bluuebunny/crossref_metadata_2025 huggingface dataset:
Peculiarities of the chemical composition of size-segregated atmospheric aerosols sampled at Fonovaya Observatory, West Siberia
Authors: Belan Boris D. , Simonenkov Denis , Arshinov Mikhail , Belan Sergey , Golobokova Lyudmila , Davydov Denis , Ivlev Georgii , Kozlov Artem , Kozlov Alexandr , Onischuk Natalia , Sklyadneva Tatyana , Tolmachev Gennadii , Fofonov Alexandr , Khodzher Tamara
Published: March 2022

Aerosols play an important role in radiation processes in the atmosphere, as well as they have a significant impact on global and regional air quality. The process of the atmospheric nanoparticle formation starts from in situ conversion of condensable vapors. Then, the freshly formed nanometer-size clusters begin to grow due to the condensation of nucleating vapours on them and a self-coagulation as well, thus reaching the optically active size ranges. The relative contribution of the above mechanisms can be estimated by the chemical composition of size-segregated particles. Here, we present preliminary results of the analysis of aerosol samples characterizing the inorganic chemical composition of particles ranging from a few nm to 10 mm. The sampling was performed at Fonovaya Observatory (West Siberia) in October 2021 by means of the Model 125R Nano-MOUDI Impactor.

The analysis showed that in the lowest size range (<10 nm), only five ions were detected: SO42-, Cl-, K+, Na+, H+. The growth of the nucleation mode particles to the size range of 60-100 nm was accompanied by increasing content of SO42-, Na+, H+ ions to 50, 37 and 13%, respectively, suggesting the condensation of H2SO4 vapours or the coagulation of particles contained mainly Na2SO4. A content of ammonium ions (NH4+) appeared to be significant only in the accumulation mode size range (0.1-1.0 mm). Nitrates (NO3-) were detected mainly in the Aitken mode particles and then their contribution increases in accumulation and coarse mode ranges.

This work was supported by the RFBR grant No. 19-05-50024 (Microparticles in the atmosphere: formation and transformation in the atmospheric surface layer and in the free troposphere, radiation effects and impact on public health).
Soil inoculation improves ecosystem function in degraded grasslands
Authors: Li Yu Hui , Han Xu , Li Ying bin , Li Qi , Bezemer Martijn
Published: March 2022

The improvement and protection of ecosystem function are important in the restoration of grassland ecosystem, especially in degraded grasslands. Soil inoculation provides an effective way for the restoration of degraded ecosystems. Here we conducted a field soil inoculation experiment and selected two well-developed soils (meadow steppe and upland meadow) to transplant them into degraded grasslands at three inoculation amounts (0.01 m3, 0.03 m3 and 0.05 m3 per square meter). After three years of soil inoculation, we assessed the ecosystem multifunctionality (including plant productivity, and functions related to nutrient cycling) of different treatments with different identity and amount of soil inoculation. Principal co-ordinates analysis suggested that different identity of soil inoculum resulted in different development of soil fungal and bacterial communities. Ecosystem multifunctionality was significantly improved with the increase of soil inoculation amounts. Spearman’s correlation analysis showed a positive association between ecosystem multifunctionality and soil fungal richness, plant cover, and the amount of soil inoculation. Our results indicate that soil inoculation can enhance ecosystem multifunctionality by affecting the soil biotic and plant communities. Our finding has important implications for better restoration of biodiversity and ecosystem functioning in degraded grassland ecosystems.
MASCDB: a database of images, descriptors and microphysical properties of individual snowflakes in free fall
Authors: Grazioli Jacopo , Ghiggi Gionata , Billault-Roux Anne-Claire , Berne Alexis
Published: March 2022

Snowfall information at the scale of individual particles is rare, difficult to gather, but fundamental for a better understanding of solid precipitation microphysics.

We present a dataset, MASCDB, (and a dedicated python software) of in-situ measurements of snow particles in free fall collected by a multi-angle snowflake camera. The dataset, includes gray-scale (255 shades) images of snowflakes, co-located surface environmental measurements, a large number of geometrical and textural snowflake descriptors as well as the output of previously published retrieval algorithms. Noteworthy examples include: hydrometeor classification, riming degree estimation, identification of melting particles, discrimination of wind-blown snow, as well as estimates of snow particle mass and volume. The measurements were collected in various locations of the Alps, Antarctica and Korea for a total of 2'555'091 snowflake images (or 851'697 image triplets). MASCDB aims to accelerate reproducible research on precipitation microphysics and to address longstanding scientific challenges on snowflake research. Given the large amount of snowflake images and associated descriptors, MASCDB can be exploited by the computer vision community for the training and benchmarking of image processing systems. MASCDB can be accessed on Zenodo (DOI: https://doi.org/10.5281/zenodo.5578920), while the pymascdb package at https://github.com/ltelab/pymascdb.

 
Transient weakening during the granulite to eclogite transformation within hydrous shear zones (Holsnøy, Norway)
Authors: Bras Erwan , Baïsset Marie , Yamato Philippe , Labrousse Loic
Published: March 2022

In Holsnøy (Bergen Arcs, Norway), metastable granulite facies anorthosite rocks are partially eclogitised within hydrous shear zones, that have been interpreted as widening over time with fluid influx and strain. We here present a detailed petrological description of metre-scale shear zones from this area. The granulite protolith (originally plagioclase + garnet + two pyroxenes) is transformed into an albite + zoisite + garnet + clinopyroxene assemblage within a few tens of centimetres of the shear zones. The outer edge of the shear zones consists in a fine-grained heterogeneous assemblage of omphacite + zoisite + kyanite + garnet + phengite ± albite ± quartz. An eclogite composed of coarser omphacite + kyanite + garnet + zoisite + phengite quartz forms the core of the shear zones. As the shear zones widened over time, this lateral evolution from the edge to the core of the shear zones reflects the temporal evolution of the granulite from the beginning to the end of the eclogitisation reaction. The outer omphacite + zoisite + kyanite + garnet + phengite ± albite ± quartz assemblage therefore represents a transient eclogite facies assemblage. This transient assemblage appears to be mechanically weaker than both the starting granulite and the final eclogite, based on field and petrological findings. We investigate the impact of transient weakening during syn-tectonic metamorphism using a one-dimensional numerical model of a fluid-fluxed, reacting shear zone. Our numerical model shows that transient weakening is required to explain the field and petrological data. Furthermore, we show that, while fluid infiltration was predominantly responsible for the widening of the shear zones, strain hardening during the end of the eclogitisation reactions sequence had a noticeable widening effect on the shear zones.
Comparison of measured and satellite-derived ASCAT surface soil moisture data in a small mountain catchment
Authors: Sleziak Patrik , Danko Michal , Jančo Martin , Holko Ladislav , Parajka Juraj
Published: March 2022

Soil moisture plays an important role in the transformation of precipitation into flow and affects the severity of droughts, floods and other hydrological processes such as transpiration and evaporation. Estimation of spatio-temporal dynamics of soil moisture is therefore crucial for all water sectors. The main objective of this study is to compare satellite-derived ASCAT soil moisture data and field soil moisture measurements in an experimental, well-documented catchment (the Jalovecký Creek catchment, Western Tatra mountains, Slovakia). For the comparison, we used data from the period of 2012 – 2019. Measured data are represented by point measurements at two localities: (a) Červenec – open area (1500 m a.s.l., measurements at a depth of 5 cm) and (b) Červenec – forest (1420 m a.s.l., measurements at a depth of 10 cm). The new, experimental version of the ASCAT product provides data with higher spatial and temporal resolutions and improved soil moisture mapping under vegetation. Satellite-derived soil moisture data represented by the Soil Water Index are determined by an exponential filter with characteristic time delays (T in days). T value represents the reduction of the infiltration of the soil moisture dynamics, and therefore, it must be carefully chosen. The suitability of the satellite data in terms of different T values (i.e., T = 1, 2, 5, 10) is assessed by the visual inspection (measurements vs satellite) and correlation coefficient. The agreement between observed ASCAT data and the field soil moisture measurements will be further evaluated using observations of snow accumulation and melt, precipitation, air temperature and global radiation. The study will discuss the factors controlling this agreement.

 

Acknowledgments

This work was supported by the Slovak Research and Development Agency under Contract No. APVV-19-0340 and the VEGA Grant Agency No. 2/0065/19. The financial support by the Stefan Schwarz grant of the Slovak Academy of Sciences is also gratefully acknowledged.
Round-the-globe racing events to fill the pCO2 data void in the Southern Ocean 
Authors: Landschützer Peter , Tanhua Toste , Behncke Jacqueline
Published: March 2022

The ocean absorbs around a quarter of the annual man-made CO2 emissions, with the Southern Ocean being responsible for the lion-share of this uptake. Despite the disproportional role of the Southern Ocean in taking up anthropogenic CO2, it still remains one of the most sparsely observed ocean regions. While autonomous measurement devices have started to fill this void, high quality shipboard measurements remain limited. One fleet with the potential to fill this gap has thus far received little attention: sailboats. There is growing willingness among skippers to help science, providing a opportunity to collect valuable measurements of the sea surface partial pressure of CO2 (pCO2) during round-the-world racing events. Using the latest membrane sensor technology, we have thus far – together with professional racing teams - collected high frequency measurements of the sea surface pCO2 from nearly all ocean basins and most notably in remote southern hemisphere ocean regions where no shipboard pCO2 data were collected in the past 70 years (based on the SOCAT database). Our results highlight the potential for equipping sail yachts as a low-cost solution to fill data gaps and provide a new constraint for high resolution model studies.
Benefits of Sentinel-1 backscatter assimilation to improve land surface model irrigation estimates in Europe
Authors: Modanesi Sara , Massari Christian , Bechtold Michel , Tarpanelli Angelica , Brocca Luca , Lievens Hans , Dorigo Wouter , Zappa Luca , De Lannoy Gabriëlle
Published: March 2022

Irrigation has been applied by humans for as long as they have been cultivating plants. Nowadays, the amount of water used for agricultural purposes is rising because of an increasing food demand. However, this human influence on the water distribution on land is typically not, or poorly, parameterized in regional and larger-scale Land Surface Models (LSM). Satellite-based microwave observations indirectly observe irrigation, when they sense the entire integrated soil-vegetation system. The optimal integration of fine-scale modeling and satellite observations using data assimilation (DA) is promising to detect irrigation and possibly improve the estimation of irrigation amounts.

This work was realized in the framework of the European Space Agency (ESA) Irrigation+ project. The main aim of this study was to test potential improvements in irrigation simulation due to the assimilation of 1-km Sentinel-1 backscatter data into a system composed by the Noah-MP LSM, equipped with a sprinkler irrigation scheme, and a backscatter operator represented by a Water Cloud Model (WCM), as part of the NASA Land Information System (LIS).  The calibrated WCM was used as an observation operator in the DA system to map model surface soil moisture and Leaf Area Index (LAI) into backscatter predictions and, conversely, map observation-minus-forecast residuals in backscatter back to updates in soil moisture and LAI through an Ensemble Kalman Filter (EnKF). Two separate DA experiments were realized using backscatter data at VV and VH polarizations. The system was tested  at two irrigated sites, located in the Po Valley (Italy) and in northern Germany.

Results confirm a stronger link between the backscatter VV with soil moisture and larger updates in the vegetation state variables when using the VH polarization. The backscatter DA introduced both improvements and degradations in soil moisture, evapotranspiration and irrigation estimates. The spatial and temporal scale had a large impact on the outcomes, with more contradicting results for a detailed analysis at the plot scale. Above all, this study sheds light on the limitations resulting from a poorly-parameterized sprinkler irrigation scheme which prevents large improvements in the irrigation simulation due to the ingestion of Sentinel-1 data and points out to future developments needed to improve the system.
Variations and Significance of Mg/Sr and 87Sr/86Sr of drip water and active speleothem in Furong Cave, Southwest China
Authors: Li Junyun , Li Ting-Yong , Shen Chuan-Chou , Yu Tsai-Luen , Zhang Tao-Tao , Wu Yao , Zhou Jing-Li , Chen Chao-Jun , Zhang Jian
Published: March 2022

Cave monitoring is an important method to investigate the deposition mechanism and factor influencing the trace elements in drip water and speleothemsThe Mg and Sr concentrations and the Mg/Ca and Sr/Ca ratios and 87Sr/86Sr in drip water and speleothems are often used to explore climate and environmental changes.Systematic monitoring was performed on the Mg and Sr contents, Mg/Sr ratio and 87Sr/86Sr of soil, soil water, cave drip water, and the active speleothems (AS) in Furong Cave in Chongqing, southwest China, during 2009–2018 (A.D). The results were interpreted in conjunction with the changes in the 87Sr/86Sr ratios to explore the main sources and controlling factors of Sr and other trace elements in drip water. (1) Mg and Sr concentrations and 87Sr/86Sr ratios in soil water were increased which was related to the prolonged residence time of water in the soil in winter and spring because of less rainfall. It indicates that the trace element contents of soil water reflect seasonal changes of the rainfall. (2) The Mg and Sr contents were higher in drip water than in soil water, as well as the 87Sr/86Sr ratios of drip water was closer to that of the bedrock, which indicates that the overlying bedrock was the main source of the trace elements in drip water and the speleothems in Furong Cave. (3) Mg contents and Mg/Sr ratios in drip water and AS showed decreasing trend corresponding to the increasing annual rainfall in the monitoring period which resulted in the shorter water-rock contact time. (4) The growth rate of AS may be an important factor to control the Sr contents in AS because of the similar increasing trend. (5) The Mg and Sr contents and the Mg/Sr ratios of drip water and AS did not exhibit seasonal variations due to the mixing of the fissure water and complex hydrology condition of the overlying bedrock, however, the geochemical indexes (Mg and Mg/Sr ratio) showed an opposite trend to the annual rainfall variation. This study suggests that the variations of Mg, Sr and Mg/Sr ratios of drip water and AS can response to the rainfall on the multi-year timescale, which contributes critical insights into the paleoclimate interpretation of proxies of speleothems in the cave with hundreds of meters thick bedrock. 
Improving photosynthesis estimation in northern temperate and boreal forest ecosystems
Authors: Luo Yunpeng , Gessler Arthur , Hufkens Koen , D’Odorico Petra , Stocker Benjamin
Published: March 2022

The projected extension of growing season length under climate change will increase the carbon uptake potential of forest ecosystems at high latitudes. However, the dynamics of carbon uptake in high latitudes, namely ecosystem scale photosynthesis have not been well represented in existing carbon models yet. This impedes the unbiased assessment of current and predicted carbon dynamics at regional and continental scales. For instance, a substantial overestimation of simulated (by applying a state-of-the-art terrestrial photosynthesis model (P-model)) compared to gross primary productivity (GPP) derived from eddy-covariance (EC) was found in early spring for many sites and years. Here we show a substantial reduction of this GPP overestimation by adding a stress function accounting for the effects of low temperature and high light intensity. We found the strong depression of light use efficiency (LUE) in the GPP overestimation sites, which is related to the high photosynthetic photon flux density (PPFD) and low daily minimum temperatures (Tmin) during the early spring and preceding weeks or months. This mismatch between modelled and EC-derived GPP can be attributed to the adjustment of leaf properties and photosynthesis, e.g., synthesizing photoprotective pigments while reducing photosynthesis pigments in evergreen trees in the cold periods to protect the photosynthesis apparatus from damage from excessive light (photoprotection). This is supported by the observed high red chromatic coordinates (RCC) and delayed increase of green chromatic coordinates (GCC) from digital repeat photography. Finally, through embedding an empirical stress function considering the direct and lagged impact from Tmin into the model, we improved the GPP estimation and reduced the model-observation mismatch in GPP in early spring. Our results demonstrate one way to improve the GPP estimation in high latitude ecosystem by taking the physiological processes (e.g. photoprotection) into account. This enables a more accurate estimation of the continental carbon dynamics under climate change.
Water isotopes in estuarine lagoons at the German Baltic Sea coast
Authors: Aichner Bernhard , Rittweg Timo , Schumann Rhena , Dahlke Sven , Duggen Svend , Dubbert David
Published: March 2022

River estuaries are characterized by mixing processes between freshwater inflows and marine water masses, with lower/higher isotope values, respectively. Therefore, they often show linear correlation between salinity and water isotopes (δ18O and δ2H values). In this study, we evaluated spatial and seasonal isotope dynamics along three estuarine lagoon transects at the German Baltic Sea coast: a) the Schlei; b) the Darß-Zingst Bodden Chain; c) an eastern transect (Stettiner Haff - Peene Stream - Greifswalder Bodden - Rügener Boddens). The data show strong seasonality of isotope values even at locations located furthest from the river mouths. They further reveal a positive and linear salinity-isotope correlation in spring 2020, but hyperbolic and partially even reverse correlation in summers 2019 and 2020. We conclude that additional physical processes, such as evaporation from the shallow lagoons, overprint the two-phase mixing correlation during summers. Understanding of those water isotope dynamics is crucial in context of ecological studies, for example when interpreting oxygen and hydrogen isotope values in aquatic organisms that depend on ambient estuarine water.
Knowledge hidden in plain sight – Extending article metadata to support meta-analysis and knowledge accumulation
Authors: Stein Lina , Wagener Thorsten
Published: March 2022

The number of publications in the field of Hydrology (and in other geoscience fields) is rising at an almost exponential rate. In 2021 alone, more than 25 000 articles were listed in Web of Science on the topic of Water Resources. There is a tremendous wealth of knowledge and data hidden in these articles, which capture our experience in studying places, datasets or models. Hidden, because we currently do not possess (or at least, do not use) the necessary tools to access this knowledge resource in an effective manner. It is increasingly difficult for an individual researcher to build on existing knowledge. New ways to approach this problem are urgently needed.  

One approach to address this problem of literature explosion might be to extend article metadata to include geoscience-specific information that can facilitate knowledge search, accumulation and synthesis in a domain specific manner. Imagine one could easily find all studies performed in a specific location/ climate/ land use thus allowing a full picture of the hydrology of that region/ climate/ land use. It is important for any geoscience, a field strongly depending on experience, that knowledge is not “forgotten” in a mountain of publications but can easily be integrated into larger understanding.

So what meta-information would be most useful in knowledge synthesis? Study location? Spatial and/or temporal scale? Models used? Here, we would like to (re-)start the discussion on geoscience-relevant metadata enrichment. With the recent advancement in text mining scholarly literature, it is critical to have this discussion now or fall behind.

The Geosciences strongly depend on experiences we gain, which we largely share through the articles we publish. Knowledge accumulation in our science is hindered if this exchange of knowledge becomes ineffective. We are afraid it already has!
Do Landsat satellite estimates of canopy disturbance reproduce tree mortality rates observed from forest inventories across Spain?
Authors: Nadal-Sala Daniel , Senf Cornelius , Pugh Thomas , Ruehr Nadine , Astigarraga Julen , Ruiz-Benito Paloma , Zabala Miguel A. , Esquivel-Muelbert Adriane
Published: March 2022

Tree mortality rates have increased in Europe during the last three decades with trends  expected to keep increasing into the future. This makes long-term forest health monitoring essential. In this regard, Landsat satellite observations provide annual estimates of canopy disturbance at moderate (30 meters) resolution. However, canopy disturbances do not always translate directly into tree mortality, as satellites only observe canopy trees at an aggregated grid level. Therefore, there is a need to validate Landsat estimates against actual ground-based tree mortality measurements. In this sense, National Forest Inventories (NFI) quantify the spatial distribution of tree mortality at regional level, but they are costly and have a lower temporal resolution than satellite observations (mostly every ten years). NFI are potentially an excellent asset to validate Landsat estimates, though the spatial agreement between NFI-derived tree mortality and Landsat disturbance estimates has yet to be assessed.

Here we compare Landsat spatial canopy disturbance rates with tree mortality rates derived from the 2nd and 3rd Spanish National Forest Inventories for the 1986-2008 period (n = 45564 stands). We compared the spatial distribution of Landsat canopy disturbance rates with the inventory-derived tree and biomass mortality rates on a grid size of 0.25°. There is positive correlation between satellite estimates and tree mortality obtained from inventories (r = 0.52, p < 0.001). In the case of biomass mortality, the correlation disappears (r = 0.26, p > 0.05). The correlation also weakens as the number of inventoried stands per forest cover extension decreases at grid level. In addition, both canopy disturbance rates and measured tree mortality rates were positively correlated with burned area, thus highlighting fire as a major driver of forest disturbance in Spain. Our results demonstrate that Landsat estimates are correlated spatially with tree mortality obtained from NFI, opening the door to make such analysis extensive to other European countries.
Analysis of strike-slip tectonics in extensional systems: the case of the Moroccan Atlas system
Authors: Vasileiou Athanasia , Gouiza Mohamed , Mortimer Estelle , Coliier Richard
Published: March 2022

The intracontinental belt of the High Atlas is an aborted rift system along NW Africa, which formed during the Mesozoic break-up of Pangaea and was inverted during the Alpine Orogeny. Although the inversion and orogeny build-up have been extensively studied, the Triassic to Jurassic rifting, synchronous to the opening of the Atlantic and the Tethys, is still poorly understood. True orthogonal rifting is proposed to occur in the Triassic to Early Jurassic, while the end of rifting is controversial and believed to be controlled by oblique extension. Restoration of the Atlantic-Tethys triple junction suggests sinistral motion between Iberia and Africa being active during the Middle Jurassic, which reactivated pre-existing NE-SW trending Hercynian weaknesses in transtension mode. This led to the formation of a series of pull-apart basins involving the basement and localised volcanic activity.

The Atlas system is an excellent field analogue to analyse the role of strike-slip tectonics in extensional systems, especially in the early stages of rifting. Despite the late Cenozoic (Alpine) inversion, the well-exposed syn-rift structures and sediments have been weakly affected by the broad contractional event.

Our study aims to investigate the kinematic and geometry of the oblique rifting phase, the strain variation lengthwise in the Atlas rift system, the relationship between the orthogonal rift structures, the strike-slip structures, and the synchronous volcanism. In this contribution, we will highlight the fieldwork results, which we used to constrain the restoration of the rift sytem, quantify extension vs. transtension, and produce a conceptual model of how strike-slip tectonics can influence the early stages of a rift system.
GNSS-IR for snow studies at PROMICE automatic weather station in Greenland
Authors: Dahl-Jensen Trine , Khan Shfaqat Abbas , Citterio Michele , Jakobsen Jakob , Ahlstrøm Andreas
Published: March 2022

The PROMICE project runs 27 Automatic Weather Stations (AWSs) in Greenland. Most of these are located in the ablation zone of the Greenland ice sheet. From March to September 2020 a multi-frequency Global Navigation Satellite System (GNSS) antenna was installed on the AWS NUK-K at a small local glacier outside Nuuk with the purpose of testing the setup for high precision positioning. Due to the remote location, power supply is limited and the GNSS setup is constructed to minimize the power consumption. Therefore, data collection is limited to three hours each day, the antenna is passive and the data is stored on a local drive and not transmitted.

This study tests if the setup is feasible for GNSS Interferometric Reflectometry (GNSS-IR) measurements of snow depth. The method estimates the average snow depth over an area on the order 10-20 • 103 m2. GNSS-IR analysis shows good reflections during most of the covered time period. A sonic ranger is mounted on the PROMICE AWSs and used for measurement of snow depth. The GNSS reflector heights are compared to measurements from the sonic ranger. Though some differences are present, the GNSS-IR estimates capture the snow melt, as measured by the sonic ranger, well. The quality of the reflections decreases towards the end of the data series when the snow is melted. We expect that this is due to a rougher ice surface. However, useful reflections are still obtained but the uncertainty on the daily estimates increase significantly. The transition from snow to ice surface is confirmed by an albedo estimate based on measurements of shortwave radiation at the AWS.
Exploring Independent Spatial Controls on the Global Distribution of Burnt Area, Fire Size and Fire Intensity through Generalized Linear Modelling
Authors: Haas Olivia , Prentice Colin , P. Harrison Sandy
Published: March 2022

Wildfires are fundamental for maintaining ecosystem structure and functioning, and thus it is important to know how projected climate and land use changes will affect wildfire regimes globally. Fire-enabled vegetation models can be used to predict changes in fire regime but are still far from perfect since many of the processes that control different aspects of the fire regime are still relatively poorly understood. In this work, we investigated the underlying relationships between potential controls of different fire properties, including fire size, intensity and burnt area, at a global scale. We fitted three generalized linear models (GLM) to monthly data from 2010 to 2015 for fractional burnt area from the Global Fire Emissions Database version 4.1 (GFEDv4), fire size from the Global Fire Atlas database and median fire radiative power divided by square root of median fire size (as a proxy for fire intensity) from the MODIS MCD14ML dataset. We used partial residual plots between each predictor and each response variable to show the underlying linear relationships fitted by each model. We show that there are different controls on burnt area, on fire size and on fire intensity. Specifically, whilst burnt area is driven mainly by fuel availability and dryness, fire size is driven primarily by wind speed and fire intensity by tree cover and road density. Land fragmentation was highly limiting for fire size and burnt area whereas dryness was limiting for fire intensity. These findings suggest that it is possible to develop empirical models of multiple aspects of fire regimes which could be used to predict how these will change in the future. Furthermore, they highlight the importance of including landscape fragmentation as a control on fire explicitly within process-based fire models. Additionally, the limiting nature of dryness on fire intensity could be due to antecedent vegetation conditions and highlights the need for better representation of these conditions and their effect on fuel load. Finally, these results also suggest that the current treatment of ignition sources as an important driver in these models is unnecessary.
Analysis of a curved shock front microstructures and associated electron/ion foreshock for a subcritical shock regime
Authors: Savoini Philippe , Lembege Bertrand
Published: March 2022

Previous numerical works on electron/ion foreshocks observed upstream of a curved shock have been already performed within a self-consistent approach based on 2D PIC simulation (Savoini et Lembege, 2010, 2013, 2015), but are restricted to a supercritical regime only. Present two dimensional PIC (Particle in cell) simulations are used in order to analyze the features of a curved shock and associated foreshocks in a subcritical regime. In order to investigate the dynamic of each electron and ion backstreaming populations, we used test-particles in a pre-computed electromagnetic field (issued from 2D PIC simulations) which allows us to define precisely the characteristic of each population in terms of initial velocity and/or their upstream position to the  θBn angle (angle between the local shock normal and the interplanetary magnetic field IMF). Then, results allow to clarify the following questions: what is the impact of the subcritical regime (i) on the persistence of each electron/ion foreshock respectively ?, (ii) in the case the persistence is confirmed,  how the location (along the curved front) and the angular direction of each foreshock edge are affected ?, and (iii) how the mapping of upstream local  distribution functions are impacted ? Preliminary results will be presented and compared with those already obtained for a supercritical shock.
The ASKOS experiment for desert dust science applications
Authors: Amiridis Vassilis ,   ASKOS team
Published: March 2022

The Joint Aeolus Tropical Atlantic Campaign (JATAC) has been conducted in summer/autumn 2021 at the Cape Verde, with the main aim to provide reference measurements for the validation of the Aeolus products and to collect information for ESA’s upcoming missions such as EarthCARE. Next to an impressive airborne fleet from AVATAR-T and CADDIWA components, situated on the island of Sal, intensive ground-based remote sensing and airborne in situ measurements performed on and above Mindelo in the framework of the ASKOS experiment. Specifically, a full ACTRIS remote sensing super site was deployed in Mindelo, Sao Vicente, including a multiwavelength-Raman-polarization lidar PollyXT, an AERONET sun photometer, a Scanning Doppler wind lidar, a microwave radiometer and a cloud radar. Additionally, ESA’s novel reference lidar system EVE, a combined linear/circular polarization lidar with Raman capabilities, was deployed, which can mimic the observations of the space-borne lidar onboard AEOLUS. Moreover, for 2 weeks in September, a light-weight airplane performed in-situ measurements in the aerosol layers around the island, in altitudes up to 3 km.

Here, will quickly introduce the measurements and present first results on the aerosols observed. Focus is given in the intensive September period, where very different aerosol conditions were observed above and around Mindelo. Usually, the marine boundary layer was up to 1 km and was topped by the Saharan Air Layer (SAL) reaching up to 6 km altitude. Three different dust events were observed. The first one had significant spatiotemporal homogeneity, which is ideal for Cal/Val objectives. The second one had strong horizontal and vertical gradients in composition and concentration and a significant anthropogenic component, making it ideal for an in-depth analysis with the synergistic dataset. After 22 of September, volcanic aerosols from the la Palma volcano were captured, mixed in the local boundary layer and partly above in the dust layer of the 3rd dust event and relevant Aeolus overpass.

As a next step, science application studies are anticipated, using the wealth of information provided by ASKOS and JATAC campaigns, including already the following applications in the framework of ESA and EU projects:

Long-range transport of the coarse and giant dust particles;

Impact of non-sphericity on dust transport;

Impact of electric charge on dust dynamics;

Dust particle orientation;

Impact of dust on radiation and dynamics;

Impact of dust deposition on ocean biogeochemistry;
Future offshore windfarm effects on ecosystem productivity: upscaling to the southern North Sea
Authors: Daewel Ute , Akhtar Naveed , Christiansen Nils Gerrit , Schrum Corinna
Published: March 2022

The North Sea has become a focus of renewable energy production with an increasingly large number and size of offshore wind farms (OWFs) planned in the German and British sectors in far deeper waters than before. As the North Sea is also a complex ecosystem that is strongly driven by hydrodynamical features such as tidal fronts and seasonal stratification, these large OWFs can be expected to impact the ecosystem dynamics in the area. Here, we use the coupled ecosystem model ECOSMO, previously used and validated for the area, to explore the consequences of large scale OWFs for marine ecosystem productivity. The model is forced with results from two model simulations of a high-resolution regional climate model, one with and one without implemented wind-farm parameterization using a near future wind farm scenario that includes existing and planned OWFs. Our major research focus lies on the large-scale, integrated effects imprinted on the ocean physics and ecosystem by changes in the atmospheric conditions rather than small scale processes. The simulations were integrated over the time period of one year and the average system response was analysed. The model shows a clear and direct response to the modifications in the atmosphere with respect to surface current speed, sea surface elevation and vertical transport depending on the wind direction. However, these immediate impacts are not visible in the ecosystem variables. Instead, the ecosystem shows an integrated (over the year) response related to the general modifications in stratification, transport pattern and bottom shear stress. It becomes evident that we cannot conclude a general increase/decrease pattern of change in ecosystem productivity, instead we can see changes in both spatial distribution and phenology of the lower trophic level ecosystem components, which we expect to be relevant for fish connectivity pattern and early larval survival for economically relevant fish species. 
A computational method for modeling spatiotemporal variability of sandy soil hydrodynamic properties under drainage and recharge
Authors: Gumiere Silvio
Published: March 2022

This paper proposes an analytical strategy that combines X-ray Computed Tomography (CT) and Continuous Wavelet Transform (CWT) analysis as an alternative solution to long-term experiments  that seek to investigate spatiotemporal variations in soil hydraulic properties induced by drainage  and recharge cycles. We conducted CT scanning on 100-cm-high column filled with two types of sandy soil in a laboratory environment to simulate, over a month, the equivalent of nearly 40 years of drainage/recharge cycles akin to agricultural fields adopting subirrigation as water management practices. We also monitored soil matric potential, water inflow and outflow, and the movement of tracers. This later consists in zirconium oxide (ZrO2) that we added to the top 20 cm of each soil column. The results revealed that drainage and recharge cycles greatly affect the evolution of soil hydraulic properties at different locations along the soil profile by reducing drainage and capillary capacities. The approach also allowed us to identify each periodic  component of drainage and recharge cycles, thereby calculating the systematic drift over time.  The proposed method can be applied to predict soil evolution according to soil texture, drainage  system design and water management, thereby offering a potential basis for proposing mitigation  measures related to soil hydrodynamics. It may find its application in agricultural farms adopting  subirrigation and surface (e.g., drip) irrigation approaches and mining and civil engineering.
Implementation of A WBLM In COAWST and Its Impact on Coastal Storm simulations
Authors: Du Jianting , Yang Youngzeng
Published: March 2022

In this study, a wave boundary layer model (WBLM) is implemented in the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system for coupling the atmospheric model WRF and the ocean wave model SWAN. The WBLM is implemented as a wind-input source function in SWAN and at the same time provide roughness length over the ocean for WRF. For comparison, the physics-based, Janssen method as well as 3 parametrization methods for roughness length calculation were also implemented. The coupled modeling system is used to investigate modeling of winds and waves with two challenging areas in focus: one is coastal, shallow water zone and the other is the storm center. Both of the two areas are strongly affected by complicated sea surface roughness. This is done through a storm case study and a systematic coupled and uncoupled simulations of storms over the eastern North Sea. Validation using ASAR data, mast and buoy measurements suggests that, the empirical parametrization approach fails to reproduce roughness in coastal areas. The WBLM method outperforms the other methods in terms of the magnitude as well as the spatial distribution of roughness length. It is found that wind-wave coupling is important for wind estimations in coastal zones and at strong wind condition.
Climate Simulations of Mars at Low Obliquity
Authors: Lange Lucas , Forget François , Vandemeulebrouck Romain , Millour Ehouarn , Delavois Antony , Naar Joseph , Spiga Aymeric , Bierjon Antoine , Dupont Etienne
Published: March 2022

In some high latitude craters, intriguing moraines are interpreted to have been deposited by CO2 ice glaciers, essentially frozen from when the local climate was colder (i.e., when Mars obliquity was low) [1]. This scenario has been little studied, but it suggests that the atmosphere could totally collapse into CO2  glaciers, leaving behind a residual atmosphere of only Ar and N2, but 20 times less dense than today [2]. 

However, these results are based on a radiative equilibrium that does not take into account all the dynamics of the atmosphere.  Such periods of low obliquities generally last tens of thousands of years [3], making a complete simulation with a classical Global Circulation Model impossible.  

We will present the preliminary results of our climate simulations of Mars at low obliquity based on our new tool which is the Planetary Evolution Model developed at the LMD (Fig 1.). This model allows us to simulate the evolution of the climate, based on the LMD GCM, over long-time steps. Particular attention will be paid to the condensation of the atmosphere in the form of CO2  glaciers, and to the composition of the residual atmosphere.

Fig 1. Principles of the Planetary Evolution Model 

References: 
[1] Kreslavsky and Head, Carbon dioxide glaciers on Mars: Products of recent low obliquity epochs(?). Icarus, 216:111–115, 2011.
[2] Kreslavsky and Head. Mars at very low obliquity: Atmospheric collapse and the fate of volatiles. Geophysical Research Letters, 32(L12202), 2005.

[3] Laskar, Correia, Gastineau, Joutel, Levrard, Robutel, Long term evolution and chaotic diffusion of the insolation quantities of Mars. Icarus 170, 343–364, 2004.

Acknowledgments:
This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 835275).
Preferential Pathways for Fluid and Solutes in Heterogeneous Groundwater Systems: Self-Organization, Entropy, Work
Authors: Zehe Erwin , Loritz Ralf , Edery Yaniv , Berkowitz Brian
Published: March 2022

This study proposes an alternative framework to quantify and explain the enigmatic emergence of preferential flow and transport in heterogeneous saturated porous media, using concepts from thermodynamics and information theory. We examined simulations of two-dimensional fluid flow and solute transport based on the methods of Edery et al. (2014) at total head differences of 100 and 10 characterized the discrete probability distribution of solute particles to cross a distinct transversal position in a plane normal to the direction of the mean flow by means of the Shannon entropy. In general, we found a declining entropy with increasing downstream transport distance, reflecting a growing downstream self-organization due to the increasing concentration of particles in preferential flow paths. Strikingly, preferential flow patterns with lower entropies emerged when analyzing simulations in media with larger variances in hydraulic conductivity, and this enhanced self-organization appeared even stronger for simulations at lower head differences. This implies that macro-states of higher order are established, despite the higher randomness of ln(K) for a range of Peclet numbers representing strong and intermediate importance of advective transport. The key to explain this almost paradoxical behavior is the finding that power in the vertical flow components grows with the variance of the hydraulic conductivity field. Due to this larger energy input, the vertical/transversal flow component may perform more work to increase the order in the flow path distribution, through steepening transversal concentration gradients as reflected in lower entropies. The emergence of spatially organized preferential transport and the related decline in flow path entropy essentially requires that the entropy is exported from the system. Consistently, we found that a declining entropy in lateral distribution of flow paths goes along with a rising entropy in the associated breakthrough curve. This space-time asymmetry in entropy implies that perfect organization and certainty about both flow paths and travel times can never simultaneously occur. This required consummation of entropy and thus violation of the second law of thermodynamics. We thus propose that the combined use of free energy and entropy holds the key to characterize, quantify and predict the self-organized emergence of preferential flow phenomena and to explain the underlying cause of their emergence.

References:
Edery, Y., Guadagnini, A., Scher, H., and Berkowitz, B.: Origins of anomalous transport in disordered media: Structural and dynamic controls, Water Resour. Res., 50, 1490-1505, doi:10.1002/2013WR015111, 2014.
Uncertainty in ocean biogeochemical simulation: Application of ensemble data assimilation to a one-dimensional model
Authors: Mamnun Nabir , Völker Christoph , Vrekoussis Mihalis , Nerger Lars
Published: March 2022

Marine biogeochemical (BGC) models are important tools in the hands of scientists and policymakers when assessing the impacts of climate change. Therefore, including an ocean BGC component in Earth System Modeling efforts is essential for climate simulation and predictions. However, current BGC models, used to simulate and thus better understand the marine ecosystem processes, are associated with large undefined uncertainties. Similar to other geoscientific models, complex biological and chemical processes are converted to simplified schemes in BGCs, a methodology known as parameterization. However, these parameter values can be poorly constrained and also involve unknown uncertainties. In turn, the uncertainty in the parameter values translates into uncertainty in the model outputs. Therefore, a systematic approach to properly quantify the uncertainties of the parameters is needed. In this study, we apply an ensemble data assimilation method to quantify the uncertainty arising from the parameterization within BGC models. We apply an ensemble Kalman filter provided by the parallel data assimilation framework (PDAF) into a one-dimensional vertical configuration of the biogeochemical model Regulated Ecosystem Model 2 (REcoM2) at two BGC time-series stations: the Bermuda Atlantic Time-series Study (BATS) and the Dynamique des Flux Atmosphériques en Méditerranée (DYFAMED). Satellite chlorophyll-a concentration data and in situ net primary production data are assimilated to estimate ten selected biogeochemical parameters and the model state. We present convergence and interdependence features of the estimated parameters in relation to the major biological processes and discuss their uncertainties. The major improvements on the parameters involved changes in phytoplankton photosynthesis rate, chlorophyll degradation, and grazing. In general, the change in the estimates of these parameters results in improvements in the model prediction and reduced prediction uncertainty. 