bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization and microbial degradation of polysaccharides in high molecular weight dissolved organic matter.
Authors: Repeta Daniel J. , Granzow Benjamin N. , Burger Andrew , DeLong Edward F.
Published: February 2023

A large fraction of marine primary production is directed towards the synthesis of polysaccharides, most of which are rapidly degraded by heterotrophs, including heterotrophic microbes. However, a novel class of polysaccharides characterized by high N-acetyl aminosugar and 6-deoxysugar content, escapes rapid degradation and accumulates as a constituent of marine dissolved organic matter (DOM). These polysaccharides, which comprise ~25% of total dissolved organic carbon, also represent a large reservoir of the potentially bioavailable organic N and P stored in DOM.   To better understand the accumulation and microbial degradation of DOM polysaccharides we used size-exclusion chromatography and diffusion-ordered NMR spectroscopy to examine the size-distribution and composition of DOM recovered from seawater by ultrafiltration. Our results show that DOM polysaccharides are relatively small, with a molecular weight range of 1.3–7.7 kD and an average molecular weight of ~6 kD in surface waters decreasing to ~3 kD at 900m. Acid hydrolysis of DOM polysaccharides releases a suite of characteristic neutral sugars (glucose, galactose, mannose, rhamnose, fucose and xylose), but most of the polysaccharide (80-90%) resists hydrolysis and undergoes Maillard-like reactions between amino- and reducing sugars. To circumvent this, we modified our hydrolysis conditions to promote sugar-sugar cleavage. With this approach, we were able to generate a suite of oligosaccharides with molecular weights between 0.3-1.8 kD that carry the same spectral characteristics as DOM polysaccharides. We are using transposon insertion sequencing (Tn-seq) of marine bacteria cultured on these oligosaccharides to identify genes and degradation pathways responsible for DOM polysaccharide degradation. 
Novel GPU-accelerated 2D model for realistic lava flow simulation: Application to La Palma volcano
Authors: Martínez-Aranda Sergio , Echeverribar Isabel , Fernández-Pato Javier , García-Navarro Pilar
Published: February 2023

Lava flows represent highly destructive hazards at volcanoes proximities around the world. The prediction and mitigation of risks associated to effusive volcano require the development of novel physically-based numerical models able to capture the complex viscoplastic behavior of these geophysical surface flows with affordable computational efforts. The accurate simulation of this type of highly transient flows becomes a challenge due to the existence of wave fronts and the spatio-temporal temperature distribution within the lava stream. Furthermore, lava propagates over large domains with sharp topography and during long temporal scales, becoming mandatory to reduce the model complexity by depth-averaging the governing equations and to apply massive parallelization techniques for an efficient simulation.Physically-based simulation of unsteady non-Newtonian gravity/thermally-driven flows requires to solve the mass continuity, momentum and energy equations combined with suitable rheological models to capture the stresses within the flow. The lava temperature evolution is dominated by the heat transfer to the ground and the air layers, leading to a diffusive cooling process and hence causing thermal expansions/contractions of the fluidized stream. Furthermore, the lava temperature influences hugely the complex viscoplastic stresses within the fluid and hence it controls the stop/going mechanism of the lava stream. The resulting 2D system of conservation laws is solved using a Finite Volume (FV) method powered by a fully-coupled Roe-type Riemann solver. The method is able to run over unstructured triangular meshes, providing flexible, robust and accurate numerical solutions under subcritical/supercritical flow regimes. A GPU-accelerated computational kernel has been implemented using NVIDIA CUDA C++ language.The model is applied to the recent event at the Cumbre Vieja volcano (2021, La Palma Island, Spain). The numerical lava front advance is compared to satellite observations, showing very good agreement. Furthermore, multiple scenarios are analyzed in order to perform hazard estimations at the proximities of the volcano. The GPU-accelerated kernel allows to an eruption of two weeks in less than 2 computation hours. Therefore, the realistic dynamical modeling of large-scale long-term catastrophic eruptions, reducing the uncertainty associated to these geophysical flows, is only possible within an affordable computational time by using GPU-accelerated computational codes.
Characterizing two types of cirrus clouds that differ in nucleation mechanism and radiative effect
Authors: Mitchell David , Garnier Anne
Published: February 2023

A new CALIPSO satellite retrieval for cirrus clouds has been developed over the last 1.5 years that retrieves ice particle number concentration, effective diameter, and ice water content.  It compares favorably with in situ measurements from many field campaigns around the world.  This talk would briefly describe the new method targeting single-layer cirrus clouds and focus on new findings resulting from this retrieval, relating them to climate model predictions.  These results indicate that there are two types or categories of cirrus clouds.  Type 1 cirrus appear to form through heterogeneous ice nucleation (het), have visible optical depths < 0.3, and are most abundant; they are what most people visualize as a “cirrus cloud”.  Type 2 cirrus may form through a combination of het and homogeneous ice nucleation, have visible optical depths > 0.3 (with visible extinction coefficients typically 4 times greater than type 1 cirrus), and are often associated with warm fronts, orographic gravity waves, and other lifting processes.  However, type 2 cirrus clouds constitute 76% to 88% (depending on latitude) of the estimated net cloud radiative effect of all cirrus clouds.  Based on comparisons between retrieved and predicted ice particle number concentrations and effective diameters, these type 2 cirrus clouds are poorly represented in climate models, possibly partly due to the predicted dependence of ice nucleation on layer-average pre-existing ice (not realistic near cloud top where ice nucleation occurs).  Predicted ice nuclei concentrations may also need revising. 
Earth Networks Lightning System Update
Authors: DiGangi Elizabeth , Lapierre Jeff , Zhu Yanan , Stock Michael
Published: February 2023

Global lightning location data has long been a critical tool for lightning research and safety. The Earth Networks Total Lightning Network (TLN) incorporates advanced lightning location technology delivering competitive lightning detection efficiency, location accuracy, and classification (intracloud vs cloud-to-ground). It consists of over 1800 wideband sensors deployed in 40+ countries to detect lightning and generate real-time localized storm alerts. TLN is constantly evolving through network expansion, as well as hardware and software development. In this presentation, we will cover some of the recent advances to the TLN hardware and processor. The new TLN sensor has been redesigned to use a dipole sensing element to help reduce the requirements of a strong ground. These new sensors are currently being used operationally and produce comparable waveforms to the previous monopole antenna. New upgrades to the lightning location algorithm have increased the detection efficiency, location accuracy, and classification accuracy of the network. Globally, TLN is locating approximately 50% more pulses than it was before. In moderately remote regions of the world, performance gains can be higher. TLN continues to use data from the World Wide Lightning Location Network (WWLLN), enhanced via raw signals from approximately 200 TLN sensors, to locate lightning in extremely remote regions like the deep oceans. However, how WWLLN data is incorporated into the TLN feed has changed, leading to significantly reduced false alarm rates in some regions. Location accuracy was improved by developing a new propagation model for signals produced by lightning, resulting in a reduction in location error by as much as a factor of 2. As a result of the improved location accuracy, as well as enhancements to the false alarms rates, there is improved clustering of lightning, which directly impacts downstream products such as lightning alerting and Dangerous Thunderstorm Alerts.
How Hydropower Operations Mitigate Flow Forecast Uncertainties to Maintain Grid Services in the Western US
Authors: Broman Daniel , Voisin Nathalie , Kern Jordan , Steinschneider Scott , Ssembatya Henry , Wi Sungwook , Turner Sean
Published: February 2023

Hydropower facilities in the United States (US) most often have non-powered objectives, for example storage and release of water for water supply or environmental benefit, or flood control. These objectives can limit the flexibility available to hydropower operations to generate power to provide maximum benefit to the power grid. There does exist however flexibility within a week to optimize hydropower generation while still ensuring non-powered objectives are met. We examine the flexibility available to optimize generation and the value of medium-range inflow forecasts using a dynamic programing reservoir optimization model applied at ~250 hydropower facilities over the US Western Interconnection. Optimization is performed using day-ahead hourly scheduling to reflect existing electricity markets, using Locational Marginal Prices (LMPs) provided by a production cost model, and using three flavors of medium-range inflow forecasts – perfect forecasts representing an upper limit on performance, persistence forecasts representing a lower benchmark, and synthetic forecasts as a surrogate for operational streamflow forecast products. Measures of direct performance and flexibility are examined at the grid-scale for Balancing Authorities within the Western Interconnection. This study highlights where and under what conditions medium-range forecasts influence flexibility in hydropower operations which will be increasingly valuable under an evolving grid with increased renewable penetration.
PO.DAAC SWOT Hydrology Data Tools and Services
Authors: Vannan Suresh , Taglialatela Catalina , Nickles Cassandra , Tarpinian Nicholas , Greguska Frank , McDonald Victoria , Armstrong Edward , Gangl Mike , McNelis Jack
Published: February 2023

The Physical Oceanography Distributed Active Archive Center (PO.DAAC https://podaac.jpl.nasa.gov/) is NASA’s data center for the Surface Water and Ocean Topography (SWOT) mission (https://podaac.jpl.nasa.gov/SWOT?sections=data), which has recently launched in December 2022. PO.DAAC also archives physical oceanography data, which includes winds, salinity, sea surface temperature, gravity, ocean circulation, and a growing number of terrestrial hydrology data. The SWOT mission provides a comprehensive view of Earth's freshwater bodies from space and allows scientists to determine changing volumes of fresh water across the globe. SWOT hydrology data (of rivers, lakes, and reservoirs) is expected to be made publicly available in the latter part of 2023 (exact timeframe TBD). PO.DAAC has been preparing its data archive to deliver various tools and services to the hydrologic community in support of streamlined data access and use. In anticipation for SWOT, PO.DAAC has gathered requirements from the hydrology community over the last several years. In this presentation we will cover the various information systems developed to meet the hydrology community needs. PO.DAAC has also been working on migrating all of its data to the cloud. Users now have the ability to explore SWOT hydrology data directly in the Earthdata Cloud and also interface with the data using Application Programming interfaces (API). Hydrology domain specific data search and discovery methods (such as search by pre-defined hydrologic units) have also been implemented. PO.DAAC has been focused on exposing its SWOT hydrology data through programming interfaces such that scripting tools to GIS software can easily interface with the SWOT data. PO.DAAC has also been developing new functionalities to support analysis of large data, and new, innovative science and applications. Those functionalities and services will be discussed, along with what datasets users can find on the cloud, which will remain free and open to discover and access. 
Rainfall-Particle Feedback in the Amazon Forest
Authors: Toledo Machado Luiz Augusto ,   Gabriela R. Unfer, Christopher Pohlker , Jonathan Williams, Harder Hartwig, Meinrat O. Andreae, Paulo Artaxo, Yafang Cheng, Joachim Curtius, Marco A. Franco, Micael A. Cecchini, Achim Edtbauer, Bruna Holanda, Leslie A. Kremper, Bruno B. Meller, Eva Pfanne
Published: February 2023

 Atmospheric aerosol particles are essential for the formation of clouds and precipitation, thereby impactingthe global energy budget and the water cycle. However, particle production in pristine environments like theAmazon rainforests are not yet well understood. New particle formation can occur in the outflow of highconvective clouds and be transported downward (top-down) or they may form and grow from oxidizedbiogenic volatile organic compounds at low altitudes before entering the largescale vertical circulation(bottom-up). In this study, we examine a comprehensive measurement dataset of aerosols, trace gases,and meteorological parameters to examine new particle formation and growth in the Amazon rainforest.The results reveal that rain events are important not only for the downdraft of particles from aloft butalso for the injection of ozone into the forest canopy. While near-ground particle enhancements bydowndrafts were modest, .another less frequent but more efficient process acted to increase sub-40 nmparticle concentrations nearly one hour after the maximum precipitation. This phenomenon occurs due todowndrafts of ozone-rich air entering the canopy containing reactive organic species and initiating particleproduction. Particularly on days when the previous night has a high ozone concentration, these particlesgrow in the early morning to form cloud condensation nuclei in the early afternoon 
Long-term atmospheric bias teleconnection and the associated spatio-temporal variability originating from the tropical Indian Ocean sea surface temperature errors
Authors: Zhao Yuan-Bing , Žagar Nedjeljka , Lunkeit Frank , Blender Richard
Published: February 2023

The state-of-the-art climate models suffer from significant sea surface temperature (SST) biases in the tropical Indian Ocean (TIO), greatly damaging the climate prediction and projection. In this study, we investigate the multidecadal atmospheric bias teleconnections caused by the TIO SST biases and their impacts on the simulated atmospheric variability. A set of century long simulations forced with idealized SST perturbations, resembling various persistent TIO SST biases in coupled climate models, are conducted with an intermediate complexity climate model. Bias analysis is performed using the normal-mode function decomposition which can differentiate between balanced and unbalanced flow regimes across spatial scales. The results show that the long-term atmospheric circulation biases caused by the TIO SST biases have the Matsuno-Gill-type pattern in the tropics and Rossby wavetrain distribution in the extratropics, similar to the steady state response to tropical heating. The teleconnection between the tropical and extratropical biases is set up by the Rossby wavetrain emanating from the subtropics. Over 90% of the total bias energy is stored in the zonal modes k≤6, and the Kelvin modes take 50-65% of the total unbalanced bias energy. The spatial and temporal variabilities have different responses to positive SST biases. In the unbalanced regime, variability changes are confined in the tropics, but the spatial variability increases whereas the temporal variability decreases. In the balanced regime, the spatial variability generally increases in the tropics and decreases in the extratropics, whereas the temporal variability decreases globally. Variability responses in the tropics are confined in the Indo-west Pacific region, and those in the extratropics are strong in the Pacific-North America region and the Europe. In the experiment with only negative SST biases, spatial and temporal variabilities increase in both regimes. In addition, the comparison between experiments indicates that the responses of the circulation and its variability are not sensitive to the structure and location of the TIO SST biases.
Appraisal of Freeboard for a Single-family Residence in United States
Authors: Mostafiz Rubayet Bin , Al Assi Ayat , Rahim Md Adilur , Friedland Carol
Published: February 2023

Valuation of hazard-resistant construction, including the economic benefits of elevation for homes in Special Flood Hazard Areas (SFHA), is essential to increase consumer, builder, and government actions to incentivize flood mitigation measures. Previous studies have documented the economic benefits of elevated homes for flood mitigation using a benefit cost ratio (BCR) and the annual flood risk reduction (i.e., avoided average annual losses). Although these studies have shown economic benefits from elevating homes, consumer behavior and the market value of homes do not consistently reflect these benefits. This study evaluates the appraisal value of adding elevation within the standard 30-year mortgage period by considering a home’s net operating income (NOI), the difference between effective gross income (EGI) and operating expenses (OpEx). The proposed method determines a homeowner’s annual EGI by treating a home purchase as an income-producing property. The cost of elevation, flood insurance premium, homeowner’s insurance, property tax, and flood risk (i.e., average annual loss) are amortized over the 30-year mortgage period and considered as the main parameters of the annual OpEx for an owner-occupied home. To demonstrate the methodology, the EGI and OpEx are evaluated at elevation increments of +1, +2, +3, and +4 feet (e.g., freeboard).  A case study for a hypothetical single-family, one-story home in Jefferson Parish, Louisiana, reveals that cumulative appraised value increase for each foot of freeboard is $4,828, $10,186, $15,591, and $20,998 for a 30-year mortgage period. The results of this study demonstrate the economic benefit and cost effectiveness of elevation and document a critical gap in appraisal valuation.
Size distribution of atmospheric particles during the Saharan dust episodes over central Europe in Spring 202
Authors: Violaki Kalliopi , Arangio Andrea Mario , Nenes Athanasios
Published: February 2023

Aeolian dust plays a major role in Earth’s climate, by absorbing and scattering radiation, and by influencing the hydrological and biogeochemical cycles. Saharan dust is a significant carrier of limited nutrients (e.g., iron and phosphorus) in many regions of the global ocean but also transfer toxic elements such as chromium, cadmium, arsenic, and lead, influencing public health and ecosystems. Annually, Europe receives millions of tons of Saharan dust while climate change is expected to increase the frequency and severity of dust episodes, especially in the south and central part, with unknown impact on sensitive ecosystems.  During this study, aerosol particles were collected with a size-segregated hi-volume sampler (Tisch 230-High Volume Cascade Impactor). The impactor separated the particles in six different stages; from larger than 7.2 µm to less than 0.49 µm. Those samples were used to characterize the properties of dust particles during the severe dust episodes in Spring, 2021 in a forest site near Lausanne, Switzerland. We analyzed trace metals and nutrients (Fe, Cu, P, N), inorganic ions, sugars, and phospholipids. Preliminary results showed that a single dust episode can cause an increase of poisonous metals, such as lead and arsenic, by up to four times, affecting public health. In addition, it could be responsible for a large fraction of nutrients deposition - accounting for a significant part of the total annual deposition in the terrestrial and lake ecosystems in the area.
Climate impact on ocean ecosystem based on 25 years of ocean color satellite data
Authors: Park Myung-Sook , Mannino Antonio , Vandermeulen Ryan A. , Lee Seonju
Published: February 2023

This study will present how climate change impacts ocean ecosystems using NASA’s historical ocean color data (SeaWiFS-MODIS-VIIRS). The general trend analyses of ocean color data for less than three decades are hard to distinguish between natural and anthropogenic changes in multiple climate-forcing impacts. Alternatively, we bring a new approach for extracting the ocean’s primary physical modes for modulating climate variability to the ocean ecosystem, called Ocean Physical Modes projection to Ocean Color data (OPM-OC) analysis. This will show how the multiple climate-forcing components separately contribute to the satellite observable biological properties, such as Chlorophyll-a concentration, Colored Dissolved Organic Matter (CDOM), and Inherent optical properties. Also, applying the OPM-OC to the Apparent Visible Wavelength (AVW) index enables to detection of a more extensive shift of ocean color remote sensing reflectance spectrum in the tropical ocean gyre circulation by global warming.
Representation of the Mean Climate and Interannual Variability of Kiremt Rains over the Ethiopian Highlands within ICON AMIP Simulation
Authors: Bahaga Titike
Published: February 2023

While it is well known that the interannual variability of Kiremt (boreal summer) Rains in Ethiopia is forced by Sea Surface Temperature (SST) in the Pacific Ocean, the mechanisms for ENSO-Kiremt Rains teleconnections and the role of other oceans are not fully understood. In this study, the Ethiopian Kiremt Rains interannual variability was analyzed using observational data and higher-resolution SST-forced ICON experiments for the period 1981–2017. Such fine-grid global and two-way nests over the Greater Horn of Africa (GHA) were carried out here for the first time. The physical mechanisms that link ENSO influence on the Kiremt Rains in the model and ERA5 reanalysis are also investigated. It is found that the model reasonably simulates the main features of the JJAS rainfall climatology over GHA and also reproduces horizontal wind intensity and patterns at (150, 600, 850, and 925- hPa) levels over Africa. It is shown that there is a substantial skill in reproducing the leading modes of Kiremt Rains interannual variability (r = 0.64), given the SSTs are known. The results suggest that the majority (> 50%) of Kiremt Rains anomalies are driven by Equatorial Pacific SST variability, while the SST effects from other regions counteracted ENSO impact in the model. Consistent with previous studies, it is found that the El Niño phase of the ENSO drives a corresponding large-scale circulation anomaly, which weakens the monsoon trough over the Arabian Peninsula, and descending motion and upper-level convergence right over Ethiopia. The subsidence over the GHA region induces upper (lower) level westerly (easterly) wind anomalies over North Africa, weakening Tropical Easterly Jet, Somali Low-Level Jet, and reducing the moist westerly from Atlantic and Congo basin, and thus a reduction of Kiremt Rains over Ethiopia. The opposite pattern is considered under La Niña events and enhanced surface westerlies leading to wetter Kiremt Rains. This mechanism represents an anomalous Walker-type circulation for the ENSO-Kiremt Rains teleconnection. The results will have ramifications for climate model improvement and seasonal forecast improvement in Ethiopia and GHA.
High-resolution reconstruction of the hydroclimate and palaeoenvironment of the last 5500 years in the Apuseni Mountains (NW Romania)
Authors: Ruskal Agnes , Diaconu Andrei-Cosmin , Panait Andrei , Gałka Mariusz , Feurdean Angelica , Tanțău Ioan
Published: February 2023

In the present study, we analyzed an ombrotrophic peat sequence from NW Romania using a multi-proxy approach (lithology, radiocarbon dating, loss on ignition, magnetic susceptibility, testate amoebae and plant macrofossil) in order to reconstruct the environmental and hydroclimate changes that occurred in the last 5500 years.The studied sequence (Molhașul Mare de la Izbuc, Apuseni Mountains) started to accumulate in 5520 cal yr BP, debutting with a lacustrine phase and evolving into an ombrotrophic Sphagnum peat bog. The palaeoenvironmental stages of the peat bog were confirmed by the lithology, loss on ignition and magnetic susceptibility results. A pan-european testate amoebae-based transfer function was used for the quantitative reconstruction of the water table levels in the peatland. The depth to water-table (DWT) values ranged between 7.3 and 28.5 cm, suggesting wetter conditions in the first 2500 years of the sequence and drier ones between 2500 cal yr BP and the present days. The occurred hydrological shifts and the changes of the surface wetness were also confirmed by the plant macrofossil analyses.We identified and assessed the local effects of several rapid climate change events that occurred in Europe such as the Piora Oscillation, Middle Bronze Age Cold Event, Iron Age Cold Event, Roman Climate Optimum, Dark Age Cold Event, Medieval Warm Period, Little Ice Age, Great Famine in Europe, the Sporer, Maunder and Dalton Minimum Events and the Year Without Summer.Our high resolution study is among the few quantitative DWT reconstructions in Romania. Our results contribute to obtaining a broader image and a better understanding of the palaeoenvironmental, palaohydrological and palaeoclimate changes in Romania and in Central Eastern Europe during the past 5500 years.
Computing and analyzing persistent merged jet state in climate model using rare event algorithm
Authors: Suresan Sohan , Harnik Nili
Published: February 2023

The climate and weather over Europe and Asia are strongly influenced by the large-scale atmospheric circulation over the North Atlantic area. During the winter of 2009/10, the usually separate Atlantic and African jets merged into one zonal jet, resulting in unusually cold and wet conditions in Eurasian regions. During this winter the jet was unusually persistent, with characteristics more typical of the Pacific jet stream, which is a mixed thermally-eddy driven jet, suggesting the jet underwent a rare dynamical regime change.  Such a merging was only observed to occur for a whole winter during winters of 1968-69 and 1969-70. In this study, we apply GKTL rare event algorithm to produce an ensemble of PlaSim model runs of similar winter flow conditions, to study such merged jet (mixed thermally-eddy driven jet) transition and its dynamics. We try to understand how the initial conditions during the beginning of the winter could affect the jet to be in a persistent merged state. It is seen that there is a larger probability to continue in a merged jet state if there is a merged jet state at the beginning of winter. Similarly, there is a larger probability to continue in an eddy-driven jet state if there is an eddy-driven jet state at the beginning of winter. On comparing the ensemble of merged jet winter trajectories with the ensemble of eddy-driven jet winter trajectories there is a significant weakening of eddy heat fluxes over the west and central North Atlantic region. Also, the typically poleward-directed eddy momentum fluxes are significantly weaker during the winter merged jet state with small increases in the subtropics over the eastern North Atlantic due to the equatorward shift of the eddies.
The role of spatial shifting in El Niño/Southern Oscillation complexity
Authors: Thual Sulian , Dewitte Boris
Published: February 2023

The El Niño-Southern Oscillation (ENSO) represents the most consequential fluctuation of the global climate system, with dramatic societal and environmental impacts. Here we show that the spatial shifting movements of the Walker circulation control the ENSO space-time complexity in a major way. First, we encapsulate the process in a conventional recharge-discharge oscillator for the ENSO by replacing the regionally fixed sea surface temperatures (SST) index against a warm pool edge index. By doing so, we can model essential ingredients of ENSO diversity and nonlinear behavior without increasing the complexity of the dynamical model. Second, we propose a data-driven method for estimating equatorial Pacific SST variability resulting from spatial shifting. It consists in time-averaging conditions respective to the evolving warm pool edge position, then generating back SST data with reduced dimensionality (one degree of freedom) from the movements of the resulting "shifted-mean" profile. It is shown that the shifted-mean SST generated in this fashion reasonably reconstructs observed interannual SSTs both in terms of amplitude and pattern diversity. We discuss implications of the present paradigm of spatial shifting for understanding ENSO complexity, including tropical basins interactions.
Development of a Low-cost Precipitation Observation Network in Africa
Authors: Kucera Paul , Steinson Martin
Published: February 2023

Accurate and reliable real-time monitoring and dissemination of observations of atmospheric and hydrologic conditions in general is critical for a variety of research and real-time monitoring applications.  Precipitation observations provide critical information for wide variety of applications ranging from drought monitoring for agriculture application and resource staging in extreme drought regions to water resource monitoring for freshwater allocation and hydroelectric power generation.  In many regions of the World, especially in Africa, weather observation network density has been declining over the past few decades.  The University Corporation for Atmospheric Research (UCAR) with support from USAID, is leading an initiative to develop low-cost hydrometeorological instrumentation (e.g., automatic weather stations, rain gauges, stream gauges) as solution to increase observation networks in sparsely observed regions of the world. We have started a new initiative to use low-cost observation network to support the Famine Early Warning Systems Network (FEWS NET: https://fews.net/). The goal of the project is to improve the number of observations (temporally and spatially) in these regions to improve the quality of the FEWS NET products.  These data will be open and publicly available to the scientific community for other applications (e.g., satellite precipitation product evaluation, weather and hydrological prediction, etc.).  The presentation will provide an overview of the low-cost observation technology and plans for the development of the precipitation monitoring network in Africa.
Changes in carbon stock in agricultural soils over 20 years in South Korea
Authors: Yoon Jung-Hwan , Kim Hyuck Soo , Yang Jae E.
Published: February 2023

In the carbon neutral era, soil carbon became more important. Soil carbon pools (2400 Gt) are about three times larger than atmospheric pools, and soil carbon sequestration can store large amounts of organic carbon. Soil carbon storage has been reported as an effective tool to mitigate climate change in various studies, including the IPCC. Among them, it is known that agricultural soil can sequester carbon every year through sustainable soil management. In this study, we investigated changes in soil carbon storage (excluding volcanic soils) using the results of the Monitoring Project on Agri-Environmental Quality in South Korea from 1999 to 2018. Land use was categorized into paddy, upland, orchards and greenhouses. The soil organic carbon content of cultivated land has increased steadily over the past two decades, with annual organic carbon increases of 0.16 g kg-1 in paddy, 0.26 g kg-1 in upland and 0.33 g kg-1 in orchard, and 0.21 g kg-1 in greenhouse. In the 2000s, the use of chemical fertilizers decreased and the amount of livestock manure compost increased, which seems to have increased soil organic carbon. As a result of calculating the total annual increase in soil organic carbon in the entire cultivated land, it was found that 770,000 tons of C were stored in the soil (0-20 cm) per year. This corresponds to about 11% (2.8 million tons CO2-eq) of the 24.7 million tons CO2-eq of Korea's agricultural and livestock greenhouse gas emissions in 2018. South Korea also presented a scenario to achieve carbon neutrality by 2050, but currently does not include a method for using carbon sequestration. Looking at changes in soil carbon over the past 20 years, we found that soil can make a significant contribution to carbon neutrality if we introduce soil management that increases soil carbon and quantify the carbon sequestration. Therefore, it is judged necessary to introduce a soil management method that can maximize the carbon sequestration of the soil.
Multistability and transient response of the Greenland ice sheet to anthropogenic CO2 emissions
Authors: Höning Dennis , Willeit Matteo , Ganopolski Andrey
Published: February 2023

Ongoing CO2 emissions into the atmosphere and associated temperature rise have dramatic consequences for the ice sheets on our planet. In this presentation, we focus on the Greenland ice sheet, which holds so much ice that a complete melting would cause the global sea level to rise by seven meters. However, a prediction of future mass loss of the Greenland ice sheet is challenging because it is a strongly non-linear function of temperature and occurs over very long timescales. With the fully coupled Earth system model of intermediate complexity CLIMBER-X, we study the stability of the Greenland ice sheet and its transient response to CO2 emissions over the next 20 kyr. We find two bifurcation points within a global mean surface air temperature anomaly of 1.5°C. Each of these bifurcation points corresponds to a critical ice volume. If the Greenland ice sheet volume decreases below these critical values, returning to a previous atmospheric CO2 concentration would not cause the ice sheet to grow back to its previous state. We also find increased mass loss rates and increased sensitivity of mass loss to cumulative CO2 emission in the vicinity of these critical ice volumes. Altogether, our results suggest that global warming near the lower 1.5°C limit of the Paris agreement would already cause the Greenland ice sheet to irreversibly melt, although a complete melting would take thousands of years.
Air-Water Interactions Along the Dead Sea Rift
Authors: Lensky Nadav G. , Abir Shai , Tau Guy , McGowan Hamish , Mor Ziv
Published: February 2023

Rifts, tectonic depressions, stretches along continents and typically collect a wide variety of waterbodies, including wetlands, lakes, terminal lakes and locked seas. Here we exploit the waterbodies along the Dead Sea Rift, which vary by geo-climatic settings (from humid Mediterranean to hyper-arid), water depth, water salinity, etc., by simultaneously measuring surface heat, gas and momentum fluxes using Eddy Covariance towers. These waterbodies are subjected to similar radiative forcing. We show that in the two desert waterbodies differ significantly by surface heat flux partitioning: In the Gulf of Eilat (extension of the Red Sea), the evaporation rate is three times larger than in the Dead Sea (a hypersaline terminal lake), this is due to the effect of water salinity in reducing water vapor pressure. In the two northern water (Lake Kinneret and Agmon Hula), which resides in the more humid, Mediterranean region, the evaporation rate is suppressed by humidity, in comparison to the Gulf of Eilat. These two waterbodies differ by their depth, which determines the dynamics of evaporation, surface heat fluxes and thermoregulation. We analyze the role of the timing of the Mediterranean Sea Breeze on evaporation rate. This observational setup, of concurrent measurements of air-water interactions along the gradients within the Dead Sea Rift provides a rare opportunity to quantify various aspects of water management policies, the formation of rocks within these waterbodies, the effect of local micrometeorology and synoptic scale circulation on the waterbodies and their surroundings.
Analysis of marine heat waves using machine learning
Authors: Ouala Said , Chapron Bertrand , Collard Fabrice , Gaultier Lucile , Fablet Ronan
Published: February 2023

Sea surface temperature (SST) is a critical parameter in the global climate system and plays a vital role in many marine processes, including ocean circulation, evaporation, and the exchange of heat and moisture between the ocean and atmosphere. As such, understanding the variability of SST is important for a range of applications, including weather and climate prediction, ocean circulation modeling, and marine resource management.The dynamics of SST is the compound of multiple degrees of freedom that interact across a continuum of Spatio-temporal scales. A first-order approximation of such a system was initially introduced by Hasselmann. In his pioneering work, Hasselmann (1976) discussed the interest in using a two-scale stochastic model to represent the interactions between slow and fast variables of the global ocean, climate, and atmosphere system. In this paper, we examine the potential of machine learning techniques to derive relevant dynamical models of Sea Surface Temperature Anomaly (SSTA) data in the Mediterranean Sea. We focus on the seasonal modulation of the SSTA and aim to understand the factors that influence the temporal variability of SSTA extremes. Our analysis shows that the variability of the SSTA can indeed well be decomposed into slow and fast components. The dynamics of the slow variables are associated with the seasonal cycle, while the dynamics of the fast variables are linked to the SSTA response to rapid underlying processes such as the local wind variability. Based on these observations, we approximate the probability density function of the SSTA data using a stochastic differential equation parameterized by a neural network. In this model, the drift function represents the seasonal cycle and the diffusion function represents the envelope of the fast SSTA response. 
Analysis of magnetic helicity generation in MHD-shell model
Authors: Abushzada Ilyas , Yushkov Egor , Sokoloff Dmitry
Published: February 2023

The mechanism of stellar large-scale magnetic field formation, including the eleven-year solar cycle, is currently generally understood. In particular, its linear mode, in which the reverse effect of the magnetic field on the velocity field can be neglected. However, the non-linear reverse influence, which stabilize the growing average magnetic field, is not completely clear. The most possible reason of the nonlinear stabilization of this process is assumed the hydrodynamic helicity, but the balance of hydrodynamic and magnetic helicity and its transport along the spectrum remains to be studied. The present report is devoted to this problem. An exponential growth of magnetic energy at sufficiently high magnetic Reynolds numbers can be observed in a random short-correlated plasma flow at small-scales relative the velocity correlation length. Magnetic helicity is generated in this case together with the small-scale energy of magnetic field. And despite the fact that this phenomenon is traditionally studied by using the Kazantsev’s approach, we are trying to recreate this process of small-scale generation by a mhd shell approach, which is more convenient for the subsequent study of the balance and energy/helicity transport from small scales to large ones. To do this, in the complex shell model we add a small magnetic field to the well-established Kolmogorov spectrum and, by observing the exponential growth of magnetic energy on small scales, we compare the generation process with the magnetic small-scale Kazantsev dynamo. We select the correlation time for the velocity field and the working spectral regions to show that, in general, both approaches describe the same process with the same generation rates and scales. Thus, we show that the shell approach can be used for the future study of small-scale energy/helicity transport along the spectrum and for the problems of large-scale stellar dynamo processes stabilization. This work was supported by the BASIS Foundation grant no. 21-1-3-63-1.
Assessment of GPM IMERG Satellite Precipitation Estimationunder Complex Climatic and Topographic Conditions
Authors: Lu Chengxuan
Published: February 2023

Satellite precipitation estimation provides crucial information for those places lacking rainfall observations from ground–based sensors, especially in terrestrial or marine areas with complex climatic or topographic conditions. This is the case over much of Western China, including Upper and Middle Lancang River Basin (UMLRB), an extremely important transnational river system in Asia (the Lancang–Mekong River Basin) with complex climate and topography that has limited long–term precipitation records and high–elevation data, and no operational weather radars. In this study, we evaluated three GPM IMERG satellite precipitation estimation (IMERG E, IMERG L and IMERG F) over UMLRB in terms of multi–year average precipitation distribution, amplitude consistency, occurrence consistency, and elevation–dependence in both dry and wet seasons. Results demonstrated that monsoon and solid precipitation mainly affected amplitude consistency of precipitation, aerosol affected occurrence consistency of precipitation, and topography and wind–induced errors affected elevation dependence. The amplitude and occurrence consistency of precipitation were best in wet seasons in the Climate Transition Zone and worst in dry seasons in the same zone. Regardless of the elevation–dependence of amplitude or occurrence in dry and wet seasons, the dry season in the Alpine Canyon Area was most positively dependent and most significant. More significant elevation–dependence was correlated with worse IMERG performance. The Local Weighted Regression (LOWERG) model showed a nonlinear relationship between precipitation and elevation in both seasons. The amplitude consistency and occurrence consistency of both seasons worsened with increasing precipitation intensity and was worst for extreme precipitation cases. IMERG F had great potential for application to hydroclimatic research and water resources assessment in the study area. Further research should assess how the dependence of IMERG’s spatial performance on climate and topography could guide improvements in global precipitation assessment algorithms and the study of mountain landslides, floods, and other natural disasters during the monsoon period.
Transport and Removal of Stormwater Vehicle-Related Contaminants in Laboratory Columns
Authors: Cruz Bolaños María Alejandra , Xu Jiaqui , Foppen Jan Willem , Teixidó Planes Marc
Published: February 2023

Stormwater runoff capture can provide means of flood control and augmentation of local water supplies. However, urban stormwater is considered a major transport vector of contaminants, primarily from vehicle-related sources. Unfortunately, conventional green infrastructures fail to consistently remove the contaminant dissolved fraction – in particular persistent, mobile, and toxic (PMT) organic pollutants. We investigated the transport and removal of stormwater vehicle-related trace organic contaminants, such as 1H-benzotriazole, N'N-diphenylguanidine, and hexamethoxymethylmelamine utilizing continuous-flow sand columns amended with granulated activated carbon (GAC) and wheat-straw produced biochar (WSP550). All the pollutants were subjected to nonequilibrium interactions in sand-only (control) and GAC/biochar-amended sand columns, with kinetic effects on transport. The Langmuir sorption kinetics model could well describe the observed breakthrough curves, which assumes the saturation of sorption sites that might occur in infiltration systems with DOM fouling. Furthermore, we found that GAC amendments can attenuate the contaminants significantly better with faster adsorption kinetics and higher sorption capacity than the biochar. Based on the optimized sorption parameters, we concluded that HMMM had the lowest affinity in both carbonaceous adsorbents. These column results corroborated observations from preliminary batch experiments. Based on the case study simulation, the amendments of pyrogenic carbonaceous adsorbents could improve vehicle-related organic contaminant removal and exhibit a service life of more than a decade in a green infrastructure. Overall, our research contributes to improving polar organic pollutant removal technologies in environmental applications.
Effective hydrological drought monitoring depending on the catchment's hydrological regime
Authors: Baez Villanueva Oscar Manuel , Zambrano-Bigiarini Mauricio
Published: February 2023

There is an expected increase in the occurrence and severity of hydrometeorological extremes in many regions worldwide. Current research indicates that despite a positive trend in reducing drought impacts, most regions still need to adapt their monitoring practices to cope with projected drought events effectively. On the other hand, we still need a clear understanding of how a changing climate can modify the hydrological regime of catchments in the future. Therefore, it is essential to understand which drought indicators are relevant to monitoring catchments with different hydrological regimes.Therefore, this study aims to elucidate which drought indices are required to effectively monitor hydrological drought depending on the catchment’s hydrological regime, using  100 near-natural Chilean catchments with contrasting climatic conditions and hydrological regimes as a case study. For this purpose, different drought indices were computed at different temporal scales: SPI and SPEI at 3, 6, 9, 12, and 24 months; the Empirical Standardised Soil Moisture Index (ESSMI) at 3, 6, and 12 months; and a standardised snow water equivalent index (SSWEI) at 3 and 6 months. State-of-the-art gridded datasets used for computing the drought indices were: CR2MET v2.5 (a Chilean dataset based on ERA5) for precipitation and potential evapotranspiration; ERA5, ERA5-Land, and SMAP (L3 and L4) for soil moisture; and ERA5 and ERA5-Land for snow water equivalent. These indices were evaluated against the Standardised Streamflow Index (SSI) to select indices that are able to effectively monitor hydrological droughts, considering different hydrological regimes. A cross-correlation analysis and an event coincidence were used to assess which index had the highest correlation with SSI. Results showed that the indices and temporal scales used to effectively monitor hydrological droughts changed according to the catchment's hydrological regime. The results of the present work are pivotal for water managers as they provide insights on how the hydrological regime of the catchments should be considered in drought monitoring.
On the Effect of Driving Turbulence on Magnetic Reconnection: A Particle-In-Cell Simulation Study
Authors: Agudelo Rueda Jeffersson Andres , Liu Yi-Hsin , Germaschewski Kai
Published: February 2023

Energy dissipation in collisionless plasmas is one of the most outstanding open questions in plasma physics. Magnetic reconnection and turbulence are two phenomena that can produce the right conditions for energy dissipation. These two phenomena are closely related to each other in a wide range of plasmas. Turbulent fluctuations can emerge in critical regions of reconnection events, and magnetic reconnection can occur as a product of the turbulent cascade. Moreover, the presence of a turbulent field can affect the onset and evolution of magnetic reconnection. In this study, we perform 2D and 3D particle-in-cell simulations of a reconnecting Harris current sheet in the presence of turbulent fluctuations to explore the effect of turbulence on the reconnection process in collisionless plasmas. We use the Langevin antenna method to drive turbulence in the reconnecting magnetic field. We compare our results with existing theories.