bluuebunny/crossref_metadata_2025 huggingface dataset:
Gravity-Wave Emission from Lee-Wave Critical Layers and Energy Budgets
Authors: Wu Yue , Kunze Eric , Tandon Amit , Mahadevan Amala
Published: February 2023

Direct measurements of dissipation rates in the Southern Ocean unveiled a deficit of lee-wave dissipation compared to lee-wave generation (Brearley et al. 2013; Sheen et al. 2013; Waterman et al. 2013, 2014; Cusack et al. 2017, 2020), which is described as “suppression of turbulence” in Waterman et al. (2014). One possible explanation is the generation of freely propagating internal gravity waves (free waves with Eulerian frequency 𝜔𝐸 ≠ 0) that can radiate outside of the lee-wave critical layer and dissipate remotely. In a numerical simulation of lee waves generated by a localized, stable geostrophic current over sinusoidal topography, free waves are observed to emanate from the lee-wave critical layer. The escaped fraction of free-wave energy (the fraction that tunnels through the lee-wave critical layer and reaches the upper ocean) is 5%, while the majority remains trapped. This excludes remote dissipation by free waves as an explanation for the observed “suppression of turbulence”. Energy budget calculations show that ~50% of the bottom-generated lee-wave radiation is reabsorbed into the geostrophic current in vertical mean shear, ~10% is transferred to free waves as an indirect route to dissipation, and ~40% is lost through nonlinear wave-wave interactions leading to the increase of background potential energy. The total dissipative fraction (dissipation of lee waves plus indirect dissipation as free waves) is consistent with predictions by wave action conservation, regardless of the selected eddy viscosity and diffusivity. This study emphasizes wave-mean and wave-wave interactions in the ocean and will shed light on the choice of turbulent parameterization schemes for numerical modelers.
Linking energy system analysis with factors of production analysis: A US case study
Authors: Zhang Chuan
Published: February 2023

Energy system analysis has been widely used to imply technologically and economically plausible energy-system transition pathways for national net-zero emissions targets. Undermining the feasibility of such energy system analysis results are the highly-resolved mapping, sector-by-sector, of the timing and spatial distribution of changes in energy infrastructure, capital investment, employment, air pollution, land use, and other key outcomes at local level. A successful net-zero transition must be accomplished with supplementary supply of factors of production (e.g., human capital, natural capital, investment etc.) to enable such low-carbon transition. Using Princeton’s net-zero America study as example, we find that each net-zero pathway results in a net increase in energy-sector employment and delivers significant reductions in air pollution, leading to public health benefits that begin immediately in the first decade of the transition. We also conclude that each transition pathway features historically unprecedented rates of deployment of multiple technologies. Impacts on landscapes, incumbent industries and communities are significant and planning will need to be sensitive to regional changes in employment and local impacts on communities.
Measurement of Highly Oxygenated Organic Compounds at the Rambouillet forest during the ACROSS Campaign
Authors: Alhajj Moussa Estephanie , Michoud Vincent , Formenti Paola , Cirtog Manuela , Picquet-Varrault Bénédicte , Harb Sergio , Cazaunau Mathieu , Gratien Aline , Di Biagio Claudia , Tison Emmanuel , F. de Brito Joel , Dusanter Sebastien , Riffault Veronique , Locoge Nadine , Lahib Ahmad , Tomas Alexandre , Jamar Marina , Espina-Martin Pablo , Cantrell Christopher
Published: February 2023

Global population increase has placed pressure on available resources and has resulted in the emission of a variety of trace gases into the troposphere that includes volatile organic compounds (VOCs). This class of molecules plays major roles in the formation of secondary products such as secondary organic aerosol (SOA) and tropospheric ozone, which adversely affect Earth’s climate and human health. Research has continued to reveal more details of complex atmospheric degradation processes involving VOCs of both anthropogenic and biogenic origins, but relatively few have been directly studied including the possible impacts of mixing of air masses of anthropogenic and biogenic origins. The ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) project aims to improve our knowledge of atmospheric chemical processes that occur in such mixed air masses and their impact on air quality. The experimental strategy of ACROSS is based on ground-based and airborne observations during an international, large-scale, comprehensive, multi-platform, multi-site field campaign that took place in the summer of 2022 in the greater Paris and suburban forested areas.As VOCs are processed in the atmosphere, secondary compounds are produced including highly oxygenated organic molecules (HOMs) that are a subset of low volatility organic compounds characterized by their contribution to formation and ageing of SOA. Nitrate ion chemical ionization (CI), coupled with an Atmospheric Pressure Interface−Time-Of-Flight Mass Spectrometer (API-TOF-MS) is an online analytical technique that detects and quantifies gas-phase HOMs (and other compounds) with high sensitivity and mass resolution in the atmosphere or laboratory systems. This instrument provides measurements that help to fill the observational gap between the aerosol and gas phases.The instrument was deployed at the top of a 40 m tower (above the canopy) in the Rambouillet forest site during the ACROSS field campaign to measure and identify HOMs formed mainly under two different composition regimes: biogenic emissions only, and biogenic air/urban air mixtures. The data collected by the instrument will be presented and used to enhance understanding of the chemical formation pathways of HOMs and their contribution to the composition of aerosols.
The Spatial and Diurnal Distribution of Lower Atmospheric Dust as Revealed by the Emirates Mars Infrared Spectrometer
Authors: Badri Khalid , Smith Michael , Edwards Christopher , AlTunaiji Eman , Christensen Philip
Published: February 2023

The Emirates Mars Mission (EMM) is on its way to achieving 1 Martian year of Scientific Observations by the end of April 2023 to explore the dynamics of the Martian atmosphere on a global scale. The Emirates Mars Infrared Spectrometer (EMIRS) instrument onboard EMM, is an interferometric thermal infrared spectrometer designed to characterize the geographic, seasonal, and diurnal variability of key characteristics of Mars such as atmospheric dust, which will be the focus of this talk, and other constituents such as water ice optical depth, water vapor abundance, surface temperature, and atmospheric temperature profiles on sub-seasonal timescales.  EMIRS observations provide full local solar time coverage at multiple emission angles providing data on these constituents over the entire Martian disk. Here, we present initial results of the spatial, seasonal and diurnal variation of dust on a global scale with particular attention to the diurnal variations of dust and the evolution of dust storms. Preliminary results show more diurnal variations during dust storm seasons. In addition, results on the biggest storm of the year will be presented which occurred after solar longitude of 300.  These new observations will continue to enhance our understanding of the dust cycle on Mars and how dust influences the current climate and atmospheric dynamics on Mars by relating the effect of dust to other EMIRS constituents mentioned above.
Hydrological feedback from projected Earth greening in the 21st century
Authors: Wu Jie , Wang Dashan , Li Laurent Z.X. , Zeng Zhenzhong
Published: February 2023

Earth satellites have observed continuous increasing vegetation growth during the past four decades, a phenomenon called Earth greening. Nearly all Earth System Models (ESMs) participated in Coupled Model Intercomparison Project (CMIP) for Intergovernmental Panel on Climate Change (IPCC) project a continuous greening of the planet during the 21st century. To investigate the hydrological feedback from projected Earth greening, we prescribed the increase in leaf area index (LAI) in the 21st century as projected by CMIP5 ESMs into a state-of-the-art ESM (IPSLCM), and simulated equilibrium climates for current CO2 and LAI, an increase of CO2 alone, an increase of LAI alone, and increases of both CO2 and LAI, respectively. We find that the greening simultaneously intensifies evapotranspiration and precipitation over land. In terms of soil moisture content, the spatial difference between the responses of evapotranspiration and precipitation causes a hydrological response of the "dry gets drier, wet gets wetter" (DDWW) paradigm. Increasing LAI significantly decreases soil moisture content over dry regions, including Western North America, Southern South America, East Siberia, Central Asia, South Asia, Northern China, Sahel, Southern Africa and Australia. Over wet regions particularly Amazon and Congo rainforests, the greening-induced increase of terrestrial evapotranspiration favors more convective precipitation, so that the new equilibrium does not decrease soil moisture content. The DDWW paradigm in terms of P-ET response does not hold over wet areas. To mitigate climate with forestry, policymakers should prevent degradation of existing forests, support afforestation over wet regions, and avoid planting trees in dry regions.
The effect of new leonardite-based soil amendments on soil organic carbon and carbon dioxide emissions from black soil
Authors: Hetmanenko Viktoriia , Volosheniuk Olesia , Skrylnyk Ievhen , Kutova Angela
Published: February 2023

The current declining soil fertility along with the need for intensification of crop production and greenhouse gas (GHG) emissions reduction is a great challenge, which may be mitigated by sound soil organic carbon (SOC) management. Organic soil amendments have long been known to increase the organic matter content of the soil. Locally available organic soil amendments are an essential source of carbon and nutrients. The significance of the production of new soil amendments has become even clearer considering the escalating prices of chemical fertilizers. Leonardite (oxidized lignite) has a high content of carbon (48.3%) and can be an efficient raw material for soil amendment production. To increase the degree of humification of leonardite and to improve its fertilization value mechano-activation with different materials was used. Iron as a variable-valent metal played the role of a catalyst for the synthesis of the humic substance while bentonite was used as matrice to their synthesis. Molasses was used as the binder during the granulation of soil amendments. For the production of organo-mineral amendment to organic granules obtained a mineral fertilizer layer was added to achieve an N:P:K ratio of 1:0.86:0.95. Correct dose and method of soil amendment application play an important role in its efficient use. We have tested two methods of application of new soil amendments (band incorporation and broadcasting) at two rates of total nitrogen fertilization (30 and 60 kg N ha-1) in a field trial for two years. The sum of positive temperatures on the experimental field is 2400-2900 ○С. The average annual precipitation is 465-680 mm. The soil - Chernozem Podzolic with organic carbon content by the Tyurin method is 2.37 %. Application of organo-mineral amendment (N60) led to an increase of total organic carbon content in the topsoil by 10% compared to the no treatment and mineral fertilization. The integral indicator of the complex dielectric permeability revealed a decrease of polarity of the humic supramolecular structure due to organo-mineral amendment application. This change led to the formation of a more complex, polydisperse, and heterogeneous molecular aggregate organization with high hydrophobicity and stability. The data obtained during the growing period of maize showed that the intensity and the dynamics of carbon dioxide (CO2) emissions from soil depend on the hydrothermal conditions and the type of soil amendments. Cumulative CO2 flux increased with an increasing application rate of soil amendments. The highest mean value of CO2 emissions (0.77 kg CO2/ha/hour) during the growing season was observed under broadcasting of organic soil amendment (N60). Further long-term measurements of soil organic carbon dynamics on different soil types across a variety of technological operations of new soil amendments application are important to reliably quantify rates of SOC accumulation and GHG emissions.
On the 2018-2020 Ice Shelf Water outflow event in the southeastern Weddell Sea
Authors: Janout Markus , van Caspel Mathias , Darelius Elin , Hattermann Tore , Østerhus Svein , Sallée Jean-Baptiste , Steiger Nadine
Published: February 2023

The southern Weddell Sea features a vast perennially ice-covered continental shelf with polynyas, strong sea ice formation, first- and multi-year ice. Sea ice and the general ocean circulation maintain predominantly near-freezing waters on the shelf, which help to maintain the comparatively moderate basal melt rates of the Filchner-Ronne Ice Shelf (FRIS), Antarctica’s largest ice shelf by volume. In contrast to FRIS, other West Antarctic ice shelves show strong basal melt rates, caused by warm intruding ocean waters. In the southern Weddell Sea, however, warm water inflows occur episodically and spatially limited, when modified warm deep water enters the continental shelf through incisions in the shelf break and flows southward towards the FRIS front. Overall, the majority of the shelf is dominated by dense and cold water masses such as High Salinity Shelf Water (HSSW) and Ice Shelf Water (ISW), which are precursors of Antarctic Bottom Water and thus relevant for the global ocean circulation. In 2018, a comprehensive CTD survey found unprecedented (in the available observations) volumes of ISW in Filchner Trough. The ISW was exported from underneath the Filchner Ice Shelf (FIS) following a shift to enhanced cavity circulation due to strong sea ice formation in front of the Ronne Ice Shelf. These Filchner Trough conditions are summarized as the “Ronne-mode”, which is in contrast to the “Berkner-mode”, characterized by a greater influence of locally-formed waters. In this presentation, we introduce new multi-year time series from an international mooring network from various Southeast Weddell Sea locations (sub-FIS, Filchner Trough and Sill), to highlight the temporal and spatial extent of the recent Ronne-mode event, which lasted from 2018-2020, before shifting back into a Berkner-mode. The dominance of either circulation mode is controlled by large-scale atmospheric forcing and has implications on ice shelf basal melt and dense water export into the Weddell Sea. 
Improving global CMIP6 Earth system model precipitation output with generative adversarial networks for unpaired image-to-image translation
Authors: Hess Philipp , Lange Stefan , Boers Niklas
Published: February 2023

Numerical Earth system models (ESMs) are our primary tool for projecting future climate scenarios. Their simulation output is used by impact models that assess the effect of anthropogenic global warming, e.g., on flood events, vegetation changes or crop yields. Precipitation, an atmospheric variable with arguably one of the largest socio-economic impacts, involves various processes on a wide range of spatial-temporal scales. However, these cannot be completely resolved in ESMs due to the limited discretization of the numerical model. This can lead to biases in the ESM output that need to be corrected in a post-processing step prior to feeding ESM output into impact models, which are calibrated with observations [1]. While established post-processing methods successfully improve the modelled temporal statistics for each grid cell individually, unrealistic spatial features that require a larger spatial context are not addressed.Here, we apply a cycle-consistent generative adversarial network (CycleGAN) [2] that is physically constrained to the precipitation output from Coupled Model Intercomparison Project phase 6 (CMIP6)  ESMs to correct both temporal distributions and spatial patterns. The CycleGAN can be naturally trained on daily ESM and reanalysis fields that are unpaired due to the deviating trajectories of the ESM and observation-based ground truth. We evaluate our method against a state-of-the-art bias adjustment framework (ISIMIP3BASD) [3] and find that it outperforms it in correcting spatial patterns and achieves comparable results on temporal distributions. We further discuss the representation of extreme events and suitable metrics for quantifying the realisticness of unpaired precipitation fields. [1] Cannon, A.J., et al. "Bias correction of GCM precipitation by quantile mapping: How well do methods preserve changes in quantiles and extremes?." Journal of Climate 28.17 (2015): 6938-6959. [2] Zhu, J.-Y., et al. "Unpaired image-to-image translation using cycle-consistent adversarial networks." Proceedings of the IEEE international conference on computer vision. 2017.[3] Lange, S. "Trend-preserving bias adjustment and statistical downscaling with ISIMIP3BASD (v1.0)." Geoscientific Model Development 12.7 (2019): 3055-3070.
Micro to Macroscale: the three-dimensional network characteristics of serpentinite dehydration veins
Authors: Arias Austin , Beinlich Andreas , Eberhard Lisa , Scambelluri Marco , John Timm , Kotowski Alissa , Plümper Oliver
Published: February 2023

On Earth, subduction zones facilitate the cycling of volatiles between the Earth’s surface and interior. Volatile cycling has significant effects on the long-term state of the Earth’s climate and tectono-magmatic events, including volcanism and earthquakes. A key stage in the volatile cycle is the devolatilization of the subducting oceanic lithosphere, in which volatiles can escape the previously hydrated rocks. However, it is not well known how efficiently volatiles are transported at this stage. To better understand how volatiles escape at these conditions, we have analyzed the dehydration-related vein networks of the Erro-Tobbio meta-serpentinites (ET-MS), Italy. The ET-MS display well preserved networks of metamorphic olivine veins. These veins are the result of the dehydration reaction of antigorite and brucite to produce H2O and olivine. However, due to the low permeability of serpentinite at depth, the dehydration reaction requires the formation of self-organizing vein networks to allow the produced fluid to escape [1]. Thus, the metamorphic olivine veins in ET-MS may be used as a proxy for fluid flow pathways. We took a multiscale approach to analyzing the network architectures. For microscale (~16 µm voxel size) and mesoscale (~200 µm voxel size) resolutions, X-ray tomography methods are sufficient to visualize the three-dimensional structure of the networks. However, for large scale observations these methods are inapplicable. To solve this, we apply a novel workflow to analyze outcrop scale (~10 m) network systems in three dimensions using only two-dimensional data. By training a generative adversarial network (GAN) with two-dimensional data conditioned by spatial orientation, we can generate statistically representative three-dimensional networks that mimic those of the ET-MS. These representations also display similar characteristics in their respective pore-network-models. With this method, it is possible to produce reasonable three-dimensional approximations of the ET-MS vein networks using only photogrammetry data of the outcrops. In turn, this allows us to extract metrics, such as permeability, that describe the volatile transport efficiency of the ET-MS, and further, how these characteristics change at a broad range of scales.  

[1] Plümper et al. (2017) Nature Geoscience 10(2), 150-156. 
Oceanic transform faults offshore São Tomé and Príncipe highlighted by integrated density and magnetic modeling of the crust
Authors: Haas Peter , Thomas Myron , Heine Christian , Ebbing Jörg , Seregin Andrey , van Itterbeeck Jimmy
Published: February 2023

The Eastern Gulf of Guinea hosts several buried Cretaceous-aged oceanic fracture zones. 3D broadband seismic data acquired offshore São Tomé and Príncipe revealed a complex crustal architecture. Mapped oceanic fracture zones show low-angle reflectors that detach onto or eventually cross through the Moho boundary, overlain by strong reflectors that are interpreted as transform process related extrusive lava flows. Here, we use a high resolution shipborne free-air gravity and total field intensity magnetic data set to reassess whether previously defined seismic models of the crust are in conformity with potential field data. The study area is located offshore São Tomé with a size of c. 150x150 km. Using the software IGMAS+, we model the gravity and magnetic properties of the crust (i.e. density and susceptibility) in 3D. Long record length seismic sections plus mapped seismic horizons, which include bathymetry, sediments, upper and lower crust, are used as constraints. While the general trend of the free-air anomaly can be explained within a range of expected crustal densities, the magnetic field anomaly reflects high residuals that are predominantly oriented parallel to the transform faults. This indicates that gravity and magnetic data cannot be explained by the same simple source geometry. Therefore, we first perform sensitivity tests to isolate the source of the residual magnetic anomaly, followed by a structural analysis along the transform faults with special emphasis to the extrusive lava flows in the crustal domain. Our final model reconciles seismic horizons and potential field data and will stimulate a discussion on the architecture and evolution of transform faults and their signatures in different data sets.    
Numerical modeling of biological processes on snow and ice surfaces on the Greenland Ice Sheet
Authors: Onuma Yukihiko , Niwano Masashi , Shimada Rigen , Takeuchi Nozomu
Published: February 2023

Biological processes on snow and glacier surfaces in the Arctic region play a key role causing albedo reduction called as “Bio-albedo effect” due to blooms of snow and glacier phototrophs. Because the bio-albedo effect varies temporally and spatially due to their biological properties including growth, death and migration, the biological processes need to be separated from accumulation processes of the other impurities such as aeolian mineral dust and black carbon. In addition, different processes causing the bio-albedo effect, which are known as red snow, dark ice and cryoconite holes, are observed in the Arctic snowpacks and glaciers. To understand the bio-albedo effect quantitatively, a numerical model to reproduce such biological processes as well as a physically based albedo model should be established. We recently established several numerical models: the snow algae model to simulate red snow phenomena caused by snow algal blooms (Onuma et al., 2020; 2022a), the glacier algae model to simulate dark ice phenomena caused by glacier algal blooms (Onuma et al., 2022b) and the cryoconite hole model to simulate vertical dynamics of cryoconite holes (Onuma et al., In prep.). In this study, we simulate spatio-temporal changes in algal abundance and bio-albedo effect in Greenland Ice Sheet since 2000 using regional climate or land surface models coupling with the established models. The simulated spatio-temporal changes are evaluated using a polar-orbit satellite, Global Change Observation Mission for Climate (GCOM-C) which carries an optical sensor capable of multi-channel observation at wavelengths from near-UV to thermal infrared wavelengths (380nm to 12µm). In addition, we also use GCOM-W satellite with a microwave sensor to discuss relationship between snow/ice surface melt periods and algal blooms. The detailed discussion will be presented at the meeting.References[1] Y. Onuma, N. Takeuchi, S. Tanaka, N. Nagatsuka, M. Niwano and T. Aoki, Physically based model of the contribution of red snow algal cells to temporal changes in albedo in northwest Greenland. The Cryosphere, 14, 2087-2101. doi:10. 5194/tc-14-2087-2020 (2020)[2] Y. Onuma, K. Yoshimura and N. Takeuchi, Global simulation of snow algal blooming by coupling a land surface and newly developed snow algae models, Journal of Geophysical Research: Biogeosciences, 127 (2), e2021JG006339. doi:10.1029/2021JG006339 (2022a).[3] Y. Onuma, N. Takeuchi, J. Uetake, M. Niwano, S. Tanaka, N. Nagatsuka and T. Aoki, Modeling seasonal growth of phototrophs on bare ice on the Qaanaaq Ice Cap, northwestern Greenland. Journal of Glaciology, 1-13. doi:10.1017/jog.2022.76 (2022b)
Near-term precipitation change highly sensitive to black carbon emissions
Authors: Samset Bjorn H. , Wilcox Laura J. , Lund Marianne T. , Iles Carley , Stjern Camilla W. , Nordling Kalle
Published: February 2023

Changes in mean and extreme precipitation are arguably the most impactful aspects of climate change. Detailed and accurate projections are therefore crucial for climate risk assessments and adaptation strategies. Generally, global mean precipitation increases with surface warming, with a global mean hydrological sensitivty of around 1 to 2 %/K, and stronger increases in rates or extreme precipitation events. Local variations are however very large, and model projections are much more uncertain than for temperature.  Absorbing aerosols, notably black carbon (BC), brown carbon (BrC) and mineral dust, are an exception to the rule. Their absorption of shortwave radiation inhibits precipitation formation, through rapid adjstments that overwhelm their influence on surface temperature. The hydrological sensitivty to black carbon emissions is therefore around -4 %/K, again with large regional variations, and with a very high spread between models ( -1 to -7 %/K) In this talk, we discuss the near-term (2015-2045) dependence of precipitation change on the evolution of absorbing aerosols. We show the transient hydrological sensitivty in CMIP6, globally and regionally, and how it is affected by air quality policy (i.e. scenario choice) and model treatment of BC, BrC and dust. We confirm that, globally, while black carbon emissions have a modest impact on surface temperature, their influence on precipitation is outsized, causing a factor of 2 difference in hydrological sensitivty beween future scenarios with strict (SSP126) and weak (SSP370) air quality control measures.  Further, for highly populated regions close to, or downwind from, major emission sources - notably India, China and northern Brazil - we find very high sensitivity of precipitation evolution to the levels of absorbing aerosol emissions. Several of these regions are therefore set for a "double whammy" of precipitation increase from global warming and a removal of short wave absorbing air pollution. We also discuss the rates of change of extreme precipitation events, and how they relate to absorbing aerosols in different regions.  Our key message is that changes in absorbing aerosols over the coming decades is a key uncertainty in near term precipitation and extreme event evolution, and therefore a burning knowledge gap for the aerosol-climate community. 
Urban flood monitoring and early warning by surveillance camera networks
Authors: Wang Xing , Yu Yihao , Nie Yunfeng
Published: February 2023

Under the dual effects of global climate change and urbanization, urban flooding has become an increasingly severe development problem. Widespread surveillance cameras provide new opportunities to observe geographic phenomena such as extreme rainfall, flooding, and hurricanes. In this study, an urban flooding observation system is constructed using the surveillance camera network to alleviate traditional flooding sensing strategies' spatial and temporal resolution shortcomings. First, based on analyzing the visual features of flooding water in surveillance videos, a deep learning model is built to extract the flooded pixels from the surveillance video with the ResNet that incorporates an Attention mechanism as the backbone network. Second, a projection model, which maps the relationship between image space and geographic space, is employed to calculate the flooding range in the real world. After that, taking the geographical information of the surveillance scenarios into account, an evaluation index system is constructed to assess the flooding risk. For the training and testing of the deep learning models, an urban flooding visual dataset was produced. Extensive experimental results have demonstrated the effectiveness of the proposed method. Our approach deploys on the existing city surveillance resources and therefore has the advantage of low cost and high resolution. 
Generation and Decay of Reconnecting Current Structures Downstream of the Bow Shock: 3D Hybrid Simulations
Authors: Gingell Imogen L. , Schwartz Steven J. , Kucharek Harald , Farrugia Charles J. , Fryer Laura J. , Plank James , Trattner Karlheinz J.
Published: February 2023

Observations of Earth’s bow shock and magnetosheath have shown that magnetic reconnection occurs within these regions at thin current sheets, typically arising from turbulence and plasma instabilities in the shock transition layer. Broad observational surveys of these regions have shown that, somewhat surprisingly, the prevalence of reconnecting current structures may not be strongly dependent on the shock Mach number or the angle between the upstream magnetic field and shock normal (θBn), despite quasi-parallel shocks typically exhibiting more disordered and non-stationary structure. To investigate how shock reconnection manifests across different parameters, we perform a series of two- and three-dimensional hybrid (fluid electron, kinetic ion) particle-in-cell simulations across a broad range of Mach numbers and orientations. These simulations isolate ion-scale mechanisms for reconnection in the shock, principally those driven by ion-ion beam instabilities in the foot and foreshock. For 2D simulations, we show that reconnection via these ion-driven mechanisms is strongly constrained to quasi-parallel shocks. However, downstream of quasi-parallel shocks, we find that the decay rate of closed-field regions, and hence thin current sheets, is not strongly dependent on upstream shock parameters. We also explore the differences that arise in shock structure, the generation of reconnecting current structures, and their decay rates for three-dimensional simulations.
3D alteration mapping and remote-sensing applications for porphyry -copper deposits (PCD) exploration, in Panagyurishte ore district, Bulgaria
Authors: Velev Stefan , Bogdanov Kamen , Krumov Ivan
Published: February 2023

The Panagyurishte ore district, Bulgaria is situated in the Srednogorie zone situated in the western part of the global Cu-Au dominant Tethyan-Eurasian Cu-Au metallogenic belt. Significant examples of Late Cretaceous volcano-plutonic structures with porphyry-copper deposits (Elatsite, Medet, Asarel, Tsar Assen, Vlaykov Vruh), connected to subvolcanic granodiorite porphyry intrusions occur in the Panagyurishte ore region, Bulgaria. The PSD are closely associated with high-sulphidation type Cu-Au epithermal deposits (Chelopech, Krasen, Radka, Elshitsa) that are related to andesite - dacite magmatic activity. 3D UAV-supported alteration mapping of Vlaykov Vruh and Tsar Assen PCD have been performed to identify and prove the geometry of the alteration mineral assemblages and ore controlling structures. Domains consisting of phyllic, argillic, propylitic and K-silicate alteration zones associated with and porphyry-copper style of mineralization in Vlaykov Vruh and Tsar Assen deposits were outlined. 3D modelling of Popovo Dere PCD by means of Leapfrog Geo and mineral alteration mapping study outlined fault controlled proximal K-silicate domain and more distal propylitic domain as a potential Cu-porphyry deposit target for further mineral exploration and evaluationTwo types of K-silicate alterations, one with magnetite and another without magnetite that hosted Cu-porphyry mineralization have been distinguished within the proximal Cu-rich zone. More distal propylitic domain has also been outlined by 3D modelling. Strike-slip fault control within the K-silicate alteration domain outlined the cone shaped Cu-porphyry ore body. The UAV-Multispectral and TIR mapping in addition to XRD study confirmed the geometry of phyllic alteration domain hosted in andesitic and dacitic volcanic rocks. The propylitic alteration zone is developed in the granodiorite porphyry intrusion in Vlaykov Vruh PCD and with K-silicate domains hosts Cu-Mo mineralization. Fe-oxide and malachite rich domains have been traced in Tsar Assen PCD in addition to Cu-rich zone in the western part of the open pit.The recent study demonstrates that combined UAV-supported remote sensing and mineral alteration field and XRD mapping could provide an effective vectoring and exploration targeting tool toward PCD mineralizationThis study is supported by the Horizon 2020 co-funded GOLDENEYE project through the Grant Agreement 869398.
Topographically Trapped Waves Around South America: Oceanic Teleconnections between Equatorial Pacific and Tropical Atlantic
Authors: Poli Léa , Artana Camila , Provost Christine
Published: February 2023

The South American continental slope hosts a variety of topographic waves. We use a 27-year-long global ocean reanalysis (1/12° Spatial resolution) to examine trapped waves (TWs) around South America at periods ranging from 40 to 130 days. The waves propagate from the Equatorial Pacific to the Tropical Atlantic (22°S) with phase velocities between 1.8 and 7 m/s according to the local background characteristics, such as stratification, slope steepness, latitude, mean flow and shelf width. The Madden-Julian Oscillation (MJO) plays a key role in forcing the TWs in two ways (a) through an oceanic connection implying equatorial Kelvin waves reaching the western American Coast and (b) through an atmospheric teleconnection enhancing southerly winds in the south-east Pacific. Furthermore, local winds, not necessarily linked with the MJO, modulate and trigger waves in specific locations, such as the Brazil-Malvinas Confluence. Trapped waves impact the along-shore currents: during the positive phase of the waves the near-surface flow is enhanced by about 0.1 m/s.
The role of marsh creeks in the development of salt marshes during storm events
Authors: Sun Jianwei , van Prooijen Bram , Wang Xianye , He Qing
Published: February 2023

Salt marshes are valuable ecosystems in coastal wetlands as they provide many functions. However, salt marshes are increasingly threatened by the sea-level rise induced by climate change. Whether there is enough sediment availability is the key to the survival of salt marshes. Storm events can provide a large amount of sediment from mud flats to salt marshes and are the main driver of marsh accretion in the long term. Sediment can be transported into the marsh via both marsh edges and marsh creeks. How important the role of marsh creeks is in delivering sediment into marshes during calm weather and storm events needs to be further investigated. Therefore, one field campaign in Paulina Saltmarsh (the Netherlands) has been conducted in the summer. As storm events frequently occur in winter in the Netherlands, the other field campaign in Paulina Saltmarsh is ongoing in January. Water depth, velocity, SSC, and bed level change have been measured simultaneously at three locations: the mud flat, the marsh creek, and the marsh edge. According to the results from the summer field campaign, we found that the marsh creek generally functions as a conduit for exporting sediment during calm weather. Sediment import can only be observed when the mud flat was eroded and provided more sediment to the creek. Due to the lack of sediment availability, mud flats cannot be recovered easily after erosion. During storm events, marsh creeks are expected to reverse the role in delivering sediment. In addition, the contribution of creeks and marsh edges to the transport of sediment will be explored. This work reveals different sediment transport regimes under different conditions, and highlights the role of creeks in the expansion of marshes during storm events.
Soilstab and Evorisk: a web-service and web-platform for landslide and rock-fall hazards monitoring using ambient seismic noise methods
Authors: Royer Alexandra , Le Breton Mathieu , Guillemot Antoine , Larose Eric , Baillet Laurent , Guyoton Fabrice , Mayoraz Raphael
Published: February 2023

Landslide monitoring is essential to a better understanding of their dynamics and to the reduction of human casualties by detecting precursors before failures. In general, observations on the surface must be supplemented by sub-surface observations, in investigating the material in depth. Ten years ago, seismic ambient noise interferometry method has been applied to monitor the relative variations in surface seismic wave velocity (dV/V). As seismic wave velocities are directly related to material stiffness, any reduction in seismic velocity can be associated with a loss of stiffness with high probability (i.e. ground liquefaction or strong fracturation). This technique has led to the detection of a decrease in wave velocity several days before the rupture of a clay landslide [1], opening the way to a new precursor signal that could be used for alerts or early warning systems. Since then, several landslides have been monitored to this end [2].In addition, by analysing the spectral content of seismic data, the natural resonance frequencies of rock instabilities (rocks columns, rock glaciers) can be monitored [3]. Their relative variation (dF/F) over time depends on the elastic properties and the geometry of the vibrating structure, which makes it possible to monitor its mechanical state, and to deduce precursor signals to significant failure.In order to make these technologies operational, we have built a web-service, Soilstab, which allows for the processing of an existing dataset with the seismological methods described previously. This service is associated with Evorisk, a web-platform that displays the temporal evolution (updated daily or over a fixed period) of the results (dV/V and/or dF/F). This platform also integrates other available observations, such as environmental parameters (temperature, rainfall, snow, …) or surface observations (photogrammetry, GNSS/GPS-based displacement measurements, extensometers, etc..). Correlating all these observations is thus made easier to better understand and quantify the effect of environmental forcings (temperature, rain, freezing, etc.) on the dynamics of landslides and rock instabilities.[1] G. Mainsant, E. Larose, C. Brönnimann, D. Jongmans, C. Michoud, M. Jaboyedoff, Ambient seismic noise monitoring of a clay landslide : toward failure prediction, J. Geophys. Res. 117, F01030 (2012).[2] M. Le Breton, N. Bontemps, A. Guillemot, L. Baillet, E. Larose, Landslide Monitoring Using Seismic Ambient Noise Interferometry:: Challenges and Applications, Earth Science Review (2020)[3] Colombero, C., Jongmans, D., Fiolleau, S., Valentin, J., Baillet, L., & Bièvre, G. (2021). Seismic noise parameters as indicators of reversible modifications in slope stability: a review. Surveys in Geophysics, 42(2), 339-375.
Urban Vulnerability: Requirements and Data Availability on the Global Scale
Authors: Stolte Tristian , Koks Elco , de Moel Hans , Reimann Lena , de Ruiter Marleen , van Vliet Jasper , Ward Philip
Published: February 2023

In this study, we compile and review the required and available data to do a global-scale urban vulnerability assessment for different hazards. Over the past decades, cities around the globe have rapidly increased in size. A larger concentration of people, assets, and economic activities in cities also mean that more elements are potentially located directly in harm’s way if a hazard occurs. The impacts of natural hazards are often expressed within the disaster risk framework, which describes disaster risk as a probabilistic function of hazard (i.e. the natural hazard event that potentially causes harm), exposure (i.e. those elements that are potentially in harm’s way), and vulnerability (i.e. the characteristics of the exposed elements that make them more or less susceptible to harm). Thus far, urban vulnerability has been investigated primarily on the local scale and is often led by data availability rather than suitability. To enable a more informed decision making process in vulnerability assessments, we aim to provide an overview of both relevant and available vulnerability indicators for six different hazards (pluvial flooding, coastal flooding, drought, earthquakes, heatwaves, and waterborne diseases). Our methodology is threefold: (1) An exhaustive overview of relevant urban vulnerability characteristics through a semi-systematic review of the peer-reviewed scientific literature (3000+ papers). Our focus is on empirically derived vulnerability characteristics, but we supplement this with information from modelled, theorized, adopted, or unknown derived sources. (2) An overview of available urban vulnerability indicators from supra-national urban datasets in a data review (100+ datasets). (3) A comparison of the relevant vulnerability information from the literature review with the available vulnerability data from the data review in order to explore what data acquisition activities are most needed in the context of urban vulnerability assessments. Lastly, we also discuss the outlook of a temporally dynamic (i.e. with values for different moments in time) vulnerability dataset with full global coverage in the urban context. The results can be used to inform researchers and urban decision makers tasked with disaster risk reduction on viable vulnerability indicators.
Restratification Structure and Processes in the Irminger Sea
Authors: de Jong Femke , Sterl Miriam
Published: February 2023

The Irminger Sea is one of the few regions in the ocean where deep (>1,000 m) convectionoccurs. Convection is followed by restratification during summer, when the stratification of the water columnis reestablished and the convectively formed water is exported at depth. There are currently no descriptionsof interannual variability and physical drivers of restratification in the Irminger Sea. We investigaterestratification in the upper 600 m of the central Irminger Sea using reanalysis data for the years 1993–2019.We find distinctly different restratification processes in the upper 100 m (the upper layer) and the water belowit (the lower layer). In the upper layer, the stratification is dominated by a seasonal cycle that matches the cycleof the surface heat flux. In 2010 and 2019, there were peaks in upper layer restratification, which could partlybe related to strong atmospheric heat and freshwater fluxes. Greenland runoff likely also contributed to thehigh restratification, although this contribution could not be quantified in the present study. In the lower layerthere is strong interannual variability in stratification, caused by variability both in the convection and therestratification strength. The restratification strength is strongly correlated with the eddy kinetic energy in theeastern Irminger Sea, suggesting that lower layer restratification is driven by lateral advection of warm, salinewaters through Irminger Current eddies. In the future, surface warming and freshening of the Irminger Seadue to anthropogenic climate change are expected to increase upper layer stratification, potentially inhibitingconvection.
Machine Learning and LiDAR Snowheight Maps from UAVs Reveal Clusters of Snow Variability in a Sub-Alpine Forest.
Authors: Geissler Joschka , Rathmann Lars , Weiler Markus
Published: February 2023

Snow plays a crucial role in the hydrological cycle as it serves as an intermediate storage of winter precipitation and renews groundwater reserves. It is therefore of central importance for, among others, our drinking water supply and agriculture. Snow interacts with its environment in many ways, is constantly changing with time, and thus has a highly heterogeneous spatial and temporal distribution. Therefore, modelling snow variability is difficult, especially when additional components such as forests add complexity. To increase our understanding of the spatiotemporal variability of snow as well as to validate snow models, we need reliable validation data. For these purposes, airborne LiDAR surveys or time series derived from snow sensors on the point scale are commonly used. However, these are disadvantageously limited to one point either in space or in time. In this study, we profited from current advances in LiDAR and drone technology, as well as machine learning, to bridge this gap. We present a new dataset on snow variability in forests for the Alptal, a sub-alpine, forested valley in the pre-alps, Switzerland. The core dataset consists of a dense sensor network, repeated UAV-based LiDAR flights and manual snow height and density measurements. Using modern machine learning algorithms, we determine four clusters of similar spatiotemporal behaviour regarding their snowheight. These clusters are characterized and further used to derive daily snow depth and snow water equivalent maps. By using the latter, we obtain spatially continuous key hydrological variables. The results suggest that snow occurs in clusters that reoccur in space. These clusters underline the relation between canopy cover and spatial snow accumulation patterns and (the much more complex) spatial ablation patterns. The presented dataset and derived products are the first to our knowledge that provide daily, high-resolution snow height and hydrologic variables based on field data. The results of this study can therefore improve our understanding of the spatiotemporal variability of snow in forested environments. Moreover, they are ideally suited for the validation of modern snow models.
Characterisation and interpretation of local climate evolution in the South-West of France
Authors: Lanet Marine , Li Laurent , Le Treut Hervé
Published: February 2023

Summer 2022 has been the second hottest summer after 2003 in France since 1900, with 33 cumulative days of heatwaves. It has also been one of the 10 driest summers in France since 1959. The average precipitation deficit reached 20% compared to the 1991-2020 period, exceeding 60% in some regions, even though June 2022 broke the monthly record of storm occurrences.These extreme climate conditions led to water restrictions and fostered the development of many wildfires. In particular, so called “megafires” burnt more than 28,000 hectares of the Landes forest in the Nouvelle-Aquitaine region, in the South-West of France.Starting from the 18th century, this swampy region has been dried out by planting maritime pines and digging ditches to drain away excess water. Due to recent events, these land management practices are questioned : the record-breaking soil dryness of summer 2022 enabled fire to propagate underground and resurface further away, making firemen’s work extremely difficult.By controlling ditch drainage, is it possible to reduce soil dryness and thus fire risk in summer, as well as mitigate heavy precipitation impacts in this flood prone area ? To answer this question, this work first aims at characterizing and interpreting local climate evolution during the last decades, in terms of trends, changes in the seasonal cycle and extreme events, using  ERA 5 reanalysis, the E-Obs dataset, and MODIS satellite observations. CORDEX regional climate projections are also analysed. Nouvelle-Aquitaine will experience both more frequent and intense heatwaves and droughts and an increase in heavy precipitations. Landes forest management thus has to be adapted.The perspective of this work is to develop a conceptual ditch drainage model and quantify the drought and flood risk reduction potential using storylines based on plausible short and long term climate conditions in Nouvelle-Aquitaine.In a broader perspective, the objective of this work is to develop a methodology replicable in other regions of the world to analyse the impacts of climate change at a local scale and explore how climate science can provide quantitative information to help decision making.