bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of the mirror force on the collision rate due to relativistic electron precipitation
Authors: Katoh Yuto , Rosendahl Paul , Ogawa Yasunobu , Hiraki Yasutaka , Tadokoro Hiroyasu
Published: March 2024

We numerically evaluate the role of the mirror force on the collision rate due to the relativistic electron precipitation into the ionosphere. We compute the motion of individual precipitating electrons with the mirror force, considering collisions with neutral gas by the Monte Carlo method. We examine the effect of the mirror force on the altitude profile of the ionization rate by comparing the results with those without the mirror force. Simulation results demonstrate that larger kinetic energy lowers the altitude profiles of the collision rate, which is consistent with previous studies. The simulation results also show that the upward motion of electrons bounced back from their mirror points results in the upward broadening of the altitude profile of the collision rate. Electrons with kinetic energies above 100 keV form a secondary peak of the collision rate near the mirror point. The formation of the secondary peak can be explained by the stagnation of electrons around the mirror point because the relatively long duration of staying in neutral gas increases the number of collisions. Simulation results show that under the precipitation of electrons in the kinetic energy range larger than tens of keV with the pitch angle close to the loss cone, the maximum collision rate in the altitude range lower than 100 km becomes one order of the magnitude smaller. The results of the present study suggest the importance of the mirror force for the precise modeling of ionospheric response due to the energetic electron precipitation caused by the pitch angle scattering through wave-particle interactions.
A secular decline in daily maximum wind speed over the Tibetan Plateau from 1973-2020 and its possible causes
Authors: Ma Yaoyao , Zhang Gangfeng , Wang Yiwen , Ma Heng
Published: March 2024

 The observed decline and reversal in average near-surface wind speeds over recent decades have been widely reported and confirmed globally and regionally (especially in mid-latitude areas). The trends in extreme wind speeds do not completely synchronize with average wind speeds, and the variability of extreme wind speeds and their driving mechanisms are still unclear, especially for the high mountainous regions, such as the Tibetan Plateau. This study utilizes a homogenized dataset of daily maximum wind speeds from 1973 to 2020 in the Tibetan Plateau to investigate the variability of daily maximum wind speed and uncover the physical processes through which atmospheric circulation influences it. The results indicate that: (1) the daily maximum wind speed in the Tibetan Plateau has significantly decreased in most areas from 1973 to 2020, with the largest decreasing trends in magnitude observed in the spring(-0.57 m s-1dec-1,p
Contribution Analysis of the SGG Observation from Different GOCE Orbital Altitudes to Static Gravity Field Solution
Authors: Chen Jianhua , Chen Qiujie , Shen Yunzhong , Zhang Xingfu , Nie Yufeng
Published: March 2024

The Satellite Gravity Gradiometry (SGG) data from the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite demonstrated unprecedented accuracy in estimating the gravity field model across medium and long wavelengths. However, the GOCE satellite re-entered Earth’s atmosphere in Nov. 2013. Leveraging SGG data for gravity field estimation will be a prominent research focus within the Next-Generation Gravity Mission (NGGM) to enhance further the spatial resolution and accuracy of solved gravity field models. During the final 15 months of the GOCE mission, there was a notable reduction in orbital altitude from 259.5 to 229 km. This decline provides essential data for assessing how different orbital altitudes affect static gravity field estimation. Based on Tongji-GMMG2021S (Gravity field Model from Multi-Gravity observation [Satellites]), this paper conducts a quantitative analysis, leading to the following conclusions: (1) The Tongji-GMMG2021S model derived from reprocessed Level-1b SGG data and the normal equation of Tongji-Grace02s, exhibits spatial and accuracy levels comparable to those of the GOCO06s model. (2) The contribution analysis at the normal matrix level shows that SGG data primarily contributes between 95 and 260 degrees to the Tongji-GMMG2021S normal matrix. (3) In terms of the geoid grid height difference to the Tongji-GMMG2021S model in the spatial domain, the period of Low Orbital Altitude from Aug. 2012 to Oct. 2013 significantly contributes to reducing residuals compared to the period of Higher Orbital Altitude from Nov. 2009 to Jul. 2012. These findings also provide a valuable reference for balancing the orbital altitude of NGGMs, the lifespan of NGGMs operational and the accuracy of the gravity field models.
Energy transport in Earth’s magnetotail by fast flows
Authors: Barik Krushna , Chaston Christopher C.
Published: March 2024

Fast flows characterized by flow speed greater than the convectional speed (≈50 km/s) carry most of the energy and momentum from the magnetotail reconnection site and distribute it throughout the magnetosphere. This input energy plays a significant role in the magnetospheric dynamics. Energy is transported either by particle energy flux, such as bulk kinetic energy flux, enthalpy flux, and heat flux, or/and by waves, such as Poynting flux.  Hence, it is important to understand the distribution of these energy fluxes and characterize their behavior. A statistical database is created irrespective of the ion flow speed using six years of night phase Magnetospheric MultiScale (MMS) data from 2017-2022 to investigate the energy transport by these fast flows. The total energy flux is decomposed into Poynting flux, bulk kinetic energy flux, enthalpy flux, and heat flux to explore the contribution of the individual energy flux. It is found that the energy fluxes show some asymmetry in the equatorial and meridional plane. The distribution of these fluxes over the three-dimensional (3-D) plane of Earth’s magnetotail will be presented. Further, their relative contribution through different magnetospheric regions will be discussed.
Developing a coupled hydrological model for UK chalk catchments
Authors: Rahman Mostaquimur , Woods Ross , Pianosi Francesca , Fung Fai , Rosolem Rafael
Published: March 2024

Chalk forms one of the most important aquifers in the UK. Extending over large parts in the south-west, chalk aquifers account for more than half of the groundwater used for drinking in England and Wales. Groundwater held in these aquifers supports flows in chalk rivers. Hence, chalk aquifers play an important role in sustaining the riverine ecosystem. It is, therefore, important to assess and manage freshwater resources in these catchments. Here we develop and evaluate a distributed numerical model for simulating coupled subsurface and land surface hydrological processes including soil moisture variability, flow, and groundwater dynamics in chalk catchments. The parsimony and computational efficiency of this model make it possible to perform numerous simulations within a reasonable time. This allows for sensitivity analysis, calibration, and multiple scenario analysis that are useful in management decision making.
Upscaling of 3D root hydraulic architectures of trees to 1D root hydraulic models
Authors: Vanderborght Jan , Baca Cabrera Juan , lobet Guillaume , Leitner Daniel , Javaux Mathieu , Couvreur Valentin , Schnepf Andrea
Published: March 2024

Root systems of trees are obviously much larger than those of herbaceous plants. Considering a root length of 30 km of roots below a surface area of 1m2 in a forest and considering that the root system of a single tree extends over a horizontal area of 10 m², this would mean that a root system of one tree is 300 km long. To simulate the water flow in the root system, the root system is typically discretized in 1cm long root segments and a set of flow equations is setup and solved to derive the water potential and flux in each segment of the 3D root hydraulic architecture. For a system with n root segments and n+1 nodes at which segments are connected, this results in a set of n equations that need to be solved. Solving this set of equations corresponds with inverting an n by n matrix. For the root system of a tree, the size of this matrix would be 3 107 by 3 107. The linear equation matrix is sparse and could be solved using equation solvers that do not calculate the inverse matrix. But, also these solutions might still be too expensive so that an upscaled and reduced set of equations is needed. We developed an approach to upscale flow equations in root hydraulic architectures (Vanderborght et al., 2021), which were subsequently coupled to non-linear flow equations that account for resistance to flow in the soil around root segments (Vanderborght et al. 2023). But, these upscaling approaches require an inversion of the linear equation matrix. In order to address this problem, we developed an inversion method that uses the hierarchical structure of the root network to divide the inversion into a set of smaller inversion problems that can be solved in parallel. In this presentation, we outline the principle of the inversion method and demonstrate it for large root systems of trees. ReferencesVanderborght, J., et al. (2021) From hydraulic root architecture models to macroscopic representations of root hydraulics in soil water flow and land surface models. Hydrol. Earth Syst. Sci., 25(9), 4835-4860. https://doi.org/10.5194/hess-25-4835-2021 Vanderborght, J., et al. (2023). Combining root and soil hydraulics in macroscopic representations of root water uptake. Vadose Zone Journal, n/a(n/a), e20273. https://doi.org/https://doi.org/10.1002/vzj2.20273
The mitigation of greenhouse gas emissions by manipulating water table level on peat soil growing grass in eastern Finland –mesocosm and field experiments
Authors: Zheng Yu , Virkajärvi Perttu , Saarnio Sanna , Räty Mari , Marjanen Marja
Published: March 2024

Finland commits to carbon neutrality by 2035. Reducing GHG emissions and strengthening carbon sequestration properties from agricultural land is on schedule. Although active agricultural peatlands account for 10% (about 310 000 ha) of total agricultural lands in Finland whereas they contribute to 60% of GHG emissions of agricultural soils. Therefore, large-scale measures are required to Finnish agricultural peatlands. Carbon dioxide (CO2) and nitrous oxide (N2O) are the culprit from agricultural peat soils due to increased soil aeration after peatland drainage. Evidently, the most effective way of remedy would be raising ground water close to soil surface. However, total rewetting is not feasible for food production and may result in methane (CH4) emissions (Regina et al. 2019). There might be a viable water table level reaching the compromise, but effects of underground water elevation in a field scale have not been studied in Finland thus it is not clear about the counterbalance between GHG mitigation and grassland crop yields (under changing water table levels).This study aimed to tackle the issues being mentioned which incorporate both field and mesocosm experiments. In the field experiment, the underground water levels are manipulated by a drainage well system separating ground water table into high and low levels. Manual chamber and snow gradient methods (Maljanen et al., 2003) were exploited measuring gas fluxes regularly between June 2021 and September 2023 (involving three growing seasons). The mesocosm study was established with the peat soil monoliths taken from the same peat site. Gas fluxes of four water level treatments (below ground -70, -50, -30, -20 cm) were measured with the same methods towards their field counterpart for one year. We will present preliminary results on how water table manipulation will affect gas fluxes and crop yields under Finnish climate. ReferencesRegina K., Heikkinen J., Maljanen M., 2019, Greenhouse Gas Fluxes of Agricultural Soils in Finland. In: Shurpali N., Agarwal A., Srivastava V. (eds) Greenhouse Gas Emissions. Energy, Environment, and Sustainability, https://doi.org/10.1007/978-981-13-3272-2_2Maljanen M., Liikanen A., Silvola J., Martikainen P.J. (2003) Measuring N2O emissions from organic soils with closed chamber or soil/snow N2O gradient methods. European Journal of Soil Science 54: 625-631.
Future scenarios of forest microclimates using a Land Surface Model.
Authors: Hes Gabriel , Vanderkelen Inne , Fisher Rosie A. , Chave Jérôme , Ogée Jérôme , Davin Edouard
Published: March 2024

The forest understory generally experiences temperature variations that are dampened compared to adjacent open areas (known as the “buffering effect”), allowing the development of a forest microclimate and associated ecological conditions. It is however unclear to what extent forests will maintain this buffering effect under increasing global warming. Providing reliable projections of future forest microclimates is therefore crucial to anticipate climate change impacts on forest biodiversity, and to identify corresponding conservation strategies. Recent empirical studies suggest that the buffering of air temperature extremes in forest understory compared to open land could increase with global warming, albeit at a slower rate than macroclimate temperatures. Here, we investigate the trend of this temperature buffering effect in a high-emission global warming scenario, using the process-based Land Surface Model CLM5.1. We find biome-dependant buffering trends with strongest values in tropical forests where buffering increases for every degree of global warming by 0.1 °C for maximum soil temperature, and by 0.2 °C for maximum canopy air temperature. In boreal regions, forest microclimate exhibits a strong seasonality and the effect of global warming on forest understory is less clear. This first Land Surface Model assessment of future forest microclimate highlights the specific importance of tropical forest canopies in particular, in maintaining hospitable conditions for understory species while also increasing their climate debt under global warming. Our research also illustrates the potential and limitations of Land Surface Models to simulate forest microclimate, and calls for further collaborations between Earth system modelers and ecologists to jointly question climate and biosphere dynamics.
Comparison of advanced multicriteria decision and FAO models for land suitability assessment 
Authors: Nabiollahi Kamal , Molani Fereshteh , Taghizadeh-Mehrjardi Ruhollah , Tahari-Mehrjardi Mohammad Hossein , Shokati Hadi , Khosravani Pegah , Kebonye Ndiye , Scholten Thomas
Published: March 2024

Land suitability assessment is an important process in modern agricultural management, involving the evaluation of various factors such as soil properties, climate, relief, hydrology, crop varieties and socio-economic considerations. Various methods have been used to assess land suitability, such as the parametric method developed by Sys et al. (1991) and the FAO (1976) approach to land evaluation. Determining the relative weighting of the factors that influence land suitability is a particularly challenging step in the evaluation process. An alternative to these procedures is the use of multi-criteria decision making (MCDM) techniques, which enable land managers and policy makers to make informed decisions about land use and development. Spatial MCDM techniques include complex spatial data and methods such as the Technique of Preference Ordering by Similarity to the Ideal Solution (TOPSIS), which are widely used in the agricultural sector. TOPSIS determines the optimal alternative according to the principle of minimizing the proximity to the ideal solution and maximizing the distance to the negative ideal solution. The aim of this study was to assess the suitability of land for wheat cultivation in western Iran, a country facing the challenge of becoming self-sufficient in wheat. Seventy soil profiles were selected and described on the basis of a geomorphologic map and the content of various soil properties and wheat yield were determined. MCDM (TOPSIS) and FAO models were applied and evaluated according to wheat yield. The Shannon entropy method (SHE) was used to extract the criteria weights. Land suitability assessment was mapped using a Random Forest machine learning model and auxiliary variables. According to the results of the Shannon entropy method, slope, cation exchange capacity (CEC) and calcium carbonate equivalent (CCE) are the most important criteria for wheat cultivation. Furthermore, the results are also confirmed by the spatial autocorrelation between the key criteria and wheat yield. These results also show that the soil suitability values calculated with the TOPSIS model have a higher correlation with wheat yield than the values calculated with the FAO model (0.73 and 0.67, respectively). The spatial distribution of the suitability values for wheat cultivation showed that 30 to 33% of the areas were very suitable, 13-16% moderately suitable and 51% and 57% unsuitable. For the areas with high and medium suitability, the TOPSIS and FAO results were largely in agreement, in contrast to the areas with low suitability. This study provided a comprehensive approach to land suitability for wheat cultivation using advanced MCDM techniques and machine learning, which can be beneficial for sustainable land management and food security in Iran and similar regions.
Transfer of sulfur and chalcophile metals via sulfide-volatile compound drops in the Christiana-Santorini-Kolumbo volcanic field
Authors: Patten Clifford G. C. , Hector Simon , Kilias Stephanos P. , Ulrich Marc , Peillod Alexandre , Beranoaguirre Aratz , Nomikou Paraskevi , Eiche Elisabeth , Kolb Jochen
Published: March 2024

Efficient transfer of S and chalcophile metals through the Earth’s crust in arc systems is paramount for the formation of large magmatic-hydrothermal ore deposits and can strongly affect the Earth’s climate. The formation of sulfide-volatile compound drops has been recognized as a potential key mechanism for such transfer but their fate during dynamic arc magmatism remains cryptic. We report evidence of compound drops preserved in the active Christiana-Santorini-Kolumbo volcanic field. The observed compound drops are micrometric sulfide blebs associated with vesicles trapped within silicate phenocrysts. The compound drops accumulate and coalesce at mafic-felsic melt interfaces where larger sulfide ovoids form. These ovoids are subsequently oxidized to magnetite during sulfide-volatile interaction. Comparison of metal concentrations between the sulfide phases and magnetite allows for determination of element mobility during oxidation. The formation and evolution of compound drops is an efficient mechanism for transferring S and chalcophile metals into shallow magmatic-hydrothermal arc systems.
Heat stroke risk in China quantified by web-based data
Authors: Han Qinmei
Published: March 2024

Heat stroke is a serious heat-related health outcome that can eventually lead to death. Due to the poor accessibility of heat stroke data, the large-scale relationship between heat stroke and meteorological factors is still unclear. We collected daily heat stroke search index and meteorological data for the period 2013–2020 in 333 Chinese cities to quantify the threshold of people may suffer from heat stroke by Random Forest model. When the daily mean temperature exceeded 23.5°C, heat stroke cases may occur in China. Then, we calculated the total heatwave duration exceeding the threshold quantified aforementioned and population exposure to heatwave in China using four scenario combinations, namely SSP1SSP1-2.6, SSP2SSP2-4.5, SSP3SSP3-7.0, SSP5SSP5-8.5, for 1986-2005, 2041-2060 and 2081-2100 periods.
How Does Extreme Precipitation Occur in SudanDuring the summer of 2020?
Authors: Alawad Kamal Aldien
Published: March 2024

In summer 2020, media and aid organizations reported on severe flash and riverine floods in many countries in the Greater Horn of Africa caused by a sequence of extreme precipitation events. However, this event was relatively controversial and much was speculated about how it occurs.  Here, the ECMWF-ERA5 dataset was used to investigate the atmospheric circulations that led to unusual extreme precipitation resulting in several loss of life and destructive socio-economic impacts over Sudan during summer 2020.
Extreme rainfall over Sudan is concurrent with a well-developed La Nina pattern over the tropical Pacific Ocean and associated with basin-wide anomalous high sea surface temperature (SST) over the Indian Ocean, especially over the Gulf of Oman (GO), where +2 °C has been observed. The unusual warming over GO seems to have three main roles: 1) deepen the monsoon layer, trigger the water vapor transport, contribute excess moisture in the entire troposphere, reduce the convective inhibition and thus, increase the extreme precipitation in the study region. 2) Enhance activity of the African Easterly Jet Stream, where above 3 m/sec wind speed anomaly over 600 GPH has been observed over the GO area. Therefore, the aforementioned reasons may be responsible for the extreme precipitation over the study area.

 
Elucidating Dominant Factors Affecting Land Surface Hydrological Simulations of the Community Land Model over China
Authors: Liu Jianguo , Jia Binghao , Xie Zhenghui
Published: March 2024

In order to compare the impacts of the choice of land surface model (LSM) parameterization schemes, meteorological forcing, and land surface parameters on land surface hydrological simulations, and explore to what extent the quality can be improved, a series of experiments with different LSMs, forcing datasets, and parameter datasets concerning soil texture and land cover were conducted. Six simulations are run for mainland China on 0.1o×0.1o grids from 1979 to 2008, and the simulated monthly soil moisture (SM), evapotranspiration (ET), and snow depth (SD) are then compared and assessed against observations. The results show that the meteorological forcing is the most important factor governing output. Beyond that, SM seems to be also very sensitive to soil texture information; SD is also very sensitive to snow parameterization scheme in the LSM. The Community Land Model version 4.5 (CLM4.5), driven by newly developed observation-based regional meteorological forcing and land surface parameters (referred to as CMFD_CLM4.5_NEW), significantly improved the simulations in most cases over mainland China and its eight basins. It increased the correlation coefficient values from 0.46 to 0.54 for the SM modeling and from 0.54 to 0.67 for the SD simulations, and it decreased the root-mean-square error (RMSE) from 0.093 to 0.085 for the SM simulation and reduced the normalized RMSE from 1.277 to 0.201 for the SD simulations. This study indicates that the offline LSM simulation using a refined LSM driven by newly developed observation-based regional meteorological forcing and land surface parameters can better model reginal land surface hydrological processes.
Investigating vertical gradients of trace gases and aerosol at the Amazon Tall Tower Observatory (ATTO) using MAX-DOAS measurements
Authors: Donner Sebastian , Lauster Bianca , Ziegler Steffen , Artaxo Paulo , Beirle Steffen , Gurk Christian , Lamneck Mark , Wagner Thomas
Published: March 2024

Multi-AXis (MAX)-Differential Optical Absorption Spectroscopy (DOAS) measurements use trace gas absorptions in spectra of scattered sun light recorded under different elevation angles to retrieve vertical profiles of trace gas concentrations and aerosol extinctions in the lower troposphere as well as the corresponding total tropospheric vertical column densities (VCDs). A major advantage of this kind of measurements is the possibility to observe multiple trace gases e.g., formaldehyde (HCHO), glyoxal (CHOCHO) and nitrogen dioxide (NO2), for the same air mass simultaneously with one instrument. A first MAX-DOAS instrument was installed at the Amazon Tall Tower Observatory (ATTO) at an altitude of 80 m above ground in October 2017. Since March 2019, a second instrument is operational at an altitude of 298 m. Besides the individual profile retrievals for both instruments, this measurement strategy allows the identification of (small scale) vertical gradients of trace gas and aerosol abundances by directly comparing the VCDs and concentrations (at instrument altitude) measured by both instruments. Such (small scale) vertical gradients provide important insights into the chemical processing of the different species. Located in a pristine rain forest region in the central Amazon Basin about 150 km north-east of Manaus, the ATTO site offers a rare possibility to study the chemical processing of tropospheric trace gases far from major anthropogenic emission sources. In the presented study, a general overview of the trace gas and aerosol results covering several years is provided. Thereby, a specific focus is put on the HCHO and glyoxal results including the annual variations of their abundances in the course of the characteristic alternation between wet and dry seasons. Based on the ratio of their abundances, our measurements indicate that different precursor compositions of both species prevail in the different seasons, whereby in the wet season the relative amount of precursors favouring the formation of glyoxal, e.g. monoterpenes, appears to be larger than in the dry season. In addition, (small scale) vertical gradients in the altitude range between both instruments are presented. Our results suggest that HCHO is mostly formed in the lowest 200 m above the canopy, while glyoxal is already degraded in this altitude range. Together with their characteristic profile shapes, these findings indicate different chemical processing (production and degradation) of HCHO and glyoxal, despite similar sources of their precursors.   
Iron mediated organic matter cycling in permeable surface sediments
Authors: Zhou Zhe , Yang Shouye
Published: March 2024

Coastal permeable sediments cover 50-60% of the continental shelves and are important filters and bioreactors that sitting between the land and ocean. In permeable surface sediments, the dynamic porewater advection can lead to frequent redox oscillation, which significantly affects the coupled cycling of organic matter (OM) and iron. In our study, we focused on the most redox active iron fraction (extractable by 0.5 M HCl), and investigated their effects on OM degradation and retention. During the transition of redox conditions, Fe(III) oxyhydroxides were quantitatively found as the dominant electron acceptors for anaerobic OM remineralization. However, the release of reduced Fe was significantly delayed, with most Fe(II) (~96%) remaining in the solid phase either through adsorption or formation of authigenic Fe(II)-bearing minerals. Under frequent redox oscillation as typically observed in natural coastal permeable sediments, Fe(II) in the solid phase can be re-oxidized and repetitively used as electron acceptor for anaerobic OM remineralization (Iron “redox battery”). In addition, based on our field study along near- to offshore transect in the North Sea, we found that the most redox active iron trapped abundant of dissolved OM (54±20 times than DOM in porewater) that enriched in aromatic and oxygen-rich compounds. It indicates that iron may preferentially promote the retention of terrigenous and aromatic DOM in permeable sediments, thus serving as an important temporal storage for terrigenous OM in the coastal ocean. Further investigations of the dynamic Fe-OM interactions in coastal sediments are warranted to better understand carbon cycling in the coastal area. 
Impact of human and natural causes on shrinking Burdur Lake in the semi-arid Mediterranean region of Turkiye
Authors: Kılıç Germeç Hatice , Yazıcıgil Hasan
Published: March 2024

Lakes are valuable natural indicators, providing insights into the impacts of natural and artificial interventions on the hydrologic system. In arid and semi-arid climates, the global interest in monitoring shrinking lakes is growing to quantitatively reveal the impacts of such interventions. The internationally important Burdur Lake (Ramsar site no. 658), located in the semi-arid Mediterranean region of Turkey, stands out as a noteworthy example, with its water levels decreasing by nearly 17 m since the early 1970s. This study aims to investigate the reasons for the continual decrease in Burdur Lake levels over time and to assess the future impacts of various factors on the lake system, utilizing a 3-D numerical groundwater flow model developed with MODFLOW. The modeling process includes three years of transient calibrations for both initial (1969-1971) and current conditions (2014-2016) by simulating the lake with an incorporated lake package. The successfully calibrated model was then simulated with the future climate change scenarios over a 46-year period. Future climatic data derived from the RCP 4.5 and RCP 8.5 scenarios of the CORDEX Regional Climate Models were incorporated into the simulations to assess the impacts of change in natural climatic conditions. The first scenario was created to assess the impacts of climate change on the lake, whereas the second scenario was simulated to investigate the effects of excessive groundwater pumping under the influence of climate change. The third scenario was generated to simulate the cumulative effects of climate change and the decrease in flows of the streams feeding the lake as a result of the reservoirs constructed. The results indicate that climate change was not the primary driver behind the drop in the lake levels until the end of 2018. However, it may exacerbate the situation in the future, amplifying the negative effects of anthropogenic activities by imposing stress on the lake. An anticipated decline of up to 7 m in Burdur Lake level is projected due to the cumulative effects of climatic variations and excessive pumping. Conversely, despite the influence of climate change, an increase of up to 3 m is expected with the release of surface water flows. These findings underscore the need for a dynamic lake management plan to maintain desired conditions in Burdur Lake and its watershed, ensuring the sustainable management of this vital surface water resource.
Characterizing the influence of riming on the spatial variability of ice water content in mixed-phase clouds using airborne data
Authors: Maherndl Nina , Moser Manuel , Mech Mario , Risse Nils , Bansemer Aaron , Maahn Maximilian
Published: March 2024

Observations show that ice water content (IWC) is not distributed homogeneously in mixed-phase clouds (MPC). Instead, high IWC tends to occur in clusters. However, it is not sufficiently understood, which ice crystal formation and growth processes play a dominant role in IWC clustering. Additionally, spatial scales of IWC clusters are not well known. This leads to uncertainties of atmospheric models in representing MPC.Riming, which occurs when liquid water droplets freeze onto ice crystals, is an important ice crystal growth process. It plays a key role in precipitation formation in MPC by efficiently converting liquid cloud water into ice.In this study, we analyze the influence of riming on IWC variability  and compare shallow Arctic MPC to mid-latitude winter storms. We use airborne data collected during the HALO-(AC)3 field campaign performed in spring 2022 west of Svalbard, and the IMPACTS field campaign, which took place over the eastern USA (winter 2020, 2022 and 2023). In both campaigns, two aircraft were flying in formation collecting closely spatially collocated and almost simultaneous in situ and remote sensing observations.We quantify the amount of riming using the normalized rime mass M, which we retrieve from a closure of measured radar reflectivity Ze and measured in situ particle size distributions (PSD). As forward operators in the M retrieval, we use the Passive and Active Microwave radiative TRAnsfer tool (PAMTRA) and empirical relationships of M and particle properties. We calculate IWC from the retrieved M and the measured PSD. In addition, we calculate IWC assuming no riming (M = 0) and perform forward simulations of Ze for the (theoretical) unrimed case. Then, we quantify spatial variability of IWC and Ze with and without riming using autocorrelation, pair correlation, and power spectra. Further, we compare shallow Arctic MPC to mid-latitude winter storms and analyze the role of ice particle number concentration and size.This will lead to a better understanding of the spatial scale and driver of IWC variability and thereby help to improve modeling of MPC.
Flash Flood Hazard: A Counterfactual Analysis for Germany
Authors: Voit Paul , Heistermann Maik
Published: March 2024

In response to heavy rainfall, flash floods can arise from rapid runoff concentration in the landscape, presenting significant damage potential due to high flow velocities and minimal lead times. Flash floods are among the most destructive natural hazards. Managing their risks usually necessitates the application of extreme value statistics. However, the small temporal and spatial scale of flash floods poses a challenge, as the requisite data for statistical methods is often unavailable or incomplete.  Furthermore, the effects of climate change may compromise the robustness of extreme value statistics.To enhance our understanding of flash flood hazards in Germany, we present a novel "counterfactual" scenario analysis. This approach considers alternative ways of how events could have unfolded. To identify worst-case scenarios is particularly interesting for risk assessment. Accordingly, we assumed that historical rainfall events could have happened anywhere else in Germany: What would have happened if a particular rainfall event occurred in a different area? Would it result in a flash flood?To address these questions, we created a catalog of extreme rainfall events for the years 2001-2022 from radar rainfall estimates. Because flash flood triggering rainfall is often embedded in precipitation fields of larger spatio-temporal extent, we used the cross-scale weather extremity index (xWEI) to identify and rate the events. We then shifted the ten most extreme events systematically across Germany and modeled the peak discharge for every shifted realization (counterfactual peaks), thus creating close to a billion runoff datasets. This approach preserves the spatio-temporal event structure that significantly influences the overlapping scales of runoff processes and hence the hazard. Results are provided to users via an interactive web interface.Our results reveal that, on average, the worst case counterfactual peaks would exceed the maximum original peak by a factor 5.3. Furthermore, it shows that not every event is equally likely to trigger high runoff peaks, even when rated similarly extreme. Our study might help to expand the view on what could happen in case certain extreme events occurred elsewhere, help to identify flash flood prone areas, and thereby reduce the element of surprise in disaster risk management. The proposed method is transferable and could be a valuable asset, especially in data-scarce regions.
Gel wax and Ultrasound Transmission Gel as upper and lower crustal rheology analogue
Authors: Biswas Uddalak , Mitra Atin Kumar , Mandal Nibir
Published: March 2024

The laboratory modelling of upper and lower crustal rocks has been challenging in terms of rheological scaling for geologists. Upper and lower crusts have been considered as coulomb-brittle or elastic and viscous rheological material, respectively, by the analogue modeller in simulating several deformation related phenomena. However, in nature, they are not purely viscous or elastic, or plastic. Rather, they behave visco-elasto-plastically. This work introduces two new materials of complex visco-elastic and visco-elastoplastic rheology i) Gel wax and, ii) Ultrasound Transmission Gel (USTG). Gel wax is a commercial wax which is composed of mineral oil and hydrocarbon-based polymer. It is used for making transparent, long-lasting candles with melting temperatures of 70-80°C. On the other hand, USTG is a gel-like substance made mainly of Carbopol powder and water.In this present work, we performed amplitude and frequency sweep tests in a rheometer for both the Gel wax and USTG to understand their complex rheology. The results suggest that Gel wax can be an appropriate analogue material to simulate upper crustal experiments. Similarly, visco-elastoplastic rheology of USTG is analogous to lower crustal rocks.Considering these materials as crustal analogues, we conducted a few dike emplacement experiments following proper geometric, kinematic and dynamic scaling. The experimental results revealed remarkable 3D dike geometry as both the materials are transparent. Finally, we matched these patterns with a few exposed dikes observed in the field, which supports the applicability of Gel wax and USTG as crustal rock analogues.
Functional traits and trait diversity of leaves: palaeoecological perspectives
Authors: Roth-Nebelsick Anita , Traiser Christopher
Published: March 2024

Functional traits were originally defined as any characteristic of an organism that contributes to fitness. From this autecological perspective, trait-based research has considerably expanded into approaches of ecosystem analysis that also have high potential for palaeoecological research. In the ecosystem context, the meaning of “trait” has become much broader, encompassing all sorts of measurable quantities carrying ecological information that are themselves categorized into different “trait classes”. For instance, “response traits” are organismal traits responding to environmental parameters whereas “effect traits” act upon the environment.As primary producers, plants represent a crucial part of ecosystem functioning. Basic ecophysiological processes of plants, particularly gas exchange and photosynthesis, are key elements in the carbon and water cycle and can thereby be understood as “effect traits”. Fossil anatomical traits, such as from fossil leaves, allow for deriving basic ecophysiological parameters from physical laws (such as calculating leaf gas conductance from the diffusion equation). Biochemical parameters, however, are not provided by fossil material and require therefore estimation based on extant plants (such as kinetic properties of the enzyme apparatus of photosynthesis) which adds a certain error margin to the results. Nevertheless, these “mixed” approaches to fossil plant ecophysiology allow for obtaining crucial benchmark data on various ecosystem characteristics, such as primary productivity or evapotranspiration.            Another branch of trait-based ecosystem research is the study of functional diversity which can be roughly described as the richness and distribution of functions expressed by organisms coexisting within a habitat. Functional diversity is less frequently considered for fossil vegetation compared to the study of autecological effect traits. One reason may be that various approaches for studying extant functional diversity are difficult or even impossible to apply to fossil plants, requiring the development of novel methods suitable for fossil remains.As a recent example, the Shannon Diversity of leaf architecture based on functional leaf traits identifiable from fossil leaf material was shown to be related to environmental parameters for extant as well as fossil angiosperms.  Devising trait-based approaches to functional diversity suitable for fossil organisms can offer additional fruitful research perspectives for studying environments of the past.
Development of Portable Weather Observation System
Authors: Park Mi Eun , Lee Yong Hee
Published: March 2024

In the event of a large-scale forest fire, the Korea Meteorological Administration (KMA)’s weather observation vehicles are deployed to obtain weather information necessary for extinguishing the fire. However, due to the limited number of vehicles and the environment to enter the field, it is difficult to observe the point where the information is actually needed. Therefore, there is an urgent need to develop a weather observation system that is easy to transport and install in the field.We developed a 'portable weather observation system' that can be easily utilized by anyone, even if the KMA does not support weather observation vehicles and their operators at the disaster site. - [Transport] Weight and size that can be easily carried by one adult in a suitcase (or backpack). - [Installation] Attached to a steel plate, such as the top of a vehicle without any additional components. If this is not possible, a tripod can be utilized for installation. - [Operation] Real-time storage, display, and transmission of observation data - [Information] Location of the observation site (latitude, longitude and altitude) and weather variables (temperature, humidity, atmospheric pressure, and wind direction*∙wind speed) of the observation site.  * Corrected regardless of the system's installation orientationThe prototype consists of a weather observation sensor, two GPS antennas, a tripod, a data processing/storage/display unit, and a power supply unit, and the total weight of the components including the suitcase (10 kg) is 20 kg. The weather observation sensor used is the Vaisala WXT-536, which can observe weather variables. Two GPS antennas were used to determine the location of the sites and correct the wind direction observed by the sensor. The system can be directly utilized by the Korea Forest Service (KFS) and the National Fire Agency (NFA) for initial extinguishment of wildfires.By applying weather observation data transmitted in real-time from the field to numerical forecasting models, the KMA can provide more accurate weather forecasts back to the field. In the future, we plan to improve the prototype by utilizing an inexpensive sensor and lightweight and long-lasting batteries to reduce the cost and weight as well as increase the operating time.
Characterization of physical properties of  a coastal upwelling filamentwith evidence of enhanced submesoscale activityand  transition from balanced to unbalanced motions in the South Atlantic
Authors: Draeger-Dietel Julia , North Ryan , Griesel Alexa
Published: March 2024

We combine high-resolution in-situ data (ADCP/Scanfish and surface drifters) and remote sensing to investigate the physical characteristics of a major filament observed in the South Atlantic in comparison to its nearby and distant environment explored by three cruises. Observations of the  Rossby number Ro from the various platforms provide the spatial distribution of Ro for different resolutions. Remote sensing focuses on geostrophic motions of the region related to the mesoscale eddies that drive the filament formation and thereby reveals Ro<0.1.  Ship based measurements in the surface mixed layer reveal 0.5<Ro<1, indicating the presence of unbalanced, ageostrophic motions. Timeseries of Ro from triplets of surface drifters trapped within the filament confirm these relatively large Ro and show a high variability along the filament. A scale dependent analysis of Ro, which relies on the second order velocity structure function, was applied  to  the latter drifter-group and to another drifter-group released in the upwelling zone. The two releases explored  the area nearly distinctly and simultaneously, and reveal that at small scales (< 15 ~km) Ro values are twice as large in the filament in comparison to its environment with Ro >1  for scales smaller than  500 m. This suggests that filaments are hotspots of ageostrophic dynamics, pointing to the presence of a forward energy cascade.  The different dynamics indicated by our Ro-analysis are confirmed by horizontal kinetic energy wavenumber spectra, which exhibit a power law  k-α with α= 5/3 for wavelengths 2π/k smaller than a transition scale of ~15 km, supporting significant submesoscale energy at scales smaller than the first baroclinic Rossby Radius (Ro1 ~ 30 km). The detected transition scale  is smaller than those found in regions with less mesoscale eddy energy, consistent with previous studies.
Prospects for Aquifer Thermal Energy Storage in the UK
Authors: Jackson Matthew , Regnier Geraldine , Staffell Iain
Published: March 2024

Aquifer Thermal Energy Storage (ATES) is an underground thermal energy storage technology that provides large capacity (of order MWth to 10s MWth), low carbon heating and cooling to large buildings or complexes of buildings, or district heating/cooling networks.  The technology operates through seasonal capture, storage and re-use of thermal energy in shallow aquifers, reducing carbon emissions and electricity demand for heating and cooling compared to direct ground- or air-sourced heat pump systems.We demonstrate that ATES could make a significant contribution to decarbonising UK heating and cooling, but uptake is currently very low.  We identify eleven low temperature (LT-ATES) systems operating in the UK, with the first having been installed in 2006. These systems currently meet
Ablation drivers over a cold-based ice cap in the Eastern Alps: a surface energy balance analysis
Authors: Baldo Anna , Nicholson Lindsey , Hartl Lea , Stocker-Waldhuber Martin
Published: March 2024

Glaciers are archives of past climatic conditions, reflected in the yearly amount of ice accumulation or depletion. Ice coring allows access to the information stored in glacial layers. However, discontinuities in an ice core create problems in reliably dating the core layers and questions regarding the origin of the discontinuity.The analysis of an ice core from 2017 on Weißseespitze, a cold-based ice cap located at 3498 m a.s.l. in Tyrol (Austria), could be explained by the presence of a discontinuity around 400 CE. Since the glacier is nowadays experiencing potentially similar mass loss conditions, this study analyses present day surface energy balance to identify the potential climatic drivers behind the supposed discontinuity.Energy balance at the core site is modelled with the COupled Snowpack and Ice surface energy and mass balance model in Python (COSIPY), forced with data collected between 2017 and 2022 by an automatic weather station on the glacier. COSIPY initialisation was optimised by comparing modelled and observed snowheight, the observed albedo was introduced as an input variable and the precipitation input was modified to better suit high altitude locations.Comparison of the modelled and observed snowheight shows minor mismatches, connected in part to the absence of a wind erosion parameterization in the model and in part to the overestimation of surface temperature from the energy balance optimization algorithm. Nevertheless, COSIPY ice melt gradient agrees very well with observations and the simulation of the ablation season is not deeply affected by such problems.Weißseespitze lost on average about 3 m of ice at the summit since 2018. The summer characterised by maximum ice melt in the observational period was 2022, where ablation stakes recorded on average 1.5 m of ice loss. On the contrary, summer 2020 was the only summer where most of the summit registered no ice loss. Comparison of energy balance components between the summer 2022 and 2020 showed that 2022 was characterised by positive and more intense sensible (9.8 W m-2 vs 5.8 W m-2) and latent (1.0 W m-2 vs -1.0 W m-2) heat fluxes and a lower outgoing shortwave energy flux (118.8 W m-2 vs 166.1 W m-2). The latter is caused by an abrupt albedo lowering at the beginning of July, which aligns with a period of uninterrupted positive air temperature of almost two weeks removing the snow from the previous winter. Therefore, air temperature and its impact on the glacier surface seems to be the main driver of ablation in 2022, which had about 20 positive temperature days more than 2020, resulting in an average air temperature 1.2 °C warmer.These preliminary results will be shortly complemented by research in local archives of paleotemperature to verify whether the time of the hypothesised discontinuity was characterised by similar conditions.