bluuebunny/crossref_metadata_2025 huggingface dataset:
Cryosphere changes and their impacts on regional water resources in the Chinese Altai Mountains from 2000 to 202
Authors: Wang Puyu
Published: March 2024

The cryosphere has an important impact on regional water resources and ecosystems in the Chinese AltaiMountains and its piedmont zone. Using the latest remote-sensing datasets of cryosphere changes and combiningwith in-situ observation data from glacier monitoring stations and snow cover surveys, the main cryosphereelements including glaciers, snow cover, and permafrost are investigated with emphasis on their changes since2000 and the current situation. Their water resource effects are also discussed. The results indicate that althoughthe glaciers in the region have experienced continuous and intensive melting, mass loss has slowed because bothglacier area shrinkage and thickness reduction were larger during 2000–2010 than during 2010–2021. Snowcoverwater equivalent (w.e.) has increased due to obvious increases in snow depth, although snow-coverarea has decreased slightly. Permafrost has been degrading. Overall, cryosphere contributions to the regionalwater resource are approximately 40.9% since 2000, among which snow-cover melting is the largest, contributing37.1% to water resources in the Irtysh River Basin and significantly more in the mountainous sub-basinswith increased snowfall. Glacier melting contributes 2.9%~3.4%, lower than earlier estimations of 3.4%~3.6% for the late 20th century. Permafrost thaw caused by active layer thickening contributes approximately0.59%. Meteorological data shows a warming and wetting trend, but summer temperature has a much lowerincrease rate and a slowing increase trend after 2013. Moreover, snowfall frequency has increased. In the future,glacier water resource contribution will continue to decrease, but the water resource effects of snow-covermelting and permafrost degradation would increase.
Decrease in fossil fuel CO2 emissions during COVID-19 lockdowns based on  Δ14CO2 observation
Authors: Niu Zhenchuan
Published: March 2024

Radiocarbon can be used as an independent and objective tracer to evaluate fossil fuel CO2 (CO2ff) emissions, because of its complete depletion in fossil fuel sources. Here, we present a study on the CO2ff emissions reduction during the COVID-19 lockdowns in 2020 based on atmospheric Δ14CO2 observation at Chinese background sites. We observed obvious enhancements (several per mill to dozens of per mill) of atmospheric Δ14CO2 during the COVID-19 lockdowns compared with that in the same period. A preliminary analysis showed that these enhancements indicate several percepts to dozens of percents CO2ff emissions reduction from Eurasia (exclude China) and different parts in China during the COVID-19 lockdowns.
Arctic sea ice loss and La Niña as precursors of extreme East Asian cold winters
Authors: Jang Yeon-Soo , Lim Hyung-Gyu , Jun Sang-Yoon , Kug Jong-Seong
Published: March 2024

Despite current global warming due to increasing greenhouse gases, severe cold winters have devastated the East Asia in recent decades. Efforts are being made to predict cold events using dynamic models and physically-based statistical models. In this study, we explore the potential predictability of the East Asian winter surface temperature by establishing a multiple linear regression model based on three precursors of time-evolved preconditions: 1) autumn Arctic sea-ice loss, 2) northern Eurasian sea level pressure pattern, and 3) the El Niño-Southern Oscillation (ENSO). Reduced autumn Arctic sea-ice was favorable for extreme cold events in the East Asia. Furthermore, the autumn Arctic sea-ice loss was accompanied by cyclonic circulations over northern Eurasia in November, which could have led to cold anomalies over the East Asia in the late winter. The preconditioning deep convection in La Niña events is a well-known indicator of exerted atmospheric wave propagation, resulting in cold winters over the East Asia. We suggested here that by combining Arctic sea-ice, atmospheric circulations, and ENSO, the predictability of East Asian winter surface temperature variability could be improved.
Tectonothermal constraints on the early-stage orogenic wedge formation along the Arabia-Eurasia suture zone in the NW Zagros orogenic belt
Authors: Koshnaw Renas , Kley Jonas , Dunkl István , Ameen Fadhil , Vasilyan Davit
Published: March 2024

Deep earth geodynamic processes shape surface geology, topography, and the earth’s crust evolution with consequences on erosion, deposition, climate, and biogeography. This research investigates the early-stage growth of the NW Zagros belt in the Kurdistan region of Iraq after the early Oligocene Arabia-Eurasia collision and the geologic signatures of potential SE-ward propagating Neotethys slab tearing. We will test two end-member hypotheses: (i) the slab has already detached, causing subsidence before slab tearing, followed by rapid regional uplift in the vicinity of the suture zone afterward, or (ii) the slab is still attached, causing no pulse of significant hinterland uplift but continuous regional lower plate subsidence. In the NW Zagros belt, where the Arabian and Eurasian plates are sutured along the Main Zagros fault, allochthonous thrust sheets of ophiolitic and arc-related terranes were emplaced onto post-collisional autochthonous units of clastic and lower-middle Miocene shallow marine carbonate rocks, now at ~1-1.5 km elevation. The allochthonous thrust sheets host pre-collisional acidic and mafic intrusions that provide exhumation rate constraints throughout collision, whereas the post-collisional marine carbonate rocks attest to a significant suture zone subsidence and uplift. Thermal history modeling of bedrock samples using zircon and apatite (U-Th)/He thermochronometers suggests an early uplift during ~30-25 Ma, with most apatite (U-Th)/He samples being reset during ~15-10 Ma. To quantitatively determine the depositional age of the lower-middle Miocene marine carbonate rocks, 87Sr/86Sr isotope chronstratigraphy will be conducted. Furthermore, the isopach maps of the middle and upper Miocene foreland deposits show a notable shift in the depocenter axis and an enhanced subsidence toward the SE, concurrent with the arrival of the Afar plume to the suture zone in the NW. These preliminary results argue for the formation of the NW Zagros orogenic wedge as early as ~30-25 Ma, followed by suture zone subsidence during the early-middle Miocene and then uplift again during ~15-10 Ma, possibly due to initiation of Neotethys slab-tearing and its subsequent propagation along the suture zone from the NW to the SE. These findings have implications for investigating the role of the Arabia-Eurasia land bridge formation and deformation on vertebrate distribution and paleoclimate response to orographic barrier development since the late Miocene in the Middle East.
Latitudinal distribution of biomarkers across the western Arctic Ocean and the Bering Sea: an approach to assess sympagic and pelagic algal production
Authors: Bai Youcheng , Sicre Marie-Alexandrine , Ren Jian , Klein Vincent , Jin Haiyan , Chen Jianfang
Published: March 2024

The drastic decline of Arctic sea ice due to global warming and polar amplification of environmental changes in the Arctic basin profoundly alter primary production with consequences for polar ecosystems and the carbon cycle. In this study, we use highly branched isoprenoids (HBIs), brassicasterol, dinosterol and terrestrial biomarkers (n-alkanes and campesterol) in surface sediments to assess sympagic and pelagic algal production with changing sea-ice conditions along a latitudinal transect from the Bering Sea to the high latitudes of the western Arctic Ocean. Suspended particulate matter (SPM) was also collected in surface waters at several stations of the Chukchi Sea to provide snapshots of phytoplankton communities under various sea-ice conditions for comparison with underlying surface sediments. Our results show that sympagic production (IP25 and HBI-II) increased northward between 62°N and 73°N, with maximum values at the sea-ice edge in the Marginal Ice Zone (MIZ) between 70°N and 73°N in southeastern Chukchi Sea and along the coast of Alaska. They were consistently low at northern high latitudes (>73°N) under extensive summer sea-ice cover and in the Ice-Free Zone (IFZ) of the Bering Sea. Enhanced pelagic sterols and HBI-III occurred in the IFZ across the Bering Sea and in southeastern Chukchi Sea up to 70°N-73°N in the MIZ conditions that marks a shift of sympagic over pelagic production. In surface water SPM, pelagic sterols display similar patterns as Chl a, increasing southwards with higher amounts found in the Chukchi shelf pointing out the dominance of diatom production. Higher cholesterol values were found in the mid-Chukchi Sea shelf where phytosterols were also abundant. This compound prevailed over phytosterols in sediments, compared to SPM, reflecting efficient consumption of algal material in the water column by herbivorous zooplankton.
Cool Skin Effect and its Impact on the Computation of the Latent Heat Flux in the South China Sea
Authors: Zhang Rongwang
Published: March 2024

The cool skin effect, known as the temperature difference (ΔT) across the skin layer of sea surface, is of vital importance for the accurate computation of the latent heat flux (LHF). The observed features of ΔT in the South China Sea are analyzed using in situ data from a buoy platform over an approximately six-week period. Only nighttime data are used to exclude the possible warm layer effect. The positive values of ΔT falling into the range of 0 to 1 K comprise 95% of the data, and the most frequently observed values occur in the range of 0.4 to 0.6 K (38%). The cool skin model in the COARE 3.0 algorithm is then validated against those observations. The cool skin model has an efficient but insufficient ability to reduce the overestimation of the LHF. The overestimation of the LHF is reduced to 9.5% from 18.0%, leaving nearly half of the biases in the LHF unresolved. The Saunders constant (λ) in the cool skin model is markedly underestimated, leading to a much weaker prediction of ΔT. A strong linear relationship exists between the mean values of λ and the LHF with a slope of -0.9 W m-2. With an approximately doubled λ, the biases in ΔT and in the LHF could be eliminated. Considering the possible uncertainties in sensors, the value of λ is estimated as 11.6±6.7 in the current study.
Investigating Stratospheric Wave Reflection Events and their Implications for Northern Hemisphere Circulation
Authors: Schutte Michael , Messori Gabriele
Published: March 2024

Stratospheric wave reflection events involve the upward propagation of planetary waves, which are subsequently reflected downward by the stratospheric polar vortex. This unique phenomenon establishes a crucial connection of large-scale atmospheric dynamics between the troposphere and stratosphere. In this study, wave reflection events are defined via increased poleward eddy heat flux over the Northwest Pacific and increased equatorward eddy heat flux over Canada. While previous research has pointed out a link between these events and an abrupt temperature decrease across North America, the dynamical mechanisms remain less clear. In order to advance the comprehension of the large-scale atmospheric dynamics during stratospheric wave reflection events, meridional eddy heat flux, Rossby wave activity and geopotential height are studied. Around the end of stratospheric wave reflection events an oscillation in meridional eddy heat flux towards opposite values is present over the Northwest Pacific and Canada in the upper troposphere and stratosphere. A westward-propagating ridge, associated with a positive anomaly of geopotential height, and development of a trough downstream can explain this oscillation. East of the ridge, colder air than usual is advected southwards in the lower troposphere over North America. This results in different anomalies of meridional eddy heat flux closer to the surface compared to the upper troposphere. The large-scale circulation anomalies align vertically from the lower troposphere up to the stratosphere and mirror the shift from a Pacific Trough to an Alaskan Ridge. Furthermore, stratospheric wave reflection events exert a far-reaching influence on atmospheric circulation across the mid-latitude and polar Northern Hemisphere. One example is the occurrence of windy extremes over Europe together with changes in mid-latitude jet stream position and strength over the Atlantic at the same time as the temperature decreases to below average values over North America.
Integrating Disaster Risk Reduction and Climate Change Adaptation: A Critical Review on Methodologies Addressing Multi-Hazard Risks
Authors: Lukman Cicilia Steffi , Huang-Lachmann Jo-Ting
Published: March 2024

In recent years extreme climate events have been increasing in frequency and severity. Multi-hazard risks and its cascading effects cause higher economic and non-economic losses, such as human lives and declines in people’s well-being. This brings forward the need for improvement in disaster risk reduction measures, including the transition from a response-based to a preventive-based measures to minimize the loss in the future. However, adaptation measures differ based on the local context, which also means one methodology in assessing disaster risk reduction in one area might be different to another. This paper will analyse the existing assessment methodologies addressing the measures taken in reducing multi-hazard risks, taking into consideration the local characteristics where the methodology is applied, the type of multi-hazards, the most effected sectors and vulnerable groups, the future scenarios considered, and the costs and benefits of the measures which are included in the assessment. The type of hazards considered in this paper are based on The HuT Nexus Project, including forest fires, landslides, droughts, heatwaves, floods, and storm-surges. The aim of this paper is to review the methodologies of disaster risk reduction and climate change adaptation assessment and analyse the strengths and weaknesses thus enhancing the possibility to be transferred and adapted in other case studies.
Targeted Observations on Arctic Sea Ice Concentration for Improving Extended-range Prediction of Ural Blocking
Authors: Gao Yangjiayi , Mu Mu , Dai Guokun
Published: March 2024

The predictability of certain extreme weather events can exceed the traditional two weeks by considering the boundary conditions. Targeted observations in sensitive areas on Arctic sea ice concentration (SIC) can improve the extended-range (4 pentads) forecast skills of long-lasting and strong Ural blocking (UB). The sensitive areas are determined based on the SIC optimally growing boundary errors, obtained by the conditional nonlinear optimal perturbation method. The sensitive areas are mainly located in the Barents Sea, Greenland Sea, and Okhotsk Sea. The results of observing system simulation experiments for 8 UB cases indicate that the targeted observations can remarkably improve the prediction skills of UB in the 4th pentad. Targeted observations have a positive effect on 75% of 160 experiment members, reduce 35% forecast errors of the 4th pentad mean blocking index, and perform even better when the original forecast errors are greater. Further diagnosis shows that targeted observations contribute to more accurate SIC boundary conditions in the Barents Sea, Greenland Sea, and Okhotsk Sea and reduce temperature errors in the lower and middle troposphere. It further results in well-described westerly winds in the Ural region and its adjacent regions, corresponding to the more skillful predictions of blocking circulations. The above results supply a theoretical base for the design of Arctic SIC observations and more skillful extended-range predictions for mid-latitude extreme weather.
Identification of thresholds to conduct efficient soils and water conservation strategies against erosion impacts: new insights from a modelling prospective in Normandy (France)
Authors: Maurié Aurélien , Patault Edouard , Ledun Jérôme , Deman Marielle , Fournier Matthieu
Published: March 2024

Erosion is recognized as a major threat worldwide and can be dramatically observed in Northwestern France as a consequence of water runoff. Recent regional studies in Normandy suggested that off-site erosion and runoff impacts led to significant economic costs over the last 25 years. Even if the regional planning strategy against erosion and runoff impacts could be seen as effective with a cost-benefice balance greater than 1, this strategy will no longer be as effective by 2050 due to climate change effects in the near future. To address this issue and conduct efficient land and water degradation neutrality strategies, local stakeholders now have to identify complementary strategies based on the deployments of nature-based solutions. However, there is a lack of references on the effectiveness of these complementary strategies.In this study, we conducted a modelling exercise with the WaterSed model at the regional scale (12,318 km²) aiming to: (i) quantify the hydro-sedimentary transfers reaching the karstic systems throughout the 15,000 sinkholes distributed across the territory, (ii) established the first regional cartography of vulnerability of sinkholes to runoff and erosion, and (iii) to evaluate the effectiveness of strategies considering nature-based solutions to prevent land and ground water degradation.The model was calibrated and validated using data of hydro-sedimentary transfer monitoring station on a local catchment. Multiples scenarios were explored (impacts of different nature-based solutions densities, localization of grasslands, ploughing of grass lands, soil and water conservation techniques, etc.) using semi-automatic positioning algorithm.The WaterSed model provided specific outputs like volume of runoff (m3) and volume of sediments (t) reaching the karstic system for different designed storms. The mean runoff per sinkhole was estimated between 7,700 and 23,200 m3 and the mean volume of sediment reached between 0.8 and 4.7 t per sinkhole.Our results suggest that increasing the density of nature-based solutions from 2 to 8 per km² can reduce from 0.5 to 1.3 % the runoff volume and from 5 to 15 % the sediment load reaching the sinkholes. Our results also suggest that a complement of 20 m to 250 m of grassland upstream a sinkhole can reduce the sediment load from 5 to 13 % and the runoff from 0.5 to 1.5 %. Our results suggest that the localization of ploughed-up grasslands can have a significant impact on the generation of hydro-sedimentary transfers (up to 10 % more sediment discharge).The results of this modeling exercise provided: (i) the first regional cartography of vulnerability of the 15,000 sinkholes to runoff and erosion, and (ii) local thresholds and valuable references to build and conduct efficient land and ground water degradation neutrality strategies with stakeholders.
Impact of ocean vertical mixing parametrization on sea ice properties using NEMO-SI3 model in the Arctic Ocean
Authors: Allende Sofia , Treguier Anne Marie , Lique Camille , de Boyer Montégut Clément , Massonnet François , Fichefet Thierry
Published: March 2024

In recent decades, global climate change has strongly affected the Arctic region, leading to a rapid decline in sea ice extent. This decline affects the interactions between sea ice, the atmosphere, and the ocean, driven by complex thermodynamic and dynamical processes. The Arctic mixed layer (ML), located in the upper ocean, plays a key role in regulating the interactions between the deep ocean, sea ice, and the atmosphere. This region is strongly affected by exchanges of mass (such as freshwater and saltwater fluxes) and momentum driven by various forces like ocean currents, tides, waves, and winds. Here, we study the ad-hoc vertical turbulent kinetic energy (TKE) mixing scheme within the NEMO-SI3 model. Specifically, we focus on the influence of surface and internal wave breaking in sea ice-covered regions. The critical parameters are the fraction of surface TKE that penetrates below the ML, the nature of the exponential TKE penetration decrease beneath the ML, and the damping effect on Langmuir and surface wave breaking beneath the ice cover. We aim to assess how these parameters affect the ML and various sea ice properties.Our findings reveal significant impacts on Arctic sea ice thickness under two scenarios: when ice cover does not affect wave dynamics and when the mixing process weakens. Stronger mixing leads to a deeper ML and reduced sea ice thickness by 30 to 40 centimeters, while weaker mixing results in a shallower ML and a moderate sea ice increase of 10 to 20 centimeters. Results also show that reduced sea ice models exhibit a larger volume of freshwater content in the ocean with consistent spatial patterns. Conversely, increased sea ice simulations reveal reduced freshwater content, although clear spatial patterns are not evident. Differences in upper ocean properties, particularly in ocean stratification, highlight the significant impact of strong sea ice attenuation in the mixing parametrization. These findings underscore the substantial influence of enhanced ocean mixing on the physical properties of ocean and sea ice.
Millions of years of landslides in the Patagonian tableland
Authors: Pánek Tomáš , Kilnar Jakub , Břežný Michal , Winocur Diego
Published: March 2024

Dating the lifespan of slow-moving landslides poses a major challenge, typically limited to the most recent slope evolution within maximally 103 to 104 years. The Patagonian tableland, characterized by plateau basalts overlying weak sedimentary and volcaniclastic rocks, ranks among Earth's largest landslide provinces. Certain contiguous landslide areas, shaped mainly by rotational slides and spreads, exceed 1000 km2, affecting hundreds of kilometers of mesa escarpments. Our new landslide mapping in eastern Patagonia has allowed us to establish an unprecedentedly long history of landslide evolution, utilizing cross-cutting relationships with dated chronological markers such as glacial moraines and trimlines, lacustrine and marine paleoshorelines, and lava flows. Our findings indicate that the escarpments of the Patagonian plateaus primarily evolved in a retrogressive mode. Both mesas within (or nearby) and outside Pleistocene ice limits involve landslides with topographic footprints that have persisted for over 1 Ma; the oldest documented landslide rim is overlain by a lava flow with a 40Ar/39Ar age exceeding 5 Ma. Even in the most arid parts of the Patagonian tableland, repeated landslide reactivations occurred in the Quaternary, including the Late Holocene. In the western glaciated area, this is likely due to glaciation/deglaciation pulses, while in the eastern extraglacial part, it is probably associated with wetter periods linked to the strengthening of the eastern Atlantic circulation. We conclude that the Patagonian tableland boasts the longest documented landslide topographic footprints on Earth. Future research should prioritize high-resolution (direct radiometric) dating of landslide (re)activations and their correlation with paleoenvironmental changes.
Wind Steering of Mid-latitude Eastern Pathway of AMOC
Authors: Gu Sifan , Liu Zhengyu , Zou Sijia , Zhang Shaoqing , Yu Yangyang , He Chengfei
Published: March 2024

The spreading pathway of the North Atlantic Deep Water (NADW), which is the lower limb of the Atlantic Meridional Overturning Circulation (AMOC), determines how climate change signals are transported throughout the global ocean. NADW is suggested to be transported from the subpolar Atlantic to the subtropics in the western basin by the deep western boundary current and the eddy-driven interior pathway west of the Mid-Atlantic Ridge (MAR). However, much less attention has been paid to AMOC cross-gyre transport in the eastern basin. Here, combining hydrographic observations and reanalysis, we identify a robust mid-depth Eastern Pathway located east of the MAR, which is further corroborated by model simulations with various resolutions, including eddy-resolving simulations. The Eastern Pathway accounts for half of the NADW transport across the intergyre boundary. Sensitivity experiments suggest that the mid-depth Eastern Pathway is formed by basin-scale ocean circulation dynamics due to wind steering on the intergyre communicating window instead of bottom topography. Our results provide a new paradigm for the AMOC pathway and call for further investigations on the climate response and variabilities associated with different AMOC pathways.
Quantifying the potential impacts of climate change on streamflow intermittence in Europe
Authors: Abbasi Mahdi , Döll Petra
Published: March 2024

Even in Europe, rivers and streams cease to flow during some time of the year. Little is known about these intermittent waterways at the continental scale because the spatial distribution of streamflow gauges is biased in favor of perennial river reaches. In our study, undertaken in two phases, we initially employed a two-step Random Forest (RF) modeling approach to predict the monthly time series of streamflow intermittence at a high spatial resolution across approximately 1.5 million European river reaches spanning the period from 1981 to 2019. Important predictors were computed from time series of monthly streamflow in 15 arc-sec (high-resolution HR) cells that were derived by downscaling the 0.5° (low-resolution LR) output of the global hydrological model WaterGAP. To set up the RF model, we utilized daily time series data of observed streamflow from 3706 gauging stations as the target variable, and incorporated a comprehensive set of 23 dynamic and static hydro-environmental variables as predictors. We computed that 3.8% of all European reach-months and 17.2% of all reaches were intermittent during 1981-2019.In the subsequent phase, we implemented the developed RF model to quantify alterations in streamflow intermittence that may occur due to future climate change. This involved utilizing the bias-adjusted output of five Global Climate Models (GCMs) from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3b) and two Representative Concentration Pathway (RCP)-specific runs (ssp126 and ssp585). The reference period spans from 1985 to 2014, with projections for two future periods (2041-2070, 2071-2100).We downscaled the LR output of WaterGAP runs driven by the different climate model output and recomputed the predictors that depend on WaterGAP output to generate predictor for the climate change impact assessment. Subsequently, we computed the intermittence status (classified as 0, 1-5, 6-15, 16-29, and 30-31 no-flow days in a month) for each reach-month across Europe by applying the developed RF models.Finally, we established various indicators, such as changes from intermittent to perennial or vice versa, changes in the average annual number of intermittent months or changes in the in the inter-annual variability. Additionally, we incorporated the uncertainty associated with the utilization of five GCMs into our analysis.
Characterizing the environmental and geochemical landscape of rock glacier outflows in the Intermountain West, USA
Authors: Munroe Jeffrey , Morriss Matthew , Carling Greg , Finn Debra , Tronstad Lusha , Hotaling Scott
Published: March 2024

The global cryosphere is rapidly changing in response to climate warming.  Rock glaciers may be more resilient to climate change than their surface ice and snow counterparts.  However, unlike surface ice features, rock glaciers are comprised of complex mixtures of ice and locally sourced rock, which may be tightly connected to local hydrologic conditions.  This close hydrogeologic connection appears to underlie substantial variability in the environmental conditions of streams associated with rock glaciers, even within the same geographic region.  Here, we analyze 13 years of field data (2011-2023) from 10 rock glaciers and 13 related ice features from four mountain ranges in Wyoming and Utah, USA, to characterize the environmental and geochemical landscape of their outflows.  Specifically, we compare water temperature, geochemistry, conductivity, and isotopic signatures (δ18O and δD) across mountain ranges and ice features.  We find an average surface water temperature of 0.97 ± 1.1 °C across all 10 rock glacier sites from all 13 years; -0.80 ± 0.82 °C at five glacier fed sites, and 1.21 ± 1.88 °C at six snowmelt fed sites.  Preliminary data from two summers of observations also reveal a consistent positive trend in specific conductivity of two rock glacier-fed streams, typical of water transitioning from snowmelt-dominated to ice-melt dominated sources.  Our results highlight the considerable variability in these ecosystems, even within mountain ranges, and underscore the need for wider sampling to better contextualize and monitor them in the future.  This context is critical when considering whether rock glaciers will promote resiliency of coldwater habitat under climate change, and the degree to which their contribution to alpine hydrologic systems may affect biodiversity and drinking water quality as contributions from snow and glacier ice decrease.
Equatorial wave diagnosis for the Atlantic Niño with an ocean reanalysis
Authors: Song Qingyang
Published: March 2024

There has been a long-standing need for a rapid-detection method for waves using simulation data for Atlantic Niño events. This study addresses this by utilizing an ocean reanalysis.  The proposed method firstly decomposes the climatological values and anomalies at each grid point are decomposed into the first four baroclinic modes based on their local density profiles, then the wave energy flux is calculated by means of a group-velocity-based scheme.  In the instance during the 2019 Niño event, the decomposed geopotential can well reproduce the displacement of the thermocline during the event. The obtained wave energy fluxes confirm the significant influence of subseasonal Kelvin waves on the event and also suggest that wave energy from off-equatorial regions likely preconditioned the event. This study is thus a useful tool for diagnosing the equatorial waveguide and can support the warning systems for Atlantic Niño events.
Exploring climate-adaptive drainage in water management: Enhancing soil moisture, crop resilience and groundwater recharge.
Authors: Rodríguez Lache Erika Lucía , Blanchy Guillaume , Mehmandoostkotlar Ali , Garré Sarah
Published: March 2024

Drainage systems are essential for cultivated fields, ensuring optimal growth conditions for crops by preventing root zone wet stress. However, these conventional drainage systems also lead to a significant loss of water, a valuable resource that could be used to sustain crops during dry (summer) months. To address this, climate adaptive drainage or controlled drainage is employed, raising the water table “when possible given the ongoing agricultural activities”. This approach enhances aquifer recharge and stores excess water for use during the summer. Nevertheless, it remains unclear for farmers and water managers whether climate-adaptive drainage will improve agricultural performance and, if so, how to precisely manage water levels throughout the growing season to optimize performance. In this study, we conduct a synthetic experiment using the SWAP model to investigate the complex interaction between drainage types under different meteorological conditions, soil characteristics, and crop types. Our research aims to provide insights into the effect of climate-adaptive drainage for both farmers and water managers.Our findings highlight that controlled drainage significantly enhances soil water content in sandy and loamy soils, contributing to climate resilience. However, its effectiveness in clay soils is small. It is important to note that climate-adaptive drainage has the potential to raise groundwater levels across all soil types, posing a potential risk of oxygen stress on crops. Regardless of soil type, the implementation of controlled drainage results in increased surface runoff and groundwater recharge, associated with a reduction in drainage flux. While the augmented surface runoff  poses potential issues such as soil erosion and water pollution, the positive aspect lies in the enhanced groundwater recharge, crucial for maintaining water availability and supporting ecological systems.
Estimate Temperature Threshold for Low to Middle-Income Dwellers of Faisalabad City during Hot Summer Days
Authors: Ibrahim Muhammad , Ehsan Sana , Abbas Farhat
Published: March 2024

With the evolution in climate, heat waves are occurring more commonly which leads to imply indoor temperatures. Several temperature thresholds have been suggested in diverse environments for the indication of indoor overheating. In this study, threshold values for perceived heat stress are evaluated and differentiated between susceptible households and non-susceptible households for the residents of Faisalabad in Pakistan. Data from 52 low to middle-income households were analyzed with the help of regression analysis, t-tests, and analysis of variances to discover characteristics associated with perceived heat stress during the nighttime period in the selected houses. We considered socio-demographic characteristics, health-related queries, heat-related health problems, and house/building material variables from the selected households. The results suggest that the health status during heat stress, age factor, climate zone, and high indoor temperature were the key attributes for the perceived heat stress. The threshold limit advised by the WHO for indoor is 24°C and most of the dwellers in case study live in 36-38°C. People appeared to be at risk for perceived heat stress without knowing to be at risk, particularly when numerous people live in one room (threshold limit 34.8◦C), suffering from disease (35.6 ◦C) and below 60 (39.8 oC); therefore they do not take it seriously, to take adaption measures.
The simultaneous effects of groundwater table dynamics on greenhouse gas emissions and phosphorus leaching in drained peatlands
Authors: Höyhtyä Iida , Liimatainen Maarit , Tolvanen Anne , Ronkanen Anna-Kaisa , Kujala Katharina , Pham Tung , Hyvärinen Maarit , Kløve Bjørn , Niiranen Milla , Nieminen Jaana , Marttila Hannu
Published: March 2024

Boreal peatlands are long-term reservoirs of carbon, and vast peatland areas are drained for variable land-use activities. Drainage of peatlands leads to elevated emissions of greenhouse gases (GHG) measured as carbon equivalents, increased leaching of nutrients, and loss of soil carbon and biodiversity. Negative GHG impacts can be reduced by raising groundwater table level (GWT), which in turn may cause leaching of nutrients such as phosphorus (P) from decaying peat layers, increasing the risk for eutrophication of water bodies. Traditionally, emissions and leaching impacts are studied separately and thus it is essential to produce more knowledge about the simultaneous effects of groundwater table conditions on GHG emissions and P leaching.Our studies explore how different GWT levels and dynamics affect greenhouse gas emissions (CO2, N2O, CH4) and P leaching risk in drained peatlands. The study areas are in North Ostrobothnia, Finland and share a similar geological history. They include afforested peatland, cultivated peatland with varying peat depths, abandoned peat field, and pristine peatland. The potential P leaching risk is studied with chemical extractions of P from different soil depths. Simultaneous GHG emissions and P leaching with different GWT levels and variable dynamics are studied with a column experiment in controlled conditions. The actual GHG emission dynamics in field conditions are studied with static dark chamber and snow gradient methods and linked to functional vegetation diversity, which is studied with visual cover estimations. Our studies increase scientific understanding of P retention and leaching processes as well as GHG emission dynamics within drained and decomposing peat soils in different GWT conditions and with different land use forms. This knowledge is essential e.g., in Finland, where extensive peatland drainage in the 1900th century has led to considerable GHG emissions and elevated nutrient leaching from large areas. Currently, national climate policy sets pressures for GHG emission reductions in drained peatlands, and these reductions must be made by avoiding further P leaching to water bodies and sea areas. Land use changes may be unavoidable in some cases, and our study setup with multiple land uses provides information for correct decision-making.
Global reference water information for flood monitoring: Increasing accessibility with STAC
Authors: Groth Sandro , Wieland Marc , Henkel Fabian , Martinis Sandro
Published: March 2024

Remote sensing data has become an essential component of today's disaster management. Copernicus Sentinel-1/2 satellites are capable of providing high spatial and temporal resolution information that has proven to be effective in inundation mapping and other water management applications. In the recent years, DLR has developed a cloud-based, automated processing chain that uses convolutional neural networks (CNN) to extract surface water extent from SAR and multi-spectral images of Sentinel-1/2 satellites. Resulting water masks are aggregated to a reference water product that can be used to rapidly permanent water from temporary flooded and to analyze seasonal and long-term surface water dynamics. To unlock the full potential of the data and encourage community use, the technical barriers in access and usability have to be minimized. We approach this challenge by utilizing Spatio-temporal Asset Catalogs (STAC) to publish a global, open access collection of reference water products based on Sentinel-1/2 data. STAC enables users to easily search for matching datasets and load the data locally using open source tools. We further store data assets in the cloud-optimized GeoTiff (COG) format to improve processing efficiency and scalability. To give users a quick start, we publish a set of Jupyter Notebooks that demonstrate common use cases in the context of flood mapping such as the computation of flood duration, inundation time series analysis as well as the visualization of seasonal changes in water extent.
Development of the Methodology to Identify Potential Modes of Dam Failure and to Estimate Structural Health of Water Management Dams
Authors: Klun Mateja , Begelj Žiga , Kryžanowski Andrej
Published: March 2024

Here we present the project activities of an ongoing project aiming at the identification of potential failure modes of dams and the development of the methodology to be applied on water management dams in Slovenia. Water is the most important natural resource for human existence, while changes in hydrological conditions have an impact on the water balance and require innovative approaches in water management. There are currently 68 registered infrastructure facilities in Slovenia, 42 of which meet the criteria of large dams or are subject to a special regime for operational safety as critical infrastructure. According to the Slovenian National Committee for Large Dams the average age of our dams is already more than 45 years.Objectives of the project proposal, which will last 24 months, are the following: the analysis of the current state of the practice in the field of dam surveillance in Slovenia, provision of a summary document with a set of potential failure mechanisms for each type of dams, and development of a methodology for identifying failure mechanisms and monitoring the condition of dams. Monitoring of dams is regularly carried out in Slovenia, at least in the form of technical monitoring of the structures. However, we must note that professional knowledge of the operational safety of dams has advanced considerably since the time when most of the dams in Slovenia were built. In particular, the understanding of dam safety has changed and is now understood in a broader sense, encompassing the safety of the dam and auxiliary structures under all conditions throughout its life cycle, as well as the safety of the population and the environment in the dams' impact area. The lifetime of dams is very long, and sound structural management improves their structural health of dams and extends their service life.The main output of the project is the development of the methodology for identification of potential failure modes. The steps of the methodology will also be implemented on at least 3 pilot cases and will be presented to the professional public and to institutions working in the field of dams and dam engineering. The project addresses both the World Declaration on Dam Safety, (Porto, 2019), and the World Declaration Water Storage for Sustainable Development, from (Kyoto, 2012). The authors acknowledge that the research is financially supported by the Slovenian Research and Innovation Agency research project No. V2-2340 and by the Ministry of Natural Resources and Spatial Planning.
Determining the relative potential of future igneous activity in Germany – a multi-criteria approach
Authors: Rummel Lisa , Bartels Alexander , May Franz , Kottwitz Maximilian O. , Baumann Tobias S.
Published: March 2024

Future volcanic activity within or around distributed volcanic fields is difficult to determine, as many processes affect the melt formation in the mantle and the ascent of melt through the lithosphere. Depending on the external and internal forces and mechanisms, the igneous activity (i.e., shallow intrusive along with extrusive magmatism) can be long lasting or be interrupted by several phases of dormancy. To determine the long-term (i.e., next 1 Myr) relative potential of igneous activity in Germany we therefore suggest to consider the characteristics of various parameters including, among others, seismic anomalies in the mantle, earthquakes, degassing of mantle fluids, ground motion, depth of Moho and LAB, tectonic activity, modelled melt potential based on numerical simulations, and past volcanic eruptions. Thereby, numerical simulations can be used to quantify uncertainties of various parameters describing the structural and thermal state of the lithosphere and the upper mantle. Melt potential calculations including these uncertainties as well as compositional variations of mantle rocks can be used to identify areas of actual critical state with regard to possible future volcanic eruptions below Central Europe.Based on all 20 parameters investigated, a semi-quantitative multi-criteria method was developed and finally applied to differentiate regions of relative potential for future igneous activity in Germany. Although, most parameters are not uniquely related to magmatic processes, the presence of values exceeding the defined thresholds of any single parameter enhances the potential of future igneous activity at specific locations. Parameter properties are scaled between 0 and 10 within their range of significance (above/below a defined threshold value) to allow their comparison and combination. Weighting factors for individual parameters are used based on the results of expert surveys. However, an index map with statistically determined weighting factors shows the insensitivity of the proposed method in terms of chosen weighting factors.The results of the multi-criteria method can be used to identify suitable regions for a safe repository for high-level radioactive waste, where areas have to be excluded, which might be directly affected by future magmatic processes. In this context, we computed Germany-wide index (“hazard”) maps, where the index values represent a combination of all 20 parameters. The resulting index maps show that a higher relative potential of future igneous activity occurs not only in regions affected by Quaternary volcanism, but also in and around older Cenozoic volcanic fields or even in regions that have not been affected previously by Cenozoic volcanism. These observations indicate the possible longevity of a geodynamic framework that facilitates magmatic activity over large time scales (millions to tens of millions of years).
Capturing the short-term dynamics of outlet glaciers:  insights from seismic monitoring on Sermeq Kujalleq in Kangia, Greenland
Authors: van Ginkel Janneke , Nap Ana , Wehrlé Adrien , Walter Fabian , Lüthi Martin
Published: March 2024

Sermeq Kujalleq in Kangia, also known as Jakobshavn Isbræ, a major outlet glacier of the Greenland Ice Sheet, exhibits a flow speed higher than 30 m/day near the terminus. Basal sliding, iceberg calving, and subglacial hydraulics play pivotal roles in ice flow dynamics of this outlet glacier, and understanding these processes is crucial for predicting the impact of outlet glaciers on the Earth system in a changing climate.  Seismic and geophysical field campaigns were conducted in 2021, 2022 and 2023 in the region of Sermeq Kujalleq in Kangia. The project has the aim to monitor the dynamic behavior of such a fast-flowing outlet glacier and its interaction with the surrounding shear margins. Shallow borehole seismic sensors and self-sufficient seismic boxes were deployed in multiple arrays on the fast-moving ice stream and its margin. The sensors capture seismic sources and monitor subglacial conditions and spatiotemporal variabilities throughout the ice mass. An on-rock broadband seismometer near the terminus records iceberg calving activity ideally complementing observations of a Terrestrial Radar Interferometer operating simultaneously. Here we report on first results of a seismic analysis that provides insights into details of ice dynamic variations of Sermeq Kujalleq. Power spectrograms of the 2023 upstream arrays feature a 4-day tremor-like signal between 2.5 and 6 Hz. This phenomenon was not observed for other calving events and was missing in the 2022 record. Beamforming techniques are employed to constrain the source location of this tremor as well as other seismic events. Potentially this multi-day tremor signal corresponds to the ice stream response to a major calving event. Additionally, beamforming and spectral analysis provide insights into hydraulic cycles of the glacier, such as widespread diurnal water drainage and the activity of moulins. By comparing these seismic observations with ice flow speed and satellite images we aim at understanding the details of short-term perturbations to ice flow, which may influence larger-scale ice stream dynamics.
Alleviation of functional limitations by soil fauna is key to climate feedbacks from arctic soils
Authors: Krab Eveline J. , Blume-Werry Gesche , Klaminder Jonatan , Monteux Sylvain
Published: March 2024

Alleviation of functional limitations by soil fauna is key to climate feedbacks from arctic soilsArctic soils play an important role in Earth’s climate system, as they store large amounts of carbon that, if released, could strongly increase greenhouse gas levels in our atmosphere. Most research to date has focused on how the turnover of organic matter in these soils is regulated by abiotic factors, and few studies have considered the potential role of biotic regulation. However, arctic soils are currently missing important groups of soil organisms, and here, we highlight recent empirical evidence that soil fauna presence or absence is key to understanding and predicting future climate feedbacks from arctic soils. We propose that the arrival of certain soil fauna into arctic soils may introduce “novel functions”, resulting in increased rates of, for example, nitrogen cycling, litter fragmentation, or bioturbation, and thereby alleviate functional limitations of the current soil organism community. This alleviation can greatly enhance decomposition rates, in parity with effects predicted due to increasing temperatures. We base this argument on a series of emerging experimental evidence suggesting that the dispersal of until-then absent micro- meso-, and macroorganisms into new regions and newly thawed soil layers can drastically affect soil functioning. These new observations make us question the current view that neglects organism-driven “alleviation effects” when predicting future feedbacks between arctic ecosystems and our planet’s climate. We therefore advocate for an updated framework in which soil biota and the functions by which they influence ecosystem processes become essential when predicting the fate of soil functions in warming arctic ecosystems.