bluuebunny/crossref_metadata_2025 huggingface dataset:
Leaf chlorophyll: a global study employing a process-based model and remote sensing observations
Authors: Miinalainen Tuuli , Ojasalo Amanda , Croft Holly , Zaehle Sönke , Caldararu Silvia , Thum Tea
Published: March 2024

Slowing down climate change calls for a strengthening of natural carbon sinks. Estimating current carbon stocks and the carbon storage potential of natural ecosystems necessitates a good understanding of carbon and nitrogen cycles. As the increase of land carbon sink is likely to be nitrogen-limited in temperate and boreal ecosystems, it is important to constrain the uncertainties related to the carbon and nitrogen processes in the ecosystems. Leaf chlorophyll (chlleaf) and leaf nitrogen allocated to photosynthetic fractions are closely related, as plants optimise their nitrogen resources between light harvesting and the reactions of the Calvin cycle. chlleaf is consequently one of the key factors in determining leaf photosynthetic rates and a strong proxy for photosynthetic capacity. The recent advances in remote sensing (RS) provide a novel opportunity for benchmarking the modelled terrestrial nitrogen cycle through leaf chlorophyll content.In this study, we utilize a terrestrial biosphere model, QUINCY, for simulating the chlleaf content for different ecosystems in a global scale. QUINCY includes a comprehensive representation of coupled carbon and nitrogen cycles, and also diagnostics for chlleaf. We use a satellite-based leaf chlorophyll RS product for evaluating how well QUINCY captures spatial and temporal patterns of chlleaf. The evaluation is conducted for a selection of 400 locations distributed world-wide to represent all major global biomes. In addition, we analyse the accuracy of chlorophyll and productivity (GPP) simulation at 169 sites of the FLUXNET eddy covariance.Our initial results reveal that on global scale, QUINCY chlleaf matches well with the RS chlleaf observations. However, the QUINCY chlleaf values seem to be constrained to a more narrow numerical range than the RS observations, indicating that not all factors contributing to the observed variation are considered in the modeling framework. For instance, the modeled grassland chlleaf shows much smaller variation between different locations when compared to RS observations at different sites. For the FLUXNET sites, the mean annual GPP values from QUINCY are slightly underestimated (on average, ~-260 gC m-2 yr-1) when compared to flux observations. Nevertheless, the QUINCY mean annual GPP for different sites correlates with the ground station data reasonably well (r=0.67). Our study paves way for more versatile use of satellite observations within terrestrial biosphere models. Harnessing satellite products to model evaluation helps to improve model parametrizations related to carbon and nitrogen cycles, which in turn would allow more precise modeling of the terrestrial carbon budget.
Physiographic and Climatic Controls on Heavy-Tailed Flood Behavior: Insights from Catchment Nonlinear Responses
Authors: Wang Hsing-Jui , Merz Ralf , Basso Stefano
Published: March 2024

The occurrence probability of rare floods is linked to the right-tail behavior of flood frequency distributions. Specifically, heavy-tailed behavior of flood distributions often signals significant hazards due to the unexpected extremeness of event magnitudes. However, conducting reliable analyses of flood tail heaviness across regions remains challenging due to the varying record lengths of available data.In this study, instead of relying solely on statistical methods to evaluate flood tail behavior, we adopt a physical-based approach—hydrograph recession analysis—to quantify the nonlinearity of catchment hydrological responses. This method has shown its efficacy in identifying heavy-tailed flood behavior across analyses with different data lengths. Our analysis covers 575 river gauges, spanning drainage areas from 4 to 40,504 km2, across Atlantic-influenced European areas, Northwestern European areas, and the Continental United States. We categorize these regions based on the Köppen climate classification to explore the relationship between physiographic/climatic conditions and heavy-tailed flood behavior, and distinguish regional characteristics using the aridity index and potential evapotranspiration.Our findings reveal a prevalence of heavy-tailed flood propensity in Atlantic-influenced European areas, prevalent nonheavy-tailed flood propensity in Northwestern European areas, and a mixed distribution with a balanced propensity in the Continental United States. Generally, drier catchments exhibit higher nonlinearity in hydrological responses, facilitating heavy-tailed floods, while catchments in which snow dynamics dominate the flood generation process tend to present linear responses. Excessively dry catchments, however, are less likely to exhibit heavy-tail floods due to insufficient moisture. Moreover, around one-third of catchments display varying tail behavior across seasons, underscoring the potential underestimation of flood tail heaviness in annual analyses. The seasonality of flood tail behavior—where instances of heavy-tailed flood behavior increase from spring to autumn but decrease in winter—is influenced by the seasonal variation of potential evapotranspiration.Our study contributes to advancing the understanding of the impact of inherent physiographic and climatic features on regional and seasonal patterns of heavy-tailed flood behavior, providing valuable insights into the emergence of a considerable occurrence probability associated with very large magnitudes of rare floods.
Model spread in the multidecadal variability of the winter North Atlantic Oscillation connected to stratosphere-troposphere coupling
Authors: Maycock Amanda , Bonnet Remy , McKenna Christine
Published: March 2024

A part of the uncertainties in global climate model projections over Europe arise from their underestimation of multidecadal variability in the winter-time North Atlantic Oscillation (NAO). This underestimation, however, remains poorly understood. Past studies have linked the weak multidecadal NAO variability in models to an underestimated atmospheric response to North Atlantic sea surface temperature variability. Using the CMIP6 large ensemble of climate models, we explore statistical relationships with physical drivers that may contribute to intermodel spread in NAO variability. We find a significant intermodel correlation between multidecadal NAO variability and multidecadal stratospheric polar vortex variability, as well as a stratosphere-troposphere coupling parameter that quantifies the relationship between stratospheric winds and the NAO. Models with the lowest NAO variance are associated with weaker polar vortex variability and a weaker stratosphere-troposphere coupling parameter. The identification of this relationship suggests that modelled spread in multidecadal NAO variability has the potential to be reduced by improved knowledge of observed multidecadal stratospheric variability, although observational records are currently too short to provide a robust constraint on these indices.
Variations in CO2 Fluxes at the Surface-Atmosphere Interface Within the Seoul Metropolitan Area
Authors: Hong Seonok , ﻿Kim ﻿Jinwon , ﻿Byun ﻿Young-Hwa , ﻿Hong ﻿Jinkyu , ﻿Hong ﻿Je-Woo , ﻿Lee ﻿Keunmin , ﻿Lee ﻿Sang-Sam , ﻿Kim ﻿Yeon-Hee
Published: March 2024

The monitoring and comprehension of CO2 fluxes in urban environments face challenges due to severe spatiotemporal heterogeneity of emissions sources and limited measurement networks. This issue is particularly critical for large cities, which stand as major contributors to anthropogenic CO2 in the climate system. Focusing on Seoul, Korea, this study analyzes CO2 fluxes at eight surface energy balance sites spanning 2017–2018. These sites comprise six urban locations (vegetation-area fraction < 15%) and two suburban sites (vegetation-area fraction > 60%), aiming to attribute the fluxes to local land-use and business types. To compare with rural area, CO2 fluxes from the Boseong Standard Meteorological Observatory, characterized by rice paddy, were utilized. Results reveal that CO2 flux variations at suburban sites are predominantly influenced by vegetation, while disparities between urban and suburban sites arise from differences in vegetation-area fraction and anthropogenic CO2 emissions.  For the CO2 fluxes at the urban sites; (1) vehicle traffic (traffic) and heating-fuel consumption (heating) contribute > 80% to the total, (2) vegetation effects are minimal, (3) the seasonal cycle is driven mainly by heating, (4) the contribution of heating is positively related to the building-area fraction, (5) the annual total is positively (negatively) correlated with the commercial-area (residential-area) fraction, and (6) the traffic at the commercial sites depend further on the main business types to induce distinct CO2 flux weekly cycles. This research demonstrates that comprehending and estimating CO2 fluxes in sizable urban areas necessitate meticulous site selections and analyses founded on detailed consideration of the refined land-use and business types, going beyond the commonly used single representative land-use type in contemporary studies. 
Lava fountains at Etna volcano deciphered in real-time by high precisions borehole strainmeters data and implications on hazard mitigation: the 21 May 2023 case
Authors: Bonaccorso Alessandro , Carleo Luigi , Currenti Gilda , Sicali Antonino
Published: March 2024

In recent decades, Etna's main eruptive activity  was characterized by prolonged sequences of lava fountain episodes. In particular, the sequence from December 2020 to February 2022 was characterized by 65 lava fountains. After the conclusion of the last sequence in February 2022, preceded a few days earlier by a shallow seismic swarm, a powerful fountain occurred on May 21, 2023. This lava fountain was unexpected since it was far from the previous sequence and did not even  belong to a new sequence. The greatest criticality was the difficulty in monitoring this eruptive event using conventional remote sensing devices due to the bad weather conditions characterized by thick cloud cover.In this study we present the strain data recorded by the borehole dilatometers network on Etna. The high precision strain changes make it possible to follow all the recent lava fountains providing a valuable interpretative contribution. Through new approaches recently implemented, the analysis of the strain data allowed us to identify the correct timing of the events, evaluate the ‘size’ of the fountain (i.e. its eruptive power) and estimate the erupted volumes in near real-time. In particular, during the 21 May 2023 event, the quantification of these features provided a useful support during the Civil Protection meeting convened in emergency at the Prefecture of Catania, where the evolution of these features was presented and updated in near real-time. The experience gained on the 21 May 2023 lava fountain demonstrates the contribution that the real-time high precision strain may provide to define and evaluate the hazard associated with a lava fountain even in unfavorable weather conditions, when the remote sensing systems may not be able to provide helpful information on the ongoing phenomenon.
Improved lightning NOx emission inventory evaluated with vertical profiles of NO2 and ozone obtained by cloud-slicing TROPOMI  
Authors: Horner Rebekah , Marais Eloise , Wei Nana
Published: March 2024

Lightning is the dominant source of nitrogen oxides (NOx) in the free troposphere. Yet, its representation in models is highly parameterised, limiting our ability to determine past and future changes in lightning NOx and causing errors in model representation of tropospheric ozone and NOx. Models such as GEOS-Chem use fixed lightning NOx production rates constrained with historic satellite instrument observations of ozone. A new approach is to model NOx production per flash (mol N fl-1) using lightning energy dependent NOx yields and lightning flash radiant energy data from the space-based lightning imaging sensor (LIS) aboard both the Tropical Rainfall Measuring Mission (TRMM) satellite and the International Space Station (ISS). This updated approach is then used in GEOS-Chem to compute total lightning NOx yields through the Harmonized Emissions Component (HEMCO), rather than using fixed values. The updated annual lightning NOx emissions total 6.5 Tg N, similar to the original parameterised representation (5.8 Tg N), but with much greater variability in NOx production rates. The original implementation uses 260 mol N fl-1 everywhere except the northern extratropics that are at 500 mol fl-1. In the updated implementation, values range from 27 to 632 mol N fl-1 over the ocean and from 66 to 482 mol N fl-1 over land. Greater values over the ocean are due to oft-reported much more energetic maritime lightning. To test the effect on tropospheric ozone and NOx, we are currently comparing seasonal mean GEOS-Chem and TROPOMI-derived vertical profiles of ozone and NO2. The TROPOMI-derived values, obtained by cloud-slicing partial columns over optically thick clouds, we have previously evaluated to be consistent with NASA DC-8 aircraft measurements in the free troposphere for cloud-sliced NO2 (differences < 20 pptv) and the global ozonesonde network for cloud-sliced ozone across the whole troposphere (differences < 35 ppbv). This offers the means to assess the representation of lightning NOx and better understand its influence on tropospheric NOx and ozone.
Data deficient saltmarsh species has climate relevant carbon stocks from the east coast of India
Authors: Mohakud Sandip Kumar , Mishra Amrit Kumar , Farooq Syed Hilal
Published: March 2024

The saltmarsh ecosystems of India are least studied,  despite being considered as nature-based solutions (NbS) towards climate change mitigation. This study quantifies the seasonal variation in carbon stocks of mono-specific saltmarsh specie (Porteresia coarctata) and its potential to play an important role in India’s climate change mitigation plans. Seasonal (pre-and post-monsoon) sampling of P. coarctata surface water, biomass and 30 cm sediment core was collected across four estuarine locations on the east coast of India to quantify the sediment dry bulk density (DBD), organic matter (OM%), organic carbon (Corg%), Corg stocks of sediment and biomass, total carbon (C%) and nitrogen (N%) and stable isotope ratios of Carbon (δ13C) and Nitrogen (δ15N).  In general, the sediment DBD, OM and Corg of P. coarctata meadows was higher in post-monsoon and was influenced by salinity and pH changes. Carbon isotope ratio (δ13C) of sediment C sources suggested, particulate organic matter (POM) contribution was highest (0.04-0.79%) followed by P. coarctata (0.01–052%) and other macrophytes across our study locations.  The seasonal variation of δ13C showed increased contribution of marine derived particulate and dissolved organic matter into P. coarctata meadows in post-monsoon season.  Higher δ15N values observed in post-monsoon season suggest an anthropogenic input, that was utilized by P. coarctata to increase its above and below-ground biomass and shoot density. The combined ecosystem (30 cm sediment + biomass) Corg stocks of P. coarctata was 1.7-fold higher in post-monsoon (4021.20± 917 Mg C) compared to pre-monsoon (2297.36 ±647 Mg C) season among the four locations with a sediment Corg contribution >70%. Based on the International Panel for Climate Change Tier II assessment the P. coarctata meadows (443 ha) can help in avoiding the pre-and post-monsoon emissions of 8431.34 and 14757.84 Mg CO2, respectively. The combined price of the total CO2 equivalent stored in P. coarctata meadows in pre- and post-monsoon is calculated to be US$ 14.50 and US$ 25.38 million, respectively. Further studies quantifying the NbS potential of mono-specific and mixed P. coarctata meadows along the coast of India is important, along with the integration of saltmarsh ecosystems into India’s National Action Plan on Climate Change.Keywords: Saltmarsh, Carbon stocks, Porterasia coarctata, Nature-based solution, Stable isotopes
Eddy variability contribution to decadal regional sea level trends
Authors: Laurent Benoit , Llovel William , Treguier Anne-Marie , Hochet Antoine
Published: March 2024

Sea level rise is one of the most direct consequences of the actual global warming. Over the 20th century, global mean sea level rises at a rate of 1.5-2 mm. yr-1. Since the beginning of the 1990s, satellite altimetry measure the changes of sea level with a near global coverage (from 66oS to 75oN). The use of satellite altimetry has, for the first time, highlighted large regional variability in sea level trends that significantly differ from the global mean estimate. If global ocean warming and land ice melting (mountain glaciers and ice sheets from Greenland and Antarctica) are the main processes explaining the observed global mean sea level rise, at regional scales, other processes are involved, such as changes in salinity or temperature associated with ocean circulation or air-sea fluxes at the ocean surface. Sea level projections used in IPCC reports are based primarily on coarse-resolution coupled climate models. Current projections are based on climate models in which ocean-eddy variabilities are parameterized and results deviate from observations especially in the Southern Ocean. Mesoscale processes transport heat/freshwater over very large distances in the ocean (both horizontally and vertically). They also regulate energy, moisture and carbon exchanges between the oceans and the atmosphere via coupling. Understanding these processes and how they might change in the future is critical for portraying robust regional sea level change. Recently, new generations of climate models have been integrated at spatial resolutions of ¼° and 1/12°, which is sufficient to partially resolve the mesoscale eddy variability. These higher resolutions enable the study of the impact of mesoscale eddies on regional sea level changes and how these processes may change in the future. In this work, we will take advantage of a suite of climate model simulations based on HadGEM3-GC3.1 at different spatial resolution (1°, ¼° and 1/12°) to assess the contribution of eddy-variability on regional sea level trends. We first present the ability of such climate models to reproduce regional sea level trends observed by satellite altimetry over decadal to multi-decadal time periods. Second, temperature and salt budget will be presented to quantify the contribution of eddy variability on these regional sea level trends.
Multi-instrumental approach for aerosol profiling in the lower troposphere, use of UAV-based instrumentation.
Authors: Pietruczuk Aleksander , Bruchkouski Ilya , Szkop Artur
Published: March 2024

This study presents a multi-instrumental approach to studying aerosol properties in the lower troposphere. It focuses on a combination of in-situ techniques with remote sensing measurements utilizing model-based study. Measurements taken at the suburban site of Raciborz in the highly industrialized region of Silesia will be used. We will apply ground-based in-situ measurements, retrieval of aerosol optical properties profile utilizing the synergy of collocated CIMEL Sun-photometer and Lufht’s CHM-15k Nimbus ceilometer, and UAV (Unmanned Aerial Vehicle) based measurements in the lowermost part of the troposphere.Aerosol size distribution will be measured by tandem Aerodynamic Particle Sizer and Scanning Mobility Particle Sizer spectrometers that will serve as the starting point of GRASP retrieval of aerosol microphysical and optical properties based on Aurora 4000 polar nephelometer measurements. These retrievals will be used to normalize UAV-based instruments that include OPC (Optical Particle Counter) and LED-based COBOLT instruments for aerosol backscatter measurements during the night. OPC instrument will provide a profile of Particulate Matter concentration (PM) at certain altitudes while COBOLT instrument will provide a profile that is proportional to the aerosol backscattering coefficient. Whilst typical COBOLT operation requires normalization in the upper troposphere or lower stratosphere where aerosol effects are neglected we will normalize it close to the ground by GRASP retrieval. Supplementary measurements of atmospheric pressure and temperature profiles will be used to determine Rayleigh scattering.Obtained UAV-based profiles of aerosol properties will be calibrated to the in-situ ground measurements while also being compared and adjusted to the lowermost part of the aerosol profile obtained by the synergy of remote measurements (GRASP) thus providing means for estimating continuous profile of aerosol properties from the ground to the mid-troposphere.This work is supported by the National Science Centre under grant 2021/41/B/ST10/03660.
Redox heterogeneity in lithospheric mantle evidenced by C-O-H-S fluid inclusions entrapped in Kerguelen mantle-plume associated pyroxenites
Authors: Choudhary Shubham , Tao Renbiao , Das Souvik , Sen Koushik , Pattnaik Jiten , Lu Yuhang , Kumar Santosh , Viljoen Fanus
Published: March 2024

The C-O-H-S fluids play a significant role in various geological processes. The participation of these fluids in redox reactions remarkably influences carbonation process, melting behaviour, and physicochemical properties of the mantle rocks. In this study, we report rare, reduced fluid inclusions in shallow upper mantle-derived pyroxenites associated with the Kerguelen mantle plume from Northeast India. Raman spectroscopy reveals primary inclusions of hydrocarbon (CH) fluid and calcite along with the nearly perpendicular exsolution lamellae of magnetite in clinopyroxene (referred to herein as Cpx 1) of these pyroxenites. A rare occurrence of pseudo-secondary polyphase fluid inclusions of hydrogen sulfide (H2S), carbon monoxide (CO), rutile, and calcite was also recorded in other clinopyroxenes (referred to herein as Cpx 2) of these pyroxenites. Mineral chemical data suggests that the studied Cpx are purely diopside and Cpx 1 hosted magnetite exsolutions are coeval with these clinopyroxenes. This is evident from the notable enrichment in MgO in these magnetite exsolutions relative to accessory magnetite, showing that they certainly do not represent a sub-solidus phase. Single Cpx geothermobarometric calculations suggest that these pyroxenites were formed at 1.2- 1.8 GPa pressure and 752- 941 °C temperature. We use a theoretical thermodynamic model to validate our natural observations of fluid inclusions. Overall, our results show that mantle plume-derived oxidized C-O-H-S fluids interacted with crystallizing diopside from pyroxenites in the shallow mantle. During this interaction, these fluids participated in redox reactions leaving the reduced fluid products such as CH, CO and H2S and minerals such as calcite and rutile trapped as co-genetic inclusions along with magnetite exsolutions in host diopsides at oxygen fugacity conditions equivalent to FMQ-2. Therefore, considering the widely accepted fact that the shallow lithospheric mantle is predominantly oxidized, these natural observations of fluid inclusions, for the first time provide direct evidence of redox heterogeneity of the shallow mantle.
 
Tracking a Vibroseis Truck and Investigating the Wavefield using 6 Rotational Sensors in Fürstenfeldbruck, Germany 
Authors: Izgi Gizem , Eibl Eva P.S. , Krüger Frank , Bernauer Felix
Published: March 2024

Six-degree-of-freedom (6-DoF) measurements, which combine rotational sensors and seismometers, provide a comprehensive dataset that allows seismologists to determine the back azimuth of a potentially moving source from a single-point measurement. Our investigation focused on tracking the movement of a vibroseis truck operating from 20 November 2019, 11:00 UTC, to 21 November 2019, 14:00 UTC. Using 480 sweep signals, each lasting 15 seconds and covering a wide frequency range from 7 to 120 Hz, we measured at 160 different locations. Back azimuths for each sweep were derived from the 6-DoF data, and root mean squares were calculated for each component. This procedure was repeated for five additional rotational sensors of the same type.During the first day, the north component of all sensors recorded larger amplitude signals than the East and Vertical, indicating the dominance of SV (shear-vertical) wave energy. Subsequently, we observed gradually increasing amplitudes on the east component, which was consistent with the direction of the moving vibroseis truck. Although the dominant wave type recorded was SV, and the method of comparing horizontal rotation rates was used to calculate the back azimuth, we observed a relatively decreasing accuracy of direction estimates as the truck moved away from the sensors due to increased scattering. To fully understand the reason for this, we investigated the specific fingerprint of each wave type in the wave field. Our results suggest that direction estimates should be made using only the portion of the wavefield containing SV-type waves when using this method, and then the moving source should be tracked accordingly. This approach provides insight into the trajectory of the truck and improves our understanding of the seismic signals generated during the experiment.
Geodiversity in Nature: Improving Natural Heritage Management 
Authors: Justice Sophie
Published: March 2024

Awareness is increasing amongst decision makers that societal challenges such as climate change, water resource management, biodiversity loss, poor soil health and air quality are interlinked. In contrast the holistic approach to Nature by pioneering 18th century natural scientists where biotic and abiotic components were interdependent, modern western science has evolved into specialised scientific disciplines. Today, science influenced global accords such as the Paris Agreement on climate change, Kunming-Montreal Global Biodiversity Framework and numerous United Nations Sustainable Development Goals place great emphasis on the biotic components of the natural world. Strategies and legislation at national level generally follow this trend and influence natural heritage management approaches.Case studies from the Chablais UNESCO Global Geopark in France illustrate the impact of a transdisciplinary approach to natural heritage management where both biotic and abiotic factors are considered. The explicit inclusion of geodiversity informed stakeholder decisions over matters such as the choice of legal conservation measures, the definition of protected area limits and content for public communication programs. Different decisions were taken as a result of this inclusive approach to Nature in the municipalities of Montriond and La Baume. The ongoing work in the Chablais region confirms the need for scientists, natural heritage managers and politicians to share a common understanding of nature and ecosystems that explicitly includes geodiversity.
Upstream plasma waves and downstream magnetic reconnection at a reforming quasi-parallel shock
Authors: Lu Quanming , Guo Ao , Yang Zhongwei , Lu San , Wang Rongsheng
Published: March 2024

With the help of a two-dimensional (2-D) particle-in-cell (PIC) simulation model, we investigate the long-time evolution of a quasi-parallel shock. Part of upstream ions are reflected by the shock front, and their interactions with the incident ions excite low-frequency magnetosonic waves in the upstream. Detailed analyses have shown that the dominant wave mode is caused by the resonant ion-ion beam instability, and the wavelength can reach tens of the ion inertial lengths. Although these plasma waves are directed toward the upstream in the upstream plasma frame, they are brought by the incident plasma flow toward the shock front, and their amplitude is enhanced during the approaching. The interaction of the upstream plasma waves with the shock leads to the cyclic reformation of the shock front. When crossing the shock front, these large-amplitude plasma waves are compressed and evolve into current sheets in the transition region of the shock. At last, magnetic reconnection occurs in these current sheets, accompanying with the generation of magnetic islands. Simultaneously, there still exist another kind of plasma waves with the wavelength of several ion inertial lengths in the ramp of the shock. The current sheets in the transition region are distorted and broken into several segments when this kind of plasma waves are transmitted into the downstream, where magnetic reconnection and the generated islands have a much smaller size.
CMIP6 climate scenarios for climate adaptation studies in Zambia
Authors: Venkataswamy Sahana , Panjwani Shweta , Amarnath Giriraj
Published: March 2024

This study investigates provincial-level extreme weather conditions over Zambia using the Coupled Model Intercomparison Project (CMIP6) climate projections for various emission scenarios from 25 Global Climate Models (GCMs). Taylor diagram analysis is performed to identify the best-performing GCMs by evaluating precipitation and temperature variables with the observed datasets for the baseline period (1950-2014). Earlier studies have investigated the changes in precipitation and temperature variables alone. This study investigates the trends in Annual Precipitation, Annual temperature (mean, maximum and minimum) as well as Standardized Precipitaion Evapotranspiration Index (SPEI) for the near future (2021-2060) and far future (2061-2100) using Sen’s Slope Estimator. While all the projected climate scenarios depict an increasing trend in the mean temperatures for both near and far future periods, upto 4˚C increase is expected at the end the 21st century under the worst-case scenario-SSP5-8.5. An overall decrease (upto -65 mm) in precipitation is expected in the near future and far future periods across the country, expect the North-eastern provinces. Corroborating with such a spike in climate conditions, the SPEI decreases by -1.16, -0.95, -0.86, -0.83 (near future, 2021-2060) and -1.36, -1.75, -1.98 and -1.99 (far future, 2061-2100) for SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5 respectively. Larger changes in SPEI is observed in Western, Southern, Northwestern and Lusaka provinces in both near and far future indicating worst drought conditions. The outcome from the present study provides a basis for undertaking provincial-level adaptation and mitigation measures under the evolving climate and framing policy interventions to combat climate change.
The RAPID-Evolution Project: Towards a low-cost and sustainable observing system of the AMOC at 26°N
Authors: Petit Tillys , Moat Ben , Blaker Adam , Cardwell Chris , Elipot Shane , Harle James , Le Henaff Matthieu , Higgs Nick , Johns William , Kajtar Jules , Rayner Darren , Sinha Bablu , Smeed David , Smith Ryan , Volkov Denis
Published: March 2024

Direct measurements of the Atlantic Meridional Overturning Circulation (AMOC) and meridional heat transport (MHT) are necessary to better understand the impact of anthropogenic greenhouse gas emissions for the global climate system. The RAPID-MOCHA-WBTS array at 26°N is the only trans-Atlantic observing system to provide 20 years of continuous measurements of the AMOC and MHT. While the design of the array has continuously evolved as our understanding of the AMOC has advanced and as new technologies have become available, the goal of the RAPID-evolution project is now to design a lower cost and sustainable observing system to continue the measurements at the accuracy required by users. Using the dataset gathered since 2004 and ocean reanalysis, a first objective seeks to evaluate the sensitivity of the AMOC estimate to the choice of methodology and data included in the calculation. The project includes the development of a new high-resolution ocean model to identify the short and longer term impacts of incorporating these datasets in the AMOC estimation. Recent technological developments also enable new approaches that could provide better and more cost-effective calculation of the AMOC. The RAPID-Evolution project investigates these approaches and develops methodologies to make use of them, including a new variation of the stepping method using glider deployments and the telemetry of mooring data via an autonomous vehicle.
Firn aquifer properties of Wilkins ice shelf from multi-source spaceborne microwave observations
Authors: Shang Xinyi , Cheng Xiao , Zheng Lei , Liang Qi , Li Teng
Published: March 2024

The potential impact of increased snowmelt and related hydrological processes on ice sheet stability has become a focus of academic attention. Hydro-fracture caused by liquid water is one of the main triggers of ice shelf disintegration. Recent discoveries of firn aquifer (FA) in the Wilkins Ice Shelf (WIS) have updated our understanding of surface hydrological processes, mass and energy balance. However, the limited field and airborne radar observations of FA cannot provide a complete picture of their distribution and characteristics. Microwave remote sensing is highly sensitive to the dielectric constant change caused by the dynamics in buried liquid water. However, it is challenging to obtain the buried depth of FA from space. In this study, the extent and depth to the water table (DWT) of FA are investigated with the combination of active and passive microwave observations, as well as airborne radar measurements. First, with the verification points from airborne radar, the extent of FA is mapped from satellite-derived snowmelt and accumulation conditions based on a K-Nearest Neighbors classification model (OA=97.2%, Kappa=0.94). Next, we use a Gaussian Process Regression model to estimate the DWT of FA (R=0.8, RMSE=2.17 m). The results show that FA occurred in most areas of WIS in 2014, with a DWT of 12.8±2.9 m. The DWT increased from north to south. Further study will examine the dynamics in FA and their hydro-fracture effect on ice shelf calving and the stability of the Antarctic ice sheet.
SNAP2DQuake: an implemented and automatic tool of ESA SNAP's Python module for DInSAR technique on ground deformation estimation from Sentinel-1 data
Authors: Occhipinti Martina , Carboni Filippo , Amorini Shaila , López-Martinez Carlos , Paltriccia Nicola , Porreca Massimiliano
Published: March 2024

Differential SAR Interferometry (DInSAR) is a largely exploited technique applicable to different case studies involving ground deformation on Earth. A key application is the detection of the effects promoted by large earthquakes, comprising detailed variations in ground deformations at large an local scales. Since one limit of this technique relies on the costs that may be present for the access of some satellitary imagery or software licenses for the data processing, this latter problematic can be solved with the adoption of an alternative processing performed via scripts. In this work, an automatic open-source implemented Python script (Snap2DQuake) based on the “snappy” module by SNAP software 9.0.8 (ESA) for the processing of Sentinel-1 images is presented. The main feature of the script is the reproduction of all the operators contained in SNAP software using the tools of “snappy”, in order to avoid some issues that can occurr using the software, and to build a complete, simple and automatic workflow to obtain LOS deformation maps and the derived Horizontal (E-W) and Vertical deformation maps. The automatization of the processing makes Snap2DQuake easy to use and suitable with basic users of programming. The proposed tool has been tested on two case studies referred two different tectonic contexts: the Mw 6.4 Petrinja earthquake (Croatia, December 2020) and the Mw 5.7 to Mw 6.3 seismic sequence occured near Tyrnavós (Greece, March 2021). The output maps of Snap2DQuake, in agreement with field observations and previous work, furnish new insights insights into the deformation pattern linked to earthquakes, demonstrating the reliability of Snap2DQuake as an alternative tool for users working on different applications, even with basic coding skills. 
Assessing the potential of tidal and ocean current energy for remote Arctic communities
Authors: Finger David C. , Audunsson Haraldur
Published: March 2024

Tidal and ocean current energy represent continuous and reliable renewable sources that can offer valuable electricity to remote communities located near ocean shores. Ocean currents result from various factors such as tidal forces, wind shear at the water surface, temperature gradients due to inflow from melting water, salinity gradients caused by incoming freshwater, the Coriolis effect, and underwater topography. In the Faeroe Islands, ocean currents have been harnessed to produce power exceeding 1 MW (https://minesto.com/), providing an essential energy source for the ongoing energy transition.Especially in the Arctic, temperature and salinity gradients can enhance water velocity within a stratified water column in coastal areas. Therefore, comprehensive monitoring, accounting for the vertical stratification of the water column, becomes imperative to accurately assess the full potential of ocean currents. To accomplish this, we intend to employ an Acoustic Doppler Current Profiler (ADCP) (Xylem, Inc, 2015) to evaluate the three-dimensional velocity field at various locations in Iceland, aiming to comprehend the complete potential of ocean current energy.We will start our investigation with preliminary monitoring in Fossvogur, a two-kilometer-long fjord situated in front of Reykjavik University in Reykjavik, Iceland. We will combine in-situ ADCP data with remotely sensed surface temperature and vertical CTD proofing of the water column. Once our data collection and processing methods are standardized, we plan to extend our approach to locations with stronger ocean currents, such as Hvammsfjördur just south of the Wastfjords. Our initial findings suggest that tidal currents, temperature and salinity gradients, and wind shear significantly contribute to increasing ocean currents, challenging the assumption that the energy potential of these currents might have been underestimated in the past. This revelation could substantially aid in the energy transition of remote coastal communities by providing them with clean, cost-efficient, and environmentally friendly energy sources.Moreover, our methodology holds promise for application in any coastal region, potentially offering a renewable energy solution for various coastal communities.
Statistical analysis of first-order anisotropy in multi-spacecraft solar energetic particle events of the solar cycle 25
Authors: Vuorinen Laura , Dresing Nina , Brüdern Maximilian , Gieseler Jan , Palmroos Christian
Published: March 2024

Solar energetic particles (SEPs) are high-energy charged particles associated with solar eruptions. They constitute a major component of the heliospheric radiation environment, presenting a key space weather hazard. SEPs are accelerated at solar flares and at shock waves driven by coronal mass ejections, but the relative importance of these sources is not fully understood — particularly in the case of electrons. In addition to the underlying acceleration mechanisms, the evolution of a SEP event is highly influenced by transport in the interplanetary space. Anisotropy of the intensity-pitch-angle distribution is an important quantity that can be used to infer information about these effects, especially when multi-spacecraft observations are available. We investigate the first-order anisotropy of electrons and protons in SEP events of the solar cycle 25 using observations from multiple spacecraft of the inner-heliospheric fleet. We pay special attention to the methodology of determining anisotropy and its uncertainty from four-sector telescope (SOLO EPD/EPT and STEREO SEPT) measurements, in which pitch-angle coverage of the telescopes significantly influences the observed anisotropy. We present our methodology and the preliminary results of our statistical analysis, where we study the peaks and durations of anisotropic periods in high-energy electron and proton events as a function of particle energy and longitudinal separation.
Prospects of returning radioactively contaminated lands in the northern part of Ukraine to economic use
Authors: Illienko Volodymyr , Kosarchuk Olga , Klepko Alla , Lazarev Dmytro , Lazarev Mykola
Published: March 2024

About tens thousands hectares of agricultural land in the norther part of Ukraine cannot be used for agricultural production under the Law 'On the Legal Regime of the Territory Affected by Radioactive Contamination as a Result of the Chornobyl Disaster' since 1986 only in Zhytomyr Oblast. Additionally, due to Russia's aggressive military actions, large areas of Ukraine (currently near 800 thousands ha) are unable to carry out agricultural work. It may take over minimum ten years to clear the territories of mines. In these circumstances, revision of the actual contamination levels of lands may help to increase the share of agricultural lands in Ukraine. But before the economic use of these lands, it is essential to conduct a survey to determine the level of soil contamination with radionuclides and assess the radiological situation. This data will form the basis to decide whether the previously contaminated lands can be returned to economic use.We conducted the radiological surveys, where the radiation background indicators were measured in 2023 in Narodychi and Vyazivka using modern devices that allow automatic registration of routes with GPS reference and marking of gamma background parameters. We recorded from 200 to 600 points on each field to build maps of the spatial distribution of soil radioactive contamination. The Narodychi community in Zhytomyr Oblast provided 30 field plots marked as 'radioactive land' in the State Land Cadastre of Ukraine. These plots include 23 agricultural lands covering an area of over 1400 hectares and 7 floodplain meadows of the Uzh and Zherev rivers covering 1200 hectares. The levels of radioactive contamination in the soil were determine on the agricultural lands, specifically with regards to 137Cs, 90Sr, and partially 238-240Pu isotopes. The maps were constructed to determine the density of radioactive contamination of soil in each field based on the obtained results.We concluded, that the density of 137Cs, 90Sr and 238-240Pu contamination in the agricultural lands around the settlements of Narodychi and Vyazivka did not exceed the lower limit of the criteria for their classification as an unconditional (mandatory) resettlement zone. Specifically, cesium, strontium and plutonium isotopes did not exceed 555 kBq/m2, 111 kBq/m2 and 3.7 kBq/m2, respectively. While the criteria for assignment to the guaranteed voluntary resettlement zone are limited to cesium isotopes from 185 to 555 kBq/m2, strontium from 5.55 to 111 kBq/m2, or plutonium from 0.37 to 3.7 kBq/m2 (according to Article 2 of the Law of Ukraine "On the Legal Regime of the Territory Affected by Radioactive Contamination as a Result of the Chornobyl Disaster"). Accordingly, all surveyed land should lose its status as 'radioactive land' and can be returned to economic use.We acknowledge the National Research Foundation of Ukraine for the financial support of this research (Project number 2022.01/0188).
Improving extreme rainfall forecasting for a flood prone region: A hybrid modelling approach
Authors: Krishnankutty Nair Athira , Singh Sarmistha
Published: March 2024

Numerical weather prediction models are utilized to forecast extreme rainfall events at fine resolutions; however, these models possess inherent errors due to the parameterization and discretization of differential equations, which diminishes simulation accuracy. Recent advancements in machine learning methods indicate their potential capability to significantly enhance forecast results. In this study, multiple extreme rainfall events for the Pamba river basin during the Indian Summer Monsoon Period spanning 2-4 days were forecasted using the WRF model. Pamba, one of the flood-prone basins in southern states of India (Kerala), experiences severe flood events annually. While numerous studies have been conducted to simulate the Kerala flood of 2018, those demonstrating the application of high-resolution rainfall data for the Pamba river basin remain unexplored. Therefore, in this study, we simulated multiple storm events during the period from 2015 to 2018 using the WRF model at a high resolution (1 km * 1 km) and a temporal resolution of a one-hour interval. The WRF-simulated rainfall dataset was further post-processed using various machine learning algorithms, including Random Forest, Support Vector Machine, and extreme gradient boost (XGBoost), to reduce bias in the hourly forecast of extreme rainfall events. Several cross-validation training and testing procedures were carried out using various algorithms, and the forecasted and predicted results were compared with ERA5 hourly data of 10*10 km resolution. Results indicated that XGBoost, with hyperparameter tunings, substantially reduced the Root Mean Square Error (RMSE); it was able to reduce the RMSE by up to 50% across the river basin. This hybrid model will provide a more accurate forecast of hourly extreme rainfall during the Indian Summer Monsoon Period for Pamba river basin, with high resolution essential for flood forecasting and warning.
The future of nuctilucent clouds
Authors: Lübken Franz-Josef , Baumgarten Gerd , Grygalashvyly Mykhaylo , Vellalassery Ashique
Published: March 2024

Noctilucent clouds (NLC) consist of water ice particles which appear in the summer mesopause region at middle and polar latitudes. They owe there existence to extremely low temperatures present in this part of the atmosphere. We have applied the background model LIMA (Leibniz Institute Modelof the Atmosphere) and a microphysical model MIMAS (Mesospheric Ice Microphysics And tranSport model) to study the long term historical development of NLC. More recently, we extended these studies including future climate change predictions by modifying the concentration of carbon dioxide and methane. Carbon dioxide leads to a cooling of nearly the entire middle atmosphere (fostering the conditions for the presence of NLC), whereas methane is nearly completely converted to water vapor in the mesosphere leading to larger and more abundent ice particles, i. e., to brighter and more frequent NLC. In this study we present model simulations of the future development of NLC. We investigate typical NLC parameters, such as mean particle radius, ice number densities, and backscatter coefficients, and their relationship to background conditions (temperature, water vapor). It turns out that ice particle parameters (size, backscatter) are nearly entirely determined by the amount of water vapor, whereas the (geometric) altitude of NLC is mainly given by a shrinking of the atmosphere (due to cooling) below NLC altitudes. The effective transport of water vapor known as `freeze drying' leads to a significant enhancement (nearly doubling) of water vapor at NLC heights within this century.