bluuebunny/crossref_metadata_2025 huggingface dataset:
Intercomparison of basin-to-global scale submesoscale-permitting ocean models at SWOT cross-overs 
Authors: Le Sommer Julien , Uchida Takaya ,   SWOT Adopt-A-Crossover Ocean Model Intercomparison Project Team
Published: March 2022

With an increase in computational power, ocean models with kilometer-scale resolution have emerged over the last decade. Using these realistic simulations, we have been able to quantify the energetic exchanges between spatial scales and inform the design of eddy parametrizations. The increase in resolution, however, has drastically increased model outputs, making it difficult to transfer and analyze the data. The realism of individual models in representing the energetics down to numerical dissipation has also come into question. Here, we showcase a cloud-based analysis framework proposed by the Pangeo Project that aims to tackle such distribution and analysis challenges. We analyze seven submesoscale permitting simulations all on the cloud at a crossover region of the upcoming SWOT altimeter mission near the Gulf Stream separation. The models used in this study are based on the NEMO, CROCO, MITgcm, HYCOM, FESOM and FIO-COM code bases. The cloud-based analysis framework: i) minimizes the cost of duplicating and storing ghost copies of data, and ii) allows for seamless sharing of analysis results amongst collaborators. In this poster, we will describe the framework and provide preliminary results (e.g. spectra, vertical buoyancy flux, and how it compares to predictions from the mixed-layer instability parametrization). Basin-to-global scale, submesoscale-permitting models are still at their early stage of development ; their cost and carbon footprints are also rather large. It would, therefore, benefit the community to compile the different model configurations for future best practices. We also believe that an emphasis on data analysis strategies would be crucial for improving the models themselves.
Observations and simulations of northward IMF magnetotail structure
Authors: Fryer Laura , Fear Robert , Gingell Imogen , Coxon John , Palmroth Minna , Hoilijoki Sanni , Janhunen Pekka , Kullen Anita
Published: March 2022

We investigate the dynamic coupling between the solar wind and Earth’s magnetosphere during northward IMF conditions. The high latitude lobe regions of the magnetosphere during such conditions are generally characterised as containing cool, very low energy plasma populations. However, when the solar wind is directed northward, hot plasma populations can sometimes be observed within the lobes, and transpolar arcs (auroral features which extend from the nightside into the polar cap) can also be present. We discuss three cases in which the Cluster spacecraft observed uncharacteristically energetic plasma populations in the lobe, with the footprint of the spacecraft intersecting a transpolar arc (Fryer et al., 2021). These observations reveal that both the hot plasma populations, and therefore transpolar arcs, are likely to form on closed field lines and are consistent with a mechanism in which magnetotail reconnection builds up closed field lines within the magnetotail, which then become “stuck” in the lobe (Milan et al., 2005).

Under certain northward IMF conditions, we find that the Grand Unified Magnetosphere-Ionosphere Coupling Simulation (GUMICS) model reproduces a similar large, closed field line region in the magnetotail. We find similarities between the structures seen within the simulation runs, the results of the in-situ observational study, and the Milan et al. (2005) magnetotail reconnection model, but also note some key differences in the configuration of the magnetotail reproduced in the simulations, compared with the remote and in situ observations. Finally, we note that the SMILE spacecraft will be ideally positioned to observe the coupling between the solar wind and Earth’s magnetosphere during northward IMF conditions, through both high latitude in situ observations and imaging of the auroral response.
Seasonal dynamics of soil microbial respiration, growth, biomass, and carbon use efficiency
Authors: Schnecker Jörg , Baldaszti Ludwig , Gündler Philipp , Pleitner Michaela , Richter Andreas , Sandén Taru , Simon Eva , Spiegel Felix , Spiegel Heide , Urbina Malo Carolina , Zechmeister-Boltenstern Sophie
Published: March 2022

Soil microbial growth, respiration and carbon use efficiency (CUE) are essential parameters to understand, describe and model the soil carbon cycle. While seasonal dynamics of microbial respiration are well studied, little is known about how microbial growth and CUE change over the course of a year, especially outside the plant growing season. In this study we measured soil microbial respiration, growth and biomass in an agricultural field and a deciduous forest 16 times over the course of two years. We sampled plots, at which harvest residues or leaf litter were either incorporated or removed. We observed strong seasonal variations of microbial respiration, growth and biomass. All microbial parameters were significantly higher at the forest site, which contained 3.5% organic C compared to the agricultural site with 0.9% organic C. CUE also varied strongly but was overall significantly higher at the agricultural site ranging from 0.1 to 0.7 compared to the forest site where CUE ranged from 0.1 to 0.6. We found that microbial respiration and to a lesser extent microbial growth followed the seasonal dynamics of soil temperature. Microbial growth was further affected by plant or foliage presence. At low temperatures in winter, both microbial respiration and growth rates were lowest. Due to higher temperature sensitivity of microbial respiration, CUE showed the highest values in the coldest months. Microbial biomass C was also strongly increased in winter. Surprisingly, this winter peak was not connected to high microbial growth or an increase in DNA content. This suggests that microorganisms accumulated osmo- or cryoprotectants but did not divide. This microbial winter bloom and following decline, where C is released and can be stabilized, could constitute the main season for C sequestration in temperate soil systems.  Highly variable CUE, and the fact that CUE is calculated from independently controlled microbial respiration and growth, ask for great caution when CUE is used to describe soil microbial physiology, soil C dynamics or C sequestration. Instead, microbial respiration, microbial growth and biomass should rather be investigated individually to better understand the soil C cycle.
Sea ice evaluation tool: application to CMIP6 OMIP and the sensitivity of sea ice simulation to atmospheric forcing uncertainties
Authors: Lin Xia , Massonnet François , Fichefet Thierry , Vancoppenolle Martin
Published: March 2022

We will introduce the Sea Ice Evaluation Tool (SITool) developed to evaluate the skill of Arctic and Antarctic model reconstructions of sea ice concentration, extent, edge location, drift, thickness, and snow depth. It is a Python-based software and consists of well-documented functions used to derive various sea ice metrics and diagnostics. The SITool version 1.0 is used to evaluate the performance of global sea ice reconstructions from nine models that provided sea ice output under CMIP6 Ocean Model Intercomparison Project with two different atmospheric forcing datasets: the Coordinated Ocean-ice Reference Experiments version 2 (CORE-II) and the updated Japanese 55-year atmospheric reanalysis (JRA55-do). The improved Arctic and Antarctic sea ice areal properties and ice drift simulation have been recognized in OMIP models forced by JRA55-do. The processes contributing to these improvements are assessed and discussed. It is found that improvements in the simulation of summer ice concentration in the interior region are linked, in both hemispheres, to improvements in the downward surface net shortwave radiation flux in JRA55-do. The austral winter ice concentration simulation is improved in the ice edge region relating to the dynamic process dominated by surface wind stress. The obvious improvement of the ice drift magnitude simulation is in the Arctic ice edge region from November to April dominated by the decreased surface wind stress forced by JRA55-do, while the improvement in the Antarctic is much smaller. This study provides clues to improve the atmospheric reanalysis product for a better sea ice simulation in ocean-sea ice models and more attention can be paid to the radiation flux and wind fields.
Controls on microplastic flux during sand bed evolution
Authors: Ockelford Annie , Beaumont Hazel
Published: March 2022

Microplastic contamination of river sediments has been found to be pervasive at the global scale however, the physical controls governing the storage, remobilization and pathways of transfer in fluvial sediments remain largely unknown. This is particularly so in sand bed rivers where the migration of bedforms has the potential to both store and release any microplastics contained within the sediment bed.  Without detailed experiments to model the movement of microplastics through, and storage within, sand bedforms it is impossible to understand what the environmental legacy of our excessive plastic pollution will be.

We report a series of mobile-bed laboratory flume experiments designed to explicitly quantify the relationship between sand bed surface development and microplastic flux characteristics. Experiments were performed within a glass sided, flow recirculating flume of rectangular cross section (8m x 0.5m x 0.5m). A uniform sand bed (D50 of 450μm) was seeded with either PVC pellets (d=1.4g/cm3), Nylon pellets (d= 1.2 g/cm3), Polycarbonate fragments (d=1.2 g/cm3), Acetal beads (d = 1.4g/cm3) or Nylon fibres (d = 1.15g/cm3). Plastics were mixed into the sediment bed at either 0.1% or 0.5% concentration by mass and sediment beds were exposed to a flow rate of either 0.6 or 0.8 ms-1. Experiments were run until equilibrium conditions were attained as measured by bedform migration rate. During each experiment aerial photographs were taken every 2.5 minutes and videos shot through both the side walls and from top down to track bedform migration and plastic flux. Transported sediment and plastics were captured at the downstream end of the flume in a sediment trap to allow fluxes to be calculated. At the end of each run photographs were taken of the drained bed surface with photogrammetry then used to model the 3D bed surfaces.

Controls on microplastic flux as a result of bed evolution is discussed in terms of both flow rate flow rate and microplastic type.  
Application of UAS laser scanning for precision crop monitoring in Hungary
Authors: Bertalan László , Riczu Péter , Bors Róbert , Szabó Szilárd , Eltner Anette
Published: March 2022

Airborne Laser Scanning (ALS) is a widely used method in Earth science, Agriculture or Forestry. This method could provide high resolution and accurate spatial data for the better understanding of surface structures, moreover, based on the laser pulses, it can even show important features of the ground below dense vegetation. However, these ALS surveys requires specially designed aircrafts, pilots and operators, detailed flight planning, which leads to an expensive way of data analysis. The application of laser scanners for Unmanned Aerial Systems (UAS) has started in the last few years. These sensor payloads provide less weight and size and decreased accuracy compared to the traditional ALS surveys but still serve as more reliable mapping technology contrary to the photogrammetric methods in many cases. However, several new UAS laser scanners are being developed but their accuracy conditions and applicability for agricultural monitoring must be studied in many ways.

In our study we applied the novel Zenmuse L1 LiDAR sensor mounted on a DJI Matrice M300 RTK UAS. We surveyed a ~50 ha area of corn field near Berettyóújfalu, Hungary in the summer of 2021. Our aim was to reveal the applicability of UAS laser scanning for the precise ground surface reconstruction. In this period, the corn was under irrigated condition, therefore, extensive weed patches were observed between the paths. The laser scanner ground filtering data was compared to a photogrammetry-based aerial survey that we have carried out at the beginning of the vegetation cycle at the same parcel. Our results showed both the potentials and limitations of this sensor for precision agriculture. The laser beams produced significant amount of noise between the paths that had to be cleaned to extract the ground surface below the corn canopy. Based on our data processing methods we were able to delineate similar drainage networks within the parcel that was also processed from the initial aerial survey. However, the UAS LiDAR gained the most accurate surface reconstruction at the more clear grassland patches around the parcel. 

L. Bertalan was supported by the INKP2022-13 grant of the Hungarian Academy of Sciences. This research was funded by the Thematic Excellence Programme (TKP2020-NKA-04) of the Ministry for Innovation and Technology in Hungary. This research was also influenced by the COST Action CA16219 “HARMONIOUS - Harmonization of UAS techniques for agricultural and natural ecosystems monitoring”.
Unraveling the secrets of the Earth through nanogeology: A correlative microscopy approach
Authors: Dubosq Renelle , Schneider David , Rogowitz Anna , Gault Baptiste
Published: March 2022

Correlative analytical approaches involving high-spatial resolution microscopy techniques allow for the compositional measurements and spatial imaging of materials at the near-atomic scale. By combining electron backscatter diffraction (EBSD) mapping, electron channeling contrast imaging (ECCI), scanning transmission electron microscopy (STEM) and atom probe tomography (APT) on various geological materials such as minerals and glasses, we have successfully documented element mobility regulated by structural defects. Although these techniques were initially developed in the materials sciences, they are now being applied to a broad range of applications within many subdisciplines of geosciences including geochemistry, geochronology, and economic geology. In one set of experiments, we applied a correlative approach on naturally deformed pyrite from an orogenic gold mine in northern Canada to assess the impact of crystal-plastic deformation on the remobilization of trace elements. This study has led us to propose a new paragenetic model for metallic ore deposits in which deformation creates nanostructures that act as traps for base- and precious-metals. By applying our approach on pyrite that is rich with fluid inclusions, we have also documented two processes that led to proposing a new fluid inclusion-induced hardening model, which is in contrast to the more commonly reported weakening effect of fluids on minerals. To broaden the applications of our approach, we have applied the same suite of analytical techniques to a synthetic andesitic glass to assess whether nanoscale chemical heterogeneities can act as nucleation sites for gas bubbles. The combined results demonstrate the existence of nanoscale chemical heterogeneities within the melt and at the bubble-melt interface supporting the hypothesis that homogeneous nucleation could in fact be a variety of heterogeneous nucleation. The interactions between trace elements and structural defects plays a vital role in determining the mechanical properties of minerals, particularly in fluid-rich environments. These sub-nanometer scale exchanges consequently control meso- to tectonic-scale geological processes. Our research work not only demonstrates the latest advancements in analytical microscopy resolving long-standing geological problems but also brings us closer to bridging the gap between the fields of materials sciences and geosciences.
Resilience service technologies for identifying climate change adaptation gaps 
Authors: Laurien Finn , Mccallum Ian , Velev Stefan , Mechler Reinhard
Published: March 2022

Communities around the world in natural hazard-prone regions are increasingly aware of the benefits of using spatio-temporal data to better understand their predicament. With the advent of new service technologies, such as web mapping, free and open satellite data and the proliferation of mobile technologies, the possibilities for both understanding and improving community resilience are on the rise. Resilience service technologies aim to provide risk-informed products in easy-to-use manner for enabling stakeholders to implement efficient and practical resilience activities in their communities.

This paper presents a service-oriented approach aiming to harnessing risks and resilience data in hazard-prone regions for raise awareness regarding early warning systems, safety conditions of minorities in community groups and plan for long-term resilience strategies. With our resilience dashboard platform, we utilize information of various risk and resilience services to identify and visualize susceptible hotspots for decision-makers. Our resilience dashboard also brings about the coordination between different web services to retrieve the features and impose the thresholds. We co-developed with local humanitarian and development teams the resilience dashboard which is designed to put geo-spatial flood resilience data into the hands of decision-makers. We identified three use cases which consider an added value of resilience service technologies by focusing on early warning systems, targeting minority groups and long-term resilience planning in Nicaragua, Nepal and Bangladesh. We will demonstrate the context-specific needs of resilience services technologies, how to target user needs and how it could potentially be scaled up and applied to similar regions around the world.
Diagnosing Lagrangian aspects of the atmospheric circulation by Eulerian tracer advection with relaxation
Authors: Mayer Amelie , Wirth Volkmar
Published: March 2022

In the past, one widely used technique to diagnose Lagrangian aspects of the atmospheric circulation has been the computation of trajectories. Trajectories provide detailed information along the pathways of individual parcels, but one has to consider a vast amount of them in order to obtain continuous-in-time, volume-filling information. As a consequence, analysing trajectories can be a painstaking task. To overcome this problem, we developed an alternative method allowing one to continuously diagnose Lagrangian information about the atmospheric circulation on a Eulerian grid. The method is based on the advection of passive tracer fields and includes a relaxation term. One thus obtains accumulated Lagrangian information, such as the recent meridional or vertical parcel displacement or the recent parcel-based diabatic heating, for each grid point at any time step. This convenient output format allows one to analyse large data sets (such as reanalysis data) in a straightforward manner. We suggest our method to be particularly useful in the field of synoptic climatology. Here, we present the underlying idea of the method and motivate its utility on the basis of examples that make use of reanalysis data.
Cutting the Gordian knot of climate control on decomposition  
Authors: Joly Francois-Xavier , Scherer-Lorenzen Michael , Hättenschwiler Stephan
Published: March 2022

Strong recent challenges of the long-standing paradigm that macroclimate predominantly controls decomposition questions the accuracy of climate change predictions. With a novel approach combining three experiments at continental scale, using 104 litter types in 194 plots in six major European forests, we show that the confusion around the macroclimate control on decomposition is mostly an experimental artefact. The relative role of decomposition drivers was incorrect when disrupting the natural context of locally-produced litter decomposing locally, with either a focus on litter characteristics neglecting microenvironmental context, or on environmental drivers neglecting local litter characteristics. Our data reaffirm macroclimate and its interaction with litter characteristics as predominant decomposition drivers. Conversely, standard litter types overrated microenvironmental control and failed to predict local decomposition of plot-specific litter. Our findings provide support for a strong macroclimate component in predictive decomposition models and call for cautious interpretation of data from experiments using standard litter types.
Annealing experiments on zircons: influence of lattice orientation and metamictization.
Authors: Morales Irene , Molina José Francisco , Montero Pilar , Bea Fernando , Cambeses Aitor
Published: March 2022

Zircon derived from crustal rocks can survive dissolution into basic melt during rock assimilation and magma hybridization if shielded in mafic phenocrysts or minerals from non-disaggregated xenoliths. Under these conditions, zircon can be subject to thermal shock that triggers recrystallization of metamict domains and reaction with its hosted mineral inclusions. In this work, we simulate this process by performing thermal annealing experiments on zircon grains with a variable degree of metamictization. The results show recrystallization of metamict domains, melting of multi-phase mineral inclusions, nanopores formation, and microcracking propagation by thermo-elastic stress. Highly metamict zircon with elevated common-Pb and radiogenic-Pb loss, which were impossible to date with SHRIMP, lost all their common-Pb and some radiogenic-Pb upon annealing, producing well-fitted discordias with significant upper intercept age. The porosity enhances intracrystalline melt mobility, leaching out impurities. Baddeleyite was formed at temperatures below the thermal decomposition of pure zircon by two mechanisms: (1) incongruent zircon dissolution into molten mineral inclusions with a high CaO/SiO2 ratio (2) recrystallization of metamict domains aided by silica migration from the reaction site.
Less-deadly heatwaves due to soil drought
Authors: Wouters Hendrik , Keune Jessica , Petrova Irina Y. , van Heerwaarden Chiel C. , Teuling Adriaan J. , Pal Jeremy S. , Vilà-Guerau de Arellano Jordi , Miralles Diego G.
Published: March 2022

Global warming increases the number and severity of deadly heatwaves. Recent heatwaves often coincided with soil droughts that acted to intensify air temperature but lower air humidity. Since lowering air humidity may reduce human heat stress, the net impact of soil desiccation on the morbidity and mortality of heatwaves remains unclear. Combining weather balloon and satellite observations, atmospheric modelling, and meta-analyses of heatwave mortality, we find that soil droughts—despite their warming effect—lead to a mild reduction in heatwave lethality. More specifically, morning dry soils attenuate the afternoon heat stress anomaly by ~5%. This occurs due to reduced surface evaporation and increased entrainment of dry air from aloft. The benefit appears more pronounced during specific events, such as the Chicago 1995 and Northern U.S. 2006 and 2012 heatwaves. Likewise, our findings suggest that irrigated agriculture may intensify lethal heat stress, and question recently proposed heatwave mitigation measures involving surface moistening to increase evaporative cooling.

The manuscript of the findings is in press for Science Advances.

 

 

 
Mechanisms controlling the abyssal transport of anthropogenic carbon in the North Atlantic
Authors: Asselot Rémy , Bajon Raphaël , López Mozos Marta , Thierry Virginie , Mercier Herlé , Pérez Fiz , Carracedo Lidia
Published: March 2022

Since the industrial revolution, human activities have emitted large amount of anthropogenic carbon (Cant) into the atmosphere through the burning of fossil fuel, the production of cement and land-use change. Via air-sea gas exchange, the ocean absorbs roughly a third of Cant, meaning that Cant is an additional source of carbon for the ocean. In particular, the North Atlantic is known to be a region with a high storage capacity of Cant. Whereas the distribution of Cant in the upper layers of the North Atlantic is well documented, its transport to the abyssal ocean and the mechanisms behind its deep redistribution remain scarcely described. To shed light on this research gap, we use a database provided by ~70 Deep-Argo floats equipped with oxygen sensors and located in the North Atlantic that allow us to explore the deep pathways of Cant. First, the macronutrients and carbon variables (pH, total alkalinity, total inorganic carbon and pCO2) are estimated with bayesian neural networks (CANYON-B and CONTENT) from the temperature, salinity and oxygen data of the floats. Second, Cant concentrations in the water column are then estimated with back-calculation methods. Here we present the first results of our study.    
Rhizosphere carbon priming: a plant mechanisms to enhance soil nitrogen accessibility?
Authors: Holz Maire , Pausch Johanna
Published: March 2022

Soil C priming is a short-term change in the turnover of soil organic matter caused by the addition of easily available organic C to the soil. The increase in SOM decomposition during priming is likely to affect not only C- but also gross N mineralization from SOM because large amounts of soil N is stored in SOM that is decomposed during priming. In order to assess whether soil C priming results in an increase in gross and mineralization and finally in enhanced plant N availability and uptake, we searched the literature for studies relating soil C priming to soil N cycling. In order to assess the effect of soil priming on soil N cycling we included studies quantifying soil C priming (PE) and gross N mineralization (GNM) in plant systems and in incubation setups. Secondly, we searched for studies measuring GNM in dependence to addition of C to the system. The third data set comprised studies, quantifying PE and the % of soil N derived N uptake as well as total N uptake of plants. Finally we included studies that quantified soil priming and enzyme activities in the respective soil samples. In order to be able to compare PE to GNM, % of soil N derived N uptake and soil enzyme activities respectively, we calculated the excess of GNM, % of soil N derived N uptake and soil enzyme activities by subtracting the parameter values of the control from the treatment values. We found a significant positive relation between soil C priming and GNM for studies with plants (R2=0.21) indicating that soil priming caused by root exudation increased soil N mineralization. In agreement with this, activities of enzymes related to the N cycle were positively related to priming (p=0.09), though, due to the small number of studies, the enzyme results must be interpreted with caution. In contrast to plant studies, the relation between soil C priming and GNM was significantly negative for incubation studies (R2=0.06). These contrasting results for plant and incubation studies indicate that incubation studies might not adequately reflect processes occurring in the rhizosphere. It is possible that plants attract particularly N mineralizing microbes for example by exudation of signaling compounds, a process that would not be reflected in incubation studies. We also found a significant positive relation between soil C priming and the % of soil N derived N uptake by plants (R2=0.56) and total plant N uptake (R²=0.21) indicating that at least part of the N mineralized during priming was available to, and taken up by the plants. In conclusion, the results of our meta-analysis indicate that rhizosphere C priming positively feeds back to plant N nutrition by causing increased N mineralization in the rhizosphere that facilitates plant N uptake.
Systematic Calibration of A Convection-Resolving Model: Application over Tropical Atlantic
Authors: Liu Shuchang , Zeman Christian , Sørland Silje Lund , Schär Christoph
Published: March 2022

Non-hydrostatic km-scale weather and climate models are promising in simulating clouds, especially convective ones. However, even km-scale models need to parameterize some physical processes and are thus subject to the corresponding uncertainty of parameters. Systematic calibration has the advantage of improving model performance with transparency and reproducibility, thus benefiting model intercomparison projects, process studies, and climate-change scenario simulations. 

In this paper, the regional atmospheric climate model COSMO v6 is systematically calibrated over the Tropical South Atlantic. First, the parameters' sensitivities are evaluated with respect to a set of validation fields (outgoing longwave radiation (OLR), outgoing shortwave radiation (OSR) and latent heat flux (LHFL)). Five of the most sensitive parameters are chosen for calibration. The objective calibration then closely follows the methodology of Bellprat et al. (2016). This includes simulations considering the interaction of all pairs of parameters and the exploitation of a quadratic-form metamodel to emulate the simulations. In the current set-up with 5 parameters, 50 simulations are required to build the metamodel. Then Latin hypercube sampling is applied and the set of parameters with the best performance score is chosen as the optimal parameter set. The model is calibrated for the year 2016 and validated in 2013. And  the optimal parameter setting lead to significant improvements for both years, especially for OSR, which is closely related to low clouds. More specifically, the domain annual mean OSR bias is reduced from 40 to 13.5 Wm-2. Moreover, when we apply the optimal setting over a larger domain with a slightly higher resolution (from 4km to 3km) in 2006, the optimal setting still works, especially for OSR and for the calibrated domain. 

The results thus show that parameter calibration is a useful and efficient tool for model improvement. We will also discuss potential limitations and highlight how the approach could be extended to global atmospheric models. Calibrating over a larger domain might help improve the overall performance, but would potentially also lead to compromises among different regions and variables, and require more computational resources.
Local magnetic anomalies in rugged volcanic terrain explain bias in paleomagnetic data: consequences for sampling
Authors: Meyer Romy , de Groot Lennart
Published: March 2022

Volcanic rocks are believed to be reliable recorders of changes in the Earths magnetic field in the past. Paleomagnetic data from volcanic edifices is used to make reconstructions of the behavior of the Earth’s magnetic field through time. Recently, however, it became evident that volcanic rocks may not always record the ambient magnetic field accurately. Therefore, we set out to test the accuracy of paleomagnetic data recorded by Mt. Etna lavas by (1) directly measuring the magnetic field above the current topography, i.e. the field that would be recorded by a future flow in that location; and (2) by assessing the paleomagnetic information in historical (1850 – today) flows.

Mt. Etna is characterized by an irregular topography with ridges and gullies that may give rise to local magnetic anomalies that a new flow would record. We measured the ambient geomagnetic field on Mt. Etna with a three-component fluxgate magnetometer at five sites along the length of three paths with an irregular surface. Paths were walked perpendicular to ridges and gullies and measurements were made every meter at different heights above the ground. We found that the declination varies between -17.5 and 18°, and on average differs -3.3° from the expected geomagnetic field. The inclination has a range between 44.4 and 59.5° and is on average 52.3°, while 53.4° is expected. Lastly, the intensity varies between 37.2 and 50.4 µT and is on average 44 µT, with an expected value of 45.2 µT. The deviation with respect to the expected value decreases as function of height above the flow for the inclination and intensity, while the variation in declination does not improve. Most importantly, the variations in inclination and intensity correlate with topographic features: both inclination and intensity are higher above ridges and lower in gullies.

The second part of our study consisted of compiling an overview of literature data on historical Mt. Etna flows and combining this with newly measured paleomagnetic data from 12 sites from 9 different flows with ages between 1865 and 2002. We observed the same trends in this data compilation as in our field observations: the reported inclinations and intensities are often too low.

Our observations have consequences for paleomagnetic sampling strategies in rugged volcanic terrain. To avoid sampling a local magnetic anomaly, samples should be taken spread out over a larger area, preferably meters apart and from different parts of the flow. While this will lead to a higher degree in scatter in paleodirections and a lower precision parameter k, they will better represent the Earth’s magnetic field at the time of cooling. Paleodirections with a high k or paleointensities with a low uncertainty most likely sample a local magnetic anomaly arising from the underlying terrain.
Gravitational Potential Difference Between Optical-Atomic Clocks onboard China Space Station (CSS) and Ground Station via Optical Time Transfer links
Authors: Ruby Abdelrahim , Shen Wenbin , Shaker Ahmed , Zhang Pengfei , Shen Ziyu , Ashry Mostafa
Published: March 2022

High accuracy and stability of time and frequency transfer links are significant to realizing high-precision time synchronization in geodesy, navigation, and metrology. Also, the current and future challenges for space and ground geodetic observatories are to transfer high-stability time and frequency signals between remote locations. Therefore, future optical spatial links, such as Laser Time Transfer (LTT) on China Space Station (CSS) which will equip with atomic clocks and optical clocks with stabilities of 2 × 10−16 and 8 × 10−18, respectively, are a promising technique for high-precision time transfer links, because laser time transfer links are highly accurate, with fewer delays, and unambiguous observable compared to microwave domain links. The most promising applications for optical time transfer links and optical clocks are fundamental physics and relativistic geodesy. For instance, gravitational redshift test and determination of relativistic geoid. Based on the gravitational frequency shift effect predicted by General Relativity Theory (GRT), this study discusses an approach for determining the gravitational potential difference between optical-atomic clocks onboard China Space Station (CSS) and ground station via optical time transfer link, which could have potential applications in geoscience. For testing purposes, we will use the observations of the Time Transfer by Laser Link (T2L2) on the Jason-2 mission to evaluate the performances of the data analysis algorithm. This study is supported by the National Natural Science Foundations of China (NSFC) under Grants 42030105, 41721003, 41804012, 41974034, 41631072, 41874023, Space Station Project (2020)228, and the Natural Science Foundation of Hubei Province of China under Grant 2019CFB611.
Modeling the depth dependence of Cs-137 concentration in Lake Onuma 
Authors: Hatano Yuko , Akasaki Kentaro , Suetomi Eiichi , Okada Yukiko , Suzuki Kyuma , Watanabe Shun
Published: March 2022

Lake Onuma on Mt. Akagi (Gunma Prefecture, Japan) is a closed lake with an average water residence time of 2.3 years. The activity concentration of radioactive cesium in the lake was high shortly after the Fukushima accident. According to Suzuki et al. [1] and Watanabe [2], after a filtration process, Cs-137 are separated into two groups: particulate form and dissolved form. These two forms appears to have very different concentration profiles with each other,  when the Cs-137 concentration plotted against the sampled water depths. In the present study, we are going to model those behavior of particulate/dissolved forms with an emphasis on the depth dependency.

We consider a creation-annihilation process of plankton for the model of the particulate form, since diatom shells are found to be a major constituent of the particulate Cs-137 [2]. We set  ∂P/∂t = f(x,t)  and  f(x,t) = χ(x) cos(ωt) (0 ≤ x ≤ L(water column height), t > 0),  where P=P(x,t) is the activity concentration of the particulate form. The term f(x,t) is the rate of the net production of the plankton at a specific location x at a specific time t. Seasonal cycle is also taken into account by the cosine function (we neglect the phase shift here). The function χ(x), depends solely on water depth x, is responsible for dynamics or inhomogeneity of lake water, such as circulation, stratification or a thermocline. We assume that such a water structure relates to the production rate of plankton through the function χ(x). Thus, we may obtain the concentration of particulate Cs-137. For the dissolved concentration S(x,t), we use the classical diffusion equation with the diffusivity K being dependent on both space and time (i.e. K(x,t)), namely ∂S/∂t =  ∇•(K(x,t) ∇S). Here S=S(x,t) is the activity concentration of the dissolved form. The total activity concentration C(x,t) is the sum of P(x,t) and S(x,t). Using the pair of the equations, we can reproduce the followings. (1) depth profiles of each of the soluble- and particulate activity concentration and (2) depth profiles of the total Cs-137 concentration.

 [1] Suzuki, K. et al., Sci. Tot. Env. (2018)

 [2] Watanabe, S. et al.,  Proc. 20th Workshop on Environmental Radioactivity (2019)
rassta: Raster-based Spatial Stratification Algorithms
Authors: Fuentes Bryan , Dorantes Minerva , Tipton John
Published: March 2022

Spatial stratification of landscapes allows for the development of efficient sampling surveys, the inclusion of domain knowledge in data-driven modeling frameworks, and the production of information relating the spatial variability of response phenomena to that of landscape processes. This
work presents the rassta R package as a collection of algorithms dedicated to the spatial stratification of landscapes, the calculation of landscape correspondence metrics across geographic space, and the application of these metrics for spatial sampling and modeling of environmental phenomena.
The theoretical background of rassta is presented through references to several studies which have benefited from landscape stratification routines. The functionality of rassta is presented through code examples which are complemented with the geographic visualization of their outputs.
Regional Trends and Physical Controls of Streamflow Drought Characteristics in Tropical Catchments
Authors: Raut Aparna , Ganguli Poulomi , Reddy Nagarjuna N. , Wöhling Thomas , Kumar Rohini , Das Bhabani Sankar
Published: March 2022

Globally around half of the population resides in the tropics. Understanding the regional trends and physical controls of streamflow drought in the present day helps us to recognize the future changes in the hydrological cycle impacting the freshwater supplies. Few studies have examined the climatic and catchment controls on the propagation of streamflow droughts in tropical catchments. This study unveils the regional pattern of drought onset and deficit volume and identifies their evolution by analyzing the dominant climatic and physiographic controls. Two crucial streamflow drought signatures, the time of onset and deficit volume, are extracted from daily observed streamflow records of 82 rain-dominated catchments from peninsular India (8-24º N, 72-87º E). A daily variable threshold approach with an 80% exceedance probability of the flow record is used to identify drought events. Despite a decreasing trend in deficit volume, we show a delayed shift in drought onset of about a week for more than 50% of catchments. However, droughts with mean onset time clustered around the summer (Mar-May) season show a sharp rise in deficit volume trends. We show that while dynamic (precipitation and soil moisture) factors influence the onset of droughts, both static (catchment, topographic, and soil properties) and dynamic properties play a significant role in deciding the deficit volume. Based on a statistical approach (Taylor skill score and non-parametric dependence metrics), we identify static features, surface (30 cm) and sub-surface (up to 1m) soil organic stock and cation exchange capacity (CEC) to be dominant soil controls, also topographic ruggedness index, slope, topographic wetness index, and curvature are found to be the main controlling catchment attributes. The derived insights add new avenues in understanding the causal chain of physical processes linking climatic and physiographic controls on streamflow drought mechanisms, elucidating tropical climate response to water availability in a changing climate.       
Study on the Occurrence and Development of Gullies under extreme Rainstorm Conditions
Authors: Yang Lijuan , Wang Chunmei , Zhang Chunmei , Pang Guowei , Long Yongqing , Wang Lei , Liu Baoyuan , Yang Qinke
Published: March 2022

 Soil erosion seriously damages land resources, which is a global environmental problem. Gully erosion is an important manifestation of soil erosion, in recent years, frequent extreme rainstorms have aggravated the occurrence and development of gully erosion. In order to study the formation and development patterns of newly formed gullies under the condition of climate change, this paper takes the Wangwugou Small Watershed of the Chabagou Watershed on the Loess Plateau in Northern Shaanxi as the research area, and takes the “7·26” extreme rainstorm in Northern Shaanxi Province in 2017 as the main research object based on UAV images, to analyze the occurrence regularity of newly formed gullies, and discuss its development characteristics, its difference with the development of existing gullies before 2017, and its relationship with topographic parameters in the following three years. The results showed that: (1) during the “7·26” extreme rainstorm in Northern Shaanxi, there were 45 newly formed gullies in the Wangwugou Small Watershed, which are about 101 gully/km2, and they could be divided into four categories: slope surface gullies, terraced field gullies, unpaved roadway gullies and bottom gullies. The slope surface gullies were the largest, and the bottom gullies and terraced field gullies were wider and larger in area. Production roads, check dam farmland and sloping farmland are most prone to the occurring of gullies under rainstorm conditions. (2) In the three years after the formation of the new gullies, the development of the new gully heads was faster than that of the original existing gullies, and 34.48% of the heads of newly formed gully was further advanced, which was 1.32 times of the original existing gullies. The average gully head retreat distance of newly formed gullies is 3 times that of the original existing gullies, which is up to 0.58 m/a, and the maximum speed could reach 2.12 m/a. (3) The increase of the drainage area could significantly promote the development of gully heads, which is an important topographic index to simulate the retreat rate of gully heads. Under extreme rainfall conditions, the soil erosion situation is highly serious in the study area, and the source of newly formed gullies could be traced more rapidly within three years after their occurrence. Therefore, special attention and enhanced management should be attached to the prevention and control of such gullies.
The first GLE (# 73 – 28-Oct-2021) of solar cycle 25: a study of the related terrestrial effects using neutron monitor data
Authors: Mishev Alexander , Larsen Nicholas , Usoskin Ilya
Published: March 2022

The first solar proton event of solar cycle 25 was detected on 28 October 2021 by several neutron monitors (NMs) in the polar regions, the strongest signal was registered by the DOMC/DOMB monitors located at the Antarctic plateau at Concordia French-Italian research station. It is identified as the GLE (ground-level enhancement) #73 in the International GLE database. Here, we report the observations of the GLE by the global NM network and present the derived angular and spectral features of solar energetic protons with their dynamical evolution throughout the event employing a state-of-the-art model based on analysis of the neutron monitor data. Using the derived spectra we computed the related terrestrial effects, namely the cosmic rate induced ionization at several altitudes on a global map and discuss possible implications.
The genesis tendency for a sea of clouds to occur at night in the Japanese Alps region derived by surface observation and satellite data
Authors: Ueno Kenichi , Kobayashi Yuki
Published: March 2022

The tendency to form a sea of clouds (SOC) with surface meteorological conditions was observed for 3-year warm periods at the foot of Mt. Yatsugatake by time-lapse camera and meteorological instruments at Fujimi Panorama ski resort, Nagano prefecture. In situ observation revealed large- and small-scale SOCs in the valley. Large-scale SOCs were commonly observed in the early morning, while small-scale SOCs in the eastern valley corresponded with low-level orographic clouds ascending over the slopes of Yatsugatake. An empirical algorithm was developed to detect the occurrence of nocturnal low-level clouds, corresponding to large-scale morning SOCs, using Hiamari-8 images on hourly basis with references to in situ camera observation. SOCs frequently occurred in the large-scale valley or basin in the inland areas in the Japanese Alps region, referred as 12 target areas, and they were infrequent in the coastal areas or high elevations over 2000 m. When we defined days of wide-ranging SOC occurrence, in which SOCs occurred in the half or more of target areas, 67% were associated with a subsidence inversion layer by a synoptic-scale high pressure system. The low-level cloud-top height determined by two camera images at different altitudes almost corresponded with the height of the inversion layer observed by radio-sounding data at Wajima station. We concluded that the synoptic-scale subsidence inversion layer plays an important role in forming large-scale SOCs in the Japanese Alps region in addition to nocturnal radiative cooling conditions.

(Publlished in Japanese on Tenki 68, 2021: https://www.metsoc.jp/tenki/year.php)