuous MAX-DOAS measurements spanning long time periods. We found that the model performs well with respect to the measured dSCDs at low elevation angles (< 8°) with an overall bias between +14 and -9%, and Pearson correlation coefficients between 0.5 and 0.8 for the different azimuth viewing directions.
Phenology studies need to account for tissue temperature, not air
Authors: Peaucelle Marc , Peñuelas Josep , Verbeeck Hans
Published: March 2021

Plant phenology is mainly driven by temperature in extratropical ecosystems. Contrasting responses of foliar phenology to climatic warming, however, have been reported in recent decades, raising important questions about the role of other environmental constraints, especially light. A striking and common aspect to past phenological studies is that all analyses have been solely based on air temperature. In fact, temperatures differ substantially between plant tissues and the air, because plants absorb and radiate energy. Using a simple model of bud energy balance, we explore how using bud instead of air temperature could change our interpretation of the phenological response to warming and explain several observed responses of phenology to temperature and light. Not accounting for the real temperature of plant tissues represents a real gap in phenology studies. Field observations of plant tissues temperature as well as experiments are needed for accurately assessing the response of vegetation to climate change.
Thin cirrus clouds that extinct supercooled water clouds in the Arctics
Authors: Iwasaki Suginori , Okamoto Hajime , Sato Kaori
Published: March 2021

We show that thin cirrus clouds, whose particle radius is greater than 50 μm and number concentration is less than 10 /L, extinct supercooled water clouds (SC) by use of the data of the space-borne lidar, Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), and the space-borne 94-GHz cloud profiling radar (CPR). We call the cirrus Large-and-Sparse-particle Clouds (LSC).

The space-borne imagers, such as Moderate Resolution Imaging Spectroradiometer (MODIS), cannot measure LSC; hence, LSC had been difficult to be found by satellites. CALIOP is less sensitive to LSC than CPR though CALIOP is usually more sensitive to clouds than CPR because of the cloud particle size distribution of LSC.

The most significant feature of LSC is that LSC extinct SC and cloud particles of SC are changed into pristine ice particles. This is because (1) SC and LSC do not tend to coexist while horizontally oriented ice particle clouds (2D) and LSC tend to coexist, (2) the cloud top height of LSC is higher than that of SC, and (3) the terminal velocity of LSC particles is about 1 km/h.

Because 10-20% of clouds in the Arctic are LSC, LSC would indirectly impact on radiative forcing in the Arctics.
Impact of groundwater – soil moisture interaction on evolution of evapotranspiration and air temperature under climate change
Authors: Arboleda Pedro , Ducharne Agnès , Cheruy Frédérique
Published: March 2021

Groundwater (GW) constitutes by far the largest volume of liquid freshwater on Earth. The most active part is soil moisture (SM), which plays a key role on land/atmosphere interactions. But GW is often stored in deep reservoirs below the soil as well, where it presents slow horizontal movements along hillslopes toward the river network. They end up forming baseflow with well-known buffering effects on streamflow variability, but they also contribute to sustain higher SM values, especially in the lowland areas surrounding streams, which are among the most frequent wetlands.  As a result, GW-SM interactions may influence the climate system, in the past but also in the future, with a potential to alleviate anthropogenic warming, at least regionally, owing to enhanced evapotranspiration rate (ET) or higher soil thermal inertia for instance.
To assess where, when, and how much GW-SM interaction affects the climate change trajectories, we use coupled land-atmosphere simulations with the IPSL-CM6 climate model, developed by the Institut Pierre Simon Laplace for CMIP6.  We contrast the results of two long-term simulations (1979-2100), which share the same sea surface temperature and radiative forcing, using the SSP5-8.5 scenario (i.e. the most pessimistic) for 2015-2100. The two simulations differ by their configuration of the land surface scheme ORCHIDEE: in the default version, there is no GW-SM interaction, while this interaction is permitted in the second simulation, within a so-called lowland fraction, fed by surface and GW runoff from the rest of the grid-cell. For simplicity, this lowland fraction is set constant over time, but varies across grid-cells based on a recently designed global scale wetland map. 
Within this framework, we analyse the impact of the GW-SM interaction on climate change trajectories, focusing on the response of evapotranspiration rates and near-surface air temperatures. The GW-SM interaction can modulate the response to climate change by amplifying, attenuating, or even inverting the climate change trend. Based on yearly mean values over land, we find that the GW-SM interaction amplifies the response of evapotranspiration to climate change, as the mean evapotranspiration rate increases 50% faster over 1980 - 2100 in the simulation with GW-SM interaction. In contrast, the mean warming over land is 1% weaker, shifting from 6.4 to 6.3 °C/100 years; thus attenuated, if the GW-SM interaction is accounted for. In both cases, these values hide important differences across climates and seasons, with mitigation or amplification for both variables, indicating the need for regional and seasonal assessment. We will also further explore how GW-SM interaction impacts the future evolution of heatwaves, in terms of duration and frequency. 
Sentinel-2 water indexes application for the underground water level analyses in Ovidiopol area of Odessa region (Ukraine).
Authors: Kadurin Sergii , Chuiko Elena , Andreeva Kseniya
Published: March 2021

Problems statement and purpose. Studied area has a high level of agricultural development. There are different irrigation and drainage systems located there. Significant part of the supplied water losses from the irrigation network because of filtration and reaches the groundwater level, which begins to rise. Raising of groundwater level can lead to waterlogging of the soil, secondary salinization and, as a consequence, to a decrease in crop yields. As result, the groundwater level is under intense technogenic impact. Control and analyses of groundwater level changes with remote sensing methods for Ovidiopol area is the main goal of that work. The object of study is the groundwater level regime in the territory of Lower Dniester irrigation system in Ovidiopol district, Odessa region. The subject of research is water indexes application for analyses of groundwater level changes.

Data and methods. The local system of groundwater observation includes 7 drillholes in Nadlimanskoe village and around. These drillholes located in different geomorphological, hydrogeological and technogenic conditions. The groundwater level was surveyed monthly in 2017.  Sentinel-2 2A images for each month from March 2017 to December 2017 were used for studied area. All satellite images has atmospheric correction. Three water indexes NDWI, MNDWI, NDPI were calculated for drillhole points for each month in 2017 year.

Results. Significant coefficients of correlation were obtained in comparison between groundwater level changes and water indexes in some drillholes points. The highest numbers of correlation connected with free of construction areas and for drillholes, which are located outside of villages. Water indexes have the same intra-annual dynamics of changing as groundwater level. NDWI is the most informative and representative index for studied area. Other types of indexes should be used for build-up areas analyses. However, existed water indexes can be used for groundwater level analyses in the open fields and in river slopes and valleys with developed irrigation system.