bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatiotemporal variations of the precipitation in the Yellow River Basin using a novel hierarchical discrete-continuous wavelet decomposition model
Authors: Wang Wenzhuo , Dong Zengchuan , Ren Li
Published: March 2024

Periods detected by an advanced, systematic technology can provide reliable basis for water resources prediction and management. One of the main challenges of period mining is getting rid of the effects of climate change and noise. This study presents the hierarchical discrete-continuous wavelet decomposition (HDCWD) model. The method provides a three-layer identification framework of detrending, denoising and mining by combining discrete wavelet transform and continuous wavelet transform. The dominating periods and their spatiotemporal features of precipitation in the Yellow River Basin are identified by applying HDCWD to different catchments. Results show the following: (1) Noise exists in the precipitation series in the Yellow River Basin and leads to overlooked period. (2) Precipitation in the Yellow River Basin has the dominating periods of 2–4 years and 7–9 years from 1956 to 1984, and period of 2 years from 1998 to 2002. (3) The periodicity of precipitation in the Yellow River Basin varies among different catchments that the ones in higher latitude exhibit a longer period and those in the lower east exhibit a shorter period.
A Morphological Algorithm for the Detection of Linear Contrails
Authors: Gourgue Nicolas , Boucher Olivier , Barthes Laurent
Published: March 2024

The climate impact of aviation can be separated into CO2 and non-CO2 effects, with the latter being potentially larger than the former. In thiscontext we are more specifically interested in condensation trails (hereafter contrails) and induced cirrus. Monitoring contrail formation and evolution isnecessary to understand their radiative effects and help the aviation industry to transition towards a more sustainable activity. Current research aimed atdetecting contrails is mostly based on geostationary satellite images because they allow to follow the contrail over a long period of time. However a majorshortcoming is that the formation phase of the contrails cannot be detected and larger, but older, contrails cannot always be attributed to the flightsthat produced them. To circumvent the problem that satellite images do not have a sufficient resolution to observe the contrail formation phase, weuse a ground-based hemispheric camera with a two-minute sampling rate as a complementary source of information. As a first step, we have developeda traditional morphological algorithm that will help preparing a sufficiently large labelled database as required to train a deep-learning algorithm. Ouralgorithm aims to detect whether each aircraft that passes in the field of view of the camera (as monitored from an ADSB radar) produces a contrail or not. We are thus able to relate contrail formation and evolution with aircrafttype, flight altitude and weather conditions. We start by focusing on the young linear contrails that appears just behind the aircraft. We also considerall weather conditions except completely cloudy conditions that prevents contrails to be observed. The algorithm combines various morphologicaltreatments to binarise the image and a linear Hough transform to identify straight lines in a direction close to the aircraft’s trajectory. Its performance is evaluated against a database that was manually annotated consisting of 400 images with 407 contrails. We find that our algorithm has a specificityof 97%, i.e. there are few false detections, but its sensitivity is about 55%, i.e. it is missing a significant fraction of contrail appearances. Looking inmore details, the sensitivity is 60% in clear-sky contidions but only 40% in conditions of a thin high cloud cover with superimposed contrails. Ananalysis of several years of contrail detection will be presented to determine precisely the fraction of contrail-producing flights and the associated weatherconditions with non-persistent and persistent contrails.
Predicting phosphorus loss from structured soils through macropores
Authors: Xin Ping , Pesch Charles , Norgaard Trine , Wollesen de Jonge Lis Wollesen , Mäenpää Maarit , Heckrath Goswin , Vangsø Iversen Bo
Published: March 2024

Macropore transport is an important process of phosphorus (P) loss from tile-drained agricultural land to surface waters where P inputs may cause accelerated eutrophication. Many laboratory experiments or plot studies have shown that P loss by macropore transport increases with increasing concentrations of mobilizable P in the topsoil. However, operational models that quantify the risk of P losses by macropore transport based on typically available information on soil properties, including P status and soil hydrological properties, are currently lacking.This study has collated and analyzed comprehensive existing data from standardized column-leaching experiments with 193 topsoils from different locations in Denmark. In addition to general physical and chemical soil properties including soil P pools, water, and P transport were measured on the large undisturbed soil columns. This data has been used to investigate relationships between P loss and soil properties under varying degrees of macropore transport. Specifically, we have used two statistical methods to analyze relationships between variables and to explore predictive models – multiple linear mixed models (MLMM) and structural equation modeling (SEM). The latter technique allows for testing complex causal relationships among observed and latent variables.Our SEM approach has so far yielded rather poor model fits, and the model structures for estimating the loss of dissolved and particulate P from the columns were characterized by low significance. This was partly due to missing data. In contrast, different MLMM fitted the measured dissolved and particulate P losses satisfactorily. Water-extractable P and saturated hydraulic conductivity were the most important variables for estimating dissolved P losses, while colloid mobilization in soils and tritium leaching breakthrough time explained particulate P losses to a large degree.Our initial statistical analyses show that P loss in dissolved and particulate form from large columns under macropore runoff scenarios can be reasonably explained by soil properties that are typically mapped in Denmark. This approach could bridge empirical and mechanistic modeling and facilitate mapping the risk of P loss by macropore transport.
Quantifying the Effect of Additional Training Data When Using Machine Learning to Predict Streamflow in Ungauged Basins
Authors: Werenka Alexander , Weijs Steven
Published: March 2024

One of the greatest challenges in hydrology is in the accurate prediction of streamflow in ungauged basins. In recent years, machine learning models have made great strides in the ability to accurately predict these flows, but these models are extremely data intensive. However, resources for streamflow monitoring are often quite limited so it is important to gather data as efficiently as possible. In this study, we establish a relationship between the amount of data used in training and the quality of predictions in ungauged basins for Long-Short Term Memory-based neural network models. First, using the CAMELS dataset, we create numerous training sets with a different number of basins in each and corresponding testing sets that use basins outside of the training set to simulate ungauged basins. We then quantify how changing the size of the training sets and the length of the training data affects the quality of predictions in the testing sets.
Can we bring alpine climate into ecotrons?
Authors: Crepaz Harald , Klotz Johannes , Cavalli Marco , Tappeiner Ulrike , Niedrist Georg
Published: March 2024

Climate change is advancing at an unprecedented pace, impacting terrestrial ecosystems, particularly those in alpine regions. Consequently, there is a growing need to comprehend the associated impacts, underlying mechanisms, and implications. Long-term monitoring may face challenges in capturing the effects of accelerated climate change, and in-situ experiments in remote alpine areas often grapple with logistical constraints. Furthermore, attributing vegetative responses to specific manipulated variables proves challenging, especially under extreme alpine conditions such as low atmospheric pressure, low temperatures, or high radiation levels.Using a specially designed ecotron called 'TerraXcube' (Bozen, Italy), we investigated the feasibility of realistically reproducing harsh alpine conditions and explored the interactions among various parameters. For our measurements, we equipped the chamber with temperature and relative humidity probes, a spectrometer, barometer, and anemometer positioned at different heights within the chamber. We tested the spatial and temporal homogeneity of the variables— atmospheric pressure, temperature, relative humidity (RH), and radiation—independently, as well as their interactions over time and in space, by simulating various realistic alpine climatic scenarios.The measurements, conducted between -20°C and +25°C with relative humidity ranging from 10% to 95%, yielded satisfactory results. Over several hours, the largest difference at a specific position was 0.6°C and 4.3% RH, while the maximum difference between two sensors simultaneously was 1°C and 7% RH. At a height of 170 cm, the LED system emitted radiation at an intensity of 1,002 W/m² within the wavelength range of 280 to 900 nm; however, with a sharp decrease in intensity from the light source. The photosynthetically active radiation (PAR) at the chamber's center reached 1,883 μmol·m−2·s−1, achieving 77% of the potential annual maximum measured at 2,400 m a.s.l. This enables us to replicate the PAR level for 97% of the days throughout the year. Despite the high light intensity, the heating effect of the LED system was limited to a maximum of 2°C in the upper 40cm of the chamber. Pressure manipulation, with the highest technical demand, nonetheless resulted in high temporal homogeneity up to 4,000m a.s.l., corresponding to 618.9 mbar.In conclusion, the results emphasize the potential and utility of ecotrons in simulating a suitable climate for alpine ecological experiments. However, as in many ecotrons, it is crucial to acknowledge that minor island effects and irregularities are inevitable. Even more sophisticated parameters such as wind effects or pollinator function are currently not sufficiently addressed. A combined in- and outdoor usage of mobile field lysimeters might be a further step to bridge this gap between experimental results obtained in ecotrons and in the field.
Beyond the Extremes: Interpretable insights based on Attention framework 
Authors: Pathania Ashish , Gupta Vivek
Published: March 2024

Extreme weather events significantly impact the economy, agriculture, infrastructure, and ecosystems of a region. According to the Center for Science and Environment (CSE), extreme weather events caused the loss of nearly 3000 lives, 2 million hectares of crops, and the death of 90,000 cattle in India in 2023 alone. Effective mitigation and adaptation strategies for the region necessitate a reliable forecasting system. The spatiotemporal interactions of several hydroclimatic components at different scales make it difficult to provide reliable forecasts for a region with multiple climate zones. The present research proposes an encoder-decoder-based deep learning framework with an attention mechanism to develop a reliable forecasting model. Attention frameworks have exhibited considerable potential in learning contextual awareness within the time series domain which will help in identifying the temporal dependencies between the meteorological variables and extreme events. The proposed architecture of the forecasting model is made interpretable as it is crucial to comprehend the underlying mechanism of climatic extremes. It recognizes the contributing variables influencing the intensity and frequency of extreme events. The study employed 0.12° × 0.12° high-resolution IMDAA (Indian Monsoon Data Assimilation and Analysis) dataset encompassing climatic variables like precipitation and temperature.Various studies have supported the association of the ENSO parameters with the anomalous climatic conditions over India. The present study also aims to ascertain the distinct contributions of ENSO variables through the implementation of an interpretable framework. Explainability results underscore the significance of precipitation patterns while forecasting drought conditions in the region. Moreover, the results highlight the complex interaction of climatic variables that affect the intensity of the extremes.
Big Data Analysis of Antarctic Ice Structures and Subglacial Lakes: Utilizing Moving IQR for Radar Intensity Processing
Authors: Park Yong-Gil , Lee Chol-Young , Lee Joo-Han , Joo Dong-Chan
Published: March 2024

The structure of Antarctic ice preserves the sequence of ice deposition, offering insights into ancient environmental conditions. Organisms discovered beneath the ice sheets, spanning from hundreds to thousands of meters in thickness, hold information on survival in extreme environments. Antarctic ice investigations are conducted using radar systems mounted on helicopters or vehicles, generating vast datasets covering hundreds of kilometers. Analyzing this large-scale data is essential to reduce time and cost for detecting ice structures and subglacial lakes. In this study, we developed algorithms for ice structure analysis and subglacial lake detection using big data analysis techniques, specifically outlier detection methods applied to radar signal values. Utilizing radar signal values represented in an 800x83,344 matrix, we employed the Spark platform with specifications of 400 cores and 1.6TB of memory for data analysis. To facilitate data processing in Spark, the data was transformed into a 3x66,675,200 dataframe after uploading to HDFS. Outlier detection, using the Moving Interquartile Range (IQR), identified abrupt changes in signal values based on columns, adjusting the IQR's range and scale to optimize the results. Detected outlier values were normalized within a 0-255 range and visualized based on intensity. Results revealed that using the Moving IQR for radar imagery processing effectively detected localized changes as the range increased; however, detection rates decreased with larger scales. Analyzing radar exploration results in a big data environment is anticipated to significantly reduce time and costs compared to traditional methods, contributing to Antarctic exploration and climate change response efforts. 
Is the sensitivity of leaf water and cellulose δ18O values sufficient for detecting effects of increasing atmospheric CO2 on stomatal conductance in plants? 
Authors: Kahmen Ansgar , Holloway-Phillips Meisha , Morgener Eva , Basler David , Nelson Daniel B.
Published: March 2024

The oxygen isotope composition of cellulose (δ18O values) has been suggested to contain information on stomatal conductance (gs) responses to rising pCO2. The extent by which pCO2 affects leaf water and cellulose δ18O values (δ18OLW and δ18OC) and the isotope processes that determine pCO2 responses of gs in δ18OLW and δ18OC are, however, unknown. We tested the effects of pCO2 on gs, δ18OLW and δ18OCin a greenhouse experiment, where six herbaceous plant species were grown under pCO2 levels ranging from 200 to 500 ppm. An increase in pCO2 caused a decline in gs. The effects of gs on δ18OLW were caused by direct and indirect mechanisms but were generally small. The model parameter effective path length (Lm) was unaffected by changes in pCO2. pCO2 effects on δ18OLW were not directly transferred to plant δ18OC but were attenuated in grasses and amplified in dicotyledonous herbs and legumes. This is likely because of functional group specific pCO2 effects on the model parameter pxpex. Our study removes critical uncertainties for using δ18OC as a proxy for gs. At the same time, our study shows that gs effects on δ18OLW and δ18OC are rather small, possibly too small to be detected in natural settings.
High precision U-Pb geochronology of Cenozoic phonolite volcanic bodies in Cenozoic Eger rift basin (Bohemian Massif)
Authors: Závada Prokop , Cajz Vladimír , Kylander-Clark Andrew , Uličný David
Published: March 2024

A new set of high-precision U-Pb data was acquired for two groups of phonolite bodies emplaced in the volcano-sedimentary sequence of the Cenozoic Eger Rift in Bohemian Massif. The phonolites are located in the western (5 bodies) and eastern (3 bodies) edge of this monogenetic volcanic field, stretched along the central part of the Eger Rift system. The selected phonolite bodies represent lava flows, cryptodomes or extrusive domes emplaced in phreatomagmatic maar-diatremes, remnants of dykes, and a laccolith. The U-Pb dates were acquired using the Laser Ablation Split Stream system at Santa Barbara University geochronology lab, which provides the coupled geochronology and also REE and selected major element geochemistry. Despite the great variety of internal zircon textures from oscillatory zoning to complex patchy patterns with a large range of cathodoluminescence intensity, the groups of spots gained coherent and surprisingly precise ages for each sample. The western group of phonolite bodies, namely the Bořeň, Želenický vrch, Špičák, Hněvín, and Ryzelský vrch display clusters of ages ranging between 33Ma and 36Ma, while zircons of the eastern group of the phonolites, Krompach, Mariánská hora and Luž (Lausche) indicate ages between 30Ma and 32Ma. Terra-Wasserburg diagrams for individual samples revealed remarkable precision marked by errors of only 90-180 thousand years (5 samples) and 300-650 thousand years (2 samples). The U-Pb zircon ages are interpreted to reflect primarily the high-temperature overprint of inherited (and possibly newly crystallized) zircons before emplacement of the phonolite bodies in the upper crust. In addition, titanite grains measured alongside the zircon grains (in another run) either overlap (Bořeň) with the zircon age error on Terra-Wasserburg diagrams (geochrone) or are 2 Ma years younger than corresponding zircon ages (Špičák phonolite body). REE binary diagrams revealed separate clusters of Sm/Nd and also Hf content of the zircons, which can be attributed to different degrees of partial melting of parental magma in the source upper mantle or the lower crust for both groups of sampled phonolites. In summary, the results suggest that U-Pb geochronology using the LASS system is a powerful tool with a great potential for deciphering the evolution of phonolites in the Cenozoic Rift system in Bohemian Massif and possibly other rift systems in the foreland of the Alpine orogeny.This research has been supported by the Czech Science Foundation (GAČR) project 22-13980S.
SPEEDY-NEMO: performance and applications of a fully-coupled intermediate-complexity climate model
Authors: Ruggieri Paolo , Abid Muhammad Adnan , Garcia-Serrano Javier , Grancini Carlo , Kucharski Fred , Pascale Salvatore , Volpi Danila
Published: March 2024

A fully-coupled general circulation model of intermediate complexity is documented. The study presents an overview of the model climatology and variability, with particular attention for the phenomenology of processes that are relevant for the predictability of the climate system on seasonal-to-decadal time-scales. It is shown that the model can realistically simulate the general circulation of the atmosphere and the ocean, as well as the major modes of climate variability on the examined time-scales: e.g. El Niño-Southern Oscillation, North Atlantic Oscillation, Tropical Atlantic Variability, Pacific Decadal Variability, Atlantic Multi-decadal Variability. We demonstrate the ability of the model in simulating non-stationarity of coupled ocean-atmosphere modes of variability. Potential applications of the model are discussed, with emphasis on the possibility to generate sets of low-cost large-ensemble retrospective forecasts. We argue that the presented model is suitable to be employed in traditional and innovative model experiments that can play a significant role in future developments of seasonal-to-decadal climate prediction.
A finite volume code for simulating debris-flow routing: preliminary results
Authors: Barbini Matteo , Bernard Martino , Lanzoni Stefano , Gregoretti Carlo
Published: March 2024

The bi-phase governing flow equations of a solid-liquid mixture are numerically integrated within the shallow water approximation using the finite volume method. The one-dimensional FORCE scheme is extended to the two-dimensional case and reviewed for use with a structured computational grid comprising quadratic cells.  The intermediate points, at which the solution is computed at time , correspond to the corners of a cell, and this solution is derived from the values of the four surrounding cells adjacent to the corner. Consequently, the solution for a (i, j) cell within the domain depends on the four intermediate solutions computed at the corners: ,, ,. Subsequently, for a (i, j) cell, the t+1 solution is reliant on the value of the at that cell and the values of its eight neighbouring cells. The model is used for replicating the flow depth, velocity, and solid concentration values observed in a systematic series of flume experiments documented in the literature. The comparison shows good agreement for solid concentration and satisfactory alignment for flow depth and velocity values. Finally, the model is used for reproducing the flow pattern of the debris flow that occurred on Rio Lazer on November 4th, 1966. The comparison results are satisfactory.
Three years of eddy covariance measurements of a tropical forest in the Congo Basin.
Authors: Daelman Roxanne , Bauters Marijn , Sibret Thomas , Lefevre Lodewijk , Mbifo José , Verbeeck Hans , Boeckx Pascal
Published: March 2024

The CongoFlux climate site in the Yangambi UNESCO biosphere reserve (0°48’52.0"N, 24°30’08.9"E) hosts the first Eddy Covariance (EC) flux tower in the central Congo Basin. The site, recently labeled as an ICOS associated ecosystem station, was built in 2020 to address the lack of observations of the tropical forest ecosystems in Central Africa. We aim to quantify the net ecosystem exchange (NEE) and the water use efficiency (WUE) of the tropical forest in the footprint of the tower. A set of meteorological and hydrological data is also recorded, including several climatic factors that could explain the seasonal patterns of NEE and WUE. However, processing EC data still remains a challenge in the tropics. Tall vegetation and frequent low turbulent conditions call for attention to the storage correction term. Multiple set ups on the site were used to study the best way to handle the nighttime buildup of CO2 in the canopy. The threshold for the friction velocity to differentiate low from wel mixed turbulent conditions, needs to be selected with care to minimize the influence of the frequent low turbulent conditions, while at the same time minimizing the amount of data that needs to be filtered out. Power cuts and data filtering result in many and sometimes large data gaps, which increase the importance of accurate gap filling techniques. An uncertainty assessment that looks into the influence of corrections and filtering steps and takes the effect of the gap filling procedure into account, is important to interpret the resulting NEE budget and to correctly use a final data set of half hourly NEE values. We here present three years of processed EC data together with the challenges of an EC station in the tropical forest of the Congo basin.
Geomorphology of the Montenegro slope (eastern Adriatic Sea): A tale of slump scars, corals and a chimney forest
Authors: Argnani Andrea , Angeletti Lorenzo , Foglini Federica , Taviani Marco
Published: March 2024

The submarine slope offshore Montenegro is a segment of the eastern slope of the Southern Adriatic Sea, which represents the current foredeep basin of the Dinaride-Hellenide fold-and-thrust belt. In this part of the Adriatic Sea shelf is 10 to 40 km wide and is receiving only a limited amount of clastic sediments. The N-NW-trending shelf break has a water depth of about 400 m, over 200 m deeper than the last sea-level low-stand because of the foreland subsidence. The submarine morphology of the Montenegro slope has been investigated using a high-resolution multibeam bathymetry. The slope appears carved by a set of closely spaced canyons that only rarely scratch the shelf break. A drainage system connected to the slope canyons is not visible on the shelf, and the canyons appear to be originated by the coalescence of multiple landslide scars. The incised canyons are closely spaced along the slope, suggesting a high maturity of the drainage system, in accordance with a destructive-type slope, dominated by mass wasting. In the head of one of the southernmost canyons a field of fossil chimneys has been exhumed by erosion at the seafloor. The stable carbon isotope signature indicates that these chimneys originated because of hydrocarbon fluid seepage within the sedimentary cover. A small field of pockmarks is present at the shelf edge, not far from the fossil chimneys, and located in an intra-canyon position, between canyon headscarps that incised the shelf break. The co-existence of chimneys and pockmarks suggests the occurrence of long-lasting fluid flow in the slope. The system of focussed fluid flow might have played a pivotal role in destabilizing the slope sediments, promoting landsliding. Standing and abated chimneys, together with their rubble and other nearby hardgrounds, have become habitat to relevant benthic fauna in the poorly sedimented slope. Megabenthic cnidarian assemblages are commonly found, also including the emblematic cold-water corals Madrepora oculata, Desmophyllum pertusum, and D. dianthus, the octocoral Callogorgia verticillata, the antipatharian Leiopathes glaberrima, and sponges.
Near-real-time monitoring of global ocean carbon sink based on CNN
Authors: Ke Piyu , Gui Xiaofan , Cao Wei , Wang Dezhi , Hou Ce , Wang Lixing , Song Xuanren , Li Yun , Zhu Biqing , Bian Jiang , Sitch Stephen , Ciais Philippe , Friedlingstein Pierre , Liu Zhu
Published: March 2024

The ocean plays a critical role in modulating climate change by absorbing atmospheric CO2. Timely and geographically detailed estimates of the global ocean-atmosphere CO2 flux provide an important constraint on the global carbon budget, offering insights into temporal changes and regional variations in the global carbon cycle. However, previous estimates of this flux have a 1 year delay and cannot monitor the very recent changes in the global ocean carbon sink. Here we present a near-real-time, monthly grid-based dataset of global surface ocean fugacity of CO2 and ocean-atmosphere CO2 flux data from January 2022 to July 2023, which is called Carbon Monitor Ocean (CMO-NRT). The data have been derived by updating the estimates from 10 Global Ocean Biogeochemical Models and 8 data products in the Global Carbon Budget 2022 to a near-real-time framework. This is achieved by employing Convolutional Neural Networks and semi-supervised learning methods to learn the non-linear relationship between the estimates from models or products and the observed predictors. The goal of this dataset is to offer a more immediate, precise, and comprehensive understanding of the global ocean-atmosphere CO2 flux. This advancement enhances the capacity of scientists and policymakers to monitor and respond effectively to alterations in the ocean's CO2 absorption, thereby contributing significantly to climate change management.
Remote sensing supporting the Arctic Methane and Permafrost Challenge (AMPAC)
Authors: Bartsch Annett , Hugelius Gustaf , Grosse Guido , Hashemi Joshua , Treat Clair , Goeckede Mathias , Tamminen Johanna , Fix Andreas , Sachs Torsten , Houweling Sander , Bergstedt Helena , Widhalm Barbara
Published: March 2024

The Arctic Methane and Permafrost Challenge (AMPAC) is an ESA and NASA collaborative community initiative to help tackle the scientific challenges in estimating current and future methane fluxes from the Arctic region. Under this umbrella, AMPAC-Net is an ESA funded project to foster collaborations and scientific exchange on the Arctic methane challenge. The six guiding goals are: (1) Engaging the community, workshops, dialogue (2) Advancing EO products, novel methods, algorithms (3) Reconciling bottom-up & top-down approaches (4) Data catalogues, open science and data sharing (5) Summer schools, training, outreach and education and (6) Networking, including supporting scientific exchanges. The initiative is further supported through the ESA funded project MethaneCamp with focus on improvement of satellite retrievals of methane concentrations in the Arctic.As part of AMPAC-Net, relevant already published datasets have been included into a catalogue (https://apgc.awi.de/group/about/ampac) including datasets for methane (in situ, satellite derived concentrations, airborne campaign data, inversions etc.) and landcover/wetlands.Bottom-up estimates rely on accurate representation of Arctic landcover, especially wetlands as potential methane source. The heterogeneity of Arctic landcover requires high spatial resolution and appropriate thematic content. Existing circumpolar landcover data and a range of in situ data have been investigated with respect to wetlands and heterogeneity supporting AMPAC goals, especially the new landcover units derived from Copernicus Sentinel-1 (Synthetic Aperture Radar) and Sentinel-2 (multispectral) satellite missions (ESA Permafrost_CCI, 10 m).Further on, the potential of new, approved European satellite missions for AMPAC goals is discussed.https://www.ampac-net.info/https://methanecamp.fmi.fi/
Multicomponent Pore Fluid Transport by Hydration Porosity Waves in the Litosphere: A Model for Continental Crust Formation
Authors: Khakimova Lyudmila , Frendak Andrey , Aranovich Leonid , Podladchikov Yury
Published: March 2024

Revealing of continental crust formation mechanism is a fundamental problem. There are metamorphic based theories and leading magmatic ones. Most recent models rely on differentiation of basaltic magma generated by partial melting of peridotite under influence of a fluid escape from subducting hydrated oceanic crust.Here we present hypothesis of alternative mechanism of continental crust formation which invokes the multicomponent pore fluid transport by reactive porosity waves through the base of the Lithosphere. It includes partial hydration of mantle peridotite due to interaction with aqueous solutions transported through fluid-rich channels-like structures in rocks undergoing visco-elastic deformation coupled with reactions, phase transformations, volume and density changes.To support the hypothesis, we propose a coupled hydro-mechanical-chemical model for simulating the filtration of multicomponent fluid through deforming mineral matrix treating zero porosity limit. Along with a number of constitutive relations, this model is closed by tabulated thermodynamic data, which are to be preliminarily calculated using linprog minimization in ThermoLab. We present 2D numerical implementation utilizing accelerated pseudo-transient numerical scheme. Results illustrate hydration porosity wave propagation witj peridotite alteration and the visco-elastic deformation of the zero porosity mineral matrix, with reference to the system up to 12 components including the corresponding solid and aqueous solutions.
Estimating and Predicting Bedform-Induced Head Gradients Using Dye Tracer Tests
Authors: Teitelbaum Yoni , Saavedra Cifuentes Edwin , Packman Aaron , Arnon Shai , Hansen Scott K.
Published: March 2024

Head induced by bedforms at the sediment-water interface (SWI) is typically represented in one of two ways: either by solving the RANS equations for the water column, or by a sinusoidal boundary condition defined by Elliott and Brooks (1997). Both of these methods have been used to model bedform-induced hyporheic exchange flux (HEF) on domains of constant shape. Under sufficiently fast flow conditions, however, bedform shape is irregular and evolves over time. For these conditions, neither method is fully appropriate: RANS is too computationally intensive, while the Elliott and Brooks boundary condition is based on measurements taken using rigid bedforms of an idealized triangular shape (Fehlman, 1985). We present a procedure for estimating head induced by arbitrarily-shaped bedforms using timelapse photos of dye tracer tests. At a given time t, an initial guess of head along the SWI is generated. The predicted evolution of the dye plume observed in the photo at time t is calculated using the model of Teitelbaum et al. (2022). The predicted dye plume location is compared against the observed plume location from the next photo. This comparison is used as the objective criterion in an optimization procedure, which is run until the estimate of head at the SWI converges. Results show agreement with experimental observations from dye tracer tests. The estimated head is used as input data to predict head distribution based solely on SWI shape. This work provides a new way to estimate head under arbitrary SWI shape. Thus, it constitutes an important advance in realistic modeling of bedform-induced hyporheic exchange flux.
Sea-ice and subsurface temperatures in the outer Labrador Sea across four Heinrich events during MIS 3
Authors: Detlef Henrieka , Mørk Jensen Mads , Andreasen Rasmus , Glasius Marianne , Seidenkrantz Marit-Solveig , Pearce Christof
Published: March 2024

Heinrich events are characterised by the collapse of ice-sheets surrounding the North Atlantic, with Hudson Strait suggested as the prominent source region. Cryosphere-ocean interactions during stadial periods of the last glacial interval have been proposed as a potential trigger for ice-sheet collapse. Extensive sea-ice cover in the Labrador Sea, in combination with a reduced overturning circulation in the North Atlantic, might have caused the build-up of a subsurface heat reservoir by preventing the release and downward mixing of heat in the water column. Increased subsurface heat then caused/supported the destabilisation of the Laurentide ice sheet.We present high-resolution records of sea-ice and subsurface temperatures in the outer Labrador Sea at IODP Site U1302/03 between 30 and 60 ka. The sea-ice record suggests that an extensive sea-ice cover established in the outer Labrador Sea around 0.8-0.9 kyr prior to the arrival of ice-rafted debris associated with Heinrich events. Subsurface temperatures also increase prior to the onset of Heinrich events, although the exact timing needs to be confirmed. As such, the sea-ice and subsurface temperatures support cryosphere-ocean interactions prior to the onset of Heinrich events.
Monitoring the Elbe estuary and coastal zone with SWOT and nadir-altimeters 
Authors: Fenoglio-Marc Luciana
Published: March 2024

Coastal-to-land sites are mostly affected by climate changes and are at multi-risks due to coastline retreat, flooding storms and river floods. New altimeter processing and new missions open new possibilities to observe fine-scale spatial changes in this region. Our hypothesis is that new altimetry remote sensing observations from the Delay Doppler nadir-altimetry and wide swath altimetry can make an unprecedented progress at monitoring the river-to-ocean continuum and understanding estuarine and coastal hydrodynamic processes.Aim of this study is the interaction between river discharge and coastal sea level in the Elbe estuary and tidal river. Region of analysis are the German coasts and Elbe estuary and tidal river. This last is under the SWOT cal/val track. SWOT’s unique, high-resolution 2D observations, combined with the field campaign data, other satellite data and models, is expected to provide a new view of many dynamical phenomena from ocean and nearshore zones to coastal and estuarine contexts.We consider the Fully-Focus (FF-SAR) processing near coast. We show that results depend on the retracking method and that land contamination is also affecting FF-SAR. The  SAMOSA+ retracker gives the best results for both FFSAR and unfocused SAR (USAR).The ability of regional ocean models to reproduce tides and the high variability at fine spatial-scale is investigated. Ocean simulation sea level is compared to nadir-altimetry along the satellite ground tracks. We show that while the coverage of nadir-altimeter is limited by the number of ground-tracks, SWOT, that provides a uniform coverage, is less affected by land contamination. We investigate the SWOT mission data. First results with low resolution 2 km x 2 km data indicate good agreement with in-situ gauges with 20-30 cm standard deviation from in-situ tide gauge stations. SWOT enhanced resolution data at 250m x 250m and higher resolution data are further investigated to more accurately monitor nearshore, estuarine, and the sea-ice interface. Due to the differences between along-track and swath-altimetry, new methods to derive accuracy and precision of the measurements and derived ocean parameters are developed. Using a large network of in-situ, model and nadir-altimetry data we perform the calibration and the validation of the SWOT products assessing the relevance of SWOT for improving numerical models over all the Elbe tidal river. We would be interested in submitting our presentation to a peer reviewed special issue in Ocean Sciences. 
Synoptic conditions corresponding to the Adriatic meteorological tsunamis
Authors: Sepic Jadranka , Metlicic Nikola , Orlic Mirko
Published: March 2024

An online catalogue of meteorological tsunamis in the Adriatic Sea was recently published. The catalogue contains information on 36 meteorological tsunamis, all with a wave height of at least 1 m, which occurred between 1931 and 2021. During this period, there were 10 exceptionally strong events with observed tsunami wave heights of over 3 metres. The strongest event was characterised by tsunami waves of up to 6 m. For all 36 events, available sea level and air pressure measurements, atmospheric synoptic conditions (using ERA5 reanalysis) and satellite images were analysed. Based on the background sea level height (from the nearest tide gauge), the meteorological tsunamis were divided into three categories: (1) storm surge meteotsunamis, i.e. tsunamis that occur at the time of a storm surge; (2) ordinary meteotsunamis, i.e. tsunamis that occur when the background sea level is low; (3) transitional tsunamis. All three types were associated with a strong south-westerly to westerly jet stream in the middle and upper troposphere, which mainly led to the advection of warm air from the southern Mediterranean to the Adriatic Sea. Similarly, convective clouds were observed over the Adriatic Sea during most events before or at the time of the meteotsunamis.At the surface, three types of events were distinguished from each other. Storm surge meteotsunamis (10 events in total) were associated with a mid-latitude cyclone, centred over the northern Adriatic or the Bay of Genoa, with the cyclone warm sector or advancing cold front over the area affected by the meteotsunami. The associated surface winds were strong and usually of a south-easterly direction (sirocco). The meteotsunamigenic air pressure disturbances were therefore probably generated in the areas of strong updrafts related to the advancing temperature fronts. Ordinary meteotsunamis (21 events) were associated with fair weather, i.e. with a gradient-free mean sea level pressure field over the Adriatic and very weak surface winds. In this type of event, the meteotsunamigenic atmospheric pressure disturbances were probably due to convective disturbances or the atmospheric gravity waves. Transitional events (5 of them) were associated with either a weak gradient of mean sea level pressure field over the Adriatic, with corresponding southeasterly winds of moderate strength, or with a closed shallow low over the Adriatic.Stronger events were more likely to occur under fair weather conditions but were also observed under stormier weather. The analysis suggests that meteotsunamis in the Adriatic occur under variety of conditions, all of which should be considered when assessing the risk of meteotsunamis.
Nitrate contamination prediction in Groundwater data in Karnataka, India, using Machine Learning (ML) Techniques
Authors: Bansal Himanshi , Devarakonda Venkataramana , Dixit Mayank
Published: March 2024

Groundwater is a natural water source crucial in sustaining ecosystems and meeting various human needs. Groundwater is often contaminated due to the various anthropogenic and non-anthropogenic activities. Nitrate is the most abundant pollutant of Groundwater, which may be exogenic and anthropogenic. We studied nitrate ion concentration in Groundwater from dug well data. The Karnataka state's nitrate ion concentration varies from 0 to 1696 mg/l, which is higher in most places than the admissible limit of 45 mg/l as per the World Health Organisation (WHO). The correlation of various parameters, such as pH, electrical conductivity (EC), fluoride, chloride, etc., was studied with nitrate, and maximum correlation was found with chloride and EC.  Our prediction concentration of nitrate ion using Different Machine Learning (ML) algorithms, including Regression, Random Forest (RF), Support Vector Regression (SVR) and Decision Tree (DT) models using the input parameters as pH, EC chloride, and fluoride.  The result showcased that the best model is Support Vector Regression (SVR) with an R2 value of 0.93 and a Mean Square Error (MSE) value of 0.02 for the region. The region's nitrate pollution might be forecast using the SVR model for better estimation.
Coordinated observations of the water cycle of marine cold-air outbreaks in the European Arctic during the ISLAS 2022 field campaign
Authors: Sodemann Harald , Thurnherr Iris , Seidl Andrew , Dekhtyareva Alena , Johannessen Aina , Kähnert Marvin , Steinslid Mari B. , Løklingholm Sander , Hole Lars R. , Voss Paul , Papritz Lukas , Dütsch Marina , David Robert O. , Carlsen Tim , Chandler David M. , Chazette Patrick , Totems Julien , Schwarzenboeck Alfons , Hellmuth Franziska , Delanoe Julien ,   ISLAS2022 Team
Published: March 2024

Marine cold-air outbreaks (mCAOs) are a characteristic type of high-impact weather in the European Arctic and are characterized by an intense water cycle where polar cloud processes play an important role. Model simulations and weather forecasts of mCAO events are challenging and associated with poor predictability. One reason is that processes related to the water cycle interact with one another on a wide range of scales. In regional models, some of these processes are resolved and others are fully or partly parameterised. To test and improve numerical weather prediction models, additional observations and novel types of measurements of water vapour are highly demanded. Stable water isotopes are an increasingly available measurement, allowing to trace sub-grid scale processes, and providing the potential to constrain the mass budget of the atmospheric water cycle during mCAO events. During the ISLAS2022 field experiment (21 March to 10 April 2022), the stable isotope composition of water vapour and liquid samples, cloud structures, and other meteorological parameters were collected between Svalbard and Northern Scandinavia on various measurement platforms. Airborne survey flights to Svalbard provided the ocean evaporation signature and subsequent processing of water vapour during mCAO conditions. During a number of flights, mCAO airmasses were repeatedly sampled over a course of hours to days, allowing to characterize their thermodynamic evolution as clouds were first forming, then glaciating and precipitating. In addition, vapour isotope and sea water isotope measurements were taken continuously onboard R/V Helmer Hanssen between Tromsø and the Greenland west coast. Finally, coordinated land-based measurement activity over Northern Norway and Sweden allowed collection of precipitation samples, thus closing the mass budget of the mCAO events. Furthermore, using buoyancy-controlled meteorological balloons launched from Ny Ålesund, we additionally obtained continuous in-situ measurements of the boundary-layer evolution during the mCAO. We provide an overview over the airborne and ground-based measurement activities during the campaign and provide several examples to highlight the potential of the stable water isotope measurements to constrain the water budget of mCAOs in conjunction with traditional meteorological observations.
Mapping soil moisture uptake by dry soils across Eddy covariance measurement sites
Authors: Paulus Sinikka , Orth Rene , Lee Sung-Ching , Nelson Jacob A. , Hildebrandt Anke , Nguyen Ngoc , Reichstein Markus , Migliavacca Mirco
Published: March 2024

Soils take up water vapor from the atmosphere through processes that involve vapor diffusion and water retention. This can theoretically occur in any ecosystem under the preconditions of a humid atmosphere and dry soil pores. It can play a critical role in dry ecosystems because it can provide a substantial proportion of the total water inputs at the daily timescale. However, it remains insufficiently investigated in many regions, partly due to the absence of continuous, dedicated measurements.In this study, we use a recently developed algorithm to detect and filter Eddy Covariance (EC) derived negative latent heat flux data collected at semi-arid and arid sites to identify soil water vapor adsorption. In a previous study, we successfully used EC data to detect soil water vapor adsorption for a Mediterranean ecosystem. Our findings indicate that these negative latent heat fluxes exhibit a correlation with soil water content and relative humidity at various sites suggesting that a part of the negative latent heat flux is related to soil water vapor adsorption. Building on these findings, we demonstrate that soil water vapor adsorption occurs during the dry season in various ecosystems, including woody savannas, grasslands, shrublands, and even some forests. The flux magnitude reaches values comparable to daily evaporation, which is in line with existing literature on the few previously measured ecosystems.Furthermore, we analyze the drivers of the occurrence and dynamics of soil water vapor across sites. Thereby we study the influence of e.g. soil texture or vegetation height. This way, our study expands our knowledge of the spatial extent and inter-annual dynamics of soil water vapor adsorption in natural ecosystems and, more generally, sheds light on a mostly overlooked aspect of land-atmosphere interaction.