bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of landscape spatial arrangement on nitrogen and phosphorus export in agricultural catchments
Authors: Dupas Rémi , Casquin Antoine , Gu Sen , Gruau Gérard , Durand Patrick
Published: March 2021

Nitrogen and Phosphorus losses from rural landscapes can cause eutrophication of inland and coastal waters. Here, we assessed the influence of the spatial configuration of nutrient sources on nitrate (NO3-) and total phosphorus (TP) exports at the catchment scale. We analyzed NO3- and TP in 19 headwater catchments (1 -14 km²) fortnightly during 17 months. The study catchments had similar soil type, climate, and farming systems but differed in their landscape composition (% agricultural land-use) and spatial configuration (field distance to streams & intersection with flow accumulation zones). We propose a landscape configuration index (LCI) that describes the spatial configuration of nutrient sources with regards to their hydrological distance to streams and flow accumulation zones. The LCI has two parameters that we calibrated to maximize rank correlation with median concentrations of TP and NO3-. Results showed that NO3- exports were correlated with %agricultural land-use whereas TP exports were better explained by the spatial configuration of agricultural fields. For a given landscape composition, landscape spatial configuration was highly heterogeneous at small scales (<10 km2) but became homogeneous at larger scales (>50 km2). This could explain why relationships between landscape composition and water quality parameters influenced by landscape spatial configuration break down below a certain size threshold.
The effect of permafrost area and types on flux and composition of dissolved organic matter in stream from alpine catchments, northeastern Qinghai-Tibet Plateau
Authors: Pan Yanxi , Sun Ziyong
Published: March 2021

Understanding optical characteristics, composition and source of dissolved organic matter (DOM) in rivers is important for region and global carbon cycle, especially in the inland rivers of the Qinghai-Tibet Plateau. In order to understand the impact of permafrost degradation on river DOM output under the background of climate warming, we selected 34 typical sub-basins in the upper reaches of the Heihe River basin on the Qinghai-Tibet Plateau according to the different proportion of permafrost area in the basin. Water samples were collected at the outlet of each sub-basin in October 2018, January, April and July 2019, respectively. The variations of DOM structure and source identification in different permafrost basin were investigated using UV–visible absorbance and fluorescence spectroscopy. The results showed that: (1) The concentration of C1 and C2 components and the values ​​of SUVA254, HIX and FI increased with the decrease of the percentage of permafrost area. , Indicating that with the degradation of frozen soil, the runoff path deepens, and more terrestrial organic matter is dissolved into the water body, which increases the terrestrial DOM in the river water, which in turn leads to the increase of DOM concentration, humification degree and aromaticity; (2) As the proportion of permafrost area decreases, the SR value shows a decreasing trend, indicating that the DOM of rivers in permafrost regions has the characteristics of low molecular weight and low humic acid, while the DOM of rivers in seasonally frozen soil regions is the opposite, indicating a frozen soil Melting may lead to the increase of terrestrial DOM in river water, and the increase in the depth of freeze-thaw cycle may release aromatic substances containing fused ring structure in frozen soil, which will enter the river with runoff, resulting in increased aromaticity and molecular weight of DOM in river water; (3) The concentrations of C1 and C2 components are positively correlated with vegetation coverage, and vegetation coverage is negatively correlated with the percentage of permafrost area. It shows that the degradation of frozen soil will increase the coverage of vegetation, thereby increasing the DOM from terrestrial sources. This study shows that the optical characteristics, composition and source of DOM have important indications for the degradation of permafrost under the background of global warming.
Antimony leaching from mine waste and soil at a stibnite mine in North-Vietnam
Authors: Cappuyns Valérie , Van Campen Axelle , Helser Jillian
Published: March 2021

While the impact of Sb mining is documented in literature from China, Australia, and Europe, little information is available concerning the environmental impact of Sb mining in Vietnam. This paper presents the results of an exploratory study of mine waste and soil samples from the Mau Due mine (North Vietnam). Besides the chemical and mineralogical composition of soils, waste rock and slag samples, water-soluble and exchangeable/reversibly adsorbed Sb species were also determined, as well as the pH dependent release of Sb. Stibnite and pyrite were found in slag and waste rock samples, with total Sb concentrations in the range of 191–15,699 mg/kg. Soils were characterized by Sb concentrations in the range of 47–95 mg/kg. 
The leaching test show that, when mine waste stored on the Mau Due mining site comes into contact with water, up to 1.7% of its total Sb content is leached. However, because of the high Sb content of some of the waste materials, high dissolved Sb concentrations are found in the leachates. Some of the investigated samples are listed by the EU as absolutely hazardous waste, because of the leaching potential of Sb. Especially in the rainy season, leaching of Sb from the mine waste and slags can contribute to the dispersion of Sb. An increased release of Sb was observed from pH 7.5 to 12.8. Modelling also indicated that the dissolution of stibnite and reprecipitation as Sb(OH)3 is not the only factor that explains Sb solubility. Desorption reactions and the incorporation of Sb in other mineral phases are most likely also important factors determining the retention and release of Sb from the waste materials and slags.
The waste heaps consist of fine-grained material, that can be prone to wind erosion in the dry season. Therefore, measures to prevent the further dispersion of Sb and other potentially hazardous elements, both via leaching and wind erosion, should be put in place. In order to establish regulations for environmental protection, it is necessary to raise governmental and public awareness. The high concentrations of Sb imply an important potential hazard for soils, water bodies, and the food chain, for which appropriate measures are necessary.

 

Reference

Cappuyns, V., Van Campen, A., Helser, J.  (2020). Antimony leaching from soils and mine waste from the Mau Due antimony mine, North-Vietnam. Journal Of Geochemical Exploration, 220, Art.No. 106663, 1-13. doi: 10.1016/j.gexplo.2020.106663 
Sensitivity of hydrological fluxes and states to groundwater representation in continental scale simulations over Europe.
Authors: Naz Bibi S. , Sharples Wendy , Goergen Klaus , Kollet Stefan
Published: March 2021

This study explores the influence of groundwater representation on soil moisture, evapotranspiration, total water storage, water table depth and groundwater recharge/discharge through the comparison of multi-model simulations using the stand-alone Community Land Model (CLM3.5) and the ParFlow hydrologic model. ParFlow simulates three-dimensional variably saturated groundwater flow solving Richards equation and overland flow with a two-dimensional kinematic wave approximation, whereas CLM3.5 applies a simple approach to simulate groundwater recharge and discharge processes via the connection of bottom soil layer and an unconfined aquifer. Over Europe with a lateral resolution of 3km, both models were driven with the COSMO-REA6 reanalysis dataset for the time period from 1997 to 2006 at an hourly time step using the same datasets for the static input variables (such as topography, vegetation and soil properties). Evaluation against independent observations including satellite-derived and in-situ soil moisture, evapotranspiration, and total water storage datasets show that both models capture the interannual and seasonal variations well at the regional scale, however ParFlow performs better in simulating surface soil moisture in comparison with in-situ data. Moreover, juxtaposition of both models shows that simulations of water fluxes and sates in both space and time are sensitive to the differences in groundwater representation in the model. For example, simulations with ParFlow have overall wetter soil moisture than CLM, particularly in humid and cold regions and driest soil moisture in the arid and semi-arid regions. Seasonally, ParFlow simulates wetter soil moisture in winter and driest in summer than CLM model. This study helps to understand and quantify uncertainties in groundwater related processes in hydrologic simulations and resulting implications for water resources assessment at regional to continental scales.
Modelling size distributions of marine plastics under the influence of continuous cascading fragmentation
Authors: Kaandorp Mikael , Dijkstra Henk , van Sebille Erik
Published: March 2021

Field studies have shown that plastic fragments make up the majority of plastic pollution in the oceans in terms of abundance. How quickly environmental plastics fragment is not well understood, however. Here, we study this process by considering a model which captures continuous fragmentation of particles over time in a cascading fashion. With this cascading fragmentation model, we simulate particle size distributions (PSDs), specifying the abundance or mass of particles for different size classes.

 

The fragmentation model is coupled to an environmental box model, simulating the distributions of plastic particles in the ocean, coastal waters, and on the beach. Transport in the box model is based on a previous study regarding a previous study regarding sources and sinks of marine plastics in the Mediterranean Sea. We compare the modelled PSDs to available observations, and use the results to illustrate the effect of size-selective processes such as vertical mixing in the water column and resuspension of particles from the beach into coastal waters.

 

Using the coupled fragmentation and environmental box model, we quantify the role of fragmentation on the marine plastic mass budget. While fragmentation is a major source of (secondary) plastic particles in terms of abundance, it seems to have a minor effect on the total mass of particles larger than 0.1 mm. Future comparison to observed PSD data should allow us to understand size-selective plastic transport in the environment, and potentially inform us on plastic longevity.
Secular geomagnetic field variations in Bulgarian lands during Classical Age and Late Antiquity – new archaeomagnetic data
Authors: Kostadinova-Avramova Maria , Dimitrov Petar , Kosterov Andrei , Kovacheva Mary
Published: March 2021

Numerous historical sources and archaeological monuments attest the age of Antiquity in Bulgaria – from both the early Roman period (I – III c.) and Late Antiquity (IV – VI c.). Owing to systematic archaeological excavations, lasting more than 100 years, plenty of information has been accumulated concerning not only all aspects and manifestations of its material culture, but also their evolution and chronology.  This in turn allows for interdisciplinary fields such as archaeomagnetism to progress.

There are many archaeomagnetically studied archaeological structures from the Antiquity. The results included in the Bulgarian database form 74 reference points. However, only 20 of them are full-vector determinations because 70 % of the investigated materials are bricks. Hence, the secular variation of declination is poorly constrained within the considered period. Moreover, the reuse of bricks in the constructions occurred quite often (especially in the Late Antiquity) providing for possible errors in archaeological dating. In addition, stronger effects of magnetic anisotropy and cooling rate are usually expected for bricks than for hearths, domestic ovens, production kilns or burnt dwelling remains (there are no results from pottery in the Bulgarian dataset) and both factors are not evaluated for most of the older results. All this can explain the contradictions observed between some of the experimental results juxtaposed over the absolute time scale. In an attempt to clarify these contradictions 13 baked clay structures from eight archaeological sites were archaeomagnetically studied producing seven new directional and eight new intensity data. The samples collected possess variable magnetic properties suggesting differences in clay sources and/or firing conditions. Magnetically soft minerals prevail in seven structures but in the remaining six, abundant HCSLT phase is detected. The success rate of archaeointensity determination experiments vary from 49 to 100 %. It appears that samples containing HCSLT phase always produces good araeointensity results unlike those with the dominant presence of soft carriers.

The new reference points are compared with the present compilation of Bulgarian archaeomagnetic dataset and with the data from the neighboring countries.

 

This study is supported by the grant KP-06-Russia-10 from the Bulgarian National Science Fund and Russian Foundation of the Basic Research grant 19-55-18006.
First results of the STIX hard X-ray telescope onboard Solar Orbiter
Authors: Battaglia Andrea Francesco , Saqri Jonas , Dickson Ewan , Xiao Hualin , Veronig Astrid , Warmuth Alexander , Battaglia Marina , Krucker Säm ,   STIX Team
Published: March 2021

With the launch and commissioning of Solar Orbiter, the Spectrometer/Telescope for Imaging X-rays (STIX) is the latest hard X-ray telescope to study solar flares over a large range of flare sizes. STIX uses hard X-ray imaging spectroscopy in the range from 4 to 150 keV to diagnose the hottest temperature of solar flare plasma and the related nonthermal accelerated electrons. The unique orbit away from the Earth-Sun line in combination with the opportunity of joint observations with other Solar Orbiter instruments, STIX will provide new inputs into understanding the magnetic energy release and particle acceleration in solar flares. Commissioning observations showed that STIX is working as designed and therefore we report on the first solar microflare observations recorded on June 2020, when the spacecraft was at 0.52 AU from the Sun. STIX’s measurements are compared with Earth-orbiting observatories, such as GOES and SDO/AIA, for which we investigate and interpret the different temporal evolution. The detected early peak of the STIX profiles relative to GOES is due either by nonthermal X-ray emission of accelerated particles interacting with the dense chromosphere or the higher sensitivity of STIX toward hotter plasma.
Effect of input variables on rainfall-runoff modeling using a deep learning method
Authors: yokoo Kazuki , ishida Kei , nagasato Takeyoshi , Ercan Ali
Published: March 2021

In recent years, deep learning has been applied to various issues in natural science, including hydrology. These application results show its high applicability. There are some studies that performed rainfall-runoff modeling by means of a deep learning method, LSTM (Long Short-Term Memory). LSTM is a kind of RNN (Recurrent Neural Networks) that is suitable for modeling time series data with long-term dependence. These studies showed the capability of LSTM for rainfall-runoff modeling. However, there are few studies that investigate the effects of input variables on the estimation accuracy. Therefore, this study, investigated the effects of the selection of input variables on the accuracy of a rainfall-runoff model by means of LSTM. As the study watershed, this study selected a snow-dominated watershed, the Ishikari River basin, which is in the Hokkaido region of Japan. The flow discharge was obtained at a gauging station near the outlet of the river as the target data. For the input data to the model, Meteorological variables were obtained from an atmospheric reanalysis dataset, ERA5, in addition to the gridded precipitation dataset. The selected meteorological variables were air temperature, evaporation, longwave radiation, shortwave radiation, and mean sea level pressure. Then, the rainfall-runoff model was trained with several combinations of the input variables. After the training, the model accuracy was compared among the combinations. The use of meteorological variables in addition to precipitation and air temperature as input improved the model accuracy. In some cases, however, the model accuracy was worsened by using more variables as input. The results indicate the importance to select adequate variables as input for rainfall-runoff modeling by LSTM.
Interplanetary dust observations with the Solar Orbiter RPW instrument: a first year of data.
Authors: Zaslavsky Arnaud , Mann Ingrid , Bale Stuart , Czechowski Andrzej , Issautier Karine , Lorfèvre Eric , Maksimovic Milan , Meyer-Vernet Nicole , Pisa David , Rackovic-Babic Kristina , Soucek Jan , Vaverka Jakub
Published: March 2021

Impacts of dust grains on spacecraft are known to produce typical impulsive signals in the voltage waveform recorded at the terminals of electric antennas. Such signals are, as could be expected, routinely detected by the radio and plasma waves (RPW) instrument aboard Solar Orbiter, therefore providing in-situ measurements of the interplanetary dust density along the spacecraft trajectory.

We present a statistical analysis of the first year and half of dust impact data recorded by Solar Orbiter RPW between 1 AU and 0.5 AU. We discuss the results in terms of constraints that can be put on beta-meteoroids and interstellar dust fluxes, and compare them to results obtained by STEREO at 1 AU and more recently by Parker Solar Probe at 0.5 AU.
Rayleigh wave ellipticity in seismic noise studies based on vector random decrement technique (VRD)
Authors: Moghadasi Naimeh Sadat , Shabani Elham
Published: March 2021

In seismic hazard assessment studies, the estimation of site effects plays an important role. In recent years, using seismic noise has become increasingly popular because of their simplicity, low cost, and non-destructively. Seismic ambient noise wavefield investigation can be fulfilled by both single-station and array methods. The RayDec single station method is used to estimate ellipticity curve of Rayleigh wave based on Random Decrement (RD) technique by putting more emphasis on Rayleigh waves in compare to other participant waves in the seismic noise wavefield. In this study, to assess measuring the ellipticity of Rayleigh waves in an array of stations, Vector Random Decrement (VRD) technique is applied. The main idea is applying vector triggering condition on vertical components in an array of stations and selecting common triggering points. Those parts of signals where common points of all stations are detected would be included in further processing. It may lead to a lower number of obtained triggering points and insufficient convergence. To control the convergence, the vector of triggering conditions could be divided into some subsets. The maximum number of subsets can be estimated as the lowest integer of N/2 in which N is the number of stations in the array. Wherever, the common triggering points are detected on three components of the stations, the time windows with the same length are extracted. In the following, the signals in the mentioned windows are stacked and the ellipticity ratio is estimated by analyzing the energy content of the horizontal and vertical signals. In order to verify the method, synthetic circular array data are simulated using the FD code including five stations regularly placed on the circumference and a station in the center. Furthemore, the real array data recorded in Ramsar site (North of Iran) are used to study the method. The data included six Nanometrics trillium 40 seismic stations in which five stations placed on the circumference as well as a station at the center regarding to array aperture of about 15m. The retrieved ellipticity curves are evaluated and compared with the results of high resolution Rayleigh three component beam-forming (RTBF) method. The RTBF and VRD methods show good performance in recognizing the right flank of peak frequency while, the peak frequency and the left flank are better retrived using VRD method. Finally, the retrieved ellipticity curve from VRD alongside with the dispersion curves obtained from RTBF for both synthetic and real array data are used as targets in a joint inversion process to validate the shear wave velocity profile.
Exploring the variation in ecosystem scale methane fluxes and its drivers within a boreal mire complex
Authors: Noumonvi Koffi Dodji , Ratcliffe Joshua L. , Öquist Mats , Nilsson Mats B. , Peichl Matthias
Published: March 2021

Northern peatlands cover a small fraction of the earth’s land surface, and yet they are one of the most important natural sources of atmospheric methane. With climate change causing rising temperatures, changes in water balance and increased growing season length, peatland contribution to atmospheric methane concentration is likely to increase, justifying the increased attention given to northern peatland methane dynamics. Northern peatlands often occur as heterogeneous complexes characterized by hydromorphologically distinct features from < 1 m² to tens of km², with differing physical, hydrological and chemical properties. The more commonly understood small-scale variation between hummocks, lawns and hollows has been well explored using chamber measurements. Single tower eddy covariance measurements, with a typical 95% flux footprint of < 0.5 km², have been used to assess the ecosystem scale methane exchange. However, how representative single tower flux measurements are of an entire mire complex is not well understood. To address this knowledge gap, the present study takes advantage of a network of four eddy covariance towers located less than 3 km apart at four mires within a typical boreal mire complex in northern Sweden. The variation of methane fluxes and its drivers between the four sites will be explored at different temporal scales, i.e. half-hourly, daily and at a growing-season scale.
Understanding groundwater metabolome trajectories
Authors: Zerfaß Christian , Pohnert Georg
Published: March 2021

Groundwater is a dilute, but biologically rich environment harbouring plenty microbial life [1]⁠. This microbiome requires influxes of dissolved organic matter (DOM) as energy source. Within the Hainich Critical Zone Observatory project [2,3]⁠, we have collected metabolomic information on groundwater DOM by liquid chromatography / mass spectrometry since late 2014, in an assembly of sampling wells across a 7 km transect. We analysed this long-term dataset with principal component analysis methods, inferring distance measures to translate individual sampling campaign information into long-term trajectories that can be compared against external influences (such as groundwater flow patterns).

Our data show that these sampling wells have fluctuating inter-well similarities in terms of the metabolome, giving evidence that some wells are mostly isolated entities while others may be receiving influxes from similar groundwater sources. We show that the groundwater hydraulic head fluctuations exert a key influence on similarity profiles, suggesting groundwater mixing. We emphasize that our inferred principal component measures may therefore serve as a basis to unravel the interactions and influences of groundwater flows, metabolome (biogeochemistry), and microbial life.

References

[1] Yan L, Herrmann M, Kampe B, Lehmann R, Totsche KU, Küsel K. Environmental selection shapes the formation of near-surface groundwater microbiomes, Water Res 2020, 170, 115341. DOI: 10.1016/j.watres.2019.115341.

[2] Küsel K, Totsche KU, Trumbore SE, Lehmann R, Steinhäuser C, Herrmann M. How Deep Can Surface Signals Be Traced in the Critical Zone? Merging Biodiversity with Biogeochemistry Research in a Central German Muschelkalk Landscape, Front Earth Sci 2016, 4. DOI: 10.3389/feart.2016.00032.

[3] Lehmann R, Totsche KU. Multi-directional flow dynamics shape groundwater quality in sloping bedrock strata, J Hydrol 2020, 580, 124291. DOI: 10.1016/j.jhydrol.2019.124291.
The Mw 8.3 2015 Illapel afterslip imaged through a time-dependent inversion of continuous and survey GPS data
Authors: Tissandier Roxane , Nocquet Jean-Mathieu , Klein Émilie , Vigny Christophe
Published: March 2021

The Mw 8.3 2015 Illapel earthquake ruptured a 190 km long segment of the Chilean subduction zone. In the past, this area ruptured several times through large and great earthquakes, the most recent event before 2015 being a Mw 7.9 earthquake in 1943. Here, we combine continuous and survey GPS ground displacements to perform a kinematic inversion of the two-months afterslip following the mainshock. We show that the postseismic slip developed South and North of the coseismic rupture, but also overlaps the deeper part of it. We estimate that two months after the large mainshock, the postseismic moment released represents 13% of the coseismic moment (the mainshock released 3.16x1021 N.m whereas the afterslip released 3.98x1020 N.m). At a first order, seismicity and areas experiencing afterslip match together and are concentrated at the edges of the coseismic rupture between 25 and 45 km depth. One interesting feature is the occurrence of two moderate size aftershocks on November, 11th at shallow depth North of the rupture. We investigate the relationship between the evolution of afterslip and these aftershocks. Finally, we interpret the result in the light of past earthquakes history and calculate the moment balance through the last centuries.
Large-scale drivers of the Mediterranean climate change hot-spot
Authors: Brogli Roman , Lund Sørland Silje , Kröner Nico , Schär Christoph
Published: March 2021

It has long been recognized that the Mediterranean is a ‘hot-spot’ of climate change. The model-projected year-round precipitation decline and amplified summer warming are among the leading causes of the vulnerability of the Mediterranean to greenhouse gas-driven warming. We investigate large-scale drivers influencing both the Mediterranean drying and summer warming in regional climate simulations. To isolate the influence of multiple large-scale drivers, we sequentially add the respective drivers from global models to regional climate model simulations. Additionally, we confirm the robustness of our results across multiple ensembles of global and regional climate simulations.

We will present in detail how changes in the atmospheric stratification are key in causing the amplified Mediterranean summer warming. Together with the land-ocean warming contrast, stratification changes also drive the summer precipitation decline. Summer circulation changes generally have a surprisingly small influence on the changing Mediterranean summer climate. In contrast, changes in the circulation are the primary driver for the projected winter precipitation decline. Since land-ocean contrast and stratification changes are more robust in global climate simulations than circulation changes, we argue that the uncertainty associated with the projected climate change patterns should be considered smaller in summer than in winter.

References:

Brogli, R., S. L. Sørland, N. Kröner, and C. Schär, 2019: Causes of future Mediterranean precipitation decline depend on the season. Environmental Research Letters, 14, 114017, doi:10.1088/1748-9326/ab4438.

Brogli, R., N. Kröner, S. L. Sørland, D. Lüthi and C. Schär, 2019: The Role of Hadley Circulation and Lapse-Rate Changes for the Future European Summer Climate. Journal of Climate, 32, 385-404, doi:10.1175/JCLI-D-18-0431.1
How many modes does it take to describe climate change?: The lessons from an experiment
Authors: Dubrulle Berengere
Published: March 2021

According to everyone's experience, predicting the weather reliably for more than 8 days seems an impossible task for our best weather agencies. At the same time, politicians and citizens are asking scientists for decades of climate predictions to help them make decisions, especially on CO2 emissions. To what extent is this request scientifically admissible?

 

In this lecture I will investigate this question, focusing on the topic of predictions of bifurcations of the atmospheric or oceanic circulations. In such case, the issue is whether present climate models, that have necessarily a finite resolution and a smaller number of degrees of freedom than the actual terrestrial systems, are able to reproduce spontaneous or forced bifurcations. For this, I will use recent results obtained by my group in a laboratory analog of such systems, so called von Karman flow, in which spontaneous bifurcations of the circulation take place. I will detail the analogy, and investigate the nature of bifurcations, the number of degrees of freedom that characterizes it and discuss what is the effect of reducing the number of degrees of freedom in such system.

I will also discuss the role of fluctuations and their origin, and stress the importance of describing very small scales to capture fluctuations of correct intensity and scale.
Bistatic radar observations of the coherent backscatter opposition effect in dry snow
Authors: Stefko Marcel , Leinss Silvan , Hajnsek Irena
Published: March 2021

In this submission we report on observations of the coherent backscatter opposition effect (CBOE) in seasonal snow layers using bistatic radar, and the possible pathways towards estimation of snow properties from these radar observations.

Bistatic radar refers to a configuration where the transmitter and the receiver are not in the same location. From the point of view of the observed target, there thus exists a non-zero angular separation between  directions towards the transmitter and towards the receiver, referred to as the bistatic angle. The coherent backscatter opposition effect (CBOE) is a phenomenon that causes increased backscatter of coherent radiation at small bistatic angles (less than 1 degree) in refractive but non-absorbing disordered media (e.g. snow). It has been previously investigated to characterize surfaces of various water-ice covered Solar System bodies [1], however it has received comparatively little attention in Earth-focused observations, despite the well-known occurrence of significant volume scattering within snow and ice.

Scattering models of CBOE relate the shape of the intensity peak (width, height) to specific parameters of the random medium (grain size, mean free path, reflectivity) [2]. Measurements of the CBOE peak profile are thus a possible pathway towards improving the accuracy of estimates of these parameters, and those closely connected to them, such as the snow water equivalent (SWE).

We report on two separate observations of the CBOE-intensity peak in snow. We carried out ground-based observations using an experimental bistatic Ku-band radar system KAPRI [3], to observe the effect in a winter snow layer on top of the peak Rinerhorn in Davos, Switzerland. We also report on observations of backscatter enhancement in the accumulation zone of Aletsch glacier, using the spaceborne bistatic X-band synthetic aperture radar system TanDEM-X. Applying the aforementioned scattering models to the observations, we can estimate the mean free path of the scattered signal within the snow layer to be 10 cm at Ku-band, and 17 cm at X-band.

We believe that further study of CBOE in the context of Earth-focused observations of snow and ice opens new opportunities for development of quantitative models aiming to derive snow properties from bistatic radar observations.

REFERENCES

[1] Black et al. 2001: Icy Galilean Satellites: Modeling Radar Reflectivities as a Coherent Backscatter Effect. Icarus, 151(2), 167–180.
[2] Hapke et al. 1998: The Opposition Effect of the Moon: Coherent Backscatter and Shadow Hiding. Icarus, 133(1), 89–97.
[3] Baffelli et al. 2017: Polarimetric Calibration of the Ku-Band Advanced Polarimetric Radar Interferometer. IEEE Transactions on Geoscience and Remote Sensing, 56(4), 2295–2311.
Deformation monitoring of typical loess landslide case studies through combining InSAR and UAV
Authors: Meng Qingkai , Raspini Federico , Confuorto Pierluigi , Peng Ying , Liu Haocheng
Published: March 2021

InSAR is an advanced earth observation (EO) technique for retrieving past, subtle (millimetre-level) and continuous surface movements over a long period, which has been widely applied in landslide deformation monitoring and detecting precursory signals of deformation. However, limited by the maximum detected deformation gradient from two consecutive scenarios, singular InSAR has hampered the recognition application for high-speed slides or earth flows, leading to a misleading understanding of slope evolution. Being a high-resolution photogrammetry technology, UAV represents a suitable tool to detect meter-level displacement rates and estimate ground detachment. Thus, InSAR and UAV's synergic analysis can detect the kinematic variation of geographical and geomorphological features, corresponding surface displacements to cross-validation. In the present work, two representative cases illustrated how the combination of InSAR and UAV could be applied in loess landslide deformation monitoring. One case, located in Hongheyan, Gansu Province, China, was selected to reconstruct landslide morphology, identify deformation evolution behaviour and produce dynamic deformation zonation maps using 85 Sentinel-1A SAR images and three UAV fight surveys from pre-sliding to post-sliding. The integrated deformation results illustrate the slide of theHongheyan slope was triggered by heavy rainfall, became suspended owing to the topography effect after the occurrence, and reactivated recently. Another case, located in Qinghai-Gansu province, calculated two-dimensional displacements (vertical-horizontal) by decomposing the ascending and descending Sentinel-1 images to reclassify the regional slope failure type into the translational slide, rotational slide and loess flow based on deformation characteristic. Overall, multi-source information fusion is a new approach for landslide monitoring from regional-scale failure classification to specific-scale slope deformation evolution, giving the comprehensive understanding for local government or Civil Protection to take sufficient precautions for risk mitigation.
Development of risk assessment model for groundwater level by wavelet-deep learning approach with smart pumping data 
Authors: Weng Tsai-Ning , Hsu Chu-Chun , Lin Yuan-Chien
Published: March 2021

Abstract

Groundwater, as a vital existence in human life and economic development, is also one of the stable sources of water resources. Therefore, how to properly utilize groundwater becomes a very important issue when faced with water shortages. However, most of the previous literature uses monthly data as the time scale, and usually uses the historical water level data of the area as the only input factor in the modeling process without considering pumping information and rainfall. This shows that the current studies of small-scale data which is based on the use of multiple factors with hydrological mechanisms to explore and predict the groundwater level is still quite lacking.

Therefore, this study proposed a novel framework combining wavelet analysis and deep learning models called wavelet-deep learning models and taking the Daliao area of ​​Kaohsiung as an example. From the historical hourly observation data during 2017/08/23-2020/01/30, including groundwater level, smart pumping measurement, tidal, and meteorological data. After abstracting important features of each factor with groundwater level by wavelet transform, using deep learning algorithms such as recurrent neural networks (RNN) and long short-term memory (LSTM) model to summarize and predict the impact of multiple variable factors on the groundwater level under different time lags. The results of hourly prediction show that the performance of the LSTM model and RNN model are both reliable in which values of the coefficient of determination () were obtained 0.813 and 0.784, respectively.

This study provides a feasible and accurate approach for groundwater level prediction by understanding and predicting different water level changes that may occur in the Daliao area in advance. As a result, the study will be an important reference for groundwater resources management and risk assessment, and achieve the goal of sustainable use of groundwater resources.

 

Keywords Groundwater prediction, Wavelet transform, Risk assessment, LSTM
New insights for direct in situ measurement of oceanic vertical velocities in fine-scale studies.
Authors: Comby Caroline , Barrillon Stéphanie , Fuda Jean-Luc , Doglioli Andrea , Tzortzis Roxane , Gregori Gérald , Thyssen Melilotus , Petrenko Anne
Published: March 2021

Vertical velocities knowledge is essential to study fine-scale dynamics in the surface layers of the ocean and to understand their impact on biological production mechanisms, in both coastal and offshore environments. Indeed, the general interest in fine-scale and, more precisely, in the determination of vertical velocities, is explained by their key role in global oceanic balance and their impact on the vertical transfer of nutrients and carbon budget despite their low intensity. With the increasing global warming issues linked to the forcing of the carbon cycle by anthropogenic activities, the estimation of vertical velocities becomes an essential information for a better representation of biogeochemical budgets. However, these vertical velocities have long been neglected, simply parameterized, or considered as not measurable, due mainly to their order of magnitude (mm s-1), generally much lower than the one of the horizontal velocities (cm s-1). Consequently, direct in situ measurement of vertical velocities is still currently one of the biggest challenges in physical oceanography.

We have been working to develop a new method for direct in situ measurement of vertical velocities using data from different Acoustic Doppler Current Profilers (ADCPs) associated with CTD probes, and we performed a comparative analysis of the results obtained by this method. The analyzed data were collected during the FUMSECK cruise (2019, Ligurian Sea), from three ADCPs: two Workhorse (conventional ADCPs), one lowered on a carousel and the other deployed in free-fall mode, and one Sentinel V (a new generation ADCP with four classical beams and a fifth vertical beam), also lowered on a carousel. Our analyses provided profiles of vertical velocities of the order of mm s-1, as expected, with standard deviations of a few mm s-1. While the fifth beam of the Sentinel V has shown a better accuracy than conventional ADCPs, the free-fall technique has provided a more accurate measurement compared to the carousel technique. Some of these measurements were gathered along the edge of the Northern Current and this new information on coastal edge currents represents a key point for the future improvement of coastal altimetry in particular.

Finally, this innovative study opens up the possibility to perform simple and direct in situ measurements of vertical velocities, coupling the free-fall technique with a five-beam ADCP. Hence, we plan to deploy a free-falling Sentinel V in offshore areas characterized by intense fine-scale ocean dynamics, but also and above all, in coastal areas, where topographic forcings are typically the source of high amplitude vertical velocities.
Stochastic analysis of the spatial stochastic structure of precipitation in the island of Crete, Greece
Authors: Akoumianaki Olianna , Iliopoulou Theano , Dimitriadis Panayiotis , Varouchakis Emmanouil , Koutsoyiannis Demetris
Published: March 2021

In the last few years, the island of Crete (Greece - Eastern Mediterranean) has been affected by extreme events. In recent decades, hydrometeorological processes in the island of Crete are monitored by an extensive network of meteorological stations. Here we stochastically analyze the spatial stochastic structure of precipitation in the island by employing sophisticated statistical tools, as well as by analyzing a large database of daily precipitation records. We investigate fifty-eight rainfall stations scattered in the four prefectures of Crete, for the years 1974-2020. Descriptive statistical analysis of precipitation examines several temporal properties in the data, while correlation analysis of precipitation variability provides relations between stations and regions for spatial patterns identification. This work also investigates the precipitation variability by employing statistical tools such as the autocorrelation, autoregressive (seasonal) analysis, probability distribution function fitting, and climacogram calculation, i.e. variance of the averaged process vs. spatial and temporal scales, to identify statistical properties, temporal dependencies, potential similarities in the dependence structure and marginal probability distribution.
Uncertainty assessment of a permanent long-range terrestrial laser scanning system at an Alpine glacier
Authors: Voordendag Annelies , Klug Christoph , Prinz Rainer , Rutzinger Martin , Kaser Georg ,   SCHISM Team
Published: March 2021

Terrestrial laser scanners (TLSs) are increasingly used to monitor glaciers. Recent developments enabled longer ranged and more frequent measurements. The quality of these high resolution topography data, especially in high mountain environments, has not been assessed in detail up to now.  An automated and permanent long-range TLS system is installed at Hintereisferner glacier (Ötztal, Austria) with the aim to detect changing snow surface patterns due to wind drift.

The scanner is controlled from Innsbruck and data is transferred daily. The system covers 66.5% of the glacier area and scans can be conducted on demand in very high frequency (e.g. daily or hourly measurements). The measurement distances range between 660 and 4600 m and with an angular step width of 0.01° (vertical and horizontal), this leads to a point spacing of 35 cm at a distance of 2 km and a resulting point cloud of approx. 43 million points. The point cloud is converted into grids with a 1 meter resolution.

Two main error sources of the system are indentified. First, the TLS used at Hintereisferner, a Riegl VZ-6000 is influenced by movements that cannot be corrected with the internal inclination sensors of the scanner. Small fluctuations in the roll and pitch of the scanner (ca. ±0.02°) result in deviations in decimetre range on the glacier. The movement of the scanner increases with increasing turbulent kinetic energy (TKE) measured with a nearby 3D sonic anemometer.

Second, atmospheric conditions at the glacier influence the laser beam way. The TLS operates by emitting light pulses and measuring the time of flight for the pulse to return. The pulse travel time changes depending on the atmospheric properties. The changes of pressure, temperature and humidity in the atmosphere differ from accumulation zone to glacier tongue and influence the pathway between TLS and the glacier surface, leading to an uncertainty in the scanning data in centimetre range.

The permanent and automated long-range TLS system promises high potential for the glaciological and environmental sciences, given the decimetre accuracy at a high spatiotemporal resolution. The first results of permanent TLS system at Hintereisferner show the ability to detect changing snow surface patterns and indicate the possibility of geodetic glacier mass balance acquisition.
Analysis of dry conditions compared with wildfires: an application in Calabria (Southern Italy)
Authors: Coscarelli Roberto , Aguilar Enric , Vicente-Serrano Sergio , Zimbo Fabio
Published: March 2021

All over the world wildfires destroy property and vegetation and can have an adverse effect on slope stability and soil erosion. Even though the number and the size of wildfires are often related to changes in land cover, population, and fire management practices, climatic and soil conditions remain the main factors influencing the extension of burnt areas. The goal of the EC Project INDECS, in which this study has been carried out, is to develop an integrated approach to produce a series of climate indicators aimed at the high priority sectors of the Global Framework for Climate Services of the World Meteorological Organization (agriculture, risk reduction, energy, health, water), with the addition of tourism. The study area is Calabria, a region of Southern Italy frequently affected by wildfires. In this research, data about the burnt areas (monthly data of extension - in hectares - and the number of fires in the period 2008-2018), provided by means of the module “Rapid Damage Assessment” (R.D.A.) of E.F.F.I.S. (European Forest Fire Information System) have been compared with the Keetch-Byram Drought Index (KBDI). This index, ranging between 0 and 203.2 (extreme dry condition of the soil), is used all over the world for monitoring and forecasting forest fires. The index was calculated with the daily rainfall and temperature data of 79 stations presenting complete and homogeneous databases. The monthly mean values were evaluated and the KBDI values were averaged for each province, given that the data of the wild fires are available for each of the five provinces of the region. The comparison results show that the peaks of the burnt areas almost always correspond with the highest of the KDBI values. Analogous results were obtained considering the number of fires. It is important to highlight that the results can be influenced by the following factors: a) the KBDI monthly mean value is evaluated by means of a database with a variable number of monthly values owing to missing data; b) the extension of the burnt areas is determined by the efficiency of the fire monitoring system and by the rapidity of first response operations; c) the RDA module database of EFFIS is referred to burnt areas with an extension greater than 30 hectares (in Europe, these fires are about 75-80% of the total fires) and does not contain differences between natural fires and human-induced fires. However, the obtained results can help to predict the impacts that tendencies of the KBDI patterns can have on the territory as an extension of burnt areas. In this way, the present study gives a useful service for agriculture and risk reduction sectors.

Acknowledgments:

The Project INDECIS is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462).