bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of large-scale circulation patterns and boundary layer conditions on precipitation formation in Corsica
Authors: Knerr Isabel , Trachte Katja , Garel Emilie , Huneau Frédéric , Santoni Sébastien , Bendix Jörg
Published: March 2020

The precipitation formation on Corsica in the western Mediterranean is highly affected by the interplay between large-scale weather patterns and the local-scale induced sea-slope breezes. Due to its geographical position the island experiences a strong seasonal cycle in the climatic conditions. From September to May, most of the precipitation is generated by large-scale weather systems, which cause frontal precipitation and in mountainous regions an orographically-induced enhancement. In contrast during the summer month the local combined sea slope breeze systems lead to rather convective precipitation events in the afternoon. The planetary boundary layer (PBL) is the surface affected atmosphere and follows in its structure and height the diurnal cycle. Its height gives information on the strength of turbulent mixing and thus, on the vertical moisture distribution.

In this study we investigate the moisture transport within and above the PBL along a west-east transect on Corsica in the period May 2017 to October 2019. PBL height was derived from wind field measurements with a 3D ultrasound anemometer at the western (Ajaccio) and eastern (Ghisonaccia) coastal sites and from sounding profiles at Ajaccio airport. In addition, the ERA5 reanalysis data along the west-east transect were used to derive the influence of the terrain on the depth of the mixed layer. In order to get further insight into the underlying processes and local mechanisms related to the PBL height development and moisture transport towards the mountains of Corsica the Weather Research and Forecasting (WRF) model is applied. Case studies of summertime convective precipitation formation related to large-scale weather types and local breezes also driven by the sea surface temperatures are presented. Finally, back-trajectory modeling is used to reflect atmospheric pathways and sources of precipitable water.
Lagrangian modeling of the active dispersal of juvenile leatherback turtles in the North Atlantic Ocean
Authors: Gaspar Philippe , Lalire Maxime , Giffard Pierrick , Candela Tony
Published: March 2020

It has long been assumed that young sea turtles drift passively with ocean currents. As a consequence, simple Lagrangian models have often been used to investigate the dispersal of various sea turtle populations during their juvenile stage. However, evidence is growing that juvenile sea turtles do not drift purely passively with ocean currents but also display some swimming activity, generally directed towards favorable habitats.

We have thus developed a new Sea Turtle Active Movement Model (STAMM) in which simulated individuals disperse under the combined influence of oceanic currents and swimming movements triggered by the need to find suitable habitats, that is areas with suitable water temperatures and sufficient food.  Preferred temperatures and food requirements are modeled to vary with the age (or size) of the simulated individuals.

STAMM is used here to investigate the active dispersal of juvenile leatherback turtles (Dermochelys coriacea) born in French Guiana, a major rookery for the Northwest Atlantic population. Our simulations reveal that:

 While currents broadly shape the dispersal area, habitat-driven movements profoundly structure the spatio-temporal distribution of juveniles within this area. Passive turtles can drift far North in deadly cold waters or concentrate in oligotrophic waters found at the center of the North Atlantic subtropical gyre. On the contrary, actively swimming juveniles tend to concentrate in favorable habitats along the northern boundary of the subtropical gyre and undertake seasonal north-south migrations allowing them to remain in suitable water temperatures.

Active juveniles ultimately target rich areas of the Eastern Atlantic basin, in particular in the Bay of Biscay, off Galicia, Portugal and Mauritania, and in the western Mediterranean Sea where juvenile leatherbacks are actually observed. These zones are inaccessible to passive turtles.

Arrival times of the active juveniles in these favorable zones are consistent with the observed sizes of individuals bycaught or stranded in these areas;

All together these results suggest that active habitat-driven swimming movements shall be systematically taken into account to produce realistic simulations of the spatial distribution of sea turtles during their pelagic juvenile stage. This is much needed to help develop effective conservation measures targeting this critical life stage.
Thermal behaviour of retrogressive thaw slumps over time revealed by ERT - an example from Herschel Island, Canada
Authors: Eppinger Saskia , Krautblatter Michael , Lantuit Hugues , Fritz Michael
Published: March 2020

In the last century the number of retrogressive thaw slumps has doubled in some arctic regions, e.g. Herschel Island, Yukon Territory, Canada [Lantuit and Pollard, 2008]. Retrogressive thaw slumps are a common thermocarst landform along the coast of Herschel Island [Lantuit and Pollard, 2005]. However mechanical conditions leading to the evolution of those retrogressive thaw slumps are poorly understood.

For a better understanding of internal thermal processes in these retrogressive thaw slumps we implemented different electrical resistivity profiles (ERT). They cross the focused thaw slump longitudinally and transversally. We compared about 2 km of new ERT-data from 2019 with the same transects from 2011 to gain information about the temperature distribution and the temperature changes in the slump ground.

The aim for our study is to gain a profound understanding of the strong and deep thermal disturbances generated by retrogressive thaw slumps and how they change over time, leading to a possible polycyclicality of these slumps.

 

 

 

 

Lantuit, H., and W. H. Pollard (2005), Temporal stereophotogrammetric analysis of retrogressive thaw slumps on Herschel Island, Yukon Territory, Nat. Hazards Earth Syst. Sci. 5 (3), 413–423.

Lantuit, H., and W. H. Pollard (2008), Fifty years of coastal erosion and retrogressive thaw slump activity on Herschel Island, southern Beaufort Sea, Yukon Territory, Canada, Geomorphology 95 (1-2), 84–102.
On the use of circulation classifications by self-organizing maps toward studying extreme weather
Authors: Stryhal Jan , Plavcová Eva
Published: March 2020

The self-organizing maps (SOMs) have become a widespread tool for studying atmospheric circulation and its links to weather elements. The SOMs do not only produce a classification, but also a topology-preserving representation of the input data—a 2D array of circulation types (CTs). Consequently, one can analyse not only CT frequencies, persistence, and their conditioning of weather elements, but also visualise these parameters in a “continuum” of representative patterns. This latter characteristic makes it in theory plausible to define a (considerably) larger number of CTs compared to other classification approaches, and thus better represent extremes of circulation variability, without necessarily compromising the utility of the output by making it unintelligible.

Here, we investigate whether increasing the number of CTs (enlarging the SOM) leads to a classification better suitable to study synoptic forcing of extreme weather, and, in particular, what the effect is of various SOM parameters, which have to be chosen a priori more or less subjectively—such as array shape and size, radius and function of neighbourhood, learning rate, and initialization—on the utility of the resulting classification. Furthermore, we present the Sammon mapping, typically used to evaluate the topological structure of SOMs, as a standalone classification tool that shares some of the advantages with SOMs while potentially circumventing some of their weaknesses.
Investigating and quantifying the uncertainty beyond the stability analysis of high unstable fractured rock cliff by Remote Piloted Aerial System (RPAS)-based Digital Photogrammetry: the example of the Gallivaggio landslide
Authors: Menegoni Niccolò , Giordan Daniele , Perotti Cesare
Published: March 2020

The recent advantages in Remote Piloted Aerial System (RPAS) and 3D Digital/Virtual Outcrop Model (DOM/VOM) development from RGB images (e.g. Structure from Motion, SfM;  Multi Stereo View, MSV; Simultaneous Localization And Mapping, SLAM)  have increased the application of these technology in stability analysis of unstable rock cliffs affected by rock fall due to possibility to perform analysis with higher resolution, accuracy, safety and time-saving to respect the traditional manual techniques, and with higher applicability and affordability to respect the Laser Scanner technology. The principal aims of a geoengineering  inspection of an unstable rock slope are to identify the possible Mode of Failure (MoF) of the rock mass (e.g. planar sliding, wedge sliding, toppling) and to estimate the rock volume that could be involved in a possible failure event. Then these results can be used for further numerical models and applications, as the rock fall simulations, here the uncertainty of the input parameters deeply influence the output results and, therefore, the reliability of the simulation. Due to the novelty of the RPAS-based DOMs, the uncertainty of the stability analysis is not always correctly identified (e.g. uncertainty equal to the DOM accuracy) and, therefore, sometimes the results and conclusion of the analysis could be partially wrong. Identifying and quantifying correctly the uncertainty is really important especially during emergency condition, when crucial decision must be made quickly.

In this study, the uncertainty of the stability analysis of the unstable rock cliff of Gallivaggio (Western Alps, Italy) is deeply investigated due to the possibility to compare the Mode of Failure and the unstable rock volume estimated before the failure event of the 29th May 2018 onto a DOM developed using the RPAS, with those identified and calculated after the failure. In particular, it is shown as uncertainty component of the instrumental error could be almost totally negligible to respect the components of the manual interpretation and analysis, also when no Ground Control Points (GCPs) are used to develop the DOM.
Assessment of operational monitoring of snow water equivalent measurements with low-cost GNSS sensors
Authors: Capelli Achille , Koch Franziska , Henkel Patrik , Lamm Markus , Marty Christoph , Schweizer Jürg
Published: March 2020

The water stored in the snowpack is a crucial contribution to the hydrological cycle in mountain areas. Estimating the spatial distribution and temporal evolution of snow water equivalent (SWE) in mountain regions is, therefore, a key question in snow hydrology research. For this reason, direct measurements of SWE are still essential, but they are often scarce, not easy to install and maintain, mostly non-continuous or rather expensive. A promising alternative to conventional SWE in-situ measurement methods is a newly developed method based on signals of the freely available Global Navigation Satellite System (GNSS), which can be received with standard low-cost sensors. In general, this measurement technique is based on signal differences between one GNSS antenna buried below the snowpack and one reference antenna above the snow cover. The signal differences reflect the GNSS carrier phase time delay and the GNSS signals strength attenuation within the snowpack, which can be translated into SWE and the snow liquid water content (LWC). So far, this method showed excellent results over several years at the high-alpine test and validation site Weissfluhjoch (Eastern Swiss Alps, 2540 m asl.). Currently, our aim is to assess whether this method is suitable for deriving SWE continuously with reasonable accuracy also at other locations with different characteristics. Therefore, we set up further GNSS sensors at different elevations, where the snow characteristics can vary considerably. At lower elevations the snow cover is normally shallower and is more frequently subject to melt-freeze cycles leading to faster snow aging and different snow densities. Moreover, rapid transition from dry- to wet-snow conditions as well as steep valley sites can be seen as a challenge. In total, we were operating for two season four GNSS stations along a steep elevation gradient (820 m, 1185 m, 1510 m, and 2540 m asl.) within only a few kilometres in the Eastern Swiss Alps. For validation purposes, we monitored SWE and snow height manually and with additional automatic sensors at all locations. We analysed the GNSS SWE derivation accuracy in general and in detail for different meteorological conditions as snowfall, snow settlement, rain on snow and dry or wet snow periods. Eventually, we compared the GNSS results with results from numerical snow cover models.
Artificial Intelligence for Improvement of Convective System Tracking and Its Surface Effect Prediction
Authors: La Tran Vu , Messager Christophe , Sahl Rémi , Honnorat Marc
Published: March 2020

Thanks to the geostationary meteorological satellites of METEOSAT (Europe), GOES (USA), and Himawari (Japan), the nowcast of convective systems (CS) can be performed in most of the world with a 5-15-minute observation time sampling and about 2.8-km spatial resolution (up to about 1-km for the new-generation satellites).

However, the CS forecast, including the prediction of their effects on the surface, is still a challenge due to the lack of high-resolution radar data and a deep understanding of this topic. Indeed, for now, most numerical weather prediction (NWP) models cannot deliver an accurate time and space estimation of surface wind patterns and wind gusts associated with the CS.

In the meantime, Synthetic Aperture Radar (SAR) and ASCAT (scatterometers) may be used for the detection of surface wind patterns potentially associated with the deep convective clouds that may be identified on METEOSAT images. Additionally, the intensity of wind patterns may be estimated from SAR and ASCAT data. Based on this result, Deep Learning (or Machine Learning) is proposed in an ongoing study for improving the predictions of wind gusts, based on the combination of several data sources such as SAR, ASCAT, METEOSAT. The obtained results of this step will be used to integrate into the current NWP models.
Barotropic Instability of a Cyclone Core at Kilometer‐Scale Resolution
Authors: Leutwyler David , Schär Christoph
Published: March 2020

Secondary disturbances spawning frontal waves along the fronts of mature midlatitude low-pressure systems were identified decades ago from satellite images. While their development has been studied using analytical models, field campaigns (e.g. FASTEX) and re-analysis datasets, simulation of the phenomenon in state-of-the-art global weather and climate models so far remained unattainable.

Today's flagship supercomputers allow performing simulations at kilometer-scale resolution on computational domains covering the entire lifecycle of synoptic-scale systems and thus enable explicit representation of small-scale disturbances embedded in large-scale circulations. We demonstrate these capabilities in two different types of kilometer-scale simulations. The first is a 10-day-long near-global simulation of an idealized moist baroclinic wave, performed at 1 km grid spacing and employing 16,001 × 36,006 × 60 grid points. The second is a real-case simulation of an extratropical low-pressure system, driven by the European Centre for Medium-Range Weather Forecasts's operational analysis. At kilometer-scale resolution, both simulations display clear evidence of embedded mesoscale vortices spawning along frontal systems of mature extratropical cyclones. The vortices appearing in the real-case simulation can also be identified in satellite imagery of the system.

 The simulated developments are due to a barotropic instability mechanism and driven by strong low-level horizontal wind shear. While the simulation of the frontal systems is amenable at model resolutions around 10–50 km, the instability mechanism itself relies on the representation of a narrow shear zone, requiring about 5 times finer resolution. Results suggest that the flow regimes suppressing or fostering barotropic vortices can coexist in the same synoptic system. Far away from the cyclone core, the instability is suppressed by deformation associated with the large-scale flow, while close to the mature cyclone core, the narrow frontal structure becomes unstable.

Leutwyler, D. and C. Schär (2019): Barotropic instability of a cyclone core at kilometer-scale resolution, J. Adv. Model. Earth Sy., 11.
Analysis of tropical urban aquifers in response to climate change
Authors: Su Huang , Lancia Michele , Zheng Chunmiao , Hiscock Kevin
Published: March 2020

Urban aquifers represent an undeveloped resource and utilization is also arising as a method to improve storm water management. In dry climate, these aquifers are an alternative water supply source and in tropical climate can mitigate waterlogging and floods. However, sources and pathways of urban groundwater are more numerous and complex than those in rural environments. Furthermore, climate change and more frequent and intense climate extremes increase the variability in precipitation, soil moisture, and surface water. Therefore, a long-term effective urban water management is imperative.

This study investigates the groundwater in Shenzhen, a major financial and high-tech center in southern China, along the left side of the Zhujiang Estuary (Pearl River Delta). Shenzhen has a population of about 14 million permanent residents and currently has a total water consumption of 2 billion m3 per annum. Previous research has investigated the hydrogeological setting and groundwater budgets via numerical flow simulations under steady-state conditions. In the present research, a MODFLOW transient model has been constructed to estimate the groundwater budgets in Shenzhen in response to projected climate change.

Model conditions are varied, considering the typical Representative Concentration Pathway (RCP) scenarios (RCP 2.6, RCP4.5, RCP 6.0 and RCP 8.5) from 2019 to 2049. Simulations are grouped into two numerical analyses. For the first analysis, the rainfall rate decreases by 37.4% (RCP2.6, RCP4.5) together with a sea-level increment of 0.36 m (RCP 4.5); for the second analysis rainfall increases by 11.82% (RCP 6.0, RCP 8.5) and a sea-level increment of 0.5 m (RCP 8.5).

In the first analysis (RCP 2.6, RCP 4.5) the groundwater budget decreases by approximately 26% within the study domain, and the water table declines from 1 to 26 m. The second analysis shows a 15.48% increase in the groundwater budget, as the water level rises on average from 0.5 to 8 m. Given the sensitivity of the model results to the choice of future climate scenario, this study indicates the importance of accurate climate change predictions to help local authorities better manage water resources in tropical urban aquifers.
What controls nucleation of ice and nitric acid hydrates by meteoric material?
Authors: James Alexander , Sikora Sebastien N. F. , Holden Mark , Mann Graham W. , Plane John M. C. , Murray Benjamin J.
Published: March 2020

Nucleation of crystalline ice and nitric acid hydrates in Polar Stratospheric Clouds (PSC) is important for the destruction of ozone, both through changing the rate of activation of ozone destroying species and through the removal by sedimentation of nitric acid, which can deactivate ozone destroying species. Nucleation is thought to proceed heterogeneously on fragmented meteoric materials, leading to formation of ice and nitric acid trihydrate. The heterogeneous nature of meteoric materials and the potential to form multiple crystalline phases makes this system particularly complex. In particular, the characteristics of meteoric fragments which allow them to nucleate crystallisation in PSCs are unknown. We have investigated the nature of nucleation of nitric acid solutions on meteorite thin section surfaces. We find that nucleation occurs on a range of sites on the surface without significant reproduction in repeat freezing experiments. Electron microscopy showed significant diversity in the type of surface features present in regions where nucleation was observed. This is in contrast to recent studies of ice nucleation on K-feldspar and quartz surfaces, where particular sites were found to dominate nucleation. We also observed a range of different crystalline phases forming competitively, some of which are not represented on the HNO3 / H2O equilibrium phase diagram. The results reinforce the complexity of nucleation in PSC and do not support simplifying assumptions commonly made in the literature e.g. around the order in which phases form. In order to facilitate a predictive capacity of future trends in ozone loss significant work is required in understanding the nucleation of nitric acid hydrates by meteoric material.
A new global Gross Primary Production (GPP) dataset based on microwave Vegetation Optical Depth Climate Archive (VODCA)
Authors: Wild Benjamin , Teubner Irene , Moesinger Leander , Dorigo Wouter
Published: March 2020

Gross Primary Production (GPP) describes the uptake of C02 by plants through photosynthesis and is essential to monitor and analyze ecosystem dynamics. Teubner et al.1 developed a carbon sink-driven approach to estimate GPP on a global scale using Vegetation Optical Depth (VOD), derived from active and passive microwave observations. This allows to analyze GPP variability, complementing existing optical GPP products which are more affected by weather conditions. The short operation time of the individual microwave sensors and the bias between them prohibit analyzing GPP variability. This issue can potentially be overcome by using the Vegetation Optical Depth Climate Archive (VODCA) developed by Moesinger et al.2, which merges multiple VOD products into a single data record. However, the use of a long-running VOD composite for estimating global GPP is challenging because the implications of the VOD aggregation process on the modelling of GPP are difficult to identify a priori.

Here, we present the results of applying the carbon sink-driven GPP estimation approach on the VODCA datasets. As model input for each pixel we used raw VOD from VODCA as well as changes in VOD and median VOD, the latter serves as proxy for vegetation cover. In order to analyze the performance of the carbon sink-driven approach when using VODCA as input, the model is cross-validated against single-sensor (AMSR-E) VOD estimates and commonly used carbon source-driven estimates (MODIS/FLUXCOM). We assessed the ability to model GPP based on single-frequency VODCA (C-, X- and Ku-band) as well as using multiple frequencies as model input.

Overall, the results show that single-band as well as multi-band VODCA performs slightly better in predicting GPP than single-sensor based VOD. Especially in the tropical regions multi-frequency VODCA GPP outperforms single-sensor based estimates. Compared to source-driven approaches, VOD based GPP estimates are higher than FLUXCOM and MODIS GPP. The spatial patterns, however, show good correspondence with the carbon source-driven GPP products, confirming that VODCA can be used to extend the GPP estimates to the past three decades.

1Teubner, I., Forkel, M., Camps-Valls, G., Jung, M., Miralles, Diego, Tramontana, G., van der Schalie, R., Vreugdenhil, M., Moesinger, L., Dorigo, W.:A carbon sink-driven approach to estimate gross primary production from microwave satellite observations, 2019. Remote Sensing of Environment. 229. 100-113. 10.1016/j.rse.2019.04.022.

2Moesinger, L., Dorigo, W., de Jeu, R., van der Schalie, R., Scanlon, T., Teubner, I., and Forkel, M.: The Global Long-term Microwave Vegetation Optical Depth Climate Archive VODCA, Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2019-42, in review, 2019.
Climate Tipping Points: Can they trigger a Global Cascade?
Authors: Armstrong McKay David , Staal Arie , Cornell Sarah , Lenton Timothy , Fetzer Ingo
Published: March 2020

Over the past 15 years climate tipping points have emerged as both an important research topic and source of public concern. Some articles have suggested that some tipping points could begin within the 1.5-2oC Paris climate target range, with many more potentially starting by the ~3-4oC of warming that current policy is projected to be committed to. Recent work has also proposed that these tipping points could interact and potentially ‘cascade’ – with the impacts of passing one tipping point being sufficient to trigger the next and so on – resulting in an emergent global tipping point for a long-term commitment to a ‘Hothouse Earth’ trajectory of 4+oC (Steffen et al., 2018). However, much of the recent discussion relies largely on a decade-old characterisation of climate tipping points, based on a literature review and expert elicitation exercise. An updated characterisation would fully utilise more recent results from coupled and offline models, model inter-comparisons, and palaeoclimate studies. The ‘tipping cascade’ hypothesis has also not yet been tested, with the suggestion of 2oC as the global tipping point remaining speculative. Furthermore, the definition of what counts as a climate tipping point is often inconsistent, with some purported tipping points represented more accurately as threshold-free positive feedbacks. Here we perform an updated systematic review of climate tipping points, cataloguing the current evidence for each suggested element with reference to rigorously-applied tipping point definitions. Based on this we test the potential for a global tipping cascade using a stylised model, from which we will present preliminary results.

References

Steffen, W., et al.: Trajectories of the Earth System in the Anthropocene, Proc. Natl. Acad. Sci., 115(33), 8252–8259, doi:10.1073/pnas.1810141115, 2018.
Isostatic and dynamic controls on neotectonic differential vertical movements and sediment transport reorganization of the Pannonian Basin, Central Europe
Authors: Balázs Attila , Kovács Ádám , Sztanó Orsolya , Matenco Liviu , Fodor László , Kovács András , Granjeon Didier , Gerya Taras
Published: March 2020

Extensive geophysical studies on gravity anomalies and seismic structure of the Pannonian Basin have determined that this extensional sedimentary basin is more elevated than predicted by Airy-type isostatic compensation models. European regional models assuming a two-layered lithosphere containing a uniform crust and a lithospheric mantle estimated ca. 750-1000 meters difference between the actual and calculated isostatic topography for the Pannonian region.

We have revisited this early finding and calculated a refined residual topography map of the Pannonian Basin that also takes into account the low-density sedimentary fill. We show that the actual residual topography of the eastern part of the region is much lower than previously thought and ca. 4-500 meters of positive residual topography characterizes the central and western part of the Pannonian Basin.

In order to interpret the observed residual topography of the basin we carried out a series of elasto-visco-plastic thermo-mechanical numerical models. Our simulation of the last 9Myr covering the classical  “post-rift” phase of the Pannonian Basin analyzes forcing factors, such as asthenospheric-scale mantle convection, elastic flexure of the lithosphere due to increased external stress and sediment re-distribution, and ductile lower crustal deformation. The large-scale positive residual topography is dominantly controlled by mantle dynamics.

Finally, 3D stratigraphic numerical forward modelling has been carried out by DionisosFlow, constrained by our previously calculated tectonic scenario. We analyzed the substantial reorganization of the main sedimentary transport routes in the Pannonian Basin mainly controlled by the development of the observed positive dynamic topography of the basin. Our preliminary model results are in good agreement with geological records, such as the ca. 200 km Pliocene eastward migration of the Paleo-Danube drainage network.
The next generation of IGS ROTI Maps: an extension toward global coverage
Authors: Krankowski Andrzej , Cherniak Iurii , Zakharenkova Irina , Fron Adam , Kotulak Kacper
Published: March 2020

The International GNSS Service (IGS) has accepted for official release a new ionospheric product for specification of ionospheric irregularities occurrence and intensity over the Northern Hemisphere as derived from multi-site ground-based GPS observations. Initially, we focused on the Northern Hemisphere auroral and midlatitude regions because of the highest concentration of the GNSS users and user supporting permanent networks located within the American, European, and Asian sectors. The IGS ROTI maps product is routinely generated by multi-step processing of carrier phase delays in dual-frequency GPS signals and transferred to the IGS CDDIS database. Now, ROTI maps allow regular monitoring of ionospheric irregularities over the Northern Hemisphere and provide information about past events when strong ionospheric irregularities developed here.

Obviously, the plasma irregularities that occur at high, middle, and low latitudes have different physical mechanisms of their origin and development. For study of the climatological features of ionospheric irregularities occurrence, investigation of the ionospheric responses for Space Weather drivers, processes derived from below, this actual ROTI Map product is required to cover low latitudes and the Southern hemisphere polar and midlatitudes.

During last decade, numerous ground-based permanent receivers were deployed within the global and regional networks and these observations are publicly available. These data can support our activity toward extending the current IGS ROTI maps product for a global coverage. In this paper, we present initial results of ROTI maps product performance to characterize ionospheric irregularities exited by different types of geophysical processes and space weather events. The next generation of the IGS ROTI maps product can be a valuable tool for global ionospheric irregularities monitoring and retrospective analysis of plasma irregularities impact on the GNSS positioning in the “worst case scenario” domain.

The research is supported by the National Science Centre, Poland, through grants 2017/25/B/ST10/00479 and 2017/27/B/ST10/02190 and the National Centre for Research and Development, Poland, through grant DWM/PL-CHN/97/2019

 

Keywords: GPS, ionosphere, ionospheric irregularities, ROTI, IGS
Analysis of Elves observations from about 2 years of ASIM operation.
Authors: Chanrion Olivier , Neubert Torsten , Zuccoti Chiara , Heumesser Matthias , Dimitriadou Krystallia , Gordillo Francisco J. , Perez-Invernon Francisco J. , Østgaard Nikolai , Mezentsev Andrey , Reglero Victor
Published: March 2020

The Atmosphere-Space Interaction (ASIM) mission was launched on April 2, 2018 and installed on an external platform of the Columbus Module of the International Space Station the 13th.

The main objectives of the mission are to observe and study thunderstorms and their interaction with the atmosphere. ASIM embarks two main instruments pointing at Nadir, the Modular Multispectral Imaging Array (MMIA) observing in the visible and the Modular X- and Gamma- ray Sensor (MXGS) observing in the X- and Gamma-ray bands.

In this presentation we focus on observations made by the MMIA which includes two cameras operating in the bands 337/5 nm and 777.4/3 nm and three photometers operating in the bands 180-230 nm, 337/5 nm and 777.4/5 nm. Specifically, we analyze the short duration pulses recorded in the 180-230 nm band.

After about 2 years of operations, more than 2500 of such events were identified in the data. They are likely to be recordings of ELVEs (Emissions of Light and Very low frequency perturbation due to Electromagnetic pulse sources), occurring in the ionosphere in response to lightning currents.

We show the amplitude, spatial and temporal distributions of the events and compare the results with those of previous studies. We present an analysis of the temporal characteristics of the pulses themselves and of their delays regarding the parent lightning observed in the other ASIM photometers or in the GLD360 ground lightning detection network recordings. Finally, we compare some typical events with modeling.
Emerging instability in global terrestrial water storage since 2010
Authors: Yi Shuang , Sneeuw Nico
Published: March 2020

Global terrestrial water storage (TWS) is an indicator of the integrated impact of climate variability on the environment. Accurate assessments of global TWS also facilitate the understanding of disturbances in global sea level rise. Gravity satellite GRACE has proved to be an effective tool in monitoring global TWS changes. With the latest observations of GRACE and GRACE Follow-on, we estimated the global TWS from April 2002 to October 2019, and found contrasting variations in global TWS before and after 2010. Before 2010, the global TWS was almost stable with variations that contribute only a few millimeters of sea level change; while the stability is ceased after the 2010/11 La Nina and three drastic fluctuations of up to 10 millimeters sea level contribution have occurred since then. We find these TWS changes have a good linear relationship with the global precipitation trend, rather than the accumulation of net precipitation, indicating that the precipitation trend is the main driving force of the recent global TWS instability. We further investigate the sensitivities of TWS to precipitation in basins.
Monitoring Mediterranean grass phenology from digital terrestrial camera and Sentinel-2 vegetation indices in an oak-grass savanna ecosystem
Authors: González-Dugo Maria P. , Gómez-Giraldez Pedro J. , Pérez-Palazón María J. , Polo María J.
Published: March 2020

Annual grasslands are an essential component of Mediterranean oak savannas, the most extensive agroforestry system in Europe, as the primary source of fodder for livestock and wildlife. Monitoring its phenology is key to adequately assess the impacts of global warming on different time scales and identify pre-critical states in the framework of early warning decision making systems. The natural variability of the climatic-hydrological regime in these areas and the usually complex spatial patterns of the vegetation, with sparse distribution and multiple layers, encourage the exploitation of available data from remote sensing sources. This work presents an assessment of vegetation indexes (VI) from Sentinel-2 validated against field data from terrestrial photography in an oak-grass system in southern Spain as a multi-approach method to monitor phenology in grass pastures. The analysis also has provided an insight into the links of the phenology dynamics with hydrological variables under these conditions.

From December 2017 to May 2019 a quantitative value of grassland greenness was computed using the Green Chromatic Coordinate (GCC) index. The phenological parameters of the start of the season (SOS), the peak of the season (POS) and end of the season (EOS) were extracted using the 50% amplitude method and confirmed using field photography. These values were compared with those provided by eight VI's derived from Sentinel-2 (NDVI, GNDVI, SAVI, EVI, EVI2, MTCI, IRECI and S2REP) and the difference in days between the key phenological dates were estimated. The results showed that for annual grasslands NDVI was the index providing estimations closest to those of ground GCC, with differences below 10 days for all phenological dates and the best correlation with GCC values (r = 0.83, p <0.001). None of the VIs using bands in the red-edge region have improved the NDVI results. Two of them, MTCI and S2REP, followed a different trend that the rest of explored indices, presenting a high temporal variability. The high diversity of species, typical of Mediterranean grasslands, might explain the high variability observed in these values. However, the third index using red-edge bands, IRECI, presented a high correlation with GCC. In this case, the index was designed to focus on the chlorophyll content of the canopy instead of the leaf scale addressed by S2REP. The influence of the vegetation ground coverage and foliage density is then higher and more similar to the broad-band indices. GNDVI also provided good general results. Soil moisture (SM) time-series were also used to estimate phenology and have presented a good agreement with GCC in SOS and EOS estimations, with SM reaching threshold values a few days before greenness ones, as measured by GCC. However, SM was not a good indicator of the POS, presenting significant biases with respect to GCC estimations.
OCRE: the game changer of Cloud and EO commercial services usage by the European research community
Authors: Delgado Blasco José Manuel , Romeo Antonio , Heyns David , Antoniou Natassa , Carrillo Rob
Published: March 2020

The OCRE project, a H2020 funded by the European Commission, aims to increase the usage of Cloud and EO services by the European research community by putting available EC funds 9,5M euro, aiming to removing the barriers regarding the service discovery and providing services free-at-the-point-of-the-user.

The OCRE project, after one year running, has completed the requirements gathering by the European research community and during Q1 2020 has launched the tenders for the Cloud and EO services.

In the first part of 2020, these tenders will be closed and companies will be awarded to offer the services for which requirements had been collected by the project during 2019. The selection of such services will be based on the requirements gathered during the activities carried out by OCRE in 2019, with online surveys, face2face events, interviews among others. Additionally, OCRE team members had participated in workshops and conferences with the scope of project promotion and increase the awareness of the possibilities offered by OCRE for both research and service providers community.

In 2020, consumption of the services will start, and OCRE will distribute vouchers for individual researchers and institutions via known research organisations, which will evaluate the incoming request and distribute funds from the European Commission regularly.

This presentation will provide an overview or the possibilities offered by OCRE to researchers interested in boosting their activities using commercial cloud services.
Conceiving a space for compassionate engagement with LGBT+ university lecturers around professional identity
Authors: Horswell Michael
Published: March 2020

Fear of harassment and physical violence (Patridge, Barthelemy and Rankin, 2014), experiences of discrimination, perceptions of a lack of support, lower job satisfaction (Cech and Pham 2017), feelings of isolation, and a need to work harder than colleagues to convince others of their competence (Yoder and Mattheis 2016) – these characterise the reported workplace experience of LGBT+ people in STEM disciplines in both academic and professional contexts.

Williams, Giuffre and Dellinger (2009) coin the term ‘the gay-friendly closet’ to reflect the experience of people who, despite being out in gay-friendly workplaces, report that they still downplay their homosexuality, or conform to stereotypes of how LGBT+ people are “expected to look, act and work” (p. 29).  Many of their respondents claimed their acceptance as ‘normal’ ran alongside their own invisibility (know-one-knows-I-am-gay narratives). Other respondents, felt their acceptance was contingent on their choice not to ‘overplay’ their homosexuality. Tensions exist between negotiating a professional identity while managing perceptions so they are situated within the bounds of acceptability (Rumens and Kerfoot 2009; Benozzo et al. 2015). Gay/lesbian respondents have suggested that acceptability in the workplace is contingent on self-censorship, selective revelation, and/or assimilative compromises, all of which legitimize heteronormative discourses around sexuality and professional identity. These issues are recognised as more significant within STEM disciplines – which is considered a stridently masculinist and heteronormative field (Bilimoria and Stewart 2009; Cech and Pham 2017).

In an educational context where LGBT+ students have the right to remain invisible, Toynton (2006) questions whether educators have the same right. Kumashiro (2015) suggests that educators may have an obligation, for fundamental educational reasons, to be ‘out’ to their learners. Toynton (2006) frames this as an element of the debate around ‘safe places’ for queer students, and suggests it sets up a dilemma for queer educators - trapping them between empathy and potential hostility – requiring a choice between an ‘enabling visibility’ and the risk of alienation.

The presentation will explore the links between critical educational praxis (focussed on Freire (1996), hooks (1994) and Britzman (1995)), queer theory (primarily Butler (1999) and Foucault (1990)), and anarchist methodologies and ethics (Deleuze and Guattari (1994) and Heckert (2016)). It will consider how this integration produces a space based on post-structural / post-human readings of sexuality and identity that enables transformative engagement, and commits to radical compassion as the primary ethos for research engagement.
Biogeochemical controls on the Black Sea oxygen dynamics : relevant diagnostics, key processes and adequacy of the monitoring infrastructure.
Authors: Capet Arthur , Luc vandenbulcke , Marilaure Grégoire
Published: March 2020

An important deoxygenation trend has been described in the Black Sea over the five past decades from in-situ observations [1]. While the implications for basin-scale biogeochemistry and possible future trends of this dynamics are unclear, it is important to consolidate our means to resolve the dynamics of the Black Sea oxygen content in order to assess the likelihood of future evolution scenario, and the possible morphology of low-oxygen events. 

Also, it is known that current global models simulate only about half the observed oceanic O2 loss and fail in reproducing its vertical distribution[2]. In parts, unexplained O2 losses could be attributed to illy parameterized biogeochemical processes within 3D models used to integrate those multi-elemental dynamics.

Biogeochemical processes involved in O2 dynamics are structured vertically and well separated in the stratified Black Sea. O2 sources proceed from air-sea fluxes and photosynthesis in the
photic zone. Organic matter (OM) is respired over a depth determined by its composition and
sinking, via succeeding redox reactions. Those intricate dynamics leave unknowns as regards the biogeochemical impacts of future deoxygenation on associated cycles, for instance on the oceanic carbon pump. Here we use the Black Sea scene to derive model-observation strategies to best address the global deoxygenation concern.

First, we decipher components of the O2 dynamics in the open basin, and discuss the way in which O2-based indicators informs on the relative importance of processes involved. Using 1D biogeochemical model set-up, we then conduct a sensitivity analysis to pin-point model parameters, ie. biogeochemical processes, that bears the largest part in the uncertainty of simulated results for those diagnostics. Finally, we identify among the most impacting parameters the ones that can most efficiently be constrained on the basis of modern observational infrastructure, and Bio-Argo in particular. 

The whole procedure aims at orienting the development of observations networks and data assimilation approaches in order to consolidate our means to anticipate the marine deoxygenation challenge. 

[1] Capet A et al., 2016, Biogeoscience, 13:1287-1297
[2] Oschlies A et al., 2018, Nature Geosci, 11(7):467–473
Vulnerability of subsea permafrost organic matter to degradation after thaw
Authors: Wild Birgit , Shakhova Natalia , Dudarev Oleg , Ruban Alexey , Kosmach Denis , Tumskoy Vladimir , Tesi Tommaso , Joß Hanna , Alexanderson Helena , Jakobsson Martin , Mazurov Alexey , Semiletov Igor , Gustafsson Örjan
Published: March 2020

Subsea permafrost contains a potentially large and vulnerable organic carbon pool that might be or become a source of greenhouse gases to the atmosphere. While organic carbon stocks and vulnerability of terrestrial permafrost are increasingly well constrained, the dynamics of subsea permafrost remain highly uncertain due to limited observational data from these hard-to-access systems. Based on a unique set of drill cores from the near-coastal Laptev Sea, we here assess the vulnerability of subsea permafrost organic matter to degradation after thaw. To that end, we combine biomarker analyses of organic matter above and below the in-situ thaw front with incubation of subsea permafrost material in the laboratory. Biomarker degradation proxies based on the lignin phenol composition of organic matter (acid/aldehyde ratios of syringyl and vanillyl phenols; 3,5-dihydroxybenzoic acid/vanillyl ratio) suggest an overall low degradation state of lignin compared to terrestrial permafrost deposits and marine sediments in the region, and no systematic change across the thaw front. These lignin-based proxies are mostly sensitive to degradation under oxic conditions, i.e. before organic matter burial in subsea permafrost deposits, and less to degradation under anoxic conditions that prevail at the thaw front of subsea permafrost. Lignin phenol proxies will therefore be complemented by other biomarker degradation proxies sensitive to degradation under anoxic conditions, as well as by first data from incubation of subsea permafrost material under cold, anoxic conditions. Together, these data will enhance our understanding of organic matter in subsea permafrost, its vulnerability to degradation after thaw and the potential for greenhouse gas emissions from this system.
Scaling Analysis of the Algal Blooms
Authors: Huang Yongxiang , Gao Yang , Xing Qianguo , Schmitt Francois , Hu Jianyu
Published: March 2020

Algal blooms, also known as ‘red tide’, are extremely harmful to the marine ecosystem since they infuse toxins into seawater and stifle oxygen in the water columns. Visually, they demonstrate rich patterns in spatial due to the interaction between the ocean current and the wind. Using the satelliate remote sensing data provided by the Chinese satellite Gaofeng 1, we first derive a normalized difference vegetation index (NDVI), which can be used to separate efficiently different types of cases, e.g., no algae bloom (NAB), macro algae bloom (MAB), and phytoplankton algae bloom (PAB), etc. The classical structure-function analysis is performed. Our preliminary results confirm the existence of the power-law behavior on the spatial scale range from 100 m to 400 m for the case of MAB. The corresponding scaling exponents are close to the ones of the classical passive scalar in three-dimension hydrodynamic turbulence. It suggests that the MAB could be treated as a passive scalar, which leads to not only a better understanding of the dynamics of algal blooms, but also a challenge of the modelling.