bluuebunny/crossref_metadata_2025 huggingface dataset:
New insights into benthic nitrogen cycling using natural-abundance stable isotopes measurements
Authors: Mazzoli Alessandra , Callbeck Cameron M. , Paulus Tim J. , Frey Claudia , Zopfi Jakob , Katsev Sergei , Canfield Donald E. , Lehmann Moritz F.
Published: February 2023

Marine and lacustrine benthic habitats represent hotspots of nitrogen (N) turnover, with many N transformation processes occurring simultaneously, and at high rates. More specifically, sedimentary microbial reduction of nitrate to dinitrogen (N2), and other modes of N2 production (e.g., anammox), are the most important sinks of fixed N in aquatic environments. Natural abundance stable isotope ratio measurements can be employed to help disentangling N-loss mechanisms, given that the isotope effects (e) associated with each process are well studied.In our study, we surveyed an array of lacustrine and marine benthic environments and assessed the isotopic composition (d15N and d18O) of porewater ammonium (NH4+) and nitrate (NO3-) – the key substrates driving the various N transformation pathways, such as denitrification, anammox, nitrification and dissimilatory nitrate reduction to ammonium (DNRA). We further examined how benthic N isotope dynamics vary in different sedimentary regimes, with distinct organic matter (OM) mineralization rates. We expect the relative importance of the various N pathways to affect the NH4+ and/or NO3- isotope pools differentially.Our preliminary porewater d15N-NH4+ results suggest a diverse pattern with regard to the isotope enrichments between oligotrophic lakes, characterized by relatively strong depth gradients, and eutrophic lakes, where no significant depth gradient was observed. We hypothesize that this distinction could be attributed to different organic N availability and/or anammox contributions in the surveyed environments. Furthermore, we compared rate measurements (based on 15N addition experiments) to the N and O nitrate isotopic signatures to quantify processes, such as denitrification and DNRA. To investigate N isotope fractionation within the narrow nitracline, we employed the whole-core squeeze method, which provided a high-resolution porewater NO3-profile. Using this method, we found that the calculated community nitrate consumption e values at the nitracline (eelim_porewater) showed strong variability among the surveyed settings. We attribute such variation to shifts in the relative importance of denitrification versus DNRA and anammox between lakes of different trophic states. Overall, eelim_porewater wasconsiderably below 25‰ – the value generally reported for the biological isotope effect of denitrification (edenit).
Using Artificial Intelligence to Reconstruct Missing Climate Data In Extreme Events Datasets
Authors: Plésiat Étienne , Dunn Robert , Donat Markus , Morice Colin , Ludwig Thomas , Thiemann Hannes , Kadow Christopher
Published: February 2023

Evaluating the trends of extreme indices (EI) is crucial to detect and attribute extreme events (EE) and establish adaptation and mitigation strategies to the current and future climate conditions. However, the observational climate data used for the calculation of these indices often contains many missing values and leads to incomplete and inaccurate EI. This problem is even greater as we go back in time due to the scarcity of the older measurements.To tackle this problem, interpolation techniques such as the kriging method are often used to fill in the gaps. However, it has been shown that such techniques are inadequate to reconstruct specific climatic patterns [1]. Deep-learning based technologies give the possibility to surpass standard statistical methods by learning complex patterns and features in climate data.In this work, we are using an inpainting technique based on a U-Net neural network made of partial convolutional layers and a loss function designed to produce semantically meaningful predictions [1]. Models are trained using vast amounts of climate model data and can be used to reconstruct large and irregular regions of missing data with few computational resources.The efficiency of the method is well demonstrated through its application to the HadEX3 dataset [2]. This dataset contains gridded land surface EI, among which the TX90p index that measures the monthly (or annual) frequency of warm days (defined as a percentage of days where daily maximum temperature is above the 90th percentile). As for other EI, there is a lack of TX90p values in many regions of the world, even in recent years. It is particularly true when looking at an intermediate product of HadEX3 where the station-based indices have been combined without interpolation. This is illustrated by the left map of the figure where the gray pixels correspond to missing values. By training our model using data from the CMIP6 archive, we have been able to reconstruct the missing TX90p values for all the time steps of HadEX3 (see right map in the figure) and detect EE that were not included in the original dataset. The reconstructed dataset is being prepared for the community in the framework of the H2020 CLINT project [3] for further detection and attribution studies.[1] Kadow C. et al., Nat. Geosci., 13, 408-413 (2020)[2] Dunn R.J.H. et al., J. Geophys. Res. Atmos., 125, 1 (2020)[3] https://climateintelligence.eu/
Association between extreme atmospheric anomalies over Antarctic sea ice, Southern Ocean polar cyclones and atmospheric rivers
Authors: Hepworth Ehlke , Vichi Marcello , Messori Gabriele
Published: February 2023

This study analyses the association of Southern Ocean extratropical cyclones and atmospheric rivers (ARs) with extreme temperature and/or moisture atmospheric anomalies over Antarctic sea ice. The hypothesis we test is whether the circulations associated with cyclones and ARs may routinely lead to the presence of unusually warm, moist airmasses over ice-covered regions. The analysis is conducted over the extended Austral winter seasons (May – September) between May 1979 and September 2012, based on the European Centre for Medium-Range Weather Forecasts Interim reanalysis data. Approximately 27% of intense Southern Ocean cyclones and 20% of ARs occur in the vicinity of extreme temperature anomalies, while 12% of intense cyclones and 46% of ARs occur in the vicinity of extreme moisture anomalies. We summarize our results as follows: (1) extreme atmospheric anomalies over sea ice often occur in the absence of cyclones or ARs; (2) intense cyclones have a stronger association with extreme temperature  anomalies than ARs; (3) approximately half of the ARs are in the vicinity of extreme moisture anomalies, while the latter’s link with cyclones is weak; (4) if an AR is in the vicinity of an extreme temperature anomaly, there will likely be a concurrent extreme moisture anomaly. This points to a strong association between ARs and moisture extremes, and a nuanced link between Southern Ocean polar cyclones and atmospheric anomalies over Antarctic sea ice.
ESA/NASA Mass change And Geosciences International Constellation (MAGIC) mission concept – science and application prospects
Authors: Daras Ilias , Tsaoussi Lucia , March Guenther , Massotti Luca , Carnicero Dominguez Bernardo , Carraz Olivier
Published: February 2023

ESA and NASA are currently intensifying their long-term efforts on a collaborative implementation of a next generation mass change and gravity monitoring satellite mission under the umbrella of the NASA-ESA Joint Programme Planning Group sub-group 1. MAss-change and Geosciences International Constellation (MAGIC) is the joint NASA/ESA constellation concept based on NASA’s MCDO and ESA’s NGGM studies. The main objective of MAGIC is to extend the mass transport time series from previous gravity missions such as GRACE and GRACE-Follow on with significantly enhanced accuracy, spatial and temporal resolutions and to demonstrate the operational capabilities of MAGIC. The concept is based on a joint ESA/NASA Mission Requirements Document (MRD) which summarizes the goal requirements of the global scientific community (including requirements from the IGWSG report, IUGG, MCDO, etc.). The first pair of the MAGIC Constellation will be implemented via a NASA/DLR fast-paced cooperation to ensure continuity of observations of GRACE-Follow On, with some potential ESA in-kind contributions for a new generation of accelerometers. The second pair will be implemented by ESA with some potential NASA in-kind contributions for the Laser Tracking Instrument.This paper will address the novel science and applications enabled by MAGIC for the fields of hydrology, cryosphere, oceanography and solid Earth and demonstrate the significant added value of MAGIC constellation for unravelling and understanding mass transport and mass change processes in the Earth system.
Soil warming accelerates above-ground litter decomposition and soil organic carbon turnover
Authors: Fuchslueger Lucia , Verbrigghe Niel , Soong Jennifer L. , Meeran Kathiravan , Vicca Sara , Cotrufo Francesca M. , Sigurdsson Bjarni D. , Bahn Michael , Janssens Ivan
Published: February 2023

The terrestrial soil organic matter (SOM) pool size depends on the balance between SOM formation and stabilization of decomposing plant litter relative to mineralization as CO2.  Decomposition and mineralization processes are to large extents mediated by microbial decomposer communities. In addition, labile fractions released by decomposing litter can be stabilized in mineral associations (MAOM). High latitude ecosystems are particularly affected by global warming. Increasing temperatures can stimulate litter decomposition and increase nutrient mineralization, thereby increasing nutrient (e.g. nitrogen) availability for plants allowing higher productivity and subsequent plant organic matter inputs. On the other hand, if warming accelerates SOM decomposition stronger than formation processes it can cause large carbon and nutrient losses.Tracing 13C/15N labelled above-ground litter we aimed to disentangle if soil warming changes the balance between litter derived SOM formation through microbial communities, over particulate organic matter (POM) and MAOM stabilization across a decadal geothermal soil warming gradient (from ambient up to +5 °C) in a grassland in Iceland. In addition, we added three levels of inorganic N to disentangle potential direct warming from indirect (over plant feedbacks) effects of increased warming on SOM dynamics.  We found that over the course of two years warming accelerated litter decomposition rates and litter-derived carbon turnover by the microbial community,  and we could recover more litter-derived carbon recovered in particulate organic matter (POM) nor MAOM. Nitrogen additions triggered a faster decomposition of structural above-ground litter compounds, but did not influence carbon turnover in different soil fractions. On the other, hand we found that overall the absolute amount of soil carbon decreased in response to warming. We therefore conclude that direct warming not only increased SOM formation, but also decomposition and mineralization processes, and – at least in the studied grassland – plant inputs may not have counterbalanced warming induced losses.   
Clustering grid cells in a land surface model
Authors: Cooper Elizabeth , Ellis Rich , Blyth Eleanor , Dadson Simon
Published: February 2023

Land surface models such as JULES (Joint UK Land Environment Simulator) are usually run on a rectilinear grid, yielding gridded outputs for variables such as soil moisture and evapotranspiration. JULES also models surface and subsurface water fluxes, and these can be used as inputs to a river routing model to predict river flows. Here we investigate the effect of clustering groups of grid cells into ‘Land Response Units’ (LRUs) in JULES, using a hierarchical multivariate clustering technique to group underlying grid cells together based on characteristics including soil type, elevation and land cover. Using LRUs rather than grid cells has the potential to reduce computational expense as well as providing an alternative to tiling approaches for capturing sub-grid heterogeneity. Here, LRUs are used exclusively in the land surface part of modelling, i.e., separate from river routing.We investigate the effect of the LRU approach on JULES soil moisture in part of the Thames catchment in the UK, and compare LRU and gridded soil moisture predictions with measurements from the UKCEH COSMOS-UK soil moisture observation network. We find that use of LRUs leads to good soil moisture prediction while reducing computational expense compared to a gridded approach, but that this is strongly dependent on the characteristics used to create the LRUs. We also consider how the LRU approach impacts predicted river flows, and compare routed JULES outputs with observed river flow from a number of NRFA gauges in the catchment. We show that less computationally expensive LRU JULES outputs give similar river flow results to standard 1 km gridded JULES outputs when routed at 1km resolution, and that the LRU approach can outperform gridded river flow predictions when routed at higher resolution.
Back and Through the Looking Glass - Space-time scattering of elastic waves
Authors: Aichele Johannes , Müller Jonas , Nissar Zabreen , van Manen Dirk-Jan , Serra-Garcia Marc
Published: February 2023

Due to causality wave scattering in time is simpler than scattering in space: Incontrast to multiple spatial boundaries, there are no infinite reflections betweentemporal boundaries. Salem and Caloz, 2015 [1] showed that wave scatter-ing can be simplified by constructing a time-space cross-mapping. We identifythe cross-mapped wavefields as the Focusing functions developed in data-drivengeophysical imaging. Experimentally, Bacot et al, 2016 [2] have shown thattime modulation of the medium properties of a capillary-gravity wave results intime-refraction and time-reflection of the original wave. This experimental re-sult should hold true for any system obeying Alembert’s equation. This shouldin principle allow us to physically compute wavefields for the single-sided inversescattering problem through forward scattering experiments. We set up a sim-ple comb-like discrete system for time-modulated 1D elastic wave propagation.Elastic beams act as the masses and an electrostatic force as the springs of oursystem. The effective coupling stiffness between the beams is modulated in timethrough a variation of the electrostatic force. A Galerkin based wave propaga-tion model shows that an experimental realization of hundreds of beams can beachieved through micro-machining. Through time-modulations of the system’swavespeed a broadband excitation is refracted and reflected everywhere in space.Time-scattering preserves the wave vector k, which implies that the frequencyω is not conserved. To elucidate the dispersion relation at time boundaries,we employ a correction method for spatial dispersion. Herefore, a correctionmethod for time-dispersion in finite difference simulations developed by Koeneet al 2018 [3] is mapped to the spatial dimension of our meta-material.[1] Salem, Mohamed A., and Christophe Caloz. “Space-Time Cross-Mappingand Application to Wave Scattering.” ArXiv:1504.02012 [Physics], April 7, 2015.http://arxiv.org/abs/1504.02012. [2] Bacot, Vincent, Matthieu Labousse, An-tonin Eddi, Mathias Fink, and Emmanuel Fort. “Time Reversal and Holographywith Spacetime Transformations.” Nature Physics 12, no. 10 (October 2016):972–77. https://doi.org/10.1038/nphys3810. [3] Koene, Erik F M, Johan O A1
 

 
Robertsson, Filippo Broggini, and Fredrik Andersson. “Eliminating Time Dis-persion from Seismic Wave Modeling.” Geophysical Journal International 213,no. 1 (April 1, 2018): 169–80. https://doi.org/10/gcz9wb.
DORIS-based Precise Orbit Determination and its geodetic applications
Authors: Kumar Vikash , Dikshit Onkar , Balasubramanian Nagarajan
Published: February 2023

DORIS (Doppler Orbitography Radio positioning Integrated by Satellite) is a space-based piggyback satellite system that when used as a terrestrial measurement system can provide an accuracy of 10 cm in the absolute position measurement and in the order of sub-cm accuracy in relative measurements. When it rides piggyback on any satellite system can provide an orbital accuracy up to cm level. Precise Orbit Determination (POD) is the process of accurately tracking the position and velocity of a satellite in orbit. DORIS is an excellent satellite tracking system supporting the precise orbit determination of satellites. The accuracy of the POD does not affect only the quality of the estimated orbit ephemerides, but also the quantities derived from a free-network solution, mainly the station coordinates and the Earth rotation parameters (ERP). The precisely determined orbit can be used in many altimetric applications including estimating the mean sea surface, marine geoid, and vertical land motion, to derive vertical deflection and mean dynamic topography. Apart from that, the gravity field variations can also be determined more precisely.  GNSS data observations alone have been used so far in India to study the plate tectonics movements and earthquake predictions in the Indian subcontinent. Since DORIS and GNSS both have homogeneous network distributions and are complementary to each other, the DORIS data observations can be combined with GNSS data observations to study plate tectonics movements and earthquake predictions more effectively. Not only that since in DORIS the signal is transmitted from the ground, but processing DORIS measurement residue helps us to better understand and model what occurs in between the layers of the atmosphere which can be used for precise tropospheric modeling.
 
This space-based geodetic measurement technique has been used for the past three decades the world over, for precise measurement on the ground as well as on all oceanographic and altimetric satellite missions, it has not been introduced in India so far. Since our Space Research Organization has been launching several satellite missions and DORIS is being used for computation of the precise orbits, this technique has come to stay for a long time. The National Centre for Geodesy was set up by the Department of Science and Technology at the IIT Kanpur has also plans to set up a Geodesy village, where the DORIS station is going to be established and our DORIS data will be used in defining ITRF.
 
How does imposing a spatially-varying map of background vertical diffusivity with rates and spatial structure informed by observations impact the modelled Arctic Ocean state?
Authors: O'Connor Benjamin , Waterman Stephanie , Scott Jeffrey , Dosser Hayley , Chanona Melanie
Published: February 2023

Mixing in the Arctic Ocean drives water mass transformations critical to the heat and freshwater budgets of the Arctic Ocean, impacting sea ice extent and volume, stratification, circulation, and heat and freshwater release to the subpolar N. Atlantic. Observations indicate that mixing rates in the Arctic Ocean are highly variable, however this variability is typically not well-represented in models.This study uses a regional Arctic Ocean model to addresses the question “How does imposing a spatially-varying map of background vertical diffusivity with rates and spatial structure informed by observations impact the modelled Arctic Ocean state?” It seeks to understand impacts based on model experiments that systematically vary the diffusivity uniformly in space.It is shown that prescribing the observationally-informed mixing map results in increased heat loss, a redistribution of freshwater storage, and increased heat and freshwater export to the N. Atlantic relative to a control case with an equal-on-average-but-spatially-uniform distribution of mixing. These effects can be understood as the result of enhancing (reducing) mixing on the shelves (basins) relative to the control case. They highlight sensitivities of the Arctic Ocean heat and freshwater budgets to shelf and basin mixing respectively.These findings are relevant to the impacts of the changing Arctic Ocean mixing environment on Arctic Ocean functioning and subpolar ocean variability. They further suggest ways in which the prescription of Arctic Ocean mixing may be important to improving model representations of Arctic Ocean dynamics.
An Update on Recent Land Subsidence in the Vietnamese Mekong Delta Derived from Advanced Sentinel-1 SAR Interferometry
Authors: Dörr Nils , Schenk Andreas , Hinz Stefan
Published: February 2023

The Vietnamese Mekong Delta has been affected by several environmental challenges for the last couple of decades, including land subsidence, coastal erosion, loss of sediment supply due to upstream dam constructions and droughts. Subsidence rates of up to several centimeters per year have been reported, adding up with the regional sea level rise of about 3.3 mm/yr. The associated risk is an increased vulnerability to flooding, salinization of water resources and permanent inundation. Precise monitoring of land subsidence with high spatial and temporal resolution is essential to understand the causes and hazards of the subsidence in order to derive and monitor the implementation of countermeasures.

In this work, we present results of recent land subsidence monitoring between 2016 and 2022 in the Vietnamese Mekong Delta based on Sentinel-1 Persistent Scatterer Interferometry (PSI). We used Sentinel-1 scenes from ascending and descending orbits and applied an advanced PSI approach which we adapted for large-scale monitoring. The advancements of the algorithm include the incorporation of Temporary Persistent Scatterers to optimize the algorithm for challenging conditions in the dynamic sprawling urban areas in the study area and derive the best possible Persistent Scatterer network for long InSAR time series. Another add-on is the integration of GIS data with the PSI results for specific object identification and their subsidence characteristics.

We present recent subsidence rates and their temporal evolution. Additionally, we highlight specific spatial and temporal features in the subsidence, which can be associated with land surface characteristics or environmental influences. Finally, we discuss further conducted studies based on the land subsidence data set which allow to separate between shallow and deep causes of land subsidence, with the overall goal to contribute to the understanding of causes of land subsidence.
A comparative study of carbon fluxes measured at two different heights over an alpine steppe
Authors: Pillai Nithin Dinesan , Wille Christian , Nieberding Felix , Ma Yaoming , Sachs Torsten
Published: February 2023

Being the most accurate, direct, and defensible method available to date for studying the ecosystem scale gas exchange, the eddy covariance (EC) method was used to examine the net carbon exchange over an alpine steppe ecosystem near the Nam Co Station for Multi-sphere Observation and Research (NAMORS) on the Tibetan Plateau. EC measurements are site-specific and the values represent the total sum of the relative contribution of fluxes from all the components within the footprint over the measurement time. The scattered and uneven distribution of EC towers and their small footprint demand upscaling of the flux observations to a regional scale for improving understanding of the net exchange of CO2 between the terrestrial biosphere and the atmosphere. Regional scale carbon estimates are highly variable and not fully explored as compared to carbon balance studies at extreme ends of the spatial scale spectrum (large continental scale and small vegetation stand scale). Translating the spatially sparse measurements into consistent, gridded flux estimates at the regional scale is a prerequisite for quantifying the current terrestrial carbon cycle. But the uncertainties caused by the representativeness error in the model grids while quantifying the regional estimates of carbon exchange are not fully investigated due to limited data availability as well as knowledge of flux variability at the grid scale. Rather than extrapolating the point scale and/or site-specific scale measurements by fitting any statistical model to predict ecosystem or earth system processes, a systematic upscaling approach is vital for refining mathematical models and accounting for the grid-scale uncertainties for better policy decisions. As an initial step to this, the net ecosystem exchange (NEE) of carbon estimated at two different measurement heights of 3 m and 19 m, in the early growing period of 2019 were used to quantify and analyze the interdependencies in the flux measurements at two heights and the influence of heterogeneity within the footprint in the measured fluxes.Keywords: Eddy covariance, Carbon flux, Net ecosystem exchange, Tibetan Plateau
ICRED: A multi-stakeholder approach for assessing the resilience to disaster of small island communities
Authors: Talubo Joan Pauline , Morse Stephen , Saroj Devendra
Published: February 2023

Despite the ongoing challenge of the operationalization of the concept of resilience, it has become a significant global political agenda. However, the lack of integration among the sectors involved – academia, politicians, civil society, and local practitioners, has resulted in problems in the usefulness and efficacy in the operationalisation of the concept in the grassroots.  The lack of participation at the grassroots and the local practitioners’ level in developing indicators that has caused gaps in the definition, assessment, and operationalisation of the concept. The measurement of community resilience is considered a significant step towards reducing risk to disasters and increasing disaster preparedness and the capacity to adapt to various kinds of disaster. Assessment tools for resilience that were developed without the consideration of the insights, perspectives, knowledge, and experience of the stakeholders are in the danger of serving a different purpose which they were originally built for.This paper introduces the Island Community Resilience to Disasters (ICRED) approach. An approach that is integrated, taking into account the different facets of a small island community’s resilience to disasters and aggregating the various indicators under the themes of small island disaster resilience. This approach is also multi-stakeholder, considering all the perspectives of the various stakeholders that play a role in the disaster resilience of a small island community – from the communities on ground, to the local decision-makers to the experts who work in the disaster risk management field.
Model hierarchies and bifurcations in QE monsoon models
Authors: Kumar S Krishna , Seshadri Ashwin K
Published: February 2023

The convective quasi-equilibrium (CQE) framework has been successfully employed in the past to build intermediate complexity models accounting for the interaction of convection and large-scale dynamics (Neelin and Zeng, 1999, JAS). As a consequence, these models find use in the study of monsoon circulations, which also experience abrupt onset among several other intriguing features. While some low-order simplifications of CQE based Quasi-equilibrium tropical circulation model (QTCM) yields insights into the mechanisms of monsoon dynamics, they are restricted in the range of processes accounted for. A hierarchy of models, on the other hand, would serve well to study monsoon dynamics and various influences. While the existence of bifurcations or 'tipping-points' in monsoon dynamics has been studied for certain simple models, a thorough investigation of this possibility across a hierarchy of models is absent. Such a hierarchy of models would provide an understanding of effects of different simplifying assumptions on dominant balances in the momentum and thermodynamic equations and resulting nonlinear dynamics, including the choice of precipitation parameterizations. This study explores a hierarchy of such models of varying complexity, based on the QTCM equations. The potential occurrence of bifurcation phenomena are considered, along with their sensitivity to various parameter changes, in the context of the role of different nonlinearities present in these models. The study builds on recent results interpreting the suppression of bifurcation phenomena in these models, as a result of shifts in equilibrium branches and consequently their physical relevance. The hierarchy of models approach, in this context, reconciles apparent contradictions between bifurcations being observed in the simplest models and the evidence from more complex models as well as observations, while identifying robust phenomena.
Observed changes in ageostrophic winds over Denmark
Authors: Kaas Eigil , Vedel Henrik , Fischereit Jana
Published: February 2023

Undisrupted wind observations at 10m level (u10, v10) have been analyzed for recent decadal changes with respect to surface geostrophic winds (ug, vg) and 10m winds from ERA5 (u10E, v10E).Thus, we analyze the difference between (u10, v10) and (ug, vg), and between (u10, v10) and (u10E, v10E). The underlying hypothesis is that the effective roughness length has increased during the last 30 years in the Danish area, including surrounding seas, due to the extensive expansion of both on- and off-shore wind turbine installations in Denmark and neighboring countries.Theoretically a gradual increase in roughness length will lead to a reduction in near-surface winds with respect to undisturbed conditions, i.e., the recent "climatic roughness length" before the present analysis. We already know from extensive measurement campaigns - mostly offshore - that direct wake effects from large wind farms can be quite substantial - with reduced near surface wind - in the wake, sometimes up to almost 100 km downstream of the wind farm.Furthermore, the cross-isobaric flow will change, resulting in a potential enhanced Ekman pumping in the planetary boundary layer, and thereby an accelerated spin down process of atmospheric synoptic scale weather systems, including induced precipitation in decaying low-pressure systems. Therefore, this is also analyzed.It is well known that we have natural decadal and interdecadal fluctuations in the near surface wind, which are not related to changing regional surface characteristics. This is the reason that we do not consider the direct wind-observations but rather the anomalies with respect to ERA5 surface geostrophic winds and near surface winds, which are only marginally "polluted" by the existence of wind farms, since these are not build into the re-analysis system (model)We have obtained results showing a change in the wind characteristics analyzed, which is in line with the original hypothesis.
Improved ecohydrologic modelling using spatial patterns of remotely sensed land surface temperature
Authors: Duethmann Doris , Anderson Martha , Maneta Marco , Tetzlaff Doerthe
Published: February 2023

Considering different types of hydrologic observations for model calibration in addition to streamflow is a suitable strategy to better constrain model parameters and improve process-consistency of hydrologic models. In this regard, land surface temperature (Ts) is an interesting variable as it is at the core of the surface energy and water balance. This study aims at evaluating the benefits of integrating spatial patterns of satellite-derived Ts into calibration of the process-based ecohydrologic model EcH2O. We furthermore explore the value of an increasing number of Ts images in the calibration period. The study is performed in a mixed land cover catchment in NE Germany and makes use of Landsat-derived Ts data. Our results show that satellite-derived Ts is useful for reducing uncertainties of energy-balance related vegetation parameters, which are hardly constrained when the model is calibrated to streamflow only. Good model performance with respect to streamflow does not preclude low performance in terms of Ts and including satellite-derived Ts for model calibration clearly improves simulated spatial patterns of Ts. Spatial patterns in observed Ts are shown to be strongly related to land cover class and a vegetation index, and our results indicate that further model improvements may be possible by better representing observed variations of leaf area index within the ecohydrologic model.
An innovative method to investigate the altering urban thermal environment by dynamic land cover change: A case study of Suwon, Republic of Korea
Authors: Lee Siwoo , Yoo Cheolhee , Im Jungho , Cho Dongjin , Lee Yeonsu , Bae Dukwon
Published: February 2023

The transformation of natural land cover into impermeable materials is a common definition of urbanization. However, it should be noted that vertical growth caused by urban renewal has been disregarded, while the horizontal expansion of urban areas has been widely studied. Understanding dynamic land cover change and its impact focusing on the thermal environment is essential for the sustainable management of urban areas. Therefore, the objective of this study is to propose a simple yet effective urban thermal environment investigation strategy that responds to dynamic land cover transformation. The study area is Suwon, Republic of Korea, where the city has recently been experiencing the most extreme urbanization along with explosive population growth. We designed a three-step approach: 1) extraction of temporal local climate zone (LCZ) to monitor the change in land cover due to urban growth over the period 2004 and 2021, 2) retrieval of high spatial-resolution land surface temperature (LST) using artificial intelligence to observe surface energy flux in heterogeneous urban area in detail, and 3) apply the filtering analysis method, which only uses the pixels classified with a higher confidence level, based on deep learning probabilistic approach to reduce the uncertainty of LCZ classification. To construct the temporal LCZ maps with a 30 m spatial resolution and retrieve the downscaled LSTs (DLSTs) with a corresponding spatial resolution, Landsat series satellites, Shuttle Radar Topography Mission (SRTM), and land cover map produced by Ministry of Environment were used. We obtained the following results: First, the overall accuracy (OA) of the LCZ classification was higher than 90% in both 2004 and 2021. Second, the average coefficient of determination (R2) and root mean square error (RMSE) of the DLSTs were greater than 0.9 and less than 1 °C, respectively. Third, through our suggested urban thermal environment investigation strategy, this study could find that the results of LST changes were clearly varied by building height and compactness changes. Especially, change of low-rise building to mid-rise building increased LST significantly. With these findings, we solidly believe the suggested strategy facilitates advanced urban climate studies.
Deciphering the role of terrestrial/atmospheric interactions in Late Devonian Kellwasser black shale deposition: A High-Resolution Cyclostratigraphic study of the Winsenberg section (Rhenish Massif, Germany)
Authors: Wichern Nina , Bialik Or , Percival Lawrence , Kaskes Pim , Nohl Theresa , Becker Thomas , De Vleeschouwer David
Published: February 2023

The Late Devonian oceans were susceptible to the development of anoxic conditions, as evidenced by repeated widespread organic-rich shale deposition. Understanding how these anoxic facies were deposited will provide insight into Devonian climatic modes. To this end, we constructed a high-resolution cyclostratigraphic model based on portable XRF-generated elemental ratio records from a Frasnian-Famennian (~372 Ma) black shale section. These black shales are associated with the Kellwasser Crisis, one of the largest mass extinctions of the Phanerozoic, which is not fully understood to this day. The studied section at Winsenberg is located in the Rhenish Massif in Germany and represents a basinal setting at southern low paleolatitudes. Spectral analysis was carried out on the Si/Ca ratios generated by XRF, which is interpreted as the detrital (distal) vs carbonaceous (local) input. The resulting astrochronology suggests a duration of ca. 1 Myr from the base of the Lower Kellwasser to the F-F boundary at the top of the Upper Kellwasser level. This corresponds to an average sedimentation rate of 0.9 cm/kyr. Both the Lower and Upper Kellwasser shales occur at the onset of a 405 kyr eccentricity cycle. We further interpret the Ti/Al record as a riverine runoff signal, as Ti is associated with the coarse-grained fraction, and K/Al as a chemical weathering signal, as K is leached easier than Al. Both tuned records exhibit eccentricity-modulated precession cycles. On precession and short eccentricity timescales, Ti/Al and K/Al are positively correlated, suggesting an orbitally forced wet/dry monsoonal climate in the region where the section was deposited. On longer timescales, the weathering signal becomes decoupled from the riverine runoff signal, highlighting that K/Al (chemical weathering) decreased even during wetter periods. This decoupling is linked to soil maturation in the hinterland, as potassium leaching from mature soils became increasingly limited. Soil build-up and maturation forms a potential mechanism for nutrient storage and subsequent release into the ocean, potentially triggering eutrophication and anoxia.
Empirical Distortions in Climate Networks
Authors: Haas Moritz , Goswami Bedartha , von Luxburg Ulrike
Published: February 2023

Climate networks have become a popular tool for detecting complex structures in spatio-temporal data. However, they require to estimate correlation values on many edges based on limited and noisy time series. Consequently any constructed network likely contains false and missing edges. To measure how severely and in which ways estimated networks are distorted by statistical errors, we simulate time-dependent isotropic random fields on the sphere. We comprehensively present several patterns of distortion in local as well as global network characteristics and demonstrate which network construction methods enhance statistical robustness. When the data has a locally coherent correlation structure, spurious link bundle teleconnections and spurious high-degree clusters have to be expected. Anisotropic estimation variance can also induce severe biases into empirical networks. We validate all our findings with ERA5 reanalysis data. Finally, we explain why commonly applied resampling procedures  are insufficient for evaluating statistical significance of network structures, and introduce a new ensemble construction framework that aims to alleviate most of the discussed shortcomings.
Analysing the added value of surface features information in the Seabed substrate data from the European sea areas - EMODnet Geology
Authors: Kihlman Susanna , Kaskela Anu , Kotilainen Aarno , Alanen Ulla , Vallius Henry , Partners EMODnet Geology
Published: February 2023

Increasing anthropogenic pressure in marine and coastal environments emphasizes the importance of the easily accessible, reliable, and suitable data on marine environment, to support conservation, research, and sustainable marine management decisions. The EMODnet (European Marine Observation and Data network) Geology project has been aiming to address this demand by collecting and harmonising geological data at different scales from all the European sea areas since 2009, at present with a collaboration of about 40 partners and subcontractors.Seabed substrate data has been collected since the beginning of the EMODnet Geology project and it is one of the key elements shaping the physical structure of benthic habitats. In the project, national seabed substrate data is harmonised into a shared schema, based on the sediment grain size. However, there are some geologically and ecologically important seabed surface features, which cannot be explained only by grain size e.g., bioclastic features, moving sediment and FeMn concretion fields. Therefore, the project has also collected information on these features that partners have considered vital for the seabed environment. At best, this data could be a valuable addition to define e.g., geodiversity of the seabed environment when grain size distribution is insufficient.The first review of the collected data aimed to identify and analyse the surface features, their occurrence and briefly discuss the prospects this additional information could provide. However, the development of a valuable surface features database requires further work, like developing guidelines concerning data collection methods, terminology, and classification. This work will need collaboration with different stakeholders and end users.The EMODnet Geology project is funded by The European Climate, Environment and Infrastructure Executive Agency (CINEA) through contract EASME/EMFF/2020/3.1.11 - Lot 2/SI2.853812_EMODnet – Geology.
Circulation in the vicinity of a submerged stream groyne under mesotidal impact (East Frisian Islands, Southern North Sea)
Authors: Albinus Michelle
Published: February 2023

In this study, the major characteristics of the circulation in the tidal inlet between the East Frisian Islands Spiekeroog and Wangerooge (Harle, Southern North Sea) are depicted by investigating current parameters using in situ Acoustic Doppler Current Profiler (ADCP) transect data. The focus is to reveal flow patterns in the area as a response to the submerged training wall Groyne H (GH) and the mesotidal impact prevailing at the East Frisian Islands. The circulation in the Harle is determined by semidiurnal tides, forcing the water to the southwest (ebb) resp. northeast (flood), thereby surrounding and overflowing the GH. The structure enhances the discharge and velocity in the main channel by blocking two thirds of the inlet horizontally and vertically.  It is assumed that depending on the water level above the groyne crest and the morphology of the inlet, vertical and/or horizontal recirculation cells develop on either the upstream or downstream side. An attempt is made to detect such cells and to give an explanation of the underlying physical processes. Therefore, ADCP transect data were obtained during two tidal cycles performing cross-sectional transects parallel to GH and a cross pattern in the groyne field south of GH. Data analysis particularly targets the computation of flow fields to resolve the circulation on a spatial scale and decompose velocity profiles into their 2D-components. Moreover, flow data is divided into different depth layers comparing surface versus average velocity over the transect to ascertain areas of velocity shearing. The consequences on each downstream side are a) the deceleration of flow in the groyne field by about 30-50 % b) a dynamic eddy at the groyne tip forming a low-velocity zone and c) a vertical recirculation cell rotating towards the groyne sole. For the latter, additional measurements need to be conducted to resolve such a cell in more detail and to analyze a broader area for the presence of horizontal circulation cells. 

 
Evaluation of Precipitation Emergent Constraints in CMIP5 and CMIP
Authors: Ferguglia Olivia , Palazzi Elisa , von Hardenberg Jost
Published: February 2023

An Emergent Constraint (EC) is a physically-explainable relationship between model simulations of a past climate variable (predictor) and projections of a future climate variable (predictand). By constraining the predictor through observations, it is possible to narrow future model projections, if a significant correlation between the predictor and the predictand exists. In our work, the EC technique has been applied to the analysis of precipitation and precipitation extremes, variables that are strongly affected by model uncertainties and still insufficiently analyzed in the context of ECs. One of the main challenges in determining an EC is establishing if the relationship found is physically meaningful and if it is robust to changes in the composition of the model ensemble. Four ECs already documented in the literature and so far tested only with CMIP3 or CMIP5, have been reconsidered in our study. Their existence and robustness are evaluated by developing a systematic methodology that involves different subsets and different scenarios of CMIP5 and CMIP6 models, verifying if an EC found in CMIP3/CMIP5 is still present in the most recent ensemble and assessing its sensitivity to the detailed ensemble composition. Three out of the four ECs considered in our work did not pass the test, being robust in CMIP5 but not in CMIP6, or (in one case) being not robust in both CMIP5 and CMIP6. Only one EC is verified and robust in both model ensembles. These results show the difficulty of identifying robust precipitation ECs and cast doubts on the usability of such ECs as a tool to  reduce uncertainties in future projections of precipitation change. At the same time, this work highlights the importance of the EC technique  as a way to improve our understanding  of climate phenomena and their drivers and to investigate precipitation-related feedbacks, providing evidence of connections between precipitation and different climate variables. This observation lays the path to further explore original ECs.
Heavy-ion-rich X-ray solar flares in December 2022 measured on Solar Orbiter
Authors: Dudnik Oleksiy , Mason Glenn , Ho George , Allen Robert , Wimmer-Schweingruber Robert , Rodríguez-Pacheco Javier , Espinosa Lara Francisco , Gómez Herrero Raul , Mrozek Tomasz , Karlicky Marian
Published: February 2023

   Energy spectra of X-ray solar flares observed by the Spectrometer-Telescope for Imaging X-rays (STIX) onboard the Solar Orbiter consist of both thermal and non-thermal parts. The thermal part is present in all solar events. When the non-thermal part of the energy spectrum begins to dominate, we can expect detection in interplanetary space of high-energy electron beams that have escaped the coronal loops. When hard X-ray flares are detected solar type III radio bursts are registered frequently with their numerous modifications like drift pairs, U-type, and structured bursts. The e-CALLISTO simple worldwide radio antenna stations allow us to identify the existence of non-thermal components in the energy spectra of strong X-ray flares. At the same time, some X-ray flares are accompanied by ejections of energetic ions including heavy ions. The specific features in X-ray bursts responsible for events with simultaneous light and heavy particle stream generation are still unclear compared with those with electron emission only.    We present preliminary results of observations gathered in December 2022 and cross-analysis of data on energetic light and heavy particle fluxes and X-ray flare parameters. The end of 2022 was distinguished by moderate to high solar activity, the presence of three periods with enhanced proton and heavy-ion fluxes at the beginning of the month, in the middle, and on 25-26 December. We demonstrate also the presence of narrow directed electron beams detected by the Electron Proton Telescope (EPT) of EPD for selected events mentioned above, and heavy ions detected by the Suprathermal Ion Spectrograph (SIS) of EPD.