bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of Fine Dust Concentration from BGR Images in Surveillance Cameras
Authors: Cha Hoyoung , Byun Jongyun , Baik Jongjin , Jun Changhyun
Published: February 2023

  This study proposes a novel approach on estimation of fine dust concentration from raw video data recorded by surveillance cameras. At first, several regions of interest are defined from specific images extracted from videos in surveillance cameras installed at Chung-Ang University. Among them, sky fields are mainly considered to figure out changes in characteristics of each color. After converting RGB images into BGR images, a number of discrete pixels with brightness intensities in a blue channel is mainly analyzed by investigating any relationships with fine dust concentration measured from automatic monitoring stations near the campus. Here, different values of thresholds from 125 to 200 are considered to find optimal conditions from changes in values of each pixel in the blue channel. This study uses the Pearson correlation coefficient to calculate the correlation between the number of pixels with values over the selected threshold and observed data for fine dust concentration. As an example on one specific date, the coefficients reflect their positive correlations with a range from 0.57 to 0.89 for each threshold. It should be noted that this study is a novel attempt to suggest a new, simple, and efficient method for estimating fine dust concentration from surveillance cameras common in many areas around the world. Keywords: Fine Dust Concentration, BGR Image, Surveillance Camera, Threshold, Correlation Analysis Acknowledgment  This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. NRF-2022R1A4A3032838) and this work was funded by the Korea Meteorological Administration Research and Development Program under Grant KMI2022-01910 and this work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (2020R1G1A1013624).
The Role of the Ocean for the Development of Heat Waves over Europe
Authors: Bischof Sabine , Pilch-Kedzierski Robin , Hänsch Martje , Matthes Katja
Published: February 2023

European heat waves are becoming more and more severe under global warming. The frequency and duration of heat waves are very likely to further increase under future climate conditions over most land areas. To improve the predictability of such extreme events, it is important to understand their driving mechanisms better.Although earlier work hints at a connection between North Atlantic sea surface temperatures (SSTs) and the occurrence of European heat waves, the role of the ocean in shaping heat waves is still not fully understood. Here, we investigate the effect of the 2018 SST pattern, which was characterized by negative anomalies in the North Atlantic, on European heat wave characteristics.Using the Flexible Ocean and Climate Infrastructure (FOCI) model we conducted two 100-year long AMIP-like model experiments: one that employs the observed global 2018 SST and sea ice patterns as a boundary forcing and another one that differs only in the North Atlantic SST field, for which we removed the cold SST anomaly. Comparing these two experimental settings, we find that cold North Atlantic SST anomalies can favor heat wave conditions especially over the most eastern part of the European continent.
Solar Energetic Electron Events with a Spectral Bump
Authors: Li Wenyan , Wang Linghua , Wang Wen
Published: February 2023

The energy spectrum of solar energetic electron (SEE) events carries crucial information on the origin/acceleration of energetic electrons at the Sun. Using  the Wind 3DP electron measurements at ~1 to 200 keV during 1995-2019, we select 11 good SEE events with a bump-like break in the peak flux vs. energy spectrum, different from the typical SEE events with a double-power-law spectrum. For the selected 11 events, the background-subtracted electron peak flux versus energy spectrum fits well to two functions: the sum of a single-power-law and a Gaussian function (spectral function #1) and the product of a single-power-law and the natural exponential form of a Gaussian function (spectral function #2). For the spectral function #1 (#2), on average, the fitted spectral index is 2.6±0.4 (2.7±0.6), significantly larger than the low-energy power-law index of typical SEE events, while the fitted center energy of spectral bump is 24±7 keV (75±38 keV) and the ratio of bump width and center is 2.0±0.7 (3.4±2.8). Among these 11 events, respectively, ~78%, ~89%, ~90%, 100% and ~55% are associated with GOES SXR flares, RHESSI HXR flares, west-limb CMEs, type III radio bursts and type II  radio bursts. Thus, these bump events have a stronger association with flares, coronal mass ejections (CMEs) and type II radio bursts, compared to the typical SEE events. In addition, we find a positive correlation between the center energy of bump and the CME speed. Therefore, we come up with an acceleration picture of these bump SEE events: the power-law portion is probably accelerated by flares with the acceleration efficiency larger at lower energies, while the bump portion is likely accelerated in CME-related processes with the acceleration efficiency increasing with the CME speed.
The ostracod clumped-isotope thermometer: A new tool to quantify continental climate change.
Authors: Marchegiano Marta , Peral Marion , Venderickx Jeroen , Martens Koen , García-Alix Antonio , Goderis Steven , Claeys Philippe
Published: February 2023

Ostracod shells are small aquatic crustaceans (0.3 - 5 mm) capable of recording climatic and environmental changes at high-resolution in sedimentary archives of modern and ancient lakes. Their stable low-Mg calcite shell mineralogy makes them ideally suited for targeted geochemical analyses. Therefore, ostracods represent the best candidate to develop a new carbonate clumped isotope (∆47) lacustrine paleothermometer that disentangles and quantifies the effects of global climate changes at regional scale. To establish the relationship between ∆47 and the temperature for ostracod shells, three different species were collected in monitored environments at 4°C and 12°C and one was cultivated in the lab at 23°C. Our results show a linear regression between ostracod-∆47 and calcification temperature that is in agreement with previous published calibrations. This implies that ostracods are an equally-good recorder of (paleo)temperatures as other carbonaceous micro- or macrofossils from the marine realm. Moreover, we report the absence of a consistent offset between the species Eucypris virens and Bradleystrandesia fuscata coming from the same environment and precipitated at the same temperature. This observation suggests the absence of a vital effect at the genus and species level. Samples from shallow Lake Trasimeno (Italy) cover the last 50000 years and confirm the ability of the ostracod clumped-isotope thermometer as well as the absence of vital effect in the fossil record. The new paleothermometer identifies warmer/colder and humid/dryer conditions during Greenland Interstadial and Greenland Stadial/Heinrich events respectively.These findings show that the ostracod-∆47 thermometer has several advantages that makes it an attractive tool for scientific drilling: (i) It is independent of ostracod species and geography. Hence, one can also use endemic species.  (ii) It is applicable throughout geological time, as extinct species can be used. (iii) Temperature reconstructions for all environments where ostracods live are within reach. We emphasize that also high-diversity lacustrine environments are suitable for ∆47 analysis, by mixing shells of different species together. This is of particular importance when working with small samples size from sediment cores.The establishment of this new lacustrine proxy enables precise paleoclimatic reconstructions from different climate belts. It opens the door to new high-resolution continental paleoclimate and paleoenvironmental reconstructions and therefore has the potential to be a key tool in future lacustrine drilling in the ICDP framework.
Understanding precipitation moisture sources of the Vietnamese Mekong Delta and their dominant factors during recent drought events
Authors: Zhou Keke , Shi Xiaogang , Renaud Fabrice
Published: February 2023

The Vietnamese Mekong Delta (VMD) is the most productive region in Vietnam in terms of agriculture and aquaculture. Unsurprisingly, droughts have been a prevalent concern for stakeholders across the VMD over the past decades. However, the VMD precipitation moisture sources and their dominant factors during drought conditions were not well understood. By using the ERA5 reanalysis data as inputs, the Water Accounting Model-2layers (WAM-2layers), a moisture tracking tool that traces moisture sources using collective information of evaporation, atmospheric moisture, and circulation, was applied to identify the VMD precipitation moisture sources from 1980 to 2020. The modelling simulation indicates that the moisture sources transported from the upwind regions dominate the VMD precipitation by 60.4% to 93.3%, and the moisture source areas vary seasonally with different monsoon types. The VMD precipitation moisture sources mainly come from the northeast area (e.g. the South China Sea) in dry seasons due to the northeast monsoon, while the southwest region (e.g. the Bay of Bengal) provides the primary precipitation moisture in wet seasons. Based on the causal inference algorithm, the driving factors in the process of moisture transport were also investigated. The results show that the specific humidity and wind speed are the dominant factors for driving moisture transport and determining the amount of VMD precipitation in dry and wet seasons, respectively. During the drought events in 2015-2016 and 2019-2020, the reduced moisture transport in the 2015 and 2016 dry seasons was mainly caused by the anomaly of both specific humidity and wind speed, while the negative anomaly of moisture sources in the 2020 dry season was dominant by the specific humidity. In the 2019 wet season, the wind speed anomaly led to the reduction of tracked moisture. These findings are important to understand the VMD precipitation moisture sources and their dominant factors during recent drought events.
The Magnetospheric Source of Theta Aurora Include Dayside and Nightside Multiple Reconnection Sites: SWMF Geospace Simulation Results
Authors: Hill Shannon , Pulkkinen Tuija , Brenner Austin , Al Shidi Qusai , Mukhopadhyay Agnit , Kullen Anita , Frey Harald , Zou Shasha , Liemohn Michael
Published: February 2023

We present simulation results of a transpolar auroral arc event that show the arc formation occurs on both open and closed field lines and is sourced from both dayside and nightside magnetospheric reconnection. The dayside and nightside precipitation sources magnetically connect across the polar cap in a flow channel to create the transpolar arc structure. We simulate the 15 May 2005 transpolar arc event observed by the IMAGE satellite with the University of Michigan Space Weather Modeling Framework (SWMF) Geospace configuration. We compare the IMAGE observations to the simulation produced ionospheric Joule heating to identify the transpolar arc features captured by the model. The features exist within an anti-sunward flow structure and coincide with the location of the R1/R2 current reversal. We map the magnetic field lines from the arc features to the magnetosphere, revealing both dayside and nightside source regions. We use four-field junction analysis to determine that the source regions are within potential simulation reconnection sites. We simulate other transpolar auroral arcs to assess the generality of our results.
EOSC-FUTURE – ENVRI-FAIR Science Project Environmental Indicators – Ocean Component – Beacon API
Authors: Krijger Tjerk , Thijsse Peter , Schaap Dick , Kooyman Robin
Published: February 2023

In the EOSC-Future project, ENVRI-FAIR partners are involved in developing two Science Projects (SPs), one about Invasive Species, and one about a Dashboard of the State of the Environment. The Dashboard should provide easy means to users to determine the state of the environment and follow trends of our Earth system for a selected number of parameters within the Earth components of Atmosphere, Ocean, and Biodiversity.MARIS leads the development of the Ocean component in cooperation with IFREMER, OGS and NOC-BODC. It consists of a Map Viewer that displays in-situ measurements of selected Essential Ocean Variables (EOVs), namely Temperature, Oxygen, Nutrients and pH. These measurements are retrieved from a datalake of selected Blue Data Infrastructures (BDIs) such as Euro-Argo and SeaDataNet CDI using tailor-made APIs for fast sub-setting at data level.Performance is a major challenge as users should not wait too long for retrieving and displaying the data in the Map Viewer following their selection criteria, while the origin data is organised in millions of observation files which make it hard to achieve fast responses. At MARIS there have been developments ongoing to create a system called beacon API with unique indexing system that could, on the fly, extract the specific data that was requested from millions of observation datafiles that contain multiple parameters in diverse units. We show the possibilities of this API by applying it to the SeaDataNet CDI database. The system is built in a way that it can be applied to other BDIs in the future as well and does not only function on the SeaDataNet CDI architecture.The user interface of the map viewer is designed for (citizen) scientists and allows them to interact with the large data collections retrieving parameter values from observation data by geographical area and using sliders for date, time and depth. The in-situ values are co-located with product layers from Copernicus Marine, based upon modelling and satellite data. These in-situ data sets are also used in algorithms to generate aggregated values as dynamic trend indicators for sea regions. These are displayed at the Environmental Indicators dashboard and provide ocean trend indicators for the selected EOVs for designated areas. For more information, users can then click on such an indicator guiding them to the Map Viewer to browse deeper into the data and details facilitating the trends.
Forecasting Earthquake Magnitudes along the East Anatolian Fault Zone using Fault Zone Segmentation, Historical Earthquakes, and GPS Slip Rates
Authors: Uçan Kaan Alper , Bulut Fatih
Published: February 2023

This study aims to forecast the magnitude of future strong (6.0≤M<7.0) and major (7.0≤M<8.0) earthquakes along the East Anatolian Fault Zone (EAFZ), a major fault zone of Turkey and an active plate boundary that lies between Arabian and Anatolian plates. We first investigated the segmentation of the EAFZ in this context after compiling the earlier research on its structural setting and historical earthquakes. In order to determine the distribution of slip deficit rates, we analyzed GPS slip rates to obtain back-slips. The current slip budgets on each fault segment are calculated using the resulting slip deficit estimates. To elaborate on whether b-values might be used to distinguish between locked and creeping fault segments, we also examined the distribution of b-values along the fault. As a result, we found a reverse correlation between slip deficit rates and b-values. According to our findings, the EAFZ has currently a slip deficit of 1.51 m. While there is a segment such as Hacılar with no slip deficit, there is enough slip deficit accumulation to generate three strong and three major earthquakes on the other fault segments. Presently, these fault segments have the potential to re-generate previous earthquakes, within the magnitude range of 6.8-7.4. The latest strong earthquake on January 24, 2020, the Elazığ earthquake (M 6.8) verified our magnitude forecasts for the Sivrice-Pütürge segment.
Flow pattern around the bridge piers with installed scour countermeasures
Authors: Cibaric Armano , Troskot Nikola , Veseljak Maja , Vukovac Mateja , Gilja Gordon
Published: February 2023

Bridges with elements interacting the flow, such as piers constructed in the main river channel or approach embankments blocking the overbanks, alter the flow conditions and initiate local and contraction scour in the bridge profile. Scour countermeasures are often placed around the bridge piers with goal to scour and associated risk of bridge failure. Effectiveness of scour countermeasures depend on its influence on the surrounding riverbed – in case that countermeasures obstruct significant area, flow can be concentrated and accelerated, inducing scour of the banks. Long-term effects of the scour countermeasures on the river morphology can lead to flow redistribution and lateral shifting of the river cross-section, altering the design conditions in the bridge vicinity. Aim of this work is to compare the flow environment at 4 distinctive bridge locations simulated in HEC-RAS model under characteristic hydraulic scenarios that induce scour. Results show that for all bridges current flow environment differs from the design state, so that additional intervention in the riverbed geometry doesn’t significantly change the flow conditions. Flow environment was simulated with sill placed on different distances downstream or excavation of the riverbed to reduce flow velocity. In all scenarios main flow remain concentrated similar to the current state, showing that countermeasures have to be substantial in order to be effective. AcknowledgmentsThis work has been supported in part by Croatian Science Foundation under the project R3PEAT (UIP-2019-04-4046).
Hot volcanic ash filters eruptive SO2 during hot transport in conduits and the lower plume: A predictive model with implications for the climate impacts of volcanic eruptions
Authors: Vasseur Jérémie , Wadsworth Fabian , Paine Alice , Dingwell Donald
Published: February 2023

Sulfate aerosols are a primary driver of climate impacts during and following volcanic eruptions and form from erupted SO2 gas. However, the amount of SO2 that is delivered to the stratosphere is not clearly related to the amount dissolved in the magma (the ‘sulfur excess problem’). Therefore, magma properties and eruption magnitude are not necessarily predictive of climate impacts from eruptions, which is exacerbated by the as-yet unknown importance of the insulated, hot transport pathway. During a magnitude 6 explosive volcanic eruption there is up to 100 seconds of transport between the magma fragmentation depth – where volcanic ash is formed and the mixture accelerates – and the Earth’s surface. Here, we present a numerical implementation of a theoretical framework which predicts the rapid reactions between gases and volcanic ash in this transport interval, which include: (1) iron oxidation state changes; (2) SO2 uptake via calcium sulfate surface crystallization; (3) HCl uptake via NaCl surface crystallization; and (4) incipient nanolite crystallization that may be related to (1). In all cases, these processes are rate-limited by a suite of diffusive exchanges between the ash bulk and surface, for which our model solves. To demonstrate the upscaled importance of these processes, we couple our models to volcanic plume simulations (using a 1991 Pinatubo baseline simulation), and output the bulk SO2 that can be captured by ash. We find that depending on the source parameters of the eruption, anywhere between 30 and 100 wt.% of the total erupted SO2 can be removed from the plume gas and captured by ash. This effectively changes the sink of SO2 from the stratosphere to the hydrosphere, as CaSO4 crystals are soluble and ultimately wash into the environment following ash deposition. We propose that these hot sulfur scrubbing processes may be crucial in mediating SO2 delivery to the atmosphere, and therefore may explain much of the complexities associated with correlating eruption magnitude with climate impacts in the recent past or back into the Last Glacial period.
First results from the ESA Precursors for aerosols and ozone ECVs project: user requirements and intercomparison of tropospheric retrievals of NO2, HCHO, SO2, CO, NH3, and glyoxal
Authors: Boersma K. Folkert , Van Roozendael Michel , Richter Andreas ,   the ESA Precursors for aerosols and ozone ECVs project team
Published: February 2023

Satellite-based observations of tropospheric trace gas concentrations are used extensively to test models, infer emissions and their trends. These observations are also needed to develop emission-based scenarios for radiative forcing by tropospheric ozone and secondary aerosols, both from anthropogenic and natural sources. Although the detection of trace gases from space is feasible and operational data streams are in place for most relevant sensors, limited effort has been devoted to the generation and quality assessment of consistent multi-decadal climate data records. The ESA Climate Change Initiative (CCI) program was established for the systematic generation of Essential Climate Variables (ECVs). It builds on long-term global satellite observational datasets. Regarding atmospheric composition, the ECVs covered have recently been extended with trace gases that lead to the formation of ozone and aerosols.Here we present first results from the ‘Precursors for aerosols and ozone ECVs’ project, funded by ESA, and the first steps in developing long-term climate data records on the precursor gases nitrogen dioxide (NO2), formaldehyde (HCHO), carbon monoxide (CO), sulfur dioxide (SO2), ammonia (NH3), and glyoxal (CHOCHO). The project’s main goal is to build consistent and harmonized long-term data records from satellite instruments including GOME, SCIAMACHY, GOME-2, OMI, TROPOMI, IASI and MOPITT. A second goal is to demonstrate the fitness-for-purpose of the data records for various users including the European Copernicus Atmosphere Monitoring Service, currently operated by ECMWF. In this presentation, we report on what users need from such data records, and on round robin activities to test and evaluate the different retrieval approaches used in the scientific community. One key motivation will be to reconcile retrieval approaches so far independently developed in the EU QA4ECV and EUMETSAT AC-SAF projects, with the aim to harmonize products from all sensors.
Automated ablation stakes to constrain temperature-index melt models
Authors: Wickert Andrew D. , Barnhart Katherine R. , Armstrong William H. , Romero Matías , Schulz Bobby , Ng Gene-Hua Crystal , Sandell Chad T. , La Frenierre Jeff D. , Penprase Shanti B. , Van Wyk de Vries Maximillian , MacGregor Kelly R.
Published: February 2023

We developed automated ablation stakes to measure colocated in-situ changes in ice-surface elevation and climatological drivers of ablation. The designs implement open-source hardware, including the Margay data logger, which records information from a MaxBotix ultrasonic rangefinder as well as a sensor to detect atmospheric temperature and relative humidity. The stakes and sensor mounts are assembled using commonly available building materials, including electrical conduit and plastic pipe. The frequent (typically 1–15 minute) measurement intervals permit an integral approach to estimating temperature-index melt factors for ablation. Regressions of ablation vs. climatological drivers improve when relative humidity is included alongside temperature. We present all materials required to construct an automated ablation stake, alongside examples of their deployment and use in Alaska (USA), Ecuador, Patagonia (Argentina), and the Antarctic archipelago. a: Alaska, 2012b: Alaska, 2013c: Ecuador, 2016d: Argentina, 2020e: Antarctica, 202
Surface processes and rift evolution in the Ethiopian Rift, East Africa
Authors: Muluneh Ameha , Brune Sascha , Corti Giacomo , Keir Derek
Published: February 2023

The Main Ethiopian Rift (MER) is characterized by a significant along-strike variation in rift evolution and strain accommodation mechanisms. The northern MER is at a transitional stage, whereas the central MER is at an intermediate stage of rifting. Previous geophysical and geological observations suggest that rift obliquity, age of onset of rifting and/or presence/absence of magma could be responsible for the observed difference in deformation style. Here, we use the geodynamic modelling software ASPECT that has recently been coupled with the landscape evolution model FastScape to understand the role that surface processes (such as erosion and sedimentation) play in controlling the style of deformation at the central and northern sectors of the MER. Our results show that the deformation in the central MER can be well explained by efficient surface processes. However, our models fail to fully capture the deformation in the northern MER implying that magma plays a significant role in this sector of the rift. We show that the MER is a unique plate boundary where surface and magmatic processes control the style of deformation at different sectors within the same tectonic setting. 
Forest fires simulation in the Alpine region. New data and innovative approaches needed
Authors: Mauri Luca , Taccaliti Flavio , Lingua Emanuele
Published: February 2023

Among the predominant natural disturbances affecting Mediterranean regions, nowadays forest fires frequently occur in Central and Northern Europe, potentially leading to several issues in ecological, geomorphological, economic and social terms. In this regard, local authorities are becoming gradually confident with their management even where forest fires were historically scarce. In this context, semi-empirical models are particularly useful in estimating fire behaviour, in order to predict key factors related with wildfires risk (e.g., flames length, fire type, rate of spread). At the same time, accurate estimation of models inputs actually represents the principal limitation to outputs reliability, mainly due to the difficulty in retrieving specific data like canopy fuel characteristics or fire behaviour fuel models. In light with the above, there is a growing need to find new methods able to infer such simulation variables, for example starting from remote sensing data acquisition and elaboration, as well as by adapting already existing equations and workflows to European specific contexts. The project RETURN aims therefore to enhance the spatial mapping of fire simulators inputs layers within the Alpine region by coupling an extensive field data collection with high-resolution Light Detection and Ranging (LiDAR) and Unmanned Aerial Vehicle (UAV)-based data collection. The results of the Project could be useful in increasing the amount of information available for local administrations of the Alpine region, aiming to ease the application of fire behavior simulators to manage such a natural disturbance increasingly frequent in this mountain area.
Investigating system controls for prediction of groundwater hydrographs at unmonitored sites transferring head duration curves
Authors: Haaf Ezra , Giese Markus , Reimann Thomas , Barthel Roland
Published: February 2023

A new method is presented to efficiently estimate daily groundwater level time series at unmonitored sites by linking groundwater dynamics to local hydrogeological system controls. The presented approach is based on the concept of comparative regional analysis, an approach widely used in surface water hydrology, but uncommon in hydrogeology. The method uses regression analysis to estimate cumulative frequency distributions of groundwater levels (groundwater head duration curves (HDC)) at unmonitored locations using physiographic and climatic site descriptors. The HDC is then used to construct a groundwater hydrograph using time series from distance-weighted neighboring monitored (donor) locations. For estimating times series at unmonitored sites, in essence, spatio-temporal interpolation, extreme gradient boosting and nearest neighbors are compared. The methods were applied to ten-year daily groundwater level time series at 157 sites in alluvial unconfined aquifers in Southern Germany. The controlling site descriptors were analyzed using shapley values, revealing that models of HDCs were physically plausible. The analysis further shows that physiographic and climatic controls on groundwater level fluctuations are nonlinear and dynamic, varying in significance from “wet” to “dry” aquifer conditions. Extreme gradient boosting yielded a significantly higher predictive skill than nearest neighbor. However, donor site selection is of key importance. The study presents a novel approach for regionalization and infilling of groundwater level time series that also aids conceptual understanding of controls on groundwater dynamics, both central tasks for water resources managers.
Satellite-based soil moisture product performance assessment among the EU Ecoregions
Authors: Albano Raffaele , Mazzariello Arianna , Lacava Teodosio , Manfreda Salvatore , Sole Aurelia
Published: February 2023

Several remote sensing (RS) microwave-based SM products are available in recent years and offer an extraordinary opportunity to quantify land surface soil moisture (SSM). These products provide soil moisture (SM) estimates with different levels of accuracy which are influenced by  climate, vegetation, and soil features. For this reason, several studies aimed at assessing satellite SM data performance also for comparison with in situ measurements (e.g., the International Soil Moisture Network – ISMN),  have already tried to investigate the relationship among SM and the type of coverage or the climatic conditions.In any case, no one of these studies (i) have considered together climate, vegetation, and soil features when characterising accuracy of SM derived from RS, or (ii) analysed separately the uncertainty due to interaction with the water-soil cycle variables and the uncertainty due to the wetting condition of the upper layer; indeed, the topsoil wetness variability affects the penetration depth of microwave radiation bringing additional errors when comparing information collected at different depths, from surface to the root zone.In this context, the present study aims (i) to assess the accuracy of SSM measurement through the implementation of an intercomparison between satellite and the terrestrial International Soil Moisture Network data among the European ecoregions which are considered the largest homogeneous area in terms of climate, vegetation and potentially investigable soil cover. Furthermore, considering that soil characteristics add further uncertainty due to the soil saturation condition when the upper soil layer is excessively dry or excessively wet, the study explores (ii) the local dynamics of soil moisture described by the probability density function of SM. Five satellite SM products have been studied, considering those derived from the National Aeronautics and Space Administration (NASA) mission (SMAP), as well as those generated by the European Space Agency (ESA) mission (SMOS, ASCAT, ESA CCI, SENTINEL -1) while the ISMN data were considered as a ground truth.The results show the best or worst performance of the above cited satellite retrievals in different climate, vegetation, and soil features by looking at their variability at ecoregion scale. Moreover, the approach of multimodality using the ASCAT product, which is provided in % of saturation, validated by the test of the excess mass of Ameijeiras-Alonso, following the removal of phenological seasonality, has proven to be an excellent tool for characterising errors in dry areas, confirming that worse performance occurs in areas with a dry phase observed.
Simulations of eddy-driven jets and circulation on gas giants
Authors: Duer Keren , Galanti Eli , Kaspi Yohai
Published: February 2023

Jupiter's atmosphere consists of three dynamical regimes: the equatorial eastward flow and retrograde jets surrounding it; the midlatitudes with alternating eddy-driven jets and circulation; and the turbulent poles. Despite intensive research conducted on each of these regimes over the past decades, they remain only partially understood. Saturn's atmosphere also encompasses similar distinguishable regimes, but evidence for deep meridional cells is lacking. Models offer a variety of explanations for each of these regions, and only a few are capable of simulating more than one of the regimes at once. This study presents new numerical simulations, using a 3D anelastic GCM, that can reproduce the equatorial flows as well as the midlatitudinal pattern of the mostly barotropic, alternating eddy-driven jets and the meridional circulation cells accompanying them. These simulations are consistent with recent gravity and microwave data coming from the Juno mission. The dynamics of the simulation are greatly influenced by varying the simulation's inner depth. As expected for a gas giant, we find that the vertical eddy momentum fluxes are just as important as the meridional eddy momentum fluxes, which drive the midlatitudinal circulation on Earth. The number of the jets/cells, their extent, strength, and location are directly related to the boundary conditions and the Ekman number. Studies have shown that the rotation rate, the forcing scheme, and the Rayleigh number are also responsible for the emergence of jets in simulations of gas giants, but we keep these constant in our simulations. Our simulations also capture the tilted convection columns outside of the tangent cylinder, leading to the superrotation at the equator and the adjacent subrotating jets. A combination of boundary conditions leads to a stacked circulation cell pattern that is aligned with numerous jets that are conceptually similar to the meridional circulation in Jupiter's midlatitudes, as suggested by several studies. This analysis provides another step toward understanding the deep atmospheres of gas giants.
The Weakest Link – Revealing the microphysical deformation mechanisms of talc under P-T conditions associated with fault creep and slow slip events
Authors: Boneh Yuval , Ohl Markus , Plümper Oliver , Hirth Greg , Peč Matěj
Published: February 2023

Talc is an important product of several hydration and dehydration reactions in deep faults and subduction zones. The unique weakness of talc along its basal planes makes it an essential component in understanding various fault slip behaviors (e.g., episodic vs continuous slip, seismic vs aseismic) or realistic geodynamic models. A recent experimental study by Boneh et al. (2023) on talc mechanical behavior at high P-T conditions highlighted: (i) talc’s low friction coefficient under all conditions (<0.14), with thermal weakening down to µ~0.01 at 700 °C. (ii) Grain-scale microstructures demonstrate a component of fracturing and microcracking under all conditions tested. And (iii) pressure-dependence of talc strength decreases at higher temperatures, where there is also a greater tendency for localization. A vital part of depicting mineral rheology is the understanding of their underlying mechanisms of deformation associated with the observed bulk mechanical and microstructural behavior. To reveal the underlying deformation mechanism/s we analyzed the deformed samples through high-resolution transmission electron microscopy (TEM) at Utrecht university of samples prepared using a focus ion beam (FIB). Five talc samples were examined – an undeformed sample, and samples deformed at 400, 600, and 700°C under 1 GPa, and at 400 °C under 1.5 GPa.Seven FIB lamellae sampled areas adjacent to the main fracture (if exists) or high damage zones. The starting material shows talc flakes with a thickness of ~100-400 nm without a sample-scale preferred alignment. The sample deformed under 400°C and 1.5 GPa exhibits distributed deformation with opening cracks along talc basal planes and pervasive kinking normal to the basal planes. The sample deformed at 400°C and lower pressure (1.0 GPa) exhibits thin lamination (~50 nm) well oriented with the orientation of the main fracture plane. The sample deformed at 600°C exhibits crystal delamination along the basal cleavage (forming grain fragments <10 nm in width) along the main fracture. The sample deformed at 700°C exhibits more areas of high damage, possibly due to the similar basal-cleavage delamination. A key incentive is to relate the observed nano-scale crystal defects with the bulk mechanical behavior and with processes that might promote the localization of deformation. Pressure-dependent strength can be accounted for by kinking and kinking-induced porosity while thermal weakening can be related to temperature-dependent mobility of crystal defects leading to delamination along the basal cleavage. We will discuss possible physical mechanisms of talc deformation and the prospect of extrapolating the mechanical behavior of talc achieved at the lab to the range of conditions expected in natural settings.
Efficacy of automatic detection and classification methods for volcano seismicity
Authors: Tan Yen Joe , Song Zilin , Zhong Yiyuan
Published: February 2023

At volcanic islands, seismometers are the main tool for monitoring various active processes including seismicity that could forewarn impending eruptions. However, the sparse seismic networks, high background noise levels, large diversity of seismic signals, and high event rates during unrest episodes make automatic detection and classification of volcano seismicity a difficult challenge. In this paper, we use the Alaska Volcano Observatory’s catalogue of ~120,000 long-period (LP) and volcano-tectonic (VT) earthquakes at 34 volcanoes from 1989-2018 to evaluate the efficacy of automatic detection and classification methods. For each event, we calculate the frequency index (FI) based on the ratio of mean spectral amplitudes in the higher and lower frequency bands of the recorded waveforms. Using the local minima in the FI distribution at each volcano as the classification boundary, we find that our labels generally agree with the catalogue’s manual labels. The classification boundaries separating LP and VT earthquakes are also relatively consistent (FI = -1) between volcanoes. Therefore, the FI method is an effective method for automatic classification of volcano seismicity. We then evaluate the performance of two machine-learning-based models (PhaseNet and EQTransformer) and the cross-correlation-based template-matching method for automatic detection. While the template-matching method is computationally more expensive, we find that most of the catalogue events can be detected by using another event as a template, with relatively low false positive rates. In comparison, both machine-learning-based models’ performances are worse than previously reported results and deteriorate systematically with decreasing FI index values. The bias might have resulted from the models having been trained using earthquake catalogues from non-volcanic regions that lack LP events. Therefore, these models should be retrained with a dataset of volcano seismicity before being applied for automatic earthquake detection at volcanic regions.  
Stable isotope ratios (δ2H, δ18O and δ17O) of precipitation in Seoul, Korea, during 2016-202
Authors: Kim Songyi , Han Yeongcheol , Moon Jangil , Nyamgerel Yalalt , Lee Jeonghoon
Published: February 2023

Precipitation plays an important role in the global hydrological cycle, and its stable isotope ratio (δ2H, δ18O and δ17O) provides useful information for atmospheric circulation in forming precipitation. However, understanding of precipitation stable isotope ratio in mid-latitude is limited by an insufficient and restricted interpretation of hydrological and meteorological processes based on insufficient datasets. To improve domain knowledge, we monitored the water stable isotopes of rainwater and snowfall in Seoul, Korea, during the period of 2016-2022. The δ2H, δ18O and δ17O values varied from -120.3 to 3.9 ‰, from -16.58 to 1.21 ‰ and from -8.76 to 0.65 ‰, respectively with characteristic seasonal patterns. The prominent patterns were the isotopic depletion during winter (Dec-Feb; the mean δ2H of -9.39 ‰) under the influence of the Siberian High system and the isotopic enrichment during the spring (Mar-May; the mean δ2H of -2.6 ‰) affected by the Asia monsoon system. The summer season was characterized by the lowest deuterium excess (δ2H­ – 8 x δ18O; 7.4 ‰). As the interplay of the northeast Asia monsoon, and the Siberian High and the North Pacific High was the major cause of the seasonality of the isotope values, their covariance with temperature or the amount of precipitation was weak. The local meteoric water line had a lower slope and intercept (δ2H = 7.67 x δ18O + 9.28) compared to the global meteoric water line. Another local meteoric water line between δ17O and δ18O appeared to be δ17O = 0.5312 x δ18O + 0.0068 with a greater slope and intercept than its global meteoric line.
Stable isotope surveys reveal variations in the air CO2 during the unrest event at Vulcano, Italy, in 202
Authors: Di Martino Roberto M. R. , Gurrieri Sergio
Published: February 2023

Monitoring volcanic gases have provided valuable information in recognizing variations of the magma outgassing at depth. The increase of magmatic volatile compounds in either crater plumes or fumarole emissions can help in tracking transitions from dormancy to unrest which can progress further in a volcanic eruption. The volcanic degassing has renewed at Vulcano since September 2021 as the result of an increase of the magma degassing at depth. This event created concerns among civil defense authorities because the CO2 concentration rose in the air, although the unrest has not produced an eruption.This study examines the air CO2 at Vulcano Porto from the early summer to autumn of 2021, when the volcanic degassing achieved the climax at La Fossa volcano. Five surveys enabled exploring lateral variations for CO2 in the air at Vulcano Porto based on measurements for stable isotope compositions of both oxygen and carbon. In addition, the continuous stable isotopes surveying at a fixed point of interest (i.e., the Centro Carapezza - INGV) enabled studying the time variations for CO2 in the air.The surveys captured a remarkable increase of the volcanic CO2 in the air throughout the settled zone of Vulcano Porto from October to November 2021. At Vulcanello, which lies a few kilometers far from the crater cone, the isotopic signature of the air CO2 revealed also an increased volcanic degassing. Several variations for the volcanic CO2 in the air occurred during the same period and some estimations of the CO2 flux from the crater plume were obtained through continuous stable isotope surveying.The results of this study represent a step forward in providing volcano monitoring techniques that enable estimating the CO2 emission in the air from active vents.
Probing the Unfathomable: Ensemble Boosting for Physical Climate Storylines of Unseen Extremes
Authors: Fischer Erich , Beyerle Urs , Bloin-Wibe Luna , Gessner Claudia , Humphrey Vincent , Lehner Flavio , Pendergrass Angeline , Sippel Sebastian , Zeder Joel , Knutti Reto
Published: February 2023

Recent unprecedented extremes such as the 2023 New Year’s winter warm spell in Europe, the 2022 summer heat and dryness in China and Europe, the 2021 Pacific Northwest heatwave, the 2021 floods in northwestern Germany and the 2020 Siberian heat anomaly broke previous observed record intensities by large margins. Based on the observations up to the year before the event, some of these record-shattering extremes were inconceivable. Could the scientific community have better quantified the potential for such unseen events based on the current generation of climate models?Here, we demonstrate how a new ensemble boosting approach can be used to generate physically coherent storylines of such unseen events. In ensemble boosting a fully-coupled free-running climate model (CESM2) is used to develop physical storylines of very rare extremes. To this end, the most extreme events in an initial-condition large ensemble for the near future are re-initialized with slightly perturbed atmospheric initial conditions to efficiently generate events with magnitudes unprecedented in the observational record.We demonstrate that, with this approach, CESM2 can simulate events that e.g. substantially exceed the magnitude of the 2021 Pacific Northwest (PNW) heatwave anomaly. Even though the most extreme ensemble members were only selected based on the local temperature anomaly over the PNW region, they show a very similar temporal evolution and spatial pattern as the observed event. The associated 500hPa geopotential height anomaly is remarkably similar to the observed event with a strong anticyclone over PNW that is part of a wave pattern extending over much of the Northern Hemisphere. We further show that in some of the storylines pre-conditioning dry soils strongly contributed to the heatwave intensity, whereas in others, heatwaves of similar magnitude occur even at average land surface conditions.We further develop storylines for heatwaves in the Greater Paris and Chicago regions of much greater intensities than ever observed. Particularly the US Midwest, where no intensification of heatwaves has been observed in recent decades, has not experienced anything close to the heatwave intensities possible in the coming years.Finally, we demonstrate examples how ensemble boosting can also be used to generate storylines for multi-year drought events and large-scale heavy precipitation extremes and compare the findings to other storyline approaches. Event storylines based on ensemble boosting can be used in impact studies that require physical consistency across variables, e.g., for the evaluation of humid heatwaves or compound events, for assessing wildfire risks or for ecosystem modelling.
Discerning TGF and Leader Current Pulse in ASIM Observation
Authors: Mezentsev Andrey , Østgaard Nikolai , Marisaldi Martino , Neubert Torsten , Chanrion Olivier , Reglero Victor
Published: February 2023

TGFs being the bursts of high energy photons shot from Earth’s atmosphere to space, are known to be produced during the initial upward propagation of the +IC lightning leader. VLF and LF radio sferics can often be found in association with the short duration TGFs. The Atmosphere-Space Interactions Monitor (ASIM) instrument provides synchronous X- and gamma-ray measurements with optical recordings in 180-240 nm, 337 nm and 777.4 nm wavelength. This allows for simultaneous detection for TGFs and the lightning processes associated with them.ASIM TGF observations have shown that TGFs within the FOV of the optical instruments are always accompanied by the prominent optical pulse which starts the lightning flash. TGFs have a clear tendency to slightly precede the optical pulse, but the short duration of TGFs together with the optical delay of the lightning light propagating through the cloud do not allow to confidently resolve the true sequence of these events.The same problem is present in radio measurements: radio signature from TGF current is usually mixed with lightning current in the recordings due to temporal proximity of the processes involved.Here we report a remarkable, high fluence and long duration TGF, together with its associated optical recordings. This observation shows clear distinction between the TGF and the associated optical pulse: the optical pulse is subsequent to the TGF, as it starts after the TGF is terminated. This allows to conclude that strong current surges inside the leader channel are not responsible for the TGF generation, and, in turn, the current surge producing the optical pulse can be conditioned by the generated TGF, or even be responsible for TGF termination.