bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing high-resolution simulations of tropospheric NO2 over Flanders using WRF-Chem
Authors: Poraicu Catalina , Müller Jean-François , Stavrakou Trissevgeni , Fonteyn Dominique , Tack Frederik , Veldeman Nele
Published: March 2021

Atmospheric chemistry is critical in determining air quality and thus impacts climate change. Anthropogenic species are released into the atmosphere, and undergo complex photochemical transformations leading to the production of secondary pollutants, among which ozone and particulate matter. This can induce adverse effects on human health, visibility, ecosystems and local meteorology.  The combination of state-of-the-art atmospheric models with accurate atmospheric measurements of atmospheric species abundances is needed to evaluate whether atmospheric models can successfully simulate the chemical and physical processes occurring, and hopefully monitor the emissions of anthropogenic compounds and help in the implementation and verification of abatement policies.

In this work, ground-based, airborne and spaceborne measuring techniques are used to evaluate the performance of the full chemistry on-line WRF-Chem model over Antwerp in Flanders, Belgium, one of the areas with the highest NO2 pollution in the world. The model is configured to allow two nested domains with spatial resolution changing from 5 to 1km, so as to pinpoint the most pollutant sources in the region, and applied to simulate the urban air quality over the Antwerp agglomeration.

We will briefly discuss the choices and adaptations made regarding the physical parameterizations, emission inventories and chemical mechanism. The model performance is evaluated through comparison with various observation types. The physics parameterizations in WRF model  are evaluated through comparison against ground-based data from two meteorological stations in the Antwerp region. The WRF-Chem NO2 distributions are evaluated against (1) hourly measured concentration values from monitoring stations in Flanders, (2) vertical columns measured by an airborne hyperspectral imager APEX, providing a 2-dimensional spatial mapping, on 27 and 29 June 2019, and (3) spaceborne NO2 columns over Belgium obtained from the high-resolution TROPOMI instrument aboard S5p. The consistency of the model biases across the three datasets will be discussed, and recommendations will be made for improving model performance in this region.
Microbiological description of self-overgrowing spoil heaps and sand quarries in Nordwest Russia
Authors: Zverev Aleksei , Kimeklis Anastasiia , Gladkov Grigory , Kichko Arina , Andronov Evgeny , Abakumov Evgeny
Published: March 2021

Self-overgrowing recovery of disturbed soils is one of important processes in reclamation of disturbed soils. Different types of anthropogenic disturbances followed by variety of soil types and their genesis leads to different bacterial communities, envolved in reclamation processes. Here we describe regional self-overgrowing soils in two location (Novgorod region, Northwest Russia). We analyse top level of industrial disturbed soils after coil mining (spoil tips with extremely low pH, and overburden soil) and sand quarry dumps followed by local undisturbed soils.

We perform 16s amplicone sequencind (v4-region) by Illumina MiSEQ and chemical routine analysis (pH, C, N and other). We provide alpha- and beta-diversity analysis, followed by CCA and analysis of differential abundance of taxa.

Sand quarry dumps and regional soils looks common on phyla level, and represent common soil phyla like Proteobacteria, Actinobacteria and Verrucomicrobia. Alpha-diversity metrics aslo are similar, despite difference in beta-diversity. Overburden soil and soil from spot tips, by contrast, is very different even in phylum level. Main intermediants here are Actinobacteria, Chloroflexi и Nitrospirae. Also they show extremely low alpha-diversity metrics.

This work was supported by RSF 17-16-01030, «Dynamics of soil biota in chronoseries of post-technogenic landscapes: analysis of soil-ecological efficiency of ecosystem restoration processes»
KI:STE Project − AI Strategy for Earth System Data
Authors: Stadtler Scarlet , Kowalski Julia , Abel Markus , Roscher Ribana , Crewell Susanne , Gräler Benedikt , Kollet Stefan , Schultz Martin
Published: March 2021

Artificial intelligence (AI) methods currently experience rapid development and are also used more and more frequently in environmental and Earth system sciences. To date however, this is often done in the context of isolated rather than systematic solutions. In particular, for researchers there is often a discrepancy between the requirements of a solid and technically sound environmental data analysis and the availability of modern AI methods such as deep learning. Their systematic use is not yet established in environmental and Earth system sciences.

The recently started KI:STE project bridges this gap with a dedicated strategy that combines both, the development of AI applications and a strong training and network concept, thereby covering  different relevant aspects of environmental and Earth system research. It creates the technical prerequisites to make high-performance AI applications on environmental data portable for future users and to establish environmental AI as a key technology. 

Specifically, within KI:STE an AI-platform is envisioned which unifies machine learning (ML) workflows designed to study five core Earth system topics: cloud variability, hydrology, earth surface processes, vegetation health and air quality. All of them are strongly coupled and will profit from ML, e.g. to extend locally available information into global maps, or the track the interplay of spatio-temporal variability on different scales along process cascades. Besides being already connected across disciplines in the classical sense, KI:STE aims to furthermore bridge between these different topics by jointly addressing cutting edge ML research questions beyond pure algorithmic approaches. In particular, we will put emphasize on an explainable AI approach, which itself is a yet to be explored highly relevant topic within the Earth system sciences. It has the potential to connect the interdisciplinary work on yet another level.

KI:STE will also launch an e-learning platform in order to support the usage of the AI-platform as well as to communicate the knowledge to adequately use ML techniques within the different Earth system science domains.
Abiotic forest disturbances in Europe: mapping distribution and trends from space
Authors: Senf Cornelius , Sebald Julius , Seidl Rupert
Published: March 2021

Abiotic forest disturbances are an important driver of ecosystem dynamics around the globe. In Europe, storms and fires have been identified as the most important abiotic disturbances. Yet, how strongly these agents drive local disturbance regimes compared to other agents (e.g., biotic, human) remains unresolved. Furthermore, whether storms and fires are responsible for the observed increase in forest disturbances in Europe is debated. We here provide a first quantitative assessment of storm and fire disturbances in Europe 1986-2020 using Landsat remote sensing data. For more than 30 million disturbance patches mapped across Europe, we determined whether they were caused by storm or fire, using a random forest classifier and a large reference dataset of true disturbance occurrence. Differentiation between abiotic and other disturbances was made possible by using a set of neighborhood metrics, describing the spatial autocorrelation of each disturbance patch within its local surrounding landscape. This approach allowed for mapping both storm and fire disturbances in a spatially explicit manner. The maps show high correlation with national data and local case studies, but provide a seamless wall-to-wall picture of abiotic disturbance distribution. We subsequently analyzed patterns of abiotic disturbance prevalence (i.e., the share of storm and fire disturbances on the overall area disturbed) in space and time. Storm- and fire-related disturbances each accounted for approximately 7 % of all disturbances recorded in Europe in the period 1986-2020. Storm-related disturbances were most prevalent in western and central Europe, and especially mountain regions, where they locally account for >50% of all canopy disturbances. We however also identified storm-related disturbance hotspots in south-eastern and eastern Europe. Fire-related disturbances were a major driver of forest dynamics in southern and south-eastern Europe, but individual fires also occurred in eastern and northern Europe. Only very limited areas in Europe were affected by disturbances of both agents. The prevalence of storm-related disturbances increased over time. No trend in the prevalence of fire-related disturbances was detected, but several high-intensity fire years related to local drought conditions could be identified. We conclude that abiotic disturbances are an important driver of forest dynamics in Europe, but that their influence varies substantially by region. Our analyses suggest that an increase in storm-related disturbances could be an important driver of Europe’s changing forest disturbance regimes, but weaker evidence is present for fires.
Diverging future surface mass balance between the Antarctic ice shelves and grounded ice sheet
Authors: Kittel Christoph , Amory Charles , Agosta Cécile , Jourdain Nicolas C , Hofer Stefan , Delhasse Alison , Doutreloup Sébastien , Huot Pierre-Vincent , Lang Charlotte , Fichefet Thiery , Fettweis Xavier
Published: March 2021

The future surface mass balance (SMB) will influence the ice dynamics and the contribution of the Antarctic ice sheet (AIS) to the sea-level rise. Most of recent Antarctic SMB projections were based on the 5th phase of the Coupled Model Intercomparison Project (CMIP5). However, new CMIP6 results have revealed a +1.3°C higher mean Antarctic near-surface temperature than in CMIP5 at the end of the 21st century enabling estimations of future SMB in warmer climates. Here, we investigate the AIS sensitivity to different warmings with an ensemble of four simulations performed with the polar regional climate model MAR forced by two CMIP5 and two CMIP6 models over 1981--2100. Statistical extrapolation allows us to expand our results to the whole CMIP5 and CMIP6 ensembles. Our results highlight a contrasting effect on the future grounded ice sheet and the ice shelves. The SMB over grounded ice is projected to increase as a response to stronger snowfall, only partly offset by enhanced meltwater runoff. This leads to a cumulated sea-level rise mitigation (i.e. an increase in surface mass) of the grounded Antarctic surface by 5.1 ± 1.9 cm sea-level equivalent (SLE) in CMIP5-RCP8.5 and 6.3 ± 2.0 cm SLE in CMIP6-ssp585. Additionally, the CMIP6 low-emission ssp126 and intermediate-emission ssp245 scenarios project a stabilised surface mass gain resulting in a lower mitigation to sea-level rise than in ssp585. Over the ice shelves, the strong runoff increase associated with higher temperature is projected to lower the SMB with a stronger decrease in CMIP6-ssp585 compared to CMIP5-RCP8.5. Ice shelves are however predict to have a close-to-present-equilibrium stable SMB under CMIP6 ssp126 and ssp245 scenarios. Future uncertainties are mainly due to the sensitivity to anthropogenic forcing and the timing of the projected warming. Furthermore,  we compare the MAR projected SMB to the ISMIP6-derived SMB, revealing large local and integrated differences between MAR and the respective forcing ESM highlighting the need of additional projections relying on more models including both RCMs and ESMs. While ice shelves should remain at a close-to-equilibrium stable SMB under the Paris Agreements, MAR projects strong SMB decrease for an Antarctic near-surface warming above +2.5°C limiting the warming range before potential irreversible damages on the ice-shelves. Finally, our results reveal the existence of a potential threshold (+7.5°C) that leads to a lower grounded SMB increase. This however has to be confirmed in following studies using more extreme or longer future scenarios.
Local diurnal variations of the geomagnetic field during magnetically quiet conditions
Authors: Haberle Veronika , Marchaudon Aurélie , Blelly Pierre-Louis , Chambodut Aude
Published: March 2021

The Earth’s magnetic field as measured from ground-based magnetometers is composed of a variety of fields generated by diverse sources, spanning a broad amplitude and frequency spectrum. Long-term variable sources induce smooth changes, whereas short-term variable sources are able to induce rapid spikes in the geomagnetic field. An important aspect of Space Weather research is to understand the contribution and impact of each of these sources. In particular, knowing the amplitude and frequency of steady-like sources, like diurnal variations, enables us to determine the impact of sudden and hazardous events such as solar storms. The basic approach to this challenge is to identify the quiet magnetic field information within the recorded time-varying signal.
In this work, we examine the variance of the magnetically quiet diurnal and semi-diurnal components of the geomagnetic field, as recorded by ground-based magnetic observatories of the INTERMAGNET network. These variations are extracted by applying appropriately designed digital filters on the geomagnetic field time series. The residual signal is analysed in terms of local time and seasonal variations for selected locations under quiet magnetic conditions. This approach allows us to evaluate the applicability of the introduced filtering method. The obtained results improve our understanding of the driving sources of quiet currents such as the Sq current and the variations of their distributions with respect to regular solar irradiance variations. They will also contribute to a better extraction and description of the remaining/residual signal related to solar wind stimuli (e.g. ICMEs, CIRs) causing magnetic storms.
 An analytical model for spatially varying clear-sky CO2 forcing
Authors: Jeevanjee Nadir , Seeley Jacob , Paynter David , Fueglistaler Stephan
Published: March 2021

Instantaneous clear-sky CO2 forcing is known to vary significantly over the globe, but the climate factors which control this are not well understood. Building upon the work of Wilson (2012), we build a first-principles, analytical model for CO2 forcing which requires as input only the temperatures at the surface and roughly 20 hPa, as well as column relative humidity. This model quantitatively captures global variations in clear-sky CO2 forcing, and shows that the meridional forcing gradient is predominantly due to the meridional surface temperature gradient, with modulation by water vapor. In particular, the Simpsonian behavior of water vapor emission implies an upper bound on CO2 forcing (with respect to surface temperature) which is realized in the present day tropics.
Predicting elastic deformations of the crust induced by environmental loading on time-scales from days to decades
Authors: Dill Robert , Dobslaw Henryk , Klos Anna
Published: March 2021

Earth’s surface is elastically deformed by time-variable surface mass loads such as variations in atmospheric surface pressure, ocean bottom pressure, and terrestrial water storage. We look at the individual environmental loading contributions from the three different subsystems (atmosphere, terrestrial water storage, ocean) as well as from sea-level variations induced by the global water mass balance between land and ocean. Dividing the contributions into a set of period bands by means of a Wavelet decomposition, we show that non-tidal atmospheric surface loading (NTAL) by far dominates non-tidal ocean (NTOL) and hydrospheric loading (HYDL) for periods as long as a few months. The contribution of terrestrial water storage is continuously growing for increasingly longer periods and dominates atmospheric pressure at periods of 300 days and above. Ocean dynamics including sea-level variations due to the seasonal global mass balance are only important in the immediate vicinity of the coast.

In representative regions, we compare different environmental loading estimates, e.g. ESMGFZ based on ECMWF operational atmospheric data, NTAL and NTOL based on ECMWF ERA5, HYDL based on GRACE/GRACE-FO. Depending on the geographical location and considered frequency range, different estimates for NTOL and HYDL can exhibit large differences. In contrast, all latest loading models show a very consistent picture of atmospheric surface pressure loading deformations.  To evaluate the ability of different GNSS solutions to confirm the vertical deformations predicted by the geophysical fluid models, we compared at selected sites vertical station coordinates from six GNSS solutions with loading model predictions. In many cases, GNSS-derived variations heavily dependent on subjective choices within the GNSS data processing.
Remote data collection methods to inventory COVID-19 interventions in low-income urban settlements
Authors: Taylor Faith , Talib Manshur , Wandera Amos , Mulligan Joseph , Bukachi Vera , Drummond John , Malamud Bruce , Pelling Mark
Published: March 2021

In this PICO, we outline methods used to inventory the spatial distribution and characteristics of COVID-19 response activities (‘interventions’) in Kibera (Nairobi, Kenya). About 1/8 of the World’s Population live in slums and informal settlements. For these people, COVID-19 has presented unique challenges for managing health and livelihoods within the constraints of high-density housing and poor-quality infrastructure. In addition, reliable spatial, demographic and health data is often limited for these areas. Between April and July 2020, using the Survey123 smartphone application, combined with social media searches and phone enumeration, we inventoried 270 individual COVID-19 interventions taking place in Kibera, an informal settlement of 2.67 km2 and an estimated 187,000 to 1 000,000 inhabitants. Results show a large variety in the type of intervention (58 unique types) and organiser (>88 individual organisers), with 39% of interventions led by small scale organisations such as local NGOs and community groups. We found an uneven spatial distribution of interventions within Kibera, with some already underserved neighbourhoods having less access to COVID-19 relief. Many interventions are clustered around the limited open spaces with good accessibility by road, highlighting the need for better coordination between organisers, and the importance of open space for resilience building. Using isochronal service area analysis, we find that 80% of structures are within a 9-minute round trip of a handwashing station. However, 64% of structures have a 24-54 minute round trip to female sanitary supplies, illustrating gender differences in the impact and recovery from COVID-19. Our data is available online in an interactive map dashboard. Our survey results illustrate that rather than being seen as vectors of disease, low income urban neighbourhoods are part of the solution for managing pandemics, and highlight the importance of infrastructure upgrading and planning to build resilience to a range of shocks and stresses.
Oceanic eddy signature on SAR-derived sea ice drift and vorticity
Authors: Cassianides Angelina , Lique Camillie , Korosov Anton
Published: March 2021

In the global ocean, mesoscale eddies are routinely observed from satellite observation. In the Arctic Ocean, however, their observation is impeded by the presence of sea ice, although there is a growing recognition that eddy may be important for the evolution of the sea ice cover. In this talk, we will present a new method of surface ocean eddy detection based on their signature in sea ice vorticity retrieved from Synthetic Aperture Radar (SAR) images. A combination of Feature Tracking and Pattern Matching algorithm is used to compute the sea ice drift from pairs of SAR images. We will mostly focus on the case of one eddy in October 2017 in the marginal ice zone of the Canadian Basin, which was sampled by mooring observations, allowing a detailed description of its characteristics. Although the eddy could not be identified by visual inspection of the SAR images, its signature is revealed as a dipole anomaly in sea ice vorticity, which suggests that the eddy is a dipole composed of a cyclone and an anticyclone, with a horizontal scale of 80-100 km and persisted over a week. We will also discuss the relative contributions of the wind and the surface current to the sea ice vorticity. We anticipate that the robustness of our method will allow us to detect more eddies as more SAR observations become available in the future.
Modelling of the offshore wind farm footprint on organic and mineral particle deposition flux
Authors: Ivanov Evgeny , Capet Arthur , De Borger Emil , Degraer Steven , Delhez Eric , Soetaert Karline , Vanaverbeke Jan , Grégoire Marilaure
Published: March 2021

Being an important source of renewable energy, offshore wind farms (OWFs) are currently flourishing in European coastal seas, with a largely unknown long-term impact on the environment. By providing hard substrate habitat to fouling species (such as the blue mussel), who filter water and excrete rapidly sinking fecal pellets, OWFs change the sediment composition and its carbon balance through biodeposition. 

Here we coupled a hydrodynamic model (including tides), a wave model and a sediment transport model with a description of organic carbon dynamics. The coupled model was run for the Southern Bight of the North Sea under different scenarios: i) no OWFs; ii)  current OWF placement; and iii) several scenarios for future OWF placement in a new concession area, that differ in the number of installed monopiles and their placements.

Simulations showed that the tidal remobilization of mineral particles by the dominant current is orders of magnitude higher than their biodeposition from the OWFs. The total organic carbon (TOC) flux, however, appeared to be highly altered (up to 50%) by OWF biodeposition, especially in 5 km vicinity of the monopiles. At a greater distance (5 - 30 km away from the monopiles), the TOC biodeposition flux decreases. The majors alteration in the TOC flux is aligned with the major axis of the regional tidal current and the main direction of the residual current, with local residual gyres acting as TOC traps.

A future OWF, whose current concession zone overlaps a protected Natura 2000 area with its gravel beds acting as biodiversity hotspots, is expected to affect them through TOC biodeposition flux alteration. However, the magnitude of the impact appeared to be strongly dependent on the monopile placement, and very little on the number of monopiles. The gravel beds will experience a 50% TOC influx increase, if the monopiles are placed over them or just next to them, but already at 3 km distance this increase would be less than 10 %.
A globally consistent probabilistic wildfire risk model to assess economic damages
Authors: Lüthi Samuel , Bresch David
Published: March 2021

Wildfire risk around the world is rapidly increasing, leading to dramatic impacts on ecosystems and society. Economic damages of the past seasons threaten individual households, insurance companies, brokers and governmental authorities alike. Here, we present a probabilistic wildfire risk model to assess fire and economic risk. The model creates synthetic fire seasons through probabilistic ignition and dynamic random-walk spreading of fires.

The risk of natural catastrophes is commonly modeled using the three components hazard, exposure and vulnerability. This approach is used in the well-established open-source platform CLIMADA (CLIMate ADAptation). Here we show its extension for a globally consistent wildfire risk model. The model allows for the evaluation of economic damages of past and current wildfire events as well as a probabilistic risk assessment for any exposure on a seasonal basis. It is built on open and global data to ensure consistent modelling, including in data-sparse regions.

The hazard component uses Fire Information for Resource Management System (FIRMS) data acquired by the MODIS and VIIRS satellite missions and provided by Earthdata. We aggregate point information of fire activity using clustering algorithms over space and time to identify separate events while allowing for different resolutions (minimum of 375 m). For the exposure component, CLIMADA’s LitPop model is used, which geographically distributes assets using data on night-light intensity and population density. To assess the vulnerability, the model has been calibrated using reported damage data. Although uncertainties remain large, error scores after calibration resemble those of well-established hazards, such as tropical cyclones. To allow for probabilistic risk assessment, synthetic fire seasons are generated using a random-walk-type stochastic fire generator, which hinges on grid-point specific fire spread probabilities combined with an overall fire propagation probability. The framework further allows for a simple integration of additional data in order to reflect climate trends.
Operational marine products from Copernicus Sentinel-3 missions
Authors: Obligis Estelle , Kwiatkowska Ewa , O'Carroll Anne , Scharroo Remko
Published: March 2021

The first Copernicus Sentinel-3 satellite, Sentinel-3A, was launched in early 2016, and its twin Sentinel-3B in April 2018. The Sentinel-3 constellation is now fully operational with Sentinel-3B satellite flying in the same orbit plan with a phase difference of 140°. This constellation provides a unique consistent, long-term collection of marine and land data for operational analysis, forecasting and environmental and climate monitoring. The marine centre is part of the Sentinel-3 Payload Data Ground Segment, located at EUMETSAT. This centre together with the existing EUMETSAT facilities provides a routine centralised service for operational meteorology, oceanography, and other Sentinel-3 marine users as part of the European Commission's Copernicus programme. The EUMETSAT marine centre delivers operational Sea Surface Temperature, Ocean Colour and Sea Surface Topography data products based on the measurements from the Sea and Land Surface Temperature Radiometer (SLSTR), Ocean and Land Colour Instrument (OLCI) and Synthetic Aperture Radar Altimeter (SRAL), all aboard Sentinel-3 satellites. All products have been developed together with ESA and industry partners and EUMETSAT is responsible for the production, distribution, performance and future evolution of Level-2 marine products. We will give an overview of the scientific characteristics and algorithms of all marine Level-2 products, as well as instrument calibration and product validation results based on on-going Sentinel-3 Cal/Val activities. Information will be also provided about the current status of the product dissemination and the future evolutions that are envisaged. Also, we will provide information how to access Sentinel-3 data from EUMETSAT and where to look for further information.
Anthropogeomorphology of marine fisheries in India: understanding the critical roles of Marine Fishery Advisories towards achieving SDG 14
Authors: Kundu Sudip Kumar , Santhanam Harini
Published: March 2021

The livelihoods of more than 30 per cent of the total population in India residing in nine maritime states and four Union Territories are dependent on the diverse ecosystem services offered by coastal and marine systems. Marine fisheries contribute significantly to the Indian economy through the foreign exchange from the export of seafood which corresponds to nearly 5 per cent of the overall export and 20 per cent of the agro-export. In recent times, the anthropogenic pressures due to extensive marine fishing introduce challenges in the marine environment. Marine anthropogeomorphology, capable of transforming the natural settings of the continental shelf dominantly, is often not studied in detail from the perspective of sustainable fishing. For example, the use of the assorted fishing gears can damage the sea floor, apart from the capture of juvenile and non-target fishes. Bottom trawling by mechanised crafts as a part of marine fishing affects the geomorphology of the continental shelf and continental slope by displacing boulders, interrupting the structure of the sediment column, resuspending sediments, and imprinting deep holes on the muddy sea bottom. Occasionally, the abandoned fishing nets/gears on the seafloor are also responsible for the geomorphological damages to the bottom of the sea and death of several marine benthic flora and fauna, a phenomenon referred to as ‘ghost fishing’. Further, Illegal, Unreported and Unregulated (IUU) fishing in the ocean also poses major threats for the marine environment. Thus, it is essential to quantify these impacts of anthropogeomorphology in order to achieve the targets of the Sustainable Development Goal (SDG) 14, promulgated by the United Nations Organisation. Marine Fishery Advisories, especially, Potential Fishing Zones (PFZ) advisories may be helpful in reducing the impacts by aiding sustainable harvesting of pelagic fishes under the current scenario. The ESSO-Indian National Centre for Ocean Information Services (INCOIS) is the nodal agency, which disseminates PFZ advisory since 1999 using remotely sensed datasets of sea surface temperature and chlorophyll-a to reduce the uncertainty during marine fishing. PFZ advisory can help to promote environment-friendly fishing by reducing the search time and hence, ensuring minimal damage to the marine environment.
Evaluating the use of Aeolus satellite observations in a regional NWP model over the Nordic countries
Authors: Hagelin Susanna , Azad Roohollah , Lindskog Magnus , Schyberg Harald , Körnich Heiner
Published: March 2021

The impact of using wind speed data from the Aeolus satellite in a limited area Numerical Weather Prediction (NWP) system is being investigated using the limited area NWP model Harmonie-Arome over the Nordic region. We assimilate the Horizontal Line of Sight (HLOS) winds observed by Aeolus using a 3D-Var data assimilation for two different periods, one in Sept-Oct 2018 when the satellite was recently launched, and a later period in Apr-May 2020 to investigate the updated data processing of the HLOS winds. We find that the quality of the Aeolus observations have degraded between the first and second experiment period over our domain. However observations from Aeolus, in particular the Mie winds, have a clear impact on the analysis of the NWP model for both periods whereas the forecast impact is neutral when compared against radiosondes. Results from evaluation of observation minus background and observation minus analysis departures based on  Desroziers diagnostics show that the observation error should be increased for Aeolus data in our experiments, but the impact of doing so is small. We also see that there is potential improvement in using 4D-Var data assimilation with the Aeolus data. 
Influence of tree cover and urban area on streamflow in the United States using multiple statistical attribution techniques
Authors: Anderson Bailey , Slater Louise , Dadson Simon , Blum Annalise
Published: March 2021

There is still limited quantitative understanding of the effects of tree cover and urbanisation on streamflow at large scales, making it difficult to generalize these relationships. We use the globally consistent European Space Agency (ESA) Climate Change Initiative (CCI) Global Land Cover dataset to estimate the relationships between streamflow, calculated as high (Q0.99), median (Q0.50), and low (Q0.01) flow quantiles, and urbanization or tree cover changes in 2865 catchments between the years 1992 through 2018. We apply three statistical modelling approaches and examine the consistencies and inconsistencies between them. First, we use distributional regression models -- generalized additive models for location, scale, and shape (GAMLSS) -- at each site and assess goodness-of-fit. Model fits suggested a strong association between land cover, especially urban area, and low and median flows at sites with statistically significant trends in streamflow. We then examine the sign of the distributional regression model coefficients to determine whether the inclusion of a land cover variable in the regression models results in a relative increase or decrease in flow, regardless of the overall direction of trends in streamflow. Finally, we use fixed effects panel regression models to estimate the average effect across all sites. Panel regression results suggested that a 1% increase in urban area corresponds to between a < 1% and 2.1% increase in streamflow for all quantiles. Results for the tree cover panel regression models were not significant. We highlight the value of statistical approaches for large-sample attribution of hydrological change, while cautioning that considerable variability exists across catchments and modelling approaches.
Initial aggregate formation: Disentangling the effects of soil texture, OM properties and microbial community using artificial model soils
Authors: Bucka Franziska B. , Felde Vincent J.M.N.L. , Peth Stephan , Kögel-Knabner Ingrid
Published: March 2021

The interaction between mineral particles and organic matter (OM) is an important and complex process in the course of soil structure formation. For a better understanding it is necessary to disentangle the texture-dependent interplay of individual OM types and mineral particles. We developed an experimental set-up to study early aggregate formation within a controlled lab environment. Artificial soil microcosms with a mineral mixture resembling arable soils of three different textures (clay loam, loam and sandy loam) were used in a short-term, 30-day incubation experiment under constant water-tension. OM was added individually either as plant litter (POM) of two different sizes (0.63-2 mm and < 63 µm, respectively) or bacterial necromass (Bacillus subtilis). The mechanisms of soil structure formation were investigated by isolating water-stable aggregates after the incubation, analyzing their mechanical stability and organic carbon allocation, and measuring the specific surface area and OM covers of the mineral surface, microbial activity, and community structure.

The dry mixing process and incubation of the mineral mixtures led to particle-particle interactions and fine particle coatings of the sand grains as shown by a reduction of the specific surface area. The OM input of all types caused between 3 to 17% of the mineral surfaces to be covered by OM, with larger covered areas in the clay-rich mixtures. The added OM was quickly accessed and degraded by microbes, as shown by the peak in CO2-release within the first 10 days of the incubation. The POM of both sizes induced the predominant formation of water-stable macroaggregates (0.63-30 mm) with a mass contribution of 72 to 91% (irrespective of texture) and fostered the development of a microbial community with a high relative abundance of fungi. The bacterial necromass induced the formation of macroaggregates, but also microaggregates (63-200 µm), while the microbial community was dominated by bacteria. The mechanical stability analysis showed that very small forces < 4 N were sufficient for aggregate failure and breakdown to 80% of the original aggregate size.

We propose that the microbial degradation of all OM types leads to small, distinct OM clusters consisting of OM substrate, microbes, and extracellular polymeric substances. These interact with mineral particles, resulting in the cross-linking of particles and formation of water-stable aggregates in all textures. The OM can thereby act both as microbial substrate and as structural building block. The initially formed aggregates are a loosely connected scaffold with a very low mechanical stability. Differences in the developed microbial community may lead to additional stabilization mechanisms, like fungal hyphae enmeshing and stabilizing larger aggregates also in sandy texture.
First results of DTRF2020 computation
Authors: Seitz Manuela , Bloßfeld Mathis , Glomsda Matthias , Angermann Detlef
Published: March 2021

The new ITRS realization, the ITRF2020, will be computed and released in 2021. Many institutions contributing to the international IAG services IGS, IVS, ILRS and IDS did work hard during the last months to finalize the ITRF2020 input data until mid of February 2021. The resulting data are series of SINEX files of daily or weekly global GNSS, VLBI, SLR and DORIS solutions. The ITRS Combination Centres (CC) are in charge of the computation of three ITRS realizations based on a combination of these input data. The three realizations can be seen as independent to some extent, as the combination strategies realized by the three CC partly differ considerably. This provides the opportunity of a cross-validation between the computed frames and ensures a high reliability of the final ITRF product. The ITRS CC will start in February 2021 with the analysis of the final input data series and their combination.
We will present first results of the analyses and computations performed at ITRS CC DGFI-TUM.
Direct and indirect pathways of convected water masses and their impacts on the overturning dynamics of the Labrador Sea
Authors: Georgiou Sotiria , Ypma Stefanie L. , Brüggemann Nils , Sayol Juan-Manuel , van der Boog Carine G. , Spence Paul , Pietrzak Julie D. , Katsman Caroline A.
Published: March 2021

The dense waters formed by wintertime convection in the Labrador Sea play a key role in setting the properties of the deep Atlantic Ocean. To understand how variability in their production might affect the Atlantic Meridional Overturning Circulation (AMOC) variability, it is essential to determine pathways and associated timescales of their export. In this study, we analyze the trajectories of Argo floats and of Lagrangian particles launched at 53oN in the boundary current and traced backwards in time in a high‐resolution model, to identify and quantify the importance of upstream pathways. We find that 85% of the transport carried by the particles at 53oN originates from Cape Farewell, and it is split between a direct route that follows the boundary current and an indirect route involving boundary‐interior exchanges. Although both routes contribute roughly equally to the maximum overturning, the indirect route governs its signal in denser layers. This indirect route has two branches: part of the convected water is exported rapidly on the Labrador side of the basin, and part follows a longer route towards Greenland and is then carried with the boundary current. Export timescales of these two branches typically differ by 2.5 years. This study thus shows that boundary‐interior exchanges are important for the pathways and the properties of water masses arriving at 53oN. It reveals a complex three‐dimensional view of the convected water export, with implications for the arrival time of signals of variability therein at 53oN and thus for our understanding of the AMOC.
Tidal Signature Detection in Midlatitude Sporadic E Occurrence Rate, Using FORMOSAT-3/COSMIC Radio Occultation Data
Authors: Sobhkhiz Sahar , Yamazaki Yosuke , Arras Christina
Published: March 2021

Sporadic E (Es) is a transient phenomenon where thin layers of enhanced electron density appear in the ionospheric E region (90-120 km altitude). Es can influence radio propagation, and its global characteristics have been of great interest to radio communications and navigations. Atmospheric diurnal and semidiurnal tides cause horizontal wind shears at E-region heights by giving rise to ions and electrons' vertical motions. These shears will lead to the formation of Es layers. This research aims to study the role of atmospheric solar and lunar tides in Mid-latitude Es occurrence. For this purpose, radio occultation data from FORMASAT-3/COSMIC mission of 11 years (2007 to 2017), which provide complete global coverage, have been used. The results show both lunar and solar tidal signatures in Es occurrence. These tidal signatures are longitudinally dependent, which can result from non-migrating tides or modulation of migrating tidal signatures by zonally varying geomagnetic field.
Deep-water syn-rift sedimentary response to alternating Late Quaternary palaeoenvironments in the Gulf of Corinth (Greece)
Authors: Fabregas Natacha , Pechlivanidou Sofia , Gawthorpe Robert , Ford Mary , Collier Richard
Published: March 2021

Relatively few detailed studies exist of rift axis depositional systems and the controls on their sedimentology and stratigraphy. Cores from the IODP Expedition 381 (Corinth Active Rift Development) provide a continuous high resolution stratigraphic record of depositional processes operating within this deep-water rift. During the Late Quaternary, the Gulf of Corinth alternated between marine and isolated/non-marine conditions due to intermittent connection with the open ocean across a sill driven by climate-related sea-level fluctuations. In this study we performed bed scale logging of the sedimentary deposits within the eastern Gulf of Corinth in order to understand key controls on sedimentation during the Late Quaternary. High resolution, mm-scale analysis was performed on the first 300 m of core from Site M0079 that records the last two glacial-interglacial cycles and the Holocene (Marine Isotope Stages 1 to 7). The succession is dominated by fine-grained gravity flows (event beds) and hemipelagic sediments. Event beds result from discrete events that interrupt/overprint ongoing low energy sedimentation. As such, these have been abstracted in order to define three main sedimentary unit types. Unit-scale logging was extended to the rest of the succession and to the other drill sites to build a stratigraphic and depositional model covering the last ca. 700 kyr of deposition. Our results show that during interglacial periods (i.e. marine conditions), the sediment record consists mainly of highly bioturbated mud with rarer occurrences of coarser grained sediment. Sedimentary structures and identifiable event beds have largely been lost due to the high degree of bioturbation. In contrast, during glacial periods (i.e. isolated/semi-isolated lake conditions) the deposits are well bedded with a low bioturbation index and background muds alternate with event beds. Transitional strata, between marine and non-marine units, show finely laminated beds rich in aragonite, often becoming more organic rich toward the top. The deepest parts of the core penetrate slumped units and thicker gravity flow deposits. This study allows us to recognise the response to high frequency climatic fluctuations recorded in the sedimentary succession of this deep-water rift.
Transfer Data from NetCDF on Hierarchical Storage to Zarr on Object Storage: CMIP6 Climate Data Use Case
Authors: Kulüke Marco , Wachsmann Fabian , Siemund Georg Leander , Thiemann Hannes , Kindermann Stephan
Published: March 2021

This study provides a guidance to data providers on how to transfer existing NetCDF data from a hierarchical storage system into Zarr to an object storage system.

In recent years, object storage systems became an alternative to traditional hierarchical file systems, because they are easily scalable and offer faster data retrieval, as compared to hierarchical storage systems.

Earth system sciences, and climate science in particular, handle large amounts of data. These data usually are represented as multi-dimensional arrays and traditionally stored in netCDF format on hierarchical file systems. However, the current netCDF-4 format is not yet optimized for object storage systems. NetCDF data transfers from an object storage can only be conducted on file level which results in heavy download volumes. An improvement to mitigate this problem can be the Zarr format, which reduces data transfers, due to the direct chunk and meta data access and hence increases the input/output operation speed in parallel computing environments.

As one of the largest climate data providers worldwide, the German Climate Computing Center (DKRZ) continuously works towards efficient ways to make data accessible for the user. This use case shows the conversion and the transfer of a subset of the Coupled Model Intercomparison Project Phase 6 (CMIP6) climate data archive from netCDF on the hierarchical file system into Zarr to the OpenStack object store, known as Swift, by using the Zarr Python package. Conclusively, this study will evaluate to what extent Zarr formatted climate data on an object storage system is a meaningful addition to the existing high performance computing environment of the DKRZ.
Inventory of active rock glaciers in the western Nyainqêntanglha Range, Tibetan Plateau
Authors: Reinosch Eike , Gerke Markus , Riedel Björn , Schwalb Antje , Ye Qinghua , Buckel Johannes
Published: March 2021

The western Nyainqêntanglha Range on the Tibetan Plateau (TP) reaches an elevation of 7162 m and is characterized by an extensive periglacial environment. Here, we present the first rock glacier inventory of the central TP containing 1433 rock glaciers over an area of 4622 km². The rock glaciers are identified based on their surface velocity. The surface velocity is derived from Sentinel-1 satellite data of 2016 to 2019 via InSAR time series analysis. 16.4 % of the inventoried rock glaciers are classified as active with a surface velocity above 10 cmyr-1 and 80.0 % are classified as transitional with 1 to 10 cmyr-1. The western Nyainqêntanglha Range forms a climate divide between the dry continental climate brought by the Westerlies from the north-west and the Indian Summer Monsoon to the south. 89.7 % of all active rock glaciers and 74 % of the free ice glacial area are located on the southern side. The higher moisture availability on the southern (windward) side of the mountain range is likely the cause of a higher rock glacier occurrence and the greater activity.

Manually identifying and outlining rock glaciers is time consuming and subjective. To ensure a high reliability and comparability of our inventory, we therefore combined a manual approach with an automated classification. Three analysts worked in tandem to generate the manual outlines according to the guidelines of the IPA action group on ‘Rock glacier inventories and kinematics’. A subset of these outlines acted as training areas for a pixel-based maximum likelihood classification. Both the manual and the automated classification were performed based on DEM parameters (elevation, slope etc.), optical datasets (Sentinel-2 and NDVI) and surface velocity (generated with InSAR). 87.8 % of all manually outlined rock glaciers were identified successfully at a true positive rate of 69.5 %. 18 additional rock glaciers were added to the inventory based on the automated classification. This combined approach is therefore beneficial to generate a complete inventory. The automated classification can, however, not replace the expertise of an analyst as it greatly overestimates the actual rock glacier area.