bluuebunny/crossref_metadata_2025 huggingface dataset:
Internal solitary wave energy transformations under ridged ice cover
Authors: Terletska Kateryna , Maderich Vladimir , Tobisch Elena
Published: March 2024

Propagation of internal solitary waves (ISW) under the edge of the ice cover may lead to theirdestabilization through overturning and breaking events. Factors such as ice cover depth, ridgingintensity, and internal wave amplitudes play crucial roles in the evolution and disintegration of ISWbeneath the ice cover. In the study, a numerical investigation of the transformation of ISWpropagating from open water in the stratified sea under ridged ice cover is carried out. Anonhydrostatic numerical model, that is based on the Reynolds averaged Navier-Stokes equations inthe Boussinesq approximation for a continuously stratified fluid, was used in the investigation. Thestudy focused on an idealized scenario with a vertical distribution of potential density anomaliesdesigned to replicate the summer profile of potential density observed over the Yermak Plateau inthe Arctic Ocean. In the numerical experiments, number of ice keels were placed beneath auniform-thickness ice layer. The ice keel shape was approximated by the Versoria function. It iscarried out calculations with a different ridging intensity, that is, the ratio of the maximum height ofthe keel to the distance between the keels. In present calculations, it varies from 1/1000 formoderately ridged ice to 1/20 for heavily ridged ice, which is broadly consistent with the oceanvalues. The transformation of ISW of depression is additionally governed by the blockingparameter β for a single keel, which is the ratio of the height of the minimum thickness of the upperlayer under the ice keel to the incident wave amplitude. An important characteristic of the ISW-ridged ice interaction is the loss of kinetic and available potential energy during the ISWtransformation. Energy transformation due to mixing leads to the transition of energy to backgroundpotential energy and energy dissipation. To characterize the dependence of energy loss on keelheight and distance between keels, we introduced the parameter, which is the ratio of the sum ofsubmerged ice thickness and maximal keel penetration to the distance between keels. An energyloss was estimated based on a budget of depth-integrated pseudoenergy before and after the wavetransformation. The results revealed that the energy loss increases with a decrease in distancebetween keels or an increase in keel height. The level of energy loss is highest for β values nearzero. For values β greater than 0.8, interaction is moderate or weak, and distance between the keelsno longer affects energy loss.
Cascading ruptures on near-orthogonal strike-slip faults controlled by simple shear: Insights from the 2019 Cotabato earthquake quartet, Philippines
Authors: Jiang Yu , Zeng Hongyu , Hu Wan-Lin , Ma Zhangfeng , Hubbard Judith , Wei Shengji
Published: March 2024

Near-orthogonal ruptures within the elastic crust cannot be explained by the classic Mohr-Coulomb theory. Instead, simple shear is a promising hypothesis to explain near-orthogonal ruptures, and we test this hypothesis on the 2019 Cotabato earthquake sequence. In 2019, an earthquake quartet struck the Cotabato province on Mindanao island, Philippines: Mw6.4 on October 15 (EQ1), Mw6.6 on October 29 (EQ2), Mw6.5 on October 31 (EQ3), and Mw6.8 on December 15 (EQ4). This was the first documented earthquake quartet involving four similar-size moderate strike-slip events in such a short period. The sequence ruptured the Sindangan-Cotabato-Daguma Lineament, which was formed during the collision of the Sundaland-Eurasia Plate and the Philippine Mobile Plate in the Late Miocene and has not hosted any large earthquake in the past century. We initially estimated the fault orientation by surface wave relocation of M>4.7 events, and then retrieved the fault slip distributions of the major earthquakes using Interferometric Synthetic Aperture Radar (InSAR) images. The geodetic inversion reveals that EQ1, EQ2, and EQ4 ruptured the NW-trending M’Lang and Makilala-Maulungoon faults, while EQ3 ruptured the NE-trending Makilala fault. Near orthogonal (88°-93°) nature between the NW-trending faults (EQ1/EQ4) and the NE-trending fault (EQ3) can be explained by the rotation of the conjugate faults due to simple shear since ~7 Myr. We find that the stepover widths between the near-parallel faults associated with EQ1, EQ2, and EQ4 may have limited the dynamic triggering of EQ2 and EQ4. Coulomb stress transfer models suggest that the coseismic slip of EQ1, EQ2, and EQs 1+2 could have triggered EQ2, EQ3, and EQ4, respectively. Fault orientation rotation modelling reveals the fault starting the near-orthogonal cascading sequence is the one accommodating the majority of the rotation, possibly because of the instability associated with rotations. Our study suggests that the shallow segments of the M’Lang and Makilala-Maulungoon faults did not fail, and that these remain a potential seismic hazard.
Short-term climatic oscillations versus long-term delta propagation: what controls sand transport into the deep Levant Basin since the Pliocene? 
Authors: Sirota Ido , Ben Dor Yoav , Gvirtzman Zohar
Published: March 2024

Sand transport and its deposition in deep marine basins is controlled by diverse climatic, tectonic, physiographic and oceanographic processes. Disentangling the impact of each of these drivers on the sedimentary record is a fundamental challenge in the study of source to sink systems. In this study, we investigate seismic and boreholes data using statistical and spectral analysis approaches to identify the factors controlling sand deposition in the deep Levant Basin (Eastern Mediterranean) during the Pliocene-Quaternary (PQ). We interpret the sand content in boreholes from Gamma Ray (GR) logs and identify two major trends in sand/shale ratio. On a million-year scale, we demonstrate that since the Early Pliocene (5.3 Ma) sand content gradually increased until it formed a ~100 m thick widespread sand sheet at the top of the section. On a shorter time-scale, we identify oscillations in sand content depicting statistically significant power of periodic components at the 350-450, 90-150, and 10s ka bands. The long-term increase in sand content reaching the deep Levant Basin is interpreted as a result of the Nile Delta propagation, which had continuously shortened the distance between the Nile delta edge that became the source of sand, and the deep Levant Basin. The superimposed short-term oscillations are interpreted as Milinković cycles that produced hydrologic oscillations of water and sediment discharge into the Eastern Mediterranean Sea by the Nile River. This demonstrates the hydroclimatic control on sand deposition in the deep Levant Basin. Our observations are consistent with the development of a submarine channel system along with the accretion of the Nile delta, which may have served as a pathway for sand delivery via high energy turbidite currents that reached the Levant Basin.    
A multiproxies paleoclimatic study of lacustrine sediment from the Castiglione maar drilling (central Italy):  first insight of the AMUSED Project.
Authors: Macrì Patrizia , Siravo Gaia , Smedile Alessandra , Caricchi Chiara , Minelli Liliana , Wagner Bernd , Regattieri Eleonora , Di Vincenzo Gianfranco , Ferretti Patrizia , Mazzini Ilaria , Giaccio Biagio , Scateni Bianca , Cascella Antonio , Isola Ilaria , Di Roberto Alessio
Published: March 2024

The AMUSED project (A MUltidisciplinary Study of past global climatE changes from continental and marine archives in the MeDiterranean region, https://progetti.ingv.it/index.php/it/amused) aims at improving knowledge of middle-late Quaternary climate variability by integrating paleoclimate multi-proxy data acquired in different geological settings of the Mediterranean region. In this context, we investigate the Castiglione maar, Colli Albani volcanic district in central Italy, for acquiring a high-resolution and geochronologically well-constrained multi-proxy record of the lacustrine succession. After geophysical exploration, two parallel 116 m- and 126.5 m-long sediment successions were recovered from the central sector of the basin. The sedimentary infilling mainly consists of fine sand, silt and clay, with minor gravel intervals and numerous tephras mostly deriving from explosive eruptions of the Roman Province volcanoes such as Mt. Vulsini, Vico, Mt. Sabatini and Alban Hills. More than fifty visible volcanic layers were identified and used, together with some lithostratigraphic features, for correlating the two parallel cores and build up a composite sediment section of 131.2 m in length. The geochemical fingerprinting of some key tephra layers allowed to establish a preliminary chronological framework for the Castiglione succession spanning the last 365 ka, with a mean sedimentation rate of 0.33 mm/yr. High resolution X-ray Fluorescence scanning was acquired at 2.5 mm intervals on the composite section and will be used, along with preliminary results from total inorganic and organic carbon, δ18O-δ14C and ostracods analyses, for paleoenvironmental reconstructions.
Exploring Water Management Strategies for Mitigating Local Drought Impacts in the Netherlands using Data-Driven methods previously used for Simulations to Projections
Authors: Hauswirth Sandra Margrit , Bierkens Marc F.P. , Beijk Vincent , Wanders Niko
Published: March 2024

Extreme events like droughts and floods can have significant impact on the environment and society. As a result effective water management strategies are necessary to limit and mitigate these impacts. In the past decade, the Netherlands has experienced several extreme drought events, raising increasing interest in adapting water management practices, traditionally focused on floods, to address droughts more directly and effectively.Machine learning techniques have previously been tested for the same region in terms of seasonal forecasting1  and projections2 under different warming scenarios3, showing the additional benefit of these techniques in downscaling large-scale input data to local-scale relevant information for water managers.This recent work aims to go a step further to explore water management options for drought mitigation by incorporating machine learning in a framework of hydrological simulations, water management scenarios and impact functions. By incorporating the insights gained from previous work, a closer focus is given on human aspects and its impact on local drought management.We developed a Multi-Target Long Short-Term Memory (LSTM) model which facilitates the exploration of different water management options. An essential finding is that taking proactive actions earlier can further limit drought impacts and help to mitigate long recovery periods that would have been observed otherwise. With the Multi-LSTM water management model we can potentially reduce drought impact by 3-5% for the droughts in 2003, 2015 and 2018. As a results, this work yields valuable insights for operational water management and potential improvements in water management strategies with machine learning techniques to effectively address future drought events.1) Hauswirth, S. M., Bierkens, M. F. P., Beijk, V., and Wanders, N.: The suitability of a seasonal ensemble hybrid framework including data-driven approaches for hydrological forecasting, Hydrol. Earth Syst. Sci., 27, 501–517, https://doi.org/10.5194/hess-27-501-2023, 2023.2) Hauswirth SM, van der Wiel K, Bierkens MFP, Beijk V and Wanders N (2023) Simulating hydrological extremes for different warming levels–combining large scale climate ensembles with local observation based machine learning models. Front. Water 5:1108108. doi: 10.3389/frwa.2023.11081083) Van der Wiel, K., Wanders, N., Selten, F. M., & Bierkens, M. F. P. (2019). Added value of large ensemble simulations for assessing extreme river discharge in a 2 °C warmer world. Geophysical Research Letters, 46, 2093– 2102.
The effect of land restoration on cloud cover in West Africa
Authors: Ruijsch Jessica , Taylor Christopher M. , Teuling Adriaan J. , Hutjes Ronald W.A.
Published: March 2024

Over the past years, many land restoration projects, including natural regeneration and tree planting, have been implemented in West Africa to combat land degradation. In addition, land restoration is often used to increase biodiversity or as a climate change mitigation measure through carbon sequestration. However, as land restoration can also affect the local climate more directly through biogeophysical processes, some projects propose a new use: implement land restoration to alter the water cycle, increase rainfall and water availability, and make regions less vulnerable to climate change.In general, vegetation can increase cloud cover (and rainfall) through changes in evapotranspiration and moisture availability for cloud formation. At the same time, the albedo and surface roughness can affect the heat fluxes required for convection. Previous research has tried to unravel these general relations between vegetation and cloud cover. Yet, it is currently unknow to what extend land restoration projects, which usually have a limited spatial extend, can affect cloud cover in West Africa.In this study, we use observational remote sensing data to study the relations between vegetation and cloud cover in the context of land restoration. The Meteosat Second Generation (MSG) satellite provides 20 years of data at a 15 minute temporal resolution. Yet, the spatial resolution of 3 km of the available MSG cloud cover products is relatively coarse to study convective clouds over small vegetated areas. Instead, we apply a statistical algorithm to calculate cloud cover from the MSG High Resolution Visible (HRV) band, in order to obtain cloud cover data on a 1 km resolution. Using this method, we can provide high resolution observational evidence of cloud cover-vegetation relationships across West Africa.Preliminary results show that in Nigeria and Benin, cloud cover frequency is higher in areas with a high vegetation cover than in surrounding areas with a lower vegetation cover. With this study, we provide insight into whether land restoration projects can be used to increase cloud cover and adapt to the negative consequences of global climate change.
Future land use influences on the global monsoon: An energetic perspective
Authors: Fahrenbach Nora L. S. , Jnglin Wills Robert , De Hertog Steven J.
Published: March 2024

Understanding the impact of future land use changes on the global monsoon system is crucial for the economy, water supply and food security. Here, we use future deforestation and afforestation simulations under different SSP scenarios from 10 CMIP6 models participating in the Land Use Model Intercomparison Project (LUMIP). We apply an energy flux potential (EFP) framework to connect shifts in the Intertropical Convergence Zone and regional monsoons to changes in the atmospheric energy transport, and examine the contribution from individual flux components (latent heat flux, sensible heat flux, shortwave and longwave radiation). The linearity of this method allows us to attribute atmospheric EFP changes to different land and ocean regions without the need for additional simulations.We find consistent zonal-mean precipitation shifts over oceanic regions across models in the deforestation and afforestation scenarios. However, changes in the global monsoon (as represented by zonal-mean precipitation changes over land) show large model dependence. The energy flux analysis reveals a consistent mechanism across models: The surface latent heat flux is the dominant driver of land use-induced changes in EFP in the tropics. In most regions and models, an increase in the latent heat flux component of EFP corresponds to tropical precipitation decrease and vice versa.Our regional analysis reveals that remote oceanic energy-budget anomalies are the main contributor to the global EFP patterns and monsoon precipitation anomalies for all models, while land energy-budget anomalies modulate both patterns over land. Decomposing the EFP pattern into the contribution from different land regions indicates model consensus regarding the strong contribution from North and South America to the land-only anomaly, while inter-model differences primarily stem from different model responses to African land use change. These findings highlight the complexity of rainfall shifts to future land use change scenarios and also emphasize the value of the energy flux potential method to quantitatively link remote forcing to regional rainfall changes.
Attributed and projected climate change impacts on maize yield in Cameroon as mediated by heat-tolerance adaptation
Authors: Jansen Lennart , Undorf Sabine , Gornott Christoph
Published: March 2024

Sub-Saharan Africa is projected to be exposed to substantial climate change hazards, especially in its agricultural sector, so adaptation will be necessary to safeguard food security. However, tropical and subtropical maize production regions approach critical temperature thresholds in the growing season already in today’s climate, and climate change might already be contributing to this. Projecting future, and attributing already observed, yield impacts due to anthropogenic climate change under adaptation assumptions can thus provide valuable context to future adaptation needs. No adaptation impact studies currently exist for heat-tolerance of maize in West Africa, let alone one that combines projections and counterfactual historical simulations to this effect.Here, we report on a study in which we focus on maize in Cameroon to model the effect and potential of crop-varietal heat-tolerance adaptation. We use climate reanalysis data (mainly W5E5), historical and counterfactual bias-corrected and downscaled CMIP6-DECK and -DAMIP simulations along with ISIMIP3a data, and future projections from CMIP6/ISIMIP3b. The two climate change scenarios SSP1-2.6 and SSP3-7.0 were analysed for 2020-2100 and historical simulations for 1984-2014.The process-based crop model APSIM was run in a spatially disaggregated, grid-based approach as to represent Cameroon’s diverse agro-ecological zones. The impact of heat tolerance adaptation in maize was assessed by parametrising one unadapted baseline variety and one synthetic heat-tolerant variety in APSIM and comparing yield outcomes.Yields are substantially higher for the heat-tolerant variety. Either variety experience similar losses in the projected future compared to now, increasing with climate change scenario and time. Impacts on maize yield are dominantly attributed to heat stress. Already observed climate change impacts compared to counterfactual climate further indicate that adaptation to present-day climate can be considered climate change adaptation beyond development.
On the analysis of geodetic height changes obtained using different observation techniques at proposed IHRF sites
Authors: Yadeta Samuel Milki , Godah Walyeldeen , Szelachowska Malgorzata , Jarmołowski Wojciech , Wielgosz Paweł
Published: March 2024

The determination of geodetic heights with high accuracy is one of the main tasks in geodesy. In 2015, a resolution for definition of International Height Reference System (IHRS) and its realization by International Height Reference Frame (IHRF) was released by the International Association of Geodesy (IAG). In the recent few years, intensive efforts have been devoted to develop the IHRF and its temporal changes. The main goal of the proposed study is to analyze temporal variations of geodetic height changes at the locations of proposed IHRF sites using data from Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) satellite missions, tide gauges, and space geodetic techniques, i.e. GNSS, SLR, VLBI, and DORIS.Monthly GRACE/GRACE-FO-based Global Geopotential Models were utilized to estimate temporal variations of ellipsoidal height at proposed IHRF sites. Moreover, geodetic height changes were obtained from the aforementioned space geodetic techniques and tide gauge stations that co-located with the proposed IHRF sites. Then, the seasonal decomposition method and Discrete Fourier Transform were implemented to analyze time series of obtained geodetic height change. Based on the results, seasonal and long-term components of geodetic height variations at the proposed IHRF sites were determined, analyzed, and discussed according to the contemporary requirements for the definition of the IHRF, as well as the precise levelling measurements.Keywords: GRACE/GRACE-FO satellite missions, space geodetic techniques, tide gauge, reference system/frame, geodetic height
Evaporation and hydrology of the Orinoco and Amazon basins modulated by the Atlantic
Authors: Duque-Gardeazabal Nicolas , Friedman Andrew R. , Brönnimann Stefan
Published: March 2024

El Niño/Southern Oscillation (ENSO) strongly impacts the hydroclimate of tropical South America. However, other ocean-atmospheric oscillations in the Atlantic also have teleconnections over the continent with the most extensive tropical rainforest; these oscillations influence hydroclimate extremes (i.e. droughts and floods). Our research focuses on the physical mechanisms that link the Atlantic Sea Surface Temperature conditions with the hydrological anomalies, i.e. soil moisture, streamflow and evaporation.This research is grounded on the consistency of a multi-evidence approach between datasets. We use independent observations of land-surface and atmospheric variables whose robustness comes from gauges, physically consistent interpolations (i.e. reanalysis), simulations or satellite-based observations. The research focuses on the satellite era (1980-) to compare several datasets. Apart from the Amazon, other important basins such as the Orinoco, Magdalena and Tocantis have received little attention; hence, we also focused on them.The Atlantic Meridional Mode (AMM) consists of cross-equatorial Sea Level Pressure anomalies that deflect climatological winds northward or southward. Hence, the seesaw of wind anomalies produces anomalous atmospheric transport, convergence and precipitation. When dividing the analysis by independent seasons, the results show changing impacts over different subbasins of the Orinoco and Amazon. On the other hand, the Atlantic El Niño/La Niña (Atl3) weakens or strengthens the trade winds from June to August, producing moisture convergence or divergence over the Guianas and eastern Orinoco.The SST impact on evaporation is a complex consequence of the anomalous atmospheric circulation. The cascade of abnormal atmospheric circulation modifies not just the surface water but also the radiation availability, causing hydrological anomalies. The radiation anomalies combined with the soil moisture memory control the evaporation anomalies. This dynamic also depends on the season analysed.
Dynamical downscaling simulations and future projections of the Arctic Ocean based on FESOM and FIO-ESM.
Authors: Shu Qi , Wang Qiang
Published: March 2024

The Arctic is one of Earth’s regions most susceptible to climate change. Climate models show that in a warming climate, the Arctic Ocean warms much faster than the global ocean mean, mainly due to the rapid warming of the Atlantic layer, which is called 'Arctic Ocean Amplification.' However, climate models still encounter challenges with large biases and considerable inter-model spread in the Arctic Ocean. For example, the Atlantic layer in the Arctic Ocean, simulated by the climate models, is too thick and too deep. This leads to the warming trend, and inter-annual variability of the simulated Atlantic Water that are too small compared to the observations. Here, we present Arctic Ocean dynamical downscaling simulations and projections based on a high-resolution ice-ocean coupled model, FESOM, and a climate model, FIO-ESM. The historical results demonstrate that the root mean square errors of temperature and salinity in the downscaling simulations are much smaller than those from CMIP6 climate models. The common biases, such as the overly deep and thick Atlantic layer in climate models, are significantly reduced by dynamical downscaling. Dynamical downscaling projections show that the Arctic Ocean may warm faster than the projections made by CMIP6 fully-coupled climate models.
Estimation of Sea Ice Production in the North Water Polynya Based on Ice Arch Duration in Winter During 2006–2019
Authors: Hui Fengming , Ren Haiyi , Shokr Mohammed , Cheng Xiao , Li Xinqing , Zhang Zhilun
Published: March 2024

The North Water Polynya (NOW) is the largest recurrent Arctic coastal polynya. The formation of the NOW is critically dependent on the development of an ice arch that defines its northern boundary. In this study, high-resolution ENVISAT Advanced Synthetic Aperture Radar data, Sentinel-1A data, and Moderate Resolution Imaging Spectroradiometer data were employed to identify the spatio-temporal characteristics of the ice arch during 2006–2019. Polynya pixels were identified based on the thin ice thickness (TIT), using a threshold of TIT
External Dynamic Mechanisms Controlling the Periodic Offshore Blooms in Beibu Gulf
Authors: Lao Qibin , Chen Fajin
Published: March 2024

Since offshore waters are less affected by human activities and nutrient-rich water masses, existing theories on periodic offshore blooms (POB) consider that the POB is proportional to the intensity of ocean fronts (nutrient supply from enhancing vertical mixing), ignoring external nutrient supply and external forcing (climatic oscillations). This study proposes an external dynamic mechanism of the POB on the basis of field observations and long-term satellite remote sensing data (1981–2022) in Beibu Gulf, which is influenced by remarkable external forcing. Three water masses, coastal current (CC), West-Guangdong coastal current (WGCC), and South China Sea water (SCSW), were identified using dual water isotopes. The seawater in the gulf mainly originated from CC in summer and fall, while it changed to the SCSW in winter. The nutrient in the gulf was mainly from the CC in summer and fall, while it shifted to the WGCC in winter. Notably, a strong thermal front with an inverted-V structure was found in the central gulf every winter due to the strong wind stress and change of water mass mixing. The intensity of the front on the east side is weaker due to the intrusion of WGCC. However, Chlorophyll-a concentrations in the eastern (nutrients supplied by WGCC) and northern (nutrients supplied by vertical mixing) were obviously higher than that in the western front (limited nutrient supply) in winter. On an interannual scale, the intensity of POB in La Niña years is remarkably stronger than in El Niño years due to the stronger WGCC supplying more nutrients in La Niña. This study suggests that the intensity and range of POB are not proportional to the frontal intensity in the gulf, but are directly driven by the internal forcing (fronts and nutrient supply from WGCC), which is controlled by the external forcing.
Impacts of Marine Heatwave Events on Three Distinct Upwelling Systems and its Implication for Marine Ecosystems in the Northern South China Sea
Authors: Liu Sihai , Lao Qibin , Chen Fajin
Published: March 2024

Under global warming, the frequency and intensity of marine heatwaves are increasing. However, the inhibition of atmospheric forcing marine heatwaves (AMHW) on upwelling and its impact on marine ecosystems remain poorly understood. To address this issue, the satellite sea surface temperature and reanalysis data during 1998-2021 were analyzed in three distinct upwelling systems, northwestern South China Sea. The results showed that the coastal tide-induced upwelling in the west (W) of Hainan Island is primarily suppressed by enhanced stratification during the AMHW events, since the coastal tide-induced upwelling is insensitive to wind weakening. Contrarily, the wind-driven upwelling in the east (E) and northeast (NE) of Hainan Island are jointly regulated by wind and stratification during the AMHW. Specifically, the AMHW events have a stronger inhibitory effect in the upwelling and phytoplankton growth in the NE than that in the E. The causes could be the followings: (1) the background upwelling in the NE region is stronger than in the E, thus the NE region has a higher susceptibility to the wind weakening; (2) the wind-driven upwelling begins to be suppressed by AMHW when the high-pressure system is aligned with the coastline of the upwelling. In the NE region, the location of the high-pressure center during the occurrence of AMHW is positioned in closer proximity to the upwelling area. Moreover, the inhibitory effect of wind weakening and stratification enhancing on upwelling changes with the development of the AMHW. Before and during the mature phase of AMHW, stratification and wind jointly inhibit upwelling and phytoplankton growth, while it shifts to stratification dominated (>85%) during the decline phase. This study suggests that MHW has a great impact on the upwelling ecosystem, especially the wind-driven upwelling, which should be given high attention under global warming (with increasing MHW events in the future).
Fine Structures of Radio Bursts from Flare Star AD Leo with FAST Observations
Authors: Zhang Jiale , Tian Hui
Published: March 2024

Radio bursts from nearby active M-dwarfs have been frequently reported and extensively studied in solar or planetary paradigms. Whereas, their substructures or fine structures remain rarely explored despite their potential significance in diagnosing the plasma and magnetic field properties of the star. Such studies in the past have been limited by the sensitivity of radio telescopes. Here we report the inspiring results from the high time-resolution observations of a known flare star AD Leo with the Five-hundred-meter Aperture Spherical radio Telescope. We detected many radio bursts in the 2 days of observations with fine structures in the form of numerous millisecondscale sub-bursts. Sub-bursts on the first day display stripe-like shapes with nearly uniform frequency drift rates, which are possibly stellar analogs to Jovian S-bursts. Sub-bursts on the second day, however, reveal a different blob-like shape with random occurrence patterns and are akin to solar radio spikes. The new observational results suggest that the intense emission from AD Leo is driven by electron cyclotron maser instability, which may be related to stellar flares or interactions with a planetary companion.
Characteristics and Mechanisms of Typhoon-Induced Decomposition of Organic Matter and Its Implication for Climate Change
Authors: Chen Fajin , Lao Qibin
Published: March 2024

Typhoons are extreme whether events that can not only affect marine dynamics, but also change marine biogeochemistry, which greatly impact on the marine eco-environment and climate. Recently, we reported that decomposition (as a carbon source) of organic matter (OM) is the dominant process in coastal waters after typhoons, which is contrary to phytoplankton blooms (as a carbon sink) in previous studies. The decomposition directly affects the global carbon and nitrogen cycles, and the efficiency of the biological pump and global climate change. Yet, the mechanisms of OM decomposition after typhoons and the question of whether the decomposition is mainly of particulate organic matter (POM) or dissolved organic matter are still unclear. To address these issues, more than ten typhoons with different intensity, moving speed, and path of the typhoon were chosen, and physicochemical parameters and multiple isotopes in the coastal waters were measured before and after typhoons. The results showed that not all typhoons can trigger phytoplankton blooms in the oceans, which mainly depends on the supply of nutrients after typhoons. However, a positive apparent oxygen utilization value occurred in the coastal waters, suggesting that decomposition of OM was the dominant biogeochemical process regardless of whether phytoplankton blooms occurred after the typhoon. Despite the overall larger DOM in the water column, the amount of POM removed by typhoon-induced decomposition is much greater than that of DOM. Our study suggests that typhoon-induced decomposition might be dominated by POM, which is not conducive to the storage of OM in sediments. It means that the capacity of sediments as a carbon sink will be weakened under global warming (increasing typhoon events).
Global technical, economic and ecological performance of different solar photovoltaic modules 
Authors: Shao Changkun , Yang Kun , Zhang Xinyao
Published: March 2024

Bifacial solar modules and solar trackers are experiencing worldwide rapid development, and they are proven to be effective in increase solar power generation. This study presents a comprehensive worldwide assessment on technical and economic potential of combination of mono or bifacial photovoltaic modules with different solar trackers based on a high-quality long-term solar radiation dataset and a physical model chain. Impact factors such as topography, land suitability, etc. were taken into consideration when evaluating electricity generation potential. Overall, bifacial photovoltaic modules can increase power generation and lower levelized tariffs globally. Solar trackers can increase the efficiency of PV panels, but reduce the total power generation due to lower land utilization. Fixed bifacial modules contributed the highest total global power generation of 2217 PWh and the lowest average global levelized cost of electricity of 3.6. The spatial distribution of the optimal PV module and solar tracker combination is also revealed by this study. Furthermore, there is a significant mismatch between energy generation and demand, despite the fact that total global electricity generation potential far exceeds total electricity demand. Countries with 70% of the total generation potential consume less than 20 % of the demand. Distributed PV may contribute to solving this problem. As for the environmental and ecological impact, the global carbon reduction and loss in ecosystems service values are 1205 million Mt and 3244 million dollars per year, respectively. The Sahara Desert and Western Asia, with high power generation potential and low ecological costs, serve to be hotspots for photovoltaic. This study providing guidance for selecting, sitting and deploying different solar modules combination, and emphasize the ecological and environmental impact of solar panels.
Crucial role of ocean dynamics for the CMIP models equatorial Pacific warming pattern diversity
Authors: Danielli Vincent , Lengaigne Matthieu , Kwatra Sadhvi , Suresh Gopika , Vialard Jérome
Published: March 2024

Coupled Model Intercomparison Project (CMIP) projections indicate a distinct future warming pattern in the tropical Pacific, with enhanced warming in the equatorial Pacific (resembling El Niño warming) and subdued warming in the southeast tropical Pacific. There is currently no consensus on the mechanisms shaping this pattern and its inter-model diversity.Here, we employ the Sea Surface Temperature (SST) heat budget proposed by Zhang and Li (2014, ZL14), adapted to Relative SST (SST minus its tropical average), a proxy for atmospheric stability and circulation changes. This approach helps uncover the mechanisms that shape the tropical Pacific Multi-Model Mean (MMM) warming pattern and its diversity across historical and unmitigated scenario (RCP85 and SSP585) simulations from 53 CMIP5 and CMIP6 models.We find that the MMM southeast Pacific relative cooling arises from locally intensified winds, leading to increased latent heat flux cooling. This process also explains the inter-model diversity in this region, alongside the diversity of cloud feedbacks.Consistent with ZL14 conclusions, our results underscore that the MMM equatorial Pacific relative warming results from a less efficient evaporative cooling feedback over the climatologically cooler central and eastern Pacific. However, our study highlights a pivotal role of ocean dynamics in driving the equatorial Pacific relative warming inter-model diversity. In the eastern Pacific, this diversity is related to the cold tongue bias, with a stronger cold tongue bias leading to a more efficient thermostat mechanism that dampens the MMM relative warming. In the western Pacific, diversity is related to the intensity of the equatorial trade winds relaxation, with stronger westerly anomalies leading to enhanced warming, suggesting a strong role of the Bjerknes feedback.These results advocate for more comprehensive studies using dynamical approaches to better understand the respective roles of the Bjerknes feedback and cold tongue bias in the equatorial Pacific warming pattern and, ultimately, in the Walker Circulation changes.
Do earthquakes cause more damage in the summer?
Authors: Fokker Eldert , Ruigrok Elmer , Trampert Jeannot
Published: March 2024

Shallow soft sedimentary layers overlaying harder bedrock are known to amplify ground motion generated by earthquakes. Such an amplification occurs when seismic waves travel from high impedance (density times wave speed) to low impedance layers. Large impedance contrasts can lead to substantially larger earthquake damages. As the impedance contrast determines the amplification factor, variations in shallow shear-wave speed contribute directly to changes in site amplification.Seasonal temperature fluctuations have been shown to induce shear-wave speed variations and, hence, affect site amplification factors. This naturally leads to the question: is the strength of earthquake damage season dependent? In this study we model by how much seasonal temperature variations affect site amplification. The site-specific physical properties determine whether site amplification is more pronounced during summer or winter. For parameters from the Groningen region of the Netherlands, affected by the gas extraction induced seismicity, we expect in the summer a relative increase in amplification of 8% with respect to the amplification factor in the winter.
Global South most affected by socio-ecosystem productivity decline due to compound heat and flash droughts
Authors: Gu Lei , Fischer Erich , Yin Jiabo , Slater Louise , Sippel Sebastian , Knutti Reto
Published: March 2024

Flash droughts (FDs) and heatwaves are posing disproportionate biophysical and social losses worldwide, particularly threatening the disadvantaged communities in the Global South. However, the underlying physical mechanisms behind compound heat-flash drought (CHFD) events and their impacts on global socio-ecosystem productivity remain elusive. Here using satellites, reanalysis, reconstructions, and field measurements, we find more dry regions (53%~62%) with above-average ratios of FDs accompanied by extreme heat than humid regions (50%~57%), due to asymmetric effects by synoptic weather systems. The CHFDs associated with strong soil moisture-temperature coupling aggravate the constraint on plant photosynthesis in dry regions, whereas this coupling-related vegetation stress is not significant in humid regions. We further develop a global risk framework that integrates CHFD hazards, population/agriculture exposures, and vulnerability, and find the Global South is the primary region affected by CHFDs, contributing to greater-than-usual carbon uptake reduction, 90%~94% and 76%~86% of risks to world population and agriculture over the past four decades. We reveal the Global South is severely affected by the impacts of CHFDs on socio-ecosystem productivity decline and underscore the importance of efforts to monitor, predict, and mitigate the rise in CHFDs. 
Atmosphere injection of sea salts during the 15 January 2022 submarine eruption of Hunga volcano, Tonga
Authors: Colombier Mathieu , Ukstins Ingrid A. , Tegtmeier Susann , Scheu Bettina , Cronin Shane J. , Thivet Simon , Paredes‑Mariño Joali , Cimarelli Corrado , Hess Kai-Uwe , Kula Taaniela , Latu’ila Folauhola H. , Dingwell Donald B.
Published: March 2024

The 15 January 2022 submarine eruption at Hunga volcano was the most explosive volcanic eruption in 140 years. It involved exceptional magma and seawater interaction throughout the entire submarine caldera collapse. The submarine volcanic jet breached the sea surface and formed a subaerial eruptive plume that transported volcanic ash, gas, sea salts and seawater up to ~ 57 km, reaching into the mesosphere. We document high concentrations of sea salts in volcanic ash collected shortly after deposition. We discuss the potential climatic consequences of large-scale injection of salts into the upper atmosphere during submarine eruptions. Sodium chloride in these volcanic plumes can reach extreme concentrations, and dehalogenation of chlorides and bromides poses the risk of long-term atmospheric and weather impact. We also discuss high concentrations of Ca-sulfates, originating from both seawater-ash interaction and gas scavenging of SO2 within ash aggregates. The discrepancy between the SO2 measured by satellites and values expected from degassing may be explained by a combination of such SO2 uptake and additional SO2 release to the sea via passive degassing prior to the eruption or with ejecta in submarine gravity currents. The balance between salt loading into the atmosphere versus deposition in ash aggregates is a key factor in understanding the atmospheric and climatic consequences of submarine eruptions.
Balloon drift estimation and improved position estimates for radiosondes
Authors: Voggenberger Ulrich , Haimberger Leopold , Amgrogi Federico , Poli Paul
Published: March 2024

When comparing model output to historical radiosonde observations, it is typically assumed that the radiosonde has ascended directly above its launch site and has not been moved by the wind. The introduction of Global Navigation Satellite System (GNSS) receivers on radiosondes in the late 1990s has led to a recent change in the availability of balloon trajectory data. However, this information was still not always transmitted, despite being the basis for estimating wind. Radiosondes can drift a few hundred kilometres, especially in mid-latitudes during winter months, depending on conditions and time of year. Position errors may result in significant representation errors when assimilating corresponding observations.We have developed a methodology to calculate changes in balloon position during vertical ascent using limited information, such as the vertical wind profile in historical observation reports. The investigation analysed the method's sensitivity to various parameters, including the vertical resolution of the input data, the assumption about the vertical ascent speed of the balloon, and the departure of the Earth's surface from a sphere. To validate the method, modern GNSS sonde data reports were considered, which provided the full trajectory of the balloon and the estimated wind. The evaluation was conducted by comparing the results with ERA5 and conducting low-resolution data assimilation experiments. The study evaluated the accuracy of reconstructing the trajectory of radiosonde using original data of varying vertical resolution. The results indicate that the accuracy of the reconstructed trajectory can be improved by using more accurate balloon positions, which reduces both representation and systematic errors.Radiosonde measurements have a wide range of applications, including near-real-time use by forecasters and Numerical Weather Prediction (NWP), as well as for air pollution and other scientific investigations, such as climate monitoring. The production of climate reanalyses that directly assimilate radiosonde observations, such as ERA5, is expected to benefit from more accurate historical balloon position data, similar to NWP. 
Complex Multi-Stage Replacement Reactions in the REE-CaCO3 System
Authors: Maddin Melanie , Rateau Remi , Szucs Adrienn Marie , Terribli Luca , Rodriguez-Blanco Juan Diego
Published: March 2024

Rare earth elements (REE) are essential in many green, modern technologies and play a critical role in a more sustainable future [1]. However, there is a substantial risk to their supply as the availability of REE deposits with minable concentrations are limited [2]. A better understanding of the mechanisms controlling REE concentration in minerals would have applications in more efficient practices as well as REE separation techniques and recycling.Our study investigated the reaction of multi-component REE (La, Ce, Pr, Nd, and Dy) aqueous solutions with carbonate grains of dolomite, aragonite and calcite at hydrothermal conditions (21-210 °C). Two different solutions were prepared (i) a solution with equal concentrations of each of the five REE: (ii) a solution with the concentrations of the five REEs normalized to a Post Archean Shale standard (PAAS), to mimic the rare earth element concentrations in continental crust and natural fluids.The interaction between the REE bearing fluids with each of the carbonate grains resulted in the replacement of the host carbonate grain with a series of REE minerals following a complex crystallization sequence (lanthanite → kozoite → bastnasite → cerianite). We have found that for most of the experiments at 165 °C, when using the equal concentration solutions, the crystallization of kozoite was promoted and the REE ratio in the newly formed solids was similar to the REE ratio in solution. In contrast, when PAAS solutions were used, REE-bearing crystals were zoned or had a heterogenous distribution of REEs, often coupled with the formation of discreet REE phases (e.g., cerianite). In addition, chemical signatures indicating the presence of metastable REE-bearing phases that transformed to more thermodynamically stable polymorphs were found in multiple samples as well as symplectite textures formed by the reaction of adjacent phases. Overall, our experiments demonstrate that the polymorph selection, crystallization pathway, the kinetics of mineral formation and the chemical texture of the newly formed rock during the mineral-fluid interaction process are dependent on the REE concentrations in solution, their ionic radii, temperature, time, and solubility of the host grains. References [1] Sinding-Larsen, R., Wellmer, F.W.,. Non-renewable resource issues: Geoscientific and societal challenges, Non-Renewable Resource Issues: Geoscientific and Societal Challenges 2012.[2] Jordens, A., Cheng, Y.P., Waters, K.E.,. A review of the beneficiation of rare earth element bearing minerals. Miner. 2013 Eng. 41, 97-114.