bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Thermal Shocks on Cement for CCS under Confined and Unconfined Conditions
Authors: Li Kai , Pluymakers Anne
Published: February 2023

In wells for carbon capture and storage (CCS), fractures can develop in the cement due to strong thermal shocks upon pressurized CO2 injection into the subsurface. The network of these fractures forms leakage pathways that can impair well integrity, and thus impede successful geological storage of CO2. In this study, we investigate how thermal shocks affect cement integrity under unconfined and confined conditions. Solid cylindrical samples (Φ3 x 7 cm) and samples of the same size but with a hole (Φ4 mm) in the middle are used. All samples are prepared using class G cement with 35% BWOC silica flour by Halliburton AS Norway, in accordance with API specification 10B-2. In unconfined experiments, we either quench the solid sample into cold water or inject cold water through the hollow-cylindrical sample to induce thermal shocks. In confined experiments, we mount the hollow-cylindrical sample in a triaxial deformation setup with confining pressure and axial stress, then inject cold water to induce the shocks. Before the shocks in all experiments, samples have been heated to 130°C. The temperature of the water is 5°C to achieve a strong thermal shock as possible. We produce eight cycles of thermal shock in all experiments. To study the extent of cracking, we use a micro-computed tomography (μ-CT) scanner to characterize the network of pores and fractures in the cement before and after experiments.Under unconfined conditions, fractures develop in cement after thermal shocks in both quenching and injecting-through experiments. Both experiments generate sufficient thermal stresses to cause cracking in cement. In quenching, multiple fractures are initiated at different orientations. However, by injecting cold water through the sample, only one longitudinal fracture is created. This fracture is intersected with the injecting hole, where most thermal stresses are built up. The volume ratio of pores and fractures in samples increases to 2.74% by quenching and 1.84% by injecting through respectively, from 0.38%. Compressive strength decreases from 97.9 MPa for intact samples to 53.9 MPa after quenching, and 83.6 MPa after the injecting-through experiment. Under confined conditions, we carry out injecting-through experiments to bring about thermal shocks under 1.5 and 10 MPa confining pressure. We haven’t observed any failure in cement integrity under either confinement. Instead, compressive strength increases by 6.2% and 7.2%, and the volume ratio of pores and fractures decreases by 7.7% and 18.2% after the experiment under the confinement of 1.5 and 10 MPa, respectively. This means the presence of confining pressure not only hinders the adverse effects of thermal stresses on cement integrity but also compacts the samples. Higher confining pressure causes more compression to the sample, then resulting in greater strength.
Airborne observations of shoaling and breaking internal waves
Authors: Vrecica Teodor , Pizzo Nick , Lenain Luc
Published: February 2023

Internal waves are crucial contributors to the transport of sediment, heat, and nutrients in coastal areas. While internal waves have been extensively studied using point measurements, their spatial variability is less well understood. Here, we present a unique set of high-resolution infrared imagery collected from a helicopter, hovering over very energetic shoaling and breaking internal waves. We compute surface velocities by tracking the evolution of thermal structures at the ocean surface and find horizontal velocity gradients with magnitudes that are more than 100 times the Coriolis frequency. Under the assumption of no vertical shear we determine vertical velocities from the obtained horizontal divergence estimates and identify areas of the wave undergoing breaking. The spatial variability of the internal wave occurs on scales from a few to a few hundred meters. These results highlight the need to collect spatio-temporal observations of the evolution of internal waves in coastal areas.
Coda-Based Estimation of Source Parameters of Laboratory Acoustic-Emission Events
Authors: Kartseva Tatiana , Shapiro Nikolai
Published: February 2023

We propose an approach that is aimed to enrich the catalogs of acoustic emission events recorded in laboratory experiments with such parameters as seismic moment and corner frequency. Because of the difficulty of separation of direct waves in experiments performed on small samples, we use the coda waves that are composed of the reverberation of the acoustic field in the tested sample. After multiple reverberations, the resulting wavefield can be approximated as nearly homogeneously distributed over the sample and with signal amplitudes decaying exponentially in time (linearly in a logarithmic scale).Within the framework of this model, the frequency-dependent coda amplitude at any moment of time is described as combination of a source spectra, of a decay rate combining internal attenuation with reverberation losses, and of a sensor response. One of the main difficulties with the laboratory experiments is that acoustic sensors are very difficult to calibrate and their absolute response function in most of cases remains unknown. With the simple reverberation model, the logarithms of coda amplitudes at different times and sensors and for multiple events are described by a system of linear equations that we solve in a least-square sense to find frequency-dependent coda-decay rates, relative signal spectra and sensor responses. In a next step, we compute spectral ratios between spectra of different events to eliminate the sensor responses and to estimate main source parameters such as corner frequencies and relative seismic moments.We provide details of our data analyses technique and present time-dependent corner frequency vs relative moment diagrams for two experiments on granite of the Voronezh massif and Berea sandstone under pseudo-triaxial loading. The dependence close to the cubic that is frequently estimated for tectonic earthquakes observed on the first stages of both experiments when confining pressure steps applied to the intact rock and therefore to the pre-existing inhomogeneties. After applying axial load changes in stress-drop is being observed: with higher stress-drops prevailing in granite and lower stress-drops in sandstone. Also there is a significant difference in Gutenberg-Richter relation in these two experimental conditions observed.
May light microscopy observations of algae play a significative role in forensic investigations of soils?
Authors: Morabito Marina , Somma Roberta
Published: February 2023

Contrarily to land plants, which display complex anatomical features useful in diagnostics, algae are problematic to identify at the species level. Taxonomic identifications classically are focused on morphological observations at the light microscopy, but current research showed extensive phenotypic plasticity and cryptic diversity resulting in different phylogenetic assemblages. Modern taxonomic approaches also include ultrastructural (SEM and/or TEM), phylogenetic and phylogenomics information, all methodologies that may be expensive and need the involvement of skilled experts. In criminal investigations, such methodologies may not be always applicable by the judicial system because of the costs, and morphological identification of algae at the light microscope is usually the standard method. Consequently, scientific data coming from algae are often neglected in forensic investigations, with the notable exceptions of the diatoms in drowning victims.This research deals with a traditional morphological investigation on the detection and identification of soil microalgae in a case of disappearance. The method was useful in forensic investigations to associate control samples from the scene of the events to detected traces of unknown origin found on the victims.Morphological characteristics (shape, size, color, taking into consideration the different state of conservation of the algae) and cellular characteristics (wall, unicellular, colonial, multicellular organization) were observed at the light microscopy.  Where species identification was not achievable with certainty, the smallest identifiable taxonomic level was recorded. A comparison of identified morphotypes as well as of the peculiar associations of taxonomic entities was made between sample of unknown origin to those of known origin and was used to evaluate similarity degree.Observations of microalgae, in association with other geological (shape, size, color, composition of mineral grains) and botanical (shape, size, color of leaves and seeds) analyses, allowed investigators to: i) associate the walking of a person under investigation in specific sites of the scene of the events; ii) exclude that the bodies of two victims were submerged under water; iii) exclude the contact of any surface of the persons’ belongings, other than the soles of their shoes, with water basins of any kind.The present investigation proved how a traditional light microscopic approach could be decisive to associate field samples to detected traces, basing on the identification of associations of morpho-types of microalgae.
A Juno-era View of the Electric Currents in Jupiter's Magnetodisc
Authors: Liu Zhi-Yang , Blanc Michel , Zong Qiu-Gang
Published: February 2023

Jupiter's main auroral emission is believed to be governed by a magnetosphere-ionosphere coupling current system resulting from the radial outflow of the iogenic plasma. To better understand, here we delineate this current system from the viewpoint of the magnetodisc, using Juno data obtained in the night-to-dawn magnetosphere during 2016-2020. We first derive a spatial distribution of the height-integrated radial (Ir) and azimuthal (Ia) currents in the magnetodisc. Then, we calculate the divergence of the two current components, which, according to current continuity, gives the field-aligned current (FAC) connecting the magnetodisc and the ionosphere. The Ir-associated FAC, Jr, flows into and out of the magnetodisc at small and large radial distances, respectively, approximately consistent with the axisymmetric corotation enforcement model. On the other hand, Ia decreases with increasing local time in the local time extent covered, indicating an additional FAC (Ja) flowing out of the magnetodisc. From Ia and Ja, we conclude that the influence of the solar wind, which compresses the dayside magnetosphere and thus breaks the axisymmetry, reaches deep to a radial distance of at least 20 Jupiter radii. Further efforts in modeling Jupiter's magnetosphere should take this factor into account.
Fine-scale characteristics and dominant synoptic factors of spring precipitation over complex terrain of the southeastern Tibetan Plateau
Authors: zhao yin , li jian , ren liwen , li nina , li puxi
Published: February 2023

Spring precipitation over the southeastern Tibetan Plateau (SETP) produces more than 34% of annual precipitation, which is comparable to summer precipitation. This pre-monsoon rainfall phenomenon, influenced synthetically by atmospheric circulations and topography, makes the SETP an exception to its surroundings. Here, fine-scale characteristics and typical synoptic backgrounds of this unique phenomenon have been investigated. The spring precipitation over the SETP is characterized by high frequency at hourly scale, with a single diurnal peak at night. Event-based analysis further demonstrates that the spring precipitation is dominated by long-lasting nocturnal rainfall events. From early to late spring, the dominant synoptic factor evolves from terrain-perpendicular low-level winds to atmospheric moisture, influencing the spatial heterogeneity and fine characteristics of the spring precipitation. The westerly-dominated type, featured by lower geopotential height over the TP and enhanced westerlies along the Himalayas, produces limited-area precipitation at those stations located at topography perpendicular to low-level winds. In contrast, the moisture-dominated type is featured by an anomalous cyclone over the Bay of Bengal and induces widespread precipitation around the SETP, which is the leading contributor to the spring precipitation there. Due to the moist environment and weak instability, the spring precipitation influenced by the moisture-dominated type is characterized by long-lasting nocturnal events, with a large portion of weak precipitation. Findings revealed in this study complete the picture of spring precipitation influenced by different dominant synoptic factors over the SETP, which deepen the current understanding of the joint influence of circulation and topography on the hydrological cycle of complex terrains.
A sustainable approach to evaluate the impact of urban sprawl on coastal flooding in Oshiwara watershed, Mumbai, India
Authors: Pathak Shray , Sivaraman Audithan , Sambandam Geetha
Published: February 2023

Urban sprawl has emerged to be the most important and expensive part of the ecosystem with so many hazardous effects on the natural environment. Flooding has a tremendous impact on the cities, encompassing the water cycle management by collective disciplines of engineering, environmental, social, and economic sciences. This study focuses on analysing urban flooding and incorporating site-specific sub-catchment spatial strategies and management techniques considering human interactions. The Oshiwara watershed in Mumbai, India was delineated which is responsible for urban flooding along with the storm surges in the study region. The flood inundation mapping was obtained for different return periods by implementing hydrologic-hydraulic modeling and further, spatial hazard zones were identified concerning non-heuristic drivers for the 100-year return period. Subsequently, four impact maps namely infrastructural, social, economic, and environmental were identified along with the overall risk. Management interventions involving flood risk mitigation, stormwater harvesting, and water reuse were analyzed to mitigate these impacts. This provides a sustainable approach to spatially mitigate effects at vulnerable zones, instead of adopting a lumped approach for decision-making. Further, it assists the water planners to deploy planning and management interventions at specific risk locations. Thus, this study provides a suitable platform for urban planners to incorporate decisions by focusing on spatial high-risk locations.  
What drives the water exchange above sill level in the Orust-Tjörn fjord system?
Authors: Brunnabend Sandra-Esther , Axell Lars , Garcia-Jove Maximo , Arneborg Lars
Published: February 2023

The Orust-Tjörn fjord system is located on the west coast of Sweden and consists of several fjords with many small islands. The fjord system has more than one connection to the open water, enabling a generally counterclockwise circulation through the fjords. It is home to nature reservoirs, different industries on land and aquaculture farms. It is threatened for example by hypoxic areas, invasive species, water pollution and algae blooms with the water quality strongly been influenced by the water exchange in the fjord system. Therefore it is important to understand the circulation, the state and the exchange of w­ater between the fjords system and the open water outside the fjord.Not much knowledge of the circulation inside the fjords and the drivers of the water exchange between the fjords and the open water exists. The reasons are that observations are spatially sparse and the resolution of regional ocean circulation models are generally too coarse to resolve this complex fjord system with its shallow and narrow straits between the different fjords. Therefore, we developed a setup of a coastal ocean circulation model with a horizontal resolution of 50 m to study the drivers of water exchange of the Orust-Tjörn fjord system. Within a sensitivity study a set of simulations are performed using (a) temporally constant wind forcing, (b) temporally and spatially constant sea level at the open boundaries (c) no tides, and (d) constant offshore density, i.e. temporally and spatially constant temperature and salinity profiles at the open boundaries. The simulation period is September 2016 – February 2017, which includes a high saline water inflow in October 2016. Model results compare well with observations from moored high-frequency velocity, temperature and salinity instruments as well as regular monitoring data. Results show for example that the density difference between the southern and northern entrance of the Orust-Tjörn fjord system highly influences the water exchange between the fjords and open water. This is because with constant offshore density applied, near surface velocities of the Baltic current as well as the circulation above sill level within the fjord system weakens. The timing and strength of the high-saline inflow event is most sensitive to the cases of constant winds and constant offshore densities. In general, we will present a detailed analysis of the main drivers of water exchange above sill level.
The FluViSat project: Measuring streamflow from space with very high resolution Planet satellite video
Authors: Everard Nick , Dixon Harry , Sarkar Sunita , Randall Mark , Schumann Guy
Published: February 2023

The measurement of streamflow in the world’s rivers is critical to the management of water as a resource and to predicting and managing the impacts of potentially damaging hydrological events such as major floods. The European Space Agency sponsored FluViSat (Fluvial Video from Satellite) project has successfully demonstrated the potential of very high resolution satellite imagery for the determination of water flow speeds, and hence streamflow rates, using established surface velocimetry techniques.Video imagery kindly provided by Planet Labs PBC from the 21 satellites in their SkySat constellation was pre-processed to stabilise and georectify it, and then analysed using Space Time Imaging Velocimetry (STIV) techniques to provide water speed vectors across the river’s surface. The method was successfully demonstrated on rivers in Australia, the UK and Africa, with field based validation undertaken where possible. Additionally, a series of six videos was obtained and analysed to provide near a sequence of observations of flood flows on the Indus River in Pakistan during the devastating flooding of 2022.Benefits of the FluViSat innovation include the ability to observe water flow rates almost anywhere on the planet, the potential for multiple daily repeat observations and largely eliminating the need for locally based people, equipment and infrastructure.This presentation presents results from the research, explains the methods employed to derive and validate flow speeds, and explores opportunities to further enhance the FluViSat methodology.
New classification showing the stratospheric memory concept: towards a better seasonal prediction
Authors: Mariaccia Alexis , Keckhut Philippe , Hauchecorne Alain
Published: February 2023

A new method of classification based upon an empirical orthogonal functions (EOFs) analysis of zonal wind anomalies of the 70 winters from 1950 to 2020, extracted from ERA5, revealed that the winter stratosphere tends to follow four independent scenarios. The first three scenarios: the January, the February, and the Double modes, are all characterized by a perturbed evolution of the polar vortex due to significant sudden stratospheric warmings (SSWs) occurring in mid-winter, generally causing the reversing of zonal winds. Unsurprisingly, these modes contain the information of preferential important SSWs’ timings, events including minor and major SSWs, and final stratospheric warming’s timings. Thus, their patterns show that the mid-winter is often anti-correlated with the winter end. This result is consistent with the conclusion done in a recent study showing that the polar vortex on a given month is anti-correlated with its state 2-3 months earlier. While the last scenario illustrates an unperturbed polar vortex evolution during winter for which only the final stratospheric warming’s timing differs, either early and dynamical or late and radiative.The study of the mean evolutions of wave-1 and wave-2 amplitude anomalies associated with these four scenarios reveals that they possess singular dynamic behavior, especially for the wave-1 activities, which are consistent with their mean evolutions of zonal mean zonal winds. Indeed, we found that the wave-1 activity drops systematically for each scenario when zonal winds weaken due to an important. In contrast, it is not the case for the wave-2 activity.
Analysis of the geoelectric field in Sweden over solar cycles 23 and 24: spatial and temporal variability during strong GICs events
Authors: Lanabere Vanina , Dimmock Andrew , Rosenqvist Lisa , Juusola Liisa , Viljanen Ari
Published: February 2023

Extreme space weather events can produce geomagnetically induced currents (GICs) that flow along long conductor systems such as power grids and pipelines. GICs can interrupt the operation of these systems by damaging transformers and increasing the rate of pipeline corrosion. GICs depend on the enhancement of the geoelectric field, where the magnitude, geographic location, and occurrence depend on the solar wind-magnetospheric-ionospheric coupling processes and the ground conductivity. Thus, countries at high latitudes are potentially more vulnerable to GICs due to higher geomagnetic activity.Magnetic field measurements (e.g. dB/dt) have been used for a long time as a proxy for GICs with some success. However, studying the behaviour of the geoelectric field is required to fully understand the GIC response during extreme space weather events. In this study, the geoelectric field was computed using data from the IMAGE network and a 1D conductivity model (SMAP) across Sweden. A 19-year statistical analysis of the daily maximum magnitude of the geoelectric field (E) has been performed for solar cycles 23 and 24. We examine the temporal and spatial distribution of the geoelectric field in Sweden to determine the importance of including the ground conductivity when assessing the strongest events and their implications to GICs. We found that the daily maximum E is more frequently registered in the dusk sector related to the eastward convection electrojet and a second relative maximum is observed in the dawn sector related to westward convection electrojet. The stronger E values are related to well-known extreme space weather events. However, these events produce different responses at different latitudes due to the changes in ground conductivity and ionospheric response. Therefore, the strongest geoelectric fields at different geographical locations are not all driven by the same events.
Resilience of emergency infrastructure networks after flooding events
Authors: Wassmer Jonas , Merz Bruno , Marwan Norbert
Published: February 2023

Extreme weather events can drastically influence the dynamics and stability of networked infrastructure systems like transportation networks or power grids. Climate change is increasing the frequency of such events, making their impact on human society and ecosystems increasingly relevant. Prominent examples include damage of critical infrastructure caused by heavy rainfalls and landslides. The devastating floods that struck Germany’s Ahr valley in 2021 are yet another reminder of the threat posed by such extreme events. Due to washed-out roads and further severe infrastructure damages, critical bottlenecks effectively cut off a substantial share of the population from assistance, hampering or even impeding their rescue.In this study, we investigate the impact of flood events on transportation networks where stability is particularly important in order to ensure the accessibility of emergency services. Local changes in the underlying network dynamics can affect the whole road network and, in the worst case, cause a total collapse of the system through cascading failures. Because of the severe consequences of cascading events, we aim to recognise such spreading processes at an early stage and, in a further step, be able to prevent them. To this end, we set up a gravity model of travel to simulate the changes of the traffic load after flooding events to identify vulnerabilities in the system. We further analyse how the accessibility of emergency services is affected and if the population can be effectively reached in time.
Study of the evolution of interplanetary coronal mass ejections in the inner heliosphere
Authors: Larrodera Carlos , Temmer Manuela
Published: February 2023

The launch of new spacecraft such as Parker Solar Probe or Solar Orbiter allow us to measure in-situ at different radial distances the physical magnitudes of ICMEs. With that, we are able to quantify the evolution of ICMEs and their substructures at a specific radial distance in order to better understand the interaction processes that occur with the background solar wind.Using multiple spacecraft covering the inner heliosphere, we extract plasma and magnetic field parameters from several ICMEs to relate the physical processes responsible for the formation of the different substructures. We present ICME case studies that prepare for a large statistical analysis.
Extreme events in multiscale systems: theory and applications
Authors: Alberti Tommaso
Published: February 2023

Many geophysical systems show emergent phenomena and extreme events at different scales, with signatures of chaos at large scales and an apparently random behavior at small scales. Despite the intrinsic morphological and/or physical difference between geophysical extremes, they all originate as temporary deviations from the typical trajectories of the large scale geophysical flows, resulting in dynamical patterns and structures. This motivated to bring together statistics (extreme value theory) and dynamics (dynamical system theory) to provide a new definition of extremes as rare recurrences in the phase space of physical systems. This means to explore the instantaneous properties of the geometrical object hosting the frequency and probability of all physical states attainable by the system, namely the so-called attractor, to inform us on the predictability, persistence and synchronization of physical states. Here we present a recently proposed formalism to explore the active number of degrees of freedom and the predictability horizon of multiscale complex systems showing non-hyperbolic chaos, randomness, state-dependent persistence and predictability. We briefly discuss the newly introduced framework in comparison with classical approaches, based on generalized fractal dimensions, Lyapunov exponents, and Renyi entropies. Finally, we demonstrate the suitability of this novel formalism to trace the instantaneous scale-dependent and state-dependent features of climate and geophysical extremes, pointing out how the predictability horizon, the persistence and synchronization of geophysical systems’ states is a matter of scales.
Hydrogeochemical modelling of water-sediment interactions during infiltration of monovalent-partial desalinated water into different dune sediments
Authors: Schloo Mareike , Braeunig Laura , Burke Victoria , Greskowiak Janek , Massmann Gudrun
Published: February 2023

The salinization of groundwater due to saltwater intrusion in coastal regions requires efficient mitigation strategies, e.g., the infiltration of desalinated water via Managed Aquifer Recharge, such as ponded infiltration or injection wells, to ensure the supply of drinking water. It has been shown that the infiltration of desalinated water into an aquifer may result in a series of deteriorating chemical reactions. To counteract this problem, the goal of the cooperative project “innovatION” is to develop a new desalination membrane, which aims to reduce mainly monovalent ions only to achieve a more sustainable and efficient desalination technology.To give an outlook on possible water-sediment interactions during the infiltration of monovalent desalinated water into aquifers, column experiments were realised using different dune sediments from the Island of Langeoog, North-West Germany. The experimental data suggest cation exchange and calcite dissolution as the main processes occurring (compare abstract Braeunig et al.). For a process-based quantitative description and analysis of all relevant processes and their interactions, PHREEQC models were created for the individual experiments. The models support the experimental data and the hypothesized reaction network, and even allowed for the identification of  reactions (e.g. cation exchange and calcite dissolution), as well as their impact on the overall system behaviour.
First practical applications of low-data, low-assumptions background leakage determination using mCFPD
Authors: van Thienen Peter , Tsiami Lydia , Schaap Peter
Published: February 2023

A new approach to rank a group of District Metered Areas (DMAs) in terms of background and unreported leakage rate and to quantify background/unreported leakage levels for individual DMAs in this group has recently been proposed (Van Thienen, 2022). It is based on an assumption of similarity in demand behavior between different DMAs, and requires no other data than net inflow timeseries for the DMAs or supply areas under consideration, and no assumptions other than that of similarity of demand. As such, it provides a low-data-requirements method for the evaluation of background and unreported leakage that does not share underlying assumptions with the commonly used Minimum Night Flow method and may potentially present a supplement or alternative to it.In this contribution, we present and explain the method, and discuss its application to datasets from Dutch drinking water utilities. We present and discuss the lower and upper bounds for background leakage and the ranking obtained for the study areas and their interpretation. Finally, we present an outlook for application and further development. Van Thienen, P. (2022) Direct assessment of background leakage levels for individual district metered areas (DMAs) using correspondence of demand characteristics between DMAs. Water Supply 22 (7): 6370–6388. doi: https://doi.org/10.2166/ws.2022.25
Large-scale fire events substantially impact plant-soil water relations across ecosystem types
Authors: Baur Martin J. , Friend Andrew D. , Pellegrini Adam F. A.
Published: February 2023

Wildfire is a global scale ecosystem phenomenon with substantial impact on the carbon cycle, climate warming, and ecosystem resilience. Fire and the hydrological cycle are strongly interlinked, with water availability determining the amount and combustibility of fuel, and fire influencing infiltration, runoff rates and evapotranspiration. Consequently, understanding soil moisture (SM) and vegetation water content (VWC) dynamics pre- and post-fire is fundamental for predicting fire occurrence, fire severity, and ecosystem recovery. Fire can modulate SM and VWC dynamics by influencing interception of rainfall, soil porosity, plant water uptake, and runoff; however, much evidence for fire effects on the hydrological cycle is obtained at the field- to watershed-scale. Therefore, we ask the following research question: What are the effects of large-scale fire events on SM and VWC dynamics across biomes globally?Here we use over six years of global SM, VWC and vapor pressure deficit (VPD) derived from different remote sensing datasets to investigate the effects of large-scale fires on SM and VWC dynamics. We apply a dry down framework, only analyzing consecutive observations of decreasing soil moisture, to describe post-fire response rates for SM, VWC and VPD relative to a pre-fire reference state.We find large scale evidence that the post-fire rate of change of SM over time is more negative, indicating faster water loss. Vegetation recovery, indicated by a positive change in VWC over time, exceeds the pre-fire reference state, which suggests that post-fire recovery is predominantly faster than undisturbed seasonal vegetation growth, likely due to succession of fast-growing plant species. Furthermore, fire affects ecosystem hydrology on shorter timescales as well, reducing diurnal VWC variation over a wide range of SM and VWC conditions. Our findings confirm several trends previously only observed at smaller scales and suggest global remote sensing of SM and VWC can substantially contribute to understanding the dynamics of post-fire plant and soil water status.
PyroCbs from Australia Fires and its Impact Study Using Satellite Observations from CrIS and TROPOMI and Reanalysis Data
Authors: Xiong Xiaozhen , Liu Xu , Wu Wan , Lei Liqiao , Yang Qiguang , Zhou Daniel , Laura Allen
Published: February 2023

Australia’s unprecedented fire disasters at the end of 2019 to early 2020 emitted huge amounts of carbon monoxide (CO) and fire aerosol particles to the atmosphere, particularly during the Pyrocumulonimbus (pyroCb) outbreak that occurred in southeast Australia between 29 December 2019 and 4 January 2020. It was estimated that at least 18 pyroCbs were generated during this episode, and some of them injected ice, smoke, and biomass burning gases above the local tropopause.  An unprecedented abundance of H2O and CO in the stratosphere, and the displacement of background ozone (O3) and N2O from rapid ascent of air from the troposphere and lower stratosphere were found from satellite observations. Some other studies also found that the fire emissions and their long-range transport resulted in stratospheric aerosol, temperature, and O3 anomalies after the 2020 Australian bushfires and altered the Antarctic ozone and vortex, posing great impact to local air qality and climate change.            This study will focus on the thermodynamic state of atmosphere associated with these pyroCbs, and its impact on the change of the cloud properties and trace gases during this unprecedented Australia fires, mainly based on a new single Field of View (SFOV) Sounder Atmospheric Products (SiFSAP) and TROPOMI. SiFSAP was developed by NASA using the Cross-track Infrared Sounder (CrIS) and Advanced Technology Microwave Sounder (ATMS) onboard SNPP and JPSS-1, and will soon be available to the public at NASA DAAC. Since this product has a spatial resolution of 15 km at nadir, which is better than most global weather and climate models and other current operational sounding products, a process-oriented analysis of the dynamic transport of CO and fire plumes during this unprecedented fire disasters will be made in this study.  Based on a Principal Component Radiative Transfer Model (PCRTM) and an optimized estimation retrieval algorithm, a simultaneously retrieval is made using the whole spectral information measured by CrIS,  and the derived SiFSAP include temperature, water vapor, trace gases (such as O3, CO2, CO, CH4 and N2O), cloud properties and surface properties. Use of ATMS together with CrIS allows SiFSAP to get accurate retrieval products under thick pyroCb conditions. An algorithm to detect pyroCb based on the hyperspectral infrared sounder spectrum from CrIS will be developed and verified. In addition to SiFSAP sounding products,  CO, O3, NO2 from TROPOMI and O3 from OMPS will be used. The wind fields from the NASA’s Modern-Era Retrospective Analysis for Research and Applications Version-2 (MERRA-2) and ERA5 will be used to characterize the transport, and the SiFSAP temperature and water vapor profiles within and around pyroCbs will be compared with MERRA-2 and ERA5 products.     
Understanding sources of contrail cirrus radiative forcing uncertainty using a new diagnostic contrail scheme for the UK Earth System Model
Authors: Zhang Weiyu , Rap Alexandru , Van Weverberg Kwinten , Furtado Kalli , Feng Wuhu , Morcrette Cyril , Forster Piers , Francis Timmy
Published: February 2023

Condensation trails (contrails) are aircraft-induced line-shaped high clouds, which may persist and grow to form contrail cirrus in ice supersaturated regions. Contrail cirrus is the largest known component of aviation radiative forcing, with a large uncertainty associated with troposphere water budgets and contrail radiative properties. In addition, due to the limited number of climate models able to simulate contrail cirrus, the uncertainty in the global contrail cirrus radiative forcing cannot be estimated statistically.The aim of this work is to implement a contrail cirrus parameterisation in the UK Earth System Model, therefore providing a new independent estimate of the contrail cirrus radiative forcing to be used in future assessments of aviation climate impacts. The new diagnostic scheme is based on the processes governing contrail formation (Schmidt-Appleman Criteria) and persistence (ice supersaturation). Persistent contrails are then added to the model cloud fields, where they interact with and evolve alongside natural clouds.We use ensemble runs of both nudged and free running model experiments to estimate the contrail cirrus cover and effective radiative forcing. Comparisons with a similar contrail scheme implemented in the NCAR Community Atmospheric Model (CAM) indicate the importance of the host climate model via (i) the host’s cloud microphysics scheme (e.g. single vs. double moment) and (ii) its ability to simulate realistic ice supersaturated regions. By providing a new independent assessment of the contrail cirrus radiative forcing, our work contributes to improving our understanding of aviation climate impacts and therefore potential mitigation strategies for current and future generation aircraft. 
Recent Improvements in the SMAP Level-4 Soil Moisture Product
Authors: Reichle Rolf , Liu Qing , Ardizzone Joseph , Bechtold Michel , Crow Wade , De Lannoy Gabrielle , Kimball John , Koster Randal
Published: February 2023

The NASA Soil Moisture Active Passive (SMAP) mission Level-4 Soil Moisture (L4_SM) product provides global, 9-km resolution, 3-hourly surface (0-5 cm) and root-zone (0-100 cm) soil moisture from April 2015 to present with a mean latency of 2.5 days from the time of observation.  The product is based on the assimilation of SMAP L-band (1.4 GHz) brightness temperature (Tb) observations into the NASA Catchment land surface model as the model is driven with observations-based precipitation forcing. In this presentation, we describe three recent improvements in the L4_SM algorithm.  First, satellite- and gauge-based precipitation from the NASA Integrated Multi-satellitE Retrievals for the Global Precipitation Measurement mission (IMERG) are used in two ways: (i) The climatology to which all L4_SM precipitation forcing inputs are rescaled is based on IMERG-Final (Version 06B) data, replacing the Global Precipitation Climatology Project v2.2 data used in previous L4_SM versions, and (ii) the precipitation forcing outside of North America and the high latitudes is corrected to match the daily totals from IMERG, replacing the gauge-only, daily product or uncorrected weather analysis precipitation used there in earlier L4_SM versions.  Second, the Catchment model now includes the recently developed PEATCLSM hydrology module for peatlands and uses an updated global map of peatlands.  Third, revised parameters are used in the L-band radiative transfer model that converts the simulated soil moisture and temperature estimates into Tb predictions for use in the radiance-based L4_SM analysis.  Specifically, climatological parameters for the scattering albedo, soil roughness, and (seasonally-varying) vegetation opacity were derived from the SMAP Level-2 radiometer soil moisture retrieval product.   The revised precipitation inputs result in considerably improved anomaly time series correlation skill of L4_SM surface soil moisture in South America, Africa, Australia, and parts of East Asia.  Particularly large improvements are seen in central Australia and Myanmar, where the quality of the gauge-only precipitation product used in earlier L4_SM versions was particularly poor.  In peatlands, the dynamics of water table depth, surface soil moisture and evapotranspiration are considerably improved when evaluated against in situ measurements.  Moreover, the time series correlation of surface and root-zone soil moisture vs. in situ measurements is slightly improved, owing to the improved annual cycle phasing of the Level-2 derived vegetation opacity parameters.  Collectively, these improvements are also manifested in smaller Tb observation-minus-forecast residuals.
Increasing water limitation of global ecosystems in a changing climate
Authors: Orth Rene , Denissen Jasper M.C. , Li Wantong , Oh Sungmin
Published: February 2023

The ongoing and projected climate change involves changes in temperatures and precipitation in many regions. These changes in turn affect terrestrial ecosystems that require sufficient water and energy to provide essential services such as food security and the uptake of human-caused CO2 emissions.This presentation will introduce the concept of ecosystem water and energy limitation, and identify areas where each limitation prevails. These areas are characterised by different sensitivities of evapotranspiration and vegetation productivity to long-term changes in temperature and precipitation. A special focus will be on the global trends of ecosystem water limitation through time, where our results show increased water sensitivity across recent and future decades in many regions. This implies an increasing ecosystem vulnerability to water availability which can lead to reductions in vegetation carbon uptake in the future, consequently amplifying climate change. In this context, near-surface soil moisture is found to be the most relevant water reservoir for vegetation functioning, while deeper soil moisture is less relevant for the investigated multi-decadal time periods.The presentation will also illustrate that the increasing water limitation can affect the consequences of droughts in related regions. These ecosystems become more vulnerable to droughts such that disruptions in vegetation functioning are more pronounced. Also evaporative cooling will decrease more strongly which promotes hotter temperatures during drought. At the same time, decreased vegetation productivity could lead to reduced availability of fuel for wildfires.These analyses are based on (i) observation-based data including reanalyses, satellite-based datasets and gridded data derived from upscaling in-situ observations, and (ii) simulations from land surface and Earth system models. Building upon this, the presentation will discuss the related model performance as well as opportunities for model development to more accurately capture and predict ecosystem water limitation. 
Exhaustive Searching and LASSO for Reliable Drought Forecasting over South Korea
Authors: Lee Taesam , Kong Yejin , Kim Taekyun , Lee Saejung
Published: February 2023

The spring drought over South Korea has been extensive damage recent years and its forecasting can be important in water management and agricultural industries. However, the drought forecasting is not an easy task because of the difficulty to find predictors to the precipitation predictand. Also, limited hydrological records for applying to complex models such as nonlinear or deep learning models do not produce reliable forecasting results. In the current study, we proposed the drought forecasting approach by exhaustive searching for explanatory variables and a regression model for limited record lengths. At first, the target drought index was set with the accumulated spring precipitation (ASP) obtained by the median of the 93 available weather stations over South Korea. Then, exhaustive searching for predictors was performed with association between the ASP and the differences of two pair combination of the global winter MSLP, say Df4m, for the time lag of the spring seasonal drought. The 37 Df4m predictors were found with high correlation over 0.55. The detected 37 variables were categorized into three subregions. The predictors in the same region contain highly similar to each other. Subsequently, the multicollinearity problem cannot be avoidable. To solve the multicollinearity problem, the Least Absolute Shrinkage and Selection Operator (LASSO) model was applied resulting five Df4m predictors and the good agreement of the forecasting value with the observed value as R2=0.72. Therefore, we concluded that the proposed LASSO model with the exhaustive searching of the global MSLP can be a good alternative to forecast the spring drought over South Korea. The spring drought forecasting with the LASSO model and the Df4m predictors can be extensively used for water managers and water industry.  
Global warming is increasing the discrepancy between green (actual) and thermal (potential) seasons of temperate trees
Authors: Fu Yongshuo H. , Chen Shouzhi
Published: February 2023

Over the past decades, global warming has led to a lengthening of the time window during which temperatures remain favorable for carbon assimilation and tree growth, resulting in a lengthening of the green season. The extent to which forest green seasons have tracked the lengthening of this favorable period under climate warming, however, has not been quantified to date. Here, we used remote sensing data and long-term ground observations of leaf-out and coloration for six dominant species of European trees at 1773 sites, for a total of 6060 species-site combinations, during 1980-2016 and found that actual green season extensions (GS: 3.1 ± 0.1 d decade-1) lag four times behind extensions of the potential thermal season (TS: 12.6 ± 0.1 d decade-1). Similar but less pronounced differences were obtained using satellite-derived vegetation phenology observations, i.e., a lengthening of 4.4 ± 0.13 d decade-1 and 7.5 ± 0.13 d decade-1 for GS and TS, respectively. This difference was mainly driven by the larger advance in the onset of the thermal season compared to the actual advance of leaf-out dates (spring mismatch: 7.2 ± 0.1 d decade-1), but to a less extents caused by a phenological mismatch between GS and TS in autumn (2.4 ± 0.1 d decade-1). Our results showed that forest trees do not linearly track the new thermal window extension, indicating more complex interactions between winter and spring temperatures and photoperiod and a justification of demonstrating that using more sophisticated models that include the influence of chilling and photoperiod are needed to accurately predict spring phenological changes under warmer climate. They urge caution if such mechanisms are omitted to predict, for example, how vegetative health and growth, species distribution, and crop yields will change in the future.