bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial and temporal changes of the winter bloom in the Arabian Sea during the past two decades
Authors: Panthakka Anjaneyan , Kuttippurath Jayanarayanan
Published: February 2023

High concentrations of Chlorophyll-a (Chl-a) appear in the Arabian Sea (AS) during the winter and early spring seasons (November–March), known as the winter blooms, primarily due to the reversing monsoon winds and associated changes in the ocean. The onset, duration, intensity and peak period of the seasonal blooms show distinctive regional characteristics in AS. Recent changes in ocean dynamics and plankton composition in AS have adverse effects on the distribution of Chl-a concentration there. Here, we examine the long-term spatio-temporal changes in winter blooms, and assess the impact of wind, mesoscale eddies, surface currents, sea surface temperature (SST), mixed layer depth (MLD) and sea surface salinity on the blooms. We observe a significant decrease in these blooms, which started in the early 2000s and intensified in recent decade (2010–2020), with a prominent decline in the adjascent Gulfs (Gulf of Aden: -1.38 ± 0.7 x 10-5 mg m-3 year-1, Gulf of Oman: -4.71 ± 1.35 x 10-6 mg m-3 year-1), and the West coast of India (-6.71 ± 2.85 x 10-6 mg m-3 year-1). The major factors that control blooms in the Gulf of Oman and open waters are MLD and ocean temperature. On the other hand, in the Gulf of Aden, blooms are largely driven by the coastal upwelling and eddies. The bloom is primarily driven by winter cooling along the north-western Indian coast, but it is inhibited to south by the inter-basin exchange of surface waters carried by the West Indian Coastal Current. This study thus reveals particular mechanisms that trigger and regulate the winter blooms in AS. These seasonal blooms may continue to decline as a result of the ongoing ocean warming, which would be a threat for the regional marine productivity and food security.
Evidence of heatwaves in two deep Italian lakes in summer 2022
Authors: Valerio Giulia , Volpini Stella , Benvenuti Elena
Published: February 2023

Lakes and their biodiversity are threatened by global warming, responding rapidly to climatic change and incorporating the effects occurring in the drained catchments. The thermal characteristics of lakes have undergone substantial alterations in response to the progressive increased air temperature. Surface waters have worldwide warmed, with a global average rate of 0.34°C per decade between 1985 and 2009 during summer. Over the last few years, increased attention is given to the response of lakes to extreme events, such as storms and heatwaves. There is evidence that climate change is leading to longer and more frequent marine heatwaves at the surface of the ocean, while much less is known about heatwaves in lakes, where field studies are generally lacking.According to the C3S ERA5 dataset, August 2022 globally tied as the third warmest on record, 0.30°C warmer than the 1991-2020 average for August and 0.42°C warmer than the 1981-2010 average in this data record. The month of August was particularly warm over Europe and was also remarkable in terms of hydrological variables with drier than normal conditions over western Europe, sustained by heatwaves with significant impacts on economy and society. In this contribution, we show the thermal response of two deep Italian lakes (Lake Garda and Lake Iseo) under the extreme meteorological conditions occurred in summer 2022. In both these lakes, a floating station measured at a 1/min sampling rate the meteorological forcing at the lake surface as well as water temperature down to 100 m of depth with 0.01 °C accuracy. Thanks to the temperature data, we identified and characterized, in terms of intensity and duration, several long-lasting heatwaves and we compared their characteristics with past observations, showing evidence of an exceptional surface warming over the last 20 years. The overall high-resolution dataset allowed us to compute the thermal balance of the two lakes, comparing the relative importance of the different forcing and that of the morphological and hydrological characteristics of the two water bodies, and to discuss the impact of the internal hydrodynamics on the surface heating. This analysis underlined the fundamental role played by the wind, which affects both the thermal fluxes at the water surface and the vertical distribution of temperature. This result raises the issue about the degree of reliability of the prediction of extreme events in lakes under climate change due to the uncertainties of the wind predictions, especially in geographical context, such as pre-alpine or alpine regions, where the wind fields provided by large-scale resolution models are less accurate. 
Reducing the effects of weather on the sampling bias in tall tower eddy covariance flux measurements
Authors: Kissas Konstantinos , Scheutz Charlotte , Ibrom Andreas
Published: February 2023

Tall tower eddy covariance (TTEC) flux measurements are employed to estimate turbulent matter and energy fluxes at landscape scales (e.g. within 1 to 5 km radius around a tower). Virtually all landscapes feature horizontal surface heterogeneity. One main complication for the interpretation of TTEC is the sampling bias by the varying local meteorological conditions. While the wind direction bias can only be considered by the choice of the location of the TTEC, we examine here how the effects of atmospheric stability can be alleviated by sampling from different measurement heights (zm). The objective is to define an optimal set of measurement heights to minimize sampling bias from variation in atmospheric stratification for TTEC long-term flux observation. To our knowledge, this problem has not yet been addressed in the scientific literature.We used a two years’ dataset from the 122 m tall tower at Risø (Denmark, 55°41'39.15" N, 12°5'17.93" E) and two flux footprint models to develop an objective statistical approach for the definition of a set of measurement heights for optimal sampling of the landscape heterogeneity. The tower is equipped with 3D ultrasonic anemometers in five different heights. The evaluations concern the Eastern sector, which is comprised of a mosaic of land uses, small settlements and comparably sparse road infrastructures.We define the criteria for optimal landscape flux sampling from the distributions of the source weights (contribution to the measured flux per unit area) sampled in a number of stability classes relative to a frequent unstable stability class as reference. The upper sampling height is set a priory to match measurements and the targeted area; here zm equal to 120 m for the 70% cumulated footprint to stay within a 5 km radius around the tower.Theoretical analysis with the footprint model shows the limitation of the attempt to compensate for lateral footprint extension at different stabilities, while the longitudinal sampling of the landscape heterogeneity can be maintained more homogeneously by the systematic choice of the measurement height according to atmospheric stability and wind speed.The results rely on the accuracy of the footprint estimation, which is generally an essential criterion for the interpretation of TTEC measurements in heterogeneous landscapes.
Satellite remote sensing based approach for water quality monitoring in a data sparse region
Authors: Oinam Bakimchandra , Anand Vicky , Sana Rajkumari Neetu , Wieprecht Silke
Published: February 2023

The application of remote sensing can aid the decision makers and the researchers in the field of water resources for the effective monitoring of water quality in a water sparse region.  The monitoring of water quality in a wetland dominated by the heterogeneous biomass becomes more intricate. This research study was carried out in Loktak Lake, a Ramsar site nestled in the Indo-Myanmar range between the time intervals February 2022 to December 2022. In order to carry out this study, high and very high resolution multispectral satellite imageries were used. The physical water quality parameters namely electrical conductivity, total suspended solids, pH, turbidity, and nitrates were considered for the assessment. The results of this study clearly indicate a strong correlation between the field-measured parameters and reflectance. The prediction algorithms were generally the best fit to derive the water quality parameters. The model performance indices indicates good performance of the model with correlation coefficient greater than 0.80. The outcomes of this study emphasize the use of high and very high multi-spectral satellite imageries for the monitoring of water bodies with complex dynamics.
USCC: A Benchmark Dataset for Crop Yield Prediction under Climate Extremes
Authors: Höhl Adrian , Ofori-Ampofo Stella , Obadic Ivica , Fernández-Torres Miguel-Ángel , Salih Kuzu Ridvan , Zhu Xiaoxiang
Published: February 2023

Climate variability and extremes are known to represent major causes for crop yield anomalies. They can lead to the reduction of crop productivity, which results in disruptions in food availability and nutritional quality, as well as in rising food prices. Extreme climates will become even more severe as global warming proceeds, challenging the achievement of food security. These extreme events, especially droughts and heat waves, are already evident in major food-production regions like the United States. Crops cultivated in this country such as corn and soybean are critical for both domestic use and international supply. Considering the sensitivity of crops to climate, here we present a dataset that couples remote sensing surface reflectances with climate variables (e.g. minimum and maximum temperature, precipitation, and vapor pressure) and extreme indicators. The dataset contains the crop yields of various commodities over the USA for nearly two decades. Given the advances and proven success of machine learning in numerous remote sensing tasks, our dataset constitutes a benchmark to advance the development of novel models for crop yield prediction, and to analyze the relationship between climate and crop yields for gaining scientific insights. Other potential use cases include extreme event detection and climate forecasting from satellite imagery. As a starting point, we evaluate the performance of several state-of-the-art machine and deep learning models to form a baseline for our benchmark dataset.
Assessment of transpiration in different almond production systems with two-source energy balance models using high-resolution aerial imagery.
Authors: Quintanilla-Albornoz Manuel , Bellvert Joaquim , Pelechá Ana , Casadesus Jaume , García-Tejera Omar , Miarnau Xavier
Published: February 2023

The almond production has increased by doubling their hectares under irrigation treatments in Spain. In a context of water scarcity, the estimation of Evapotranspiration (ET) and its components, Transpiration (T) and Evaporation (E), are key variables to monitor and manage the water resources. High-resolution ET can be retrieved from surface energy flux modeling, such as a Two-Source Energy Balance (TSEB) model, using an Unmanned Aerial System (sUAS). sUAS equipped with Thermal and Multispectral cameras allows us to obtain the main parameters required in TSEB. Currently, there are no studies that evaluate the T obtained with TSEB Priestley Taylor (TSEB-PT) and TSEB-2T models in tree-scale almonds under different irrigation treatments (IR) and production systems (PS). In this context, we evaluated the T retrieved with TSEB-PT and TSEB-2T models using Sap Flows sensor in trees with three PS, Open Vase with Minimal Pruning (OVMP), Central Axis (CA) and Hedgerow (HGR), and three levels IR, Full Irrigation (FI), Mild Stressed (MS) and Stressed (SS). Five flights were conducted from March 2021 to July 2021 to analyze the almond growing season with an aircraft equipped with a thermal and multispectral camera. Leaf area index (LAI), stem water potential (Ψstem) and Fractional Intercepted Photosynthetically Active Radiation (fIPAR) was also measured concomitant to image acquisition. PS presents significant differences in fractional canopy cover (F_C), tree height (H_C), LAI and Sap Flow transpiration (Tsf). The two TSEB models show a generalized overestimation with a BIAS of 0.99 and 1.22 for TSEB-2T and TSEB-PT respectively. TSEB-PT presented worse statistics and R2 decreases in the more intensive production system. HGR has equal or greater LAI but lower F_C, which would imply an overestimation of canopy temperature (T_C) by the PT method. This is in addition to the difficulty of setting the PT coefficient according to the context of the crop. The overestimation in both models could be associated with an error in Campbell (1998) Radiative Transfer Model used to estimate transmittance, which has an error of 0.14 RMSE and 0.12 BIAS compared with fIPAR. Our results suggest the use of TSEB-2T with high resolution images considering the current available technology that allows us to estimate T_C and T_S separately, especially in intensive or super-intensive almond crops. To improve the T estimation, it is recommended to use in situ PAR measurement to decrease the influence of LAI measurements on the models.
A storyline approach to select the CMIP6 model ensemble to be downscaled for the South America domain
Authors: Andrade Cardoso Andressa , Coppola Erika , Mindlin Julia , G. Shepherd Theodore
Published: February 2023

The selection of the Global Climate Models (GCMs) needed to provide the initial and boundary conditions for the Regional Climate Model (RCM) downscaling is the first research question to answer for each RCM simulation in a given domain. The methodology is not unique and depends on the second research question that is typically behind any study based on dynamical downscaling, which is the physical process we want to study and which are the mechanisms that are relevant for it, or in a more general way which is the storyline of large-scale circulation we are interested in. In the South America region there are several large-scale circulation features that are relevant to describe the climate of this region together with the specific geographical characteristics and local scale processes and their interaction. In this work we will focus on two different large-scale circulation features: the South America Monsoon and the extratropical cyclones. For each of the two a criterion needs to be established to select which CMIP6 ensemble is more suitable for one or the other or for both, and to represent the uncertainty in their future evolution. To this aim we have defined and used a series of indicators derived from the comparison between the observation and the model and based on precipitation in specific regions of interest like La Plata and Amazon basin, and Southeastern Brazil region. A second set of indicators were based on the mean sea level pressure and wind at two different levels (850 hPa and 200 hPa) aimed at characterizing the main large scale circulation patterns (South American Low-Level jets, South Atlantic Subtropical High, South Pacific Subtropical High, trade winds, Bolivian High, cyclonic circulation vortex and upper-level jet stream). By mean of these indicators a sub set of CMIP6 models has been identified for each of the large-scale circulation features and the fitness for purpose of the whole ensemble evaluated. It is common to use different model climate sensitivities to represent the uncertainty in future evolution. Here we take a different approach and represent the uncertainty in terms of the influence of a small set of large-scale drivers, including both tropical and polar regions, which are known to affect the local circulation feature of interest and which optimally span the range of local circulation response uncertainty. The uncertainty in climate sensitivity is handled by expressing these dynamical storylines of change in terms of global warming levels. In this way, a small set of CMIP6 models can be chosen which is both fit for purpose and which avoids missing plausible worst-case scenarios for regional climate risk.
Study of sediment cores to establish the history of organic and inorganic contaminants through the Anthropocene
Authors: Picó Yolanda , Soriano Yolanda , Gimeno Eugenia , Andreu Vicente
Published: February 2023

Sediments are excellent archives for studying the long-term variations of pollutants in the environment. For this reason, records derived from the chemical analysis of sediment cores are useful to trace the history of pollutant emissions.This study aimed to study the vertical variation of organic contaminants (OCs) and metals sediment cores collected in two sites (northern and southern part) of the L´Albufera Natural Park (Valencia, Spain) to obtain information regarding historical variation in the composition of sediments. Other sediment characteristics, such as organic matter, organic carbon content, humidity, were also studied.A sediment core sampler (57 mm inner diameter, 1.00 m length; Beeker, Eijelkamp) was used to extract the cores from the lake of L’Albufera. The cores were sampled from boat. The sediment cores were 80–87 cm in length and 5 cm in diameter. The tubes were kept upright in a bucket with ice until they arrived at the laboratory where they were frozen. Once frozen, the tubes were cut into 8 segments of the same thickness (8 slices of 10 cm) using a stainless steel cutter. Pharmaceuticals, pesticides, poly and perfluoroalkyl substances (PFASs) and phosphorous flame retardants (PFRs) were analysed using Orbitrap Exploris 120 mass spectrometer. The compounds were extracted by different extraction methods and determined both, using wide target screening against a positive list of compounds and non-target screening applying ddMS2 of the 4 more intense ions in each cycle as well as all ions fragmentation. Both positive and negative ionization were used. Several pollutants, especially pesticides such as Azoxystrobin, Imazalil, Molinate, Tebuconazole, Thiabendazole and Tricyclazol were detected in the sediment in contact with water. Some infiltration of the compounds in the inner layers of sediments were also detected. Superficial sediments provide information on the actual deposited material and the actual status of pollution but the study of sediment profiles provides information on the historical variation in the composition of sediments settled. These sediments can also be used to examine pollution mechanisms, which are significant for predicting future pollution tendencies and assessing potential environmental risks.Acknowledgments: This work has been supported by Grant RTI2018-097158-B-C31 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe” and the grant of the Generalitat Valenciana Prometeo Programme CIPROM/2021/032. Y. Soriano also thanks MCIN/AEI/ 10.13039/501100011033 and ERDF for their Predoc contract (PRE2019-089042).
Surface solar radiation trends over Europe assessed from ground-based measurements and satellite imagery and their comparison with climate models
Authors: Segado-Moreno Leandro Cristian , Ruiz-Arias José Antonio , Montávez Juan Pedro
Published: February 2023

Downward surface solar radiation (SSR) is the main component in the surface energy balance and the climate system, as well as being the fundamental source of energy in various forms of solar and photovoltaic technologies. It is therefore of great importance to know in detail the spatio-temporal variation of SSR, as well as its long-term trends. Scientific evidence has shown that the amount of solar radiation incident on the Earth’s surface is not stable over the years, but undergoes significant variations every decade. Until recently, ground-based observations have been the most reliable data source for SSR monitoring. Nevertheless, satellite-derived SSR measurements have a better spatial and temporal coverage, though the scientific literature on the use of satellite imagery for the study of SSR is still limited.This study covers several purposes. First, a direct comparison between ground-based observations and satellite-derived estimates has been carried out, to determine the capability of the latter to reproduce measurements from surface observations. Monthly averaged time series of 108 land stations from GEBA (Global Energy Balance Archive) dataset (ground observations) have been compared to those estimated from satellite imagery by the Solargis model over the same locations. Solargis is a company based in Bratislava, dedicated to the assessment of the solar resource worldwide, using GIS (Geographic Information Systems). SSR anomalies measured at the surface and estimated from satellite images have been compared over Europe for the period 1994-2019. Second, multiannual SSR trends have also been calculated in detail (station-averaged and station-separated) for both ground-based and satellite-derived datasets, in the period of study. Finally, SSR time series have been compared to several CMIP6 (Coupled Model Intercomparison Project Phase 6 ) climate models runs.The results show that the method of estimating SSR from satellite images is able to reproduce around 94% of the variability of the SSR measured by ground-based methods in Europe. In addition, trend analysis shows a general increase of SSR over the continent in the period of this study, with an average trend of 3.5 Wm-2decade-1for the observational data and 1.7 Wm-2decade-1for the satellite estimations. This increase in SSR may be associated with changes in the transmission of the atmosphere due to variations in cloud properties and aerosols. Finally, CMIP6 time series average over all models for RCP8.5 scenario shows exactly the same trend as the satellite-derived dataset, which suggests there are still some variables not considered by satellite imagery methods and climate models.
A model-based investigation of hydrological processes in an agricultural peatland field
Authors: Salla Aleksi , Koivusalo Harri , Salo Heidi , Tähtikarhu Mika , Liimatainen Maarit , Marttila Hannu , Läpikivi Miika
Published: February 2023

Drained peatlands have peculiar hydrological properties and cause environmental concerns due to carbon dioxide emissions and nutrient fluxes resulting from decomposition of organic matter in peat. As peat degradation is strongly controlled by soil moisture conditions, it is assumed that flexible water management methods, such as controlled drainage, can be used to reduce the environmental impacts of drained peatlands in agriculture. While peat soils have been extensively researched, there is a need for increased understanding about the hydrological responses of peatlands to various water management schemes. Research is needed to quantify these responses, and a promising approach is to exploit simulation models for describing peatland hydrology at field scale. The goal was to calibrate and validate a hydrological model FLUSH to describe the hydrology of an agricultural field block having a shallow peat cover and managed with controlled drainage. FLUSH is a spatially distributed three-dimensional (3D) process model which simulates the hydrology of agricultural fields managed with controlled subsurface drains and open ditches. The soil description of FLUSH includes both soil matrix and macropores accounting preferential flow. Richards equation and Mualem-van Genuchten water retention model are applied for subsurface flow. The modeled field block is located in Ruukki, northwestern Finland, and the study period was from August 2018 to October 2021. Groundwater table depth and drain discharge observations were used for the calibration and validation. The Kling-Gupta efficiencies for the simulated groundwater table depths in soil matrix and macropore domains were 0.50 and 0.47, respectively, during the calibration period, and 0.23 and 0.33 during the validation period. The efficiency values for the simulated drain discharge during the calibration and validation periods were 0.18 and 0.19, respectively. Limiting the modeled area to the block lead to cumulative drain discharges clearly smaller than the observations. The underprediction was improved by extending the modeled area beyond the block, which suggested a presence of a hydrological connection in terms of groundwater flux originating from outside the block. Thus, the surrounding environment can play a role in the hydrology of peatland fields, and this should be considered in water management design. Despite the large difference between observed and simulated cumulative drain discharges, the main hydrological dynamics were captured, and the model formed a useful tool to simulate drainage scenarios in peatlands and to study the role of the surrounding areas on field hydrology.
Rayleigh wave tomography in the north-eastern margin of the Tibetan Plateau by way of training physics-informed neural networks
Authors: de Ridder Sjoerd , Chen Yunpeng , Rost Sebastian , Guo Zhen , Chen Yongshun
Published: February 2023

Machine learning is rapidly becoming ubiquitous in the Earth Sciences promising to provide scalable algorithms for data-mining, interpretation, and model building. Initially heralded for its ability to exclude complicated physics from data analysis, recent innovations seek to merge machine learning  solutions with conventional physics-based methods in order to enhance their capabilityWe present a novel eikonal tomography approach for Rayleigh wave phase velocity and azimuthal anisotropy based on the elliptical-anisotropic eikonal equation, by formulating the tomography problem as the training of a physics informed neural network (PINN). The PINN eikonal tomography (pinnET) neural network utilizes deep neural networks as universal function approximators and extracts traveltimes and medium properties during the optimization process. Whereas classical eikonal tomography uses a generic non-physics-based interpolation and regularization step to reconstruct traveltime surfaces, optimizing the network parameters in pinnET means solving a physics constrained traveltime surface reconstruction inversion, tackling measurement noise and resolving the underlying velocities that govern the physics. The fast and slow velocity and the anisotropic direction information can be directly evaluated from the trained medium property networks. Checkerboard tests indicate that the input velocity model can be well recovered by using this approach and synthetic data.We demonstrate this approach by applying it to multi-frequency surface wave data from ChinArray phase II sampling the north-eastern Tibetan plateau. We are able to use much less data to achieve similar subsurface images because of the benefit of including the physics constraint while reconstructing the traveltime surfaces. We are able to obtain excellent results using only 10 sources.  Comparing results from pinnET with conventional eikonal tomography, we find good agreement with distinct low velocity structures beneath the Songpang-Ganzi block, Qilian and Western Qinling Orogen. Large phase velocity uncertainties occur in a small part of the southeastern Ordos Block, the western Songpan-Ganzi Block and the eastern Sichuan basin, which correspond to the reduced data coverage dependent on the selection of the 10 sources. We also verify the accuracy and reliability of the pinnET by choosing only one station as virtual source, the retrieved velocities show relatively good resolution which is much better than in conventional eikonal tomography using similar sized datasets. The method is memory efficient because compressing the traveltimes as outputs to a NN is a concept akin to compressed sensing and offers advantages over traditional anisotropic eikonal tomography or neural network approaches.
Detailed monitoring and simulation of groundwater salinity in response to extractions in a coastal aquifer system
Authors: Hendrikx Thijs , Oude Essink Gualbert , Karaoulis Marios , Bierkens Marc
Published: February 2023

High-resolution three-dimensional variable-density groundwater flow and coupled salt transport models (abbreviated 3D-VD-FT models) are useful instruments to support coastal groundwater management strategies and to forecast impacts of climate change. However, the ability of 3D-VD-FT models to provide accurate groundwater salinity predictions depends on computational capabilities, availability of sufficient and adequate high-resolution data and understanding of coastal groundwater salinity processes in the subsurface. Often, local aquifer heterogeneities are simplified in numerical models. In doing so, flow and transport are simplified, and consequently, local groundwater salinity changes become difficult to predict accurately. New avenues in data acquisition and computational methods have opened up the possibility to greatly improve the accuracy of predictions. Recent developments in innovative geophysical monitoring methods are able to observe salinity and (indirect) flow velocities in detail. For instance, one can use automated measurements with Electrical Resistivity Tomography (abbreviated ERT) to monitor salinity changes. In addition, new parallelization methods are able to overcome computational challenges that plague 3D-VD-FT models. In this research, we are examining the ability of 3D-VD-FT models to reproduce observed groundwater salinity changes during multi-level groundwater extractions and the impact of these extractions on upconing and subsequent downconing of brackish and saline groundwater. To achieve this, we are developing a 3D-VD-FT model that is able to simulate groundwater salinity changes at high resolution that occur in response to multi-level groundwater extractions during the brackish groundwater extraction pilot project FRESHMAN in Scheveningen. The FRESHMAN project allows for a unique view in the subsurface during groundwater extractions due to close monitoring by innovative geophysical monitoring methods such as ERT. Preliminary results show that heterogeneity of the aquitard in the study area can affect the ability of the 3D-VD-FT model to reproduce observed groundwater salinity changes. For instance, accounting for potential high conductivity conduits in the aquitard can improve the fit of the observed upconing to the simulated upconing. To account for heterogeneity of the aquitard, sequential indicator simulation will be applied to generate multiple realizations of the aquitard. For each realization, the 3D-VD-FT model will be run and results subsequently evaluated in terms of fit and the best-fitting realizations selected. In addition, for the selected best fit realizations, hydrogeological model parameters will be further optimized using PEST in combination with chloride measurements.
The impact of subgrid-scale gravity waves on the Brewer-Dobson circulation
Authors: Masur Gökce Tuba , Kim Young-Ha , Achatz Ulrich
Published: February 2023

The Brewer-Dobson circulation (BDC) is a meridional circulation mainly driven through mean-flow forcing by Rossby-wave breaking that is, however, also influenced by gravity waves (GW). As some part of GW dynamics is subgrid-scale in numerical climate and weather prediction models, an appropriate wave parameterization and later an accurate separation of the drivers are necessary to understand the impact of the subgrid-scale GWs on the BDC.Polichtchouk et al. (2018) explored the sensitivity of BDC to the parameterized GW drag by separating the drivers of the residual circulation using the downward-control principle. Even in relatively high-resolution simulations, the parameterized drags are found to significantly contribute to the BDC in the lower stratosphere, especially for northern hemisphere winter-pole downwelling.We parameterize subgrid-scale GWs in the Lagrangian ray-tracing scheme Multi-Scale Gravity-Wave Model (MS-GWaM) (Bölöni et al. 2021; Kim et al. 2021). MS-GWaM includes interactions between the GW field and the resolved flow, which are neglected in the traditional GW parameterization schemes. It has been implemented successfully into of the Icosahedral Non-hydrostatic (ICON) model in its upper-atmosphere configuration. Using the MS-GWaM output, we diagnose the sensitivity of the BDC using the downward-control principle.
Direct air measurements using the high resolution Thermo Ultra mass spectrometer: O2/N2 and Ar/N2 ratios, and O2, N2 and Ar isotopic composition
Authors: Popa Maria Elena
Published: February 2023

I will present a newly developed method for analyzing major air components and their isotopic composition, using the high resolution Thermo Ultra mass spectrometer. The main characteristics of this instrument that are interesting in this context are the high resolution, stability and sensitivity.  The high resolution results in fewer isobaric interferences; low abundance compounds (e.g. multiply substituted molecules) can be observed due to the high resolution and high sensitivity; and the instrument stability allows long measurements, as needed for obtaining high precision for the low abundance compounds.The species that can be analyzed so far with useful precision are:- O2/N2 and Ar/N2 (precision in permeg range)- O2 isotopologues, including clumped: 16O2, 16O17O, 16O18O, 17O18O, 18O2- N2 isotopologues, including clumped: 14N2, 14N15N, 15N2- Ar isotopes: 36Ar, 38Ar, 40ArThe whole suite of measurements uses about 10 ml of dry air, and takes up to two days for one sample.The first application of this method is planned for stratospheric and icecore samples.
Biofilm growth at pore scale in laminar flow
Authors: Martín Candilejo Araceli
Published: February 2023

Natural soils are home to an enormous variety of microorganisms. Microbial transport is important for a wide range of natural and artificial processes. However, the transport and distribution of bacteria in water flow at porous scale is still to be fully understood.The Biofilm is a collective structure of microorganisms and it is covered by a protective layer secreted by the microorganisms themselves. The objective of this study is to identify and characterize the Elemental Biofilm Architectures that develop in a porous medium crossed by a laminar flow. This is a process that frequently occurs in nature, when there is water flow through the soil.In the case of this study, different flow velocities and the percentage of nutrients (% LB Broth diluted in water) were tested, as well as oxygen control. A non-flagellated fluorescent mutant bacterium of P.Putida was used to analyze bacterial and biofilm growth through a homogeneous porous medium. Also, two different methodologies were carried out during the experiments: Methodology A and B. With methodology A the bacteria were initially grown in the porous media, and then and bacterial free flow was injected at a constant flow rate. In methodology B, the porous media was initially free of bacteria, and a bacterial solution was injected at a constant flow rate during the experiment.In the experiments, the results show different architectural formations such as streamers, chains, ripples and fine lines. With both methodologies, bacteria develop similar biofilm architectures, such as streamers and ripples; but distributed differently throughout the porous media. The biggest difference relies on the deposit profile: in Methodology A most of the biomass accumulates towards the outlet of the porous media, while for Methodology B towards the inlet.
Does vertical mobility of eDNA in old soils affect the reconstruction of past environments?
Authors: Huang Doreen Yu-Tuan , Cutler Nick , Rodriguez Saúl , Morlock Marina , Klaminder Jonatan
Published: February 2023

Environmental DNA (eDNA) in sediments (soils, lake and marine sediments) can – in principle - be used to reconstruct past environments, provided the DNA is readily preserved and is relatively immobile within the sedimentary sequence (to allow accurate dating). Concerns over the mobility of DNA in soils have meant that these sediments have not been considered a reliable source of eDNA for palaeo-reconstruction. However, eDNA in soils could be preserved and immobilized through adsorption to secondary minerals (predominantly clays) in sediments. The potential of clay minerals to immobilize DNA is poorly understood; to address this knowledge gap, we conducted an experiment to evaluate the vertical mobility of eDNA between soil layers.Our experiment involved the application of spiked (non-indigenous) DNA to an experimental plot in eastern Greenland over a period of two years. During this period, we took soil samples at different depths below the plot and sequenced the samples to detect the spiked DNA. In addition to our experiment, we analyzed plant DNA from sequences of paleosols at a site in west Greenland and a site in south Iceland, to attempt to reconstruct long-term changes in vegetation cover.Our Greenland experiment indicated that faint traces of alien DNA can be transported to deep (thus old) soil horizons by percolating rainwater and can remain intact for at least two years. We suspect this occurred in Greenland because a) rainfall is high and b) the soils are skeletal and exceptionally porous. Despite this result, we observed changes in plant DNA with depth at our other two sites; these changes seemed to track century-scale environmental changes. We could not date the changes in the Greenlandic record due to the scarcity of macrofossils for radiocarbon dating. However, macroscopic tephra layers at the site in Iceland provided isochrons (time parallel marker beds) that allowed us to assign approximate dates using tephrochronology.Our results indicate that most of the spiked eDNA was either retained at the surface or degraded in the soil profile: only very tiny quantities leached to deep soil horizons. Therefore, we propose that eDNA in paleosols, especially those on tephra beds, possesses great potential in palaeo-reconstruction, especially when other archives (fossils, lake sediments) are not available. However, we recommend that more studies are required to examine how mineralogy and soil types govern eDNA mobility and longevity in soils.
A data fusion approach for retrieving 3D slope displacements from satellite InSAR and UAV-based orthoimagery correlation data: application to a reclaimed coal mining area
Authors: López-Vinielles Juan , García-Davalillo Juan Carlos , Sarro Roberto , Martínez-Corbella Mónica , Hernández Mario , Ezquerro Pablo , Bru Guadalupe , Barra Anna , Reyes‑Carmona Cristina , Mulas Joaquín , Herrera Gerardo , Fernández-Merodo José Antonio , Mateos Rosa María
Published: February 2023

Detecting and monitoring slope movements in mining areas is essential to better understand their causes and mitigate their adverse consequences. Satellite radar interferometry (InSAR) techniques allow to generate deformation maps at high resolution (both spatial and temporal), especially since 2014, when the European Space Agency's Sentinel-1 mission (6-day revisit frequency) became operational. The application of InSAR is, however, constrained by a number of limitations. One of the most important of them relates to its ability to measure only one component (or, at best, two components, provided that ascending and descending data are available) of the surface displacement (i.e., the line-of-sight component). In addition to this, InSAR offers a very low sensitivity in the north-south (NS) direction, which makes it difficult to study, solely on the basis of InSAR data, phenomena characterized by a strong NS component. In this context, this work discusses the potential role of UAV-based SfM image correlation as a possible data source to resolve the NS component of the motion, which in turn allows resolving, in the strict sense of the term, the three components of the motion from (at least) one ascending and one descending InSAR dataset.In this work we present the results of a local-scale study carried out in El Feixolín (León), a former open-pit and underground mining area affected by a rapid (1.67 m/year according to in situ measurements), large slope movement. Results include ground displacement velocity data obtained using (i) FASTVEL (and Sentinel-1 ascending and descending imagery), an on-demand, unsupervised InSAR processing service available on the Geohazards Exploitation Platform (GEP) (https://geohazards-tep.eu/), (ii) image correlation techniques (applied on UAV-based SfM orthoimagery) and (iii) DGNSS techniques. Further, this study provides as final result a dataset of 3D displacement velocity values (InSAR 3D dataset) derived by integrating the InSAR data obtained in ascending (InSAR ASC dataset) and descending (InSAR DES dataset) geometry, with the data obtained in NS direction through image correlation (SfM NS dataset). Comparison of the results with the data acquired in situ through DGNSS surveying revealed Root Mean Square Error (RMSE) values of 0.05, 0.23, 0.16 and 0.03 m/year (and relative RMSE values of 34, 67, 13 and 19%), respectively for the InSAR ASC, InSAR DES, SfM NS and InSAR 3D datasets, highlighting the effectiveness of UAV-based SfM image correlation for deriving NS ground deformation data to support InSAR processing and obtain 3D ground deformation vectors.
Improving GOCI-II In-Orbit Radiometric Calibration for the Stability of Ocean Color Data
Authors: Kim Minsang , Park Myung-Sook , Ahn Jae-Hyun , Lee Sun-Ju , Kang Gm-Sil
Published: February 2023

In ocean color remote sensing, the importance of developing and validating atmospheric correction and ocean bio-optical algorithms has been emphasized. However, if uncertainty remains in the fundamental procedure of converting the sensor signal to the top of the atmosphere (TOA) radiance, the errors will affects the overall reliability of the ocean satellite products.The purpose of this study is to monitor the gain parameters of two on-board GOCI-II calibration using Solar Diffuser (SD) and Diffuser Aging Monitoring Device (DAMD) and to improve the accuracy of ocean color sensors for radiometric calibration (RC) quality at the TOA level. Our results show that the SD gains parameter tends to decrease with seasonal periodicity in all bands, confirming sensor degradation and solar azimuth angle over time. In addition to the current RC model using only SD gain in the relationship between the sensor-observed digital counts and TOA radiance, we develop an azimuth angle correction model and a sensor degradation correction model. Verification will be performed by calculating the TOA radiation applied with an improved RC model around the Korean Peninsula. It will contribute to providing more stable GOCI-II ocean color products for short-term and long-term analysis.
Sharpening our community research on the initiation of subduction zones
Authors: Crameri Fabio
Published: February 2023

Current research on how, when, and where subduction zones initiate (one of the key, long-lasting open questions in the Earth Sciences) spans a multitude of (if not all) Earth and Planetary Science disciplines, engages most geoscientists at least once during their career, occupies research vessels and supercomputers, remains a steady appearance in overarching science journals, and often is considered the holy grail of our field.It is maybe not surprising that the study of subduction zone initiation (SZI) has therefore created a multitude of different research approaches and divided sub-disciplines applying specific methodologies and field-specific jargons and terms, of which neither is understood across sub-discipline boundaries any longer. To make it worse, a few leading SZI researchers have stopped acknowledging each other’s work, even scientifically.Within all sub-disciplines that exploit the rock record, plate reconstructions, geophysical measurements like seismic tomography, and theoretical and numerical modelling, we have never learned more about the formation of subduction zones than in the past couple of years. As a community, however, we failed to bring the dispersed knowledge (and sources of information) to a common ground and progress: Numerous numerical models on passive margin SZI made some geoscientists believe that it is the most likely place for SZI to occur. Misleading terminology made others believe that SZI can occur "spontaneously" or that "fore-arc basalts" (FABs) are formed in fore-arcs.With the community-based, community-driven, community-accessible Subduction-Zone Initiation (SZI) Database (www.SZIdatabase.org), we turn the helm towards a more unified, collaborative approach again. We provide the most extensive and detailed collection of current, trans-disciplinary SZI data (and from just this, a wealth of new insights), suggest a commonly-accessible SZI-related terminology, and offer a platform for community-wide, always-on discussion (see Crameri et al., 2020).Everything is put in place to reunite, and not loose track of, all our individual efforts and advances, so we, as a community, can learn and understand more about this enigmatic, truly cross-disciplinary hallmark of our fascinating planet. Crameri, F., V. Magni, M. Domeier, G.E. Shephard, K. Chotalia, G. Cooper, C. Eakin, A.G. Grima, D. Gürer, A. Király, E. Mulyukova, K. Peters, B. Robert, and M. Thielmann (2020), A transdisciplinary and community-driven database to unravel subduction zone initiation, Nature Communications, 11, 3750. doi:10.1038/s41467-020-17522-9
Arctic sea ice dynamics at 1km resolution with SI3
Authors: Rynders Stefanie , Aksenov Yevgeny , Coward Andrew C.
Published: February 2023

Sea ice plays a key role setting up a climate state of the Polar Oceans through moderating interactions between the ocean and atmosphere. As it is seen from satellite data, on the synoptic and sub-seasonal time-scales sea ice partly moves as a solid body – large areas of sea ice cover drift as single polygons – and partly deforms as a plastic material, shearing along the deformation lines – linear kinematic features (leads). Leads are important for the heat fluxes and also for navigational safety.In this study we focus on winter sea ice. Currently sea ice is thinning and more deformable; thinner ice is easier to crack. We compare the effect of different rheologies on sea ice and have developed a very high resolution (1 km) Arctic model, which allows for examining lead formation. The model shows a step change in behaviour compared to the previous high-resolution configuration (3 km). Specifically, we compare the EVP and EAP sea ice rheologies; these show substantial differences in the number and orientation of leads. EAP produces diamond patterns which has so far been difficult to create in models. The stand-alone sea ice model simulations will be coupled to ocean to examine eddy interaction.We acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 821926 (IMMERSE project) and from the LTS-S CLASS Programme (grant NE/R015953/1). The work reflects only the authors’ view; the European Commission and their executive agency are not responsible for any use that may be made of the information the work contains. This work also used the ARCHER-II UK National Supercomputing Service and JASMIN, the UK collaborative data analysis facility.