bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding atmospheric differences in the water vapor transport for the Atacama and Namib deserts
Authors: Vicencio José , Böhm Christoph , Löhnert Ulrich , Crewell Susanne
Published: March 2022

The Atacama and Namib Deserts are one of the driest places in the world. They are both located west coast of their respective continents (18-28ºS), under the effects of the east margin of the subtropical anticyclones, strong subsidence and cold ocean currents. However, they also differ in terms of topography, precipitation, and humidity, being the Atacama much higher and drier than the Namib. Our understanding of how water vapor is brought to these regions and interacts with the different local circulations and topography is still limited. The objective of this study is to investigate similarities and differences of the spatio-temporal variability of water vapor between both deserts in order to assess the impact of the distinctive local factors. To this end, we use state-of-the-art satellite observations and reanalysis for a long-term perspective on total column water vapor (TCWV) as well as on the vertical distribution of humidity, temperature and on cloud structure. The analysis is aided by a one-year measurement campaign at Iquique airport (22ºS).

We found a marked seasonal cycle in the total column water vapor (TCWV) in both offshore deserts areas. While both deserts share a similar timing of the annual TCWV peak between January and March, the values of the maxima differ. The Namib surpasses the Atacama by 30%. Our analysis suggests that at least two factors contribute to the common summer maxima of the TCWV. First, warmer sea surface temperatures (SSTs) along the west coasts produce a moistening of the marine boundary layer (MBL). Second, as a consequence of the southward displacement of the subtropical anticyclones, weaker southerly winds decrease the dry advection in the MBL. The excess of humidity in the Namib is associated with a strong moisture advection feature observed in the lower part of the free-troposphere (900-750 hPa). The easterlies also transport clouds and precipitation. In the Atacama, the presence of the Andes cordillera blocks most of the potential exchange of humidity with the continent, resulting in the Pacific Ocean being the main source of moisture.

While the respective driest period presents similar TCWV amounts (~12 Kg/m2) for both deserts, it is surprising to find that it occurs later in the Atacama (spring season) than in the Namib (winter). Potential causes for this shift, such as a stronger dependence of TCWV on the SST for the Atacama, are investigated and discussed.

Furthermore, we identified a recurring atmospheric feature for the summer which exhibits a strong northerly humidity advection above the MBL. This structure is only observed in the Atacama Desert and has not been described in the literature. However, it could be a major source of humidity for the inland region in Atacama.
Three-dimensional Hybrid-Vlasov Simulations of Geomagnetic Storms
Authors: Horaites Konstantinos , Alho Markku , Battarbee Markus , Dubart Maxime , Ganse Urs , George Harriet , Grandin Maxime , Manglayev Talgat , Palmroth Minna , Papadakis Konstantinos , Suni Jonas , Tarvus Vertti , Turc Lucile , Zaitsev Ivan , Zhou Hongyang
Published: March 2022

Vlasiator (https://www2.helsinki.fi/en/researchgroups/vlasiator) is a high-performance kinetic code that is now conducting the first ever 3D hybrid-Vlasov simulations of the global magnetospheric system. In recent months, the driving conditions of these simulations have been scaled up to emulate intense space weather events. Specifically, we have investigated the impact of a pressure pulse with southward-oriented Bz on the Earth's magnetosphere. Our simulations reproduce many known effects, for example the expansion of the auroral oval, compression of the magnetopause, the development of field-aligned currents, and enhanced particle precipitation near the open/closed field line boundary. We compare our data with spacecraft observations of real events that exhibit similar parameters to those imposed in the simulation. Our analysis shows that the hybrid-Vlasov approach captures many of the important aspects of the magnetospheric response to an incoming pressure pulse. With sufficient validation of our simulations by comparison with moderate storms, we aim to show that Vlasiator can be used as a tool to study even the most extreme events and their potential impacts on Earth's critical infrastructure.
Spatial correlations and slicing mechanisms during subduction of the Liguro-Piemont ocean (Western Alps)
Authors: Herviou Clément , Agard Philippe , Plunder Alexis , Mendes Kevin , Verlaguet Anne , Deldicque Damien , Cubas Nadaya
Published: March 2022

Fragments of subducted slow-spreading oceanic lithosphere are exposed continuously in the Liguro-Piemont domain of the Western Alps. By combining new and literature petrological data, interpolated maps of maximum temperatures, maximum Si contents of phengite as a proxy for peak pressure and thermodynamic modelling, we provide a detailed framework of the peak metamorphic conditions experienced by the distinct subduction slices. High-resolution mapping confirms the marked eastward increase in metamorphic grade throughout the domain, as well as within some slices. The compilation of lithostratigraphic, structural and radiochronological data and the estimation of sediment/mafic-ultramafic ratio for each slice allow refining the origin of these tectonometamorphic units within the former oceanic domain. The refined structural sketchmap allows to restore the geometries of the Alpine subduction at peak burial conditions. Results point to a trimodal distribution of the units with an increase in metamorphic conditions from the Upper (LPU; 320-400°C- 1.2-1.9 GPa) to the Middle (LPM; 415-475°C- 1.7-2.2 GPa) and to the Lower units (LPL; 500-580°C- 2.2-2.8 GPa). The blueschist-facies LPU and LPM units are dominated by sediments (>90%), whereas the eclogitic LPL units are far richer in mafic-ultramafic rocks (>40%). These characteristics, along with lithostratigraphic differences, reflect major differences in their initial paleogeography and/or in the mechanisms responsible for material offscraping from the downgoing slab. The peak burial depths of the LPU, LPM and LPL units are similar to those inferred for slicing and underplating in both modern and fossil subduction zones. Petrological and lithostratigraphic data suggest that the offscraping of the LPU and LPM units was mostly controlled by lithological contrasts, within pelagic shales or along contacts with the serpentinized mantle. In contrast, major dehydration reactions (such as lawsonite breakdown in sediments) likely controlled the offscraping of the LPL units at eclogite-facies conditions, possibly through high fluid pressure conditions and rocks embrittlement.
Changes in the discharge regime of a major spring in the Northern Apennines over a century (1920-2020): a comparison between ancient and recent monitoring surveys in relation to climate change
Authors: Gargini Alessandro , Filippini Maria , Grazzini Federico , Segadelli Stefano
Published: March 2022

It is scientifically established that global warming induced by greenhouse gases, affecting the surface energy budget, can significantly alter the Earth's water cycle, with consequent modification of precipitation typology and regime. However, the net effects of these changes on the process of groundwater discharge are still uncertain at local scale. The lack of historical series of monitoring data, dating back to at least 60-100 years ago, is among the main drawbacks, with the rare exception of major karst springs exploited for public water supply. In hard rock aquifers, like those dominant in the Northern Apennines, the dynamic of spring outflow during the first half of the XX century is an absolute black-box. For this reason, it appeared noteworthy to analyze detailed monthly-based monitoring data, over the 1915-1920 time span, of the whole discharge of the Nadìa spring, one of the most productive spring in the Emilia-Romagna region, in low flow season, among those used for drinking water. Such data were reported in a century-old study functional to the drilling of a draining tunnel for water uptake. We present a comparison between the monthly regime of the spring discharge 100 years ago and a continuous monitoring performed by the authors during the 2020/2021 hydrological year, integrated with the total water uptaken in years 2018-2020. Nadìa spring discharges from an arenitic fractured aquifer deposited in a neritic setting above mainly clayey units acting as a permeability threshold. The abundance of calcite in the grains and cement of the arenite enhances corrosion and enlargement of fractures. In 2018-2021 the spring discharge range has been 80-50 L/s whereas in 1915-1920 it was 140-63 L/s. The two (ancient and recent) sets of data were compared with a focus on the evolution of precipitation, snow-fall and thermal regime.
Heat events in the Indian subcontinent under a warming climate scenario: Detection and Implications on human health
Authors: Kapoor Ritika , Alvarez-Castro Carmen , Heaviside Clare , Scoccimarro Enrico , Materia Stefano , Gualdo Silvio
Published: March 2022

Global temperatures have shown a warming trend over the last century, mainly as a result of anthropogenic activities. Rising temperatures are a potential cause for increase of extreme climate events, such as heat waves, both in severity and frequency. Under an increasing extreme event scenario, the world population of mid- and low-latitude countries is more vulnerable to heat related mortality and morbidity. In India, the events occurred in recent years have made this vulnerability clear, since the numbers of heat related deaths are on a rise.

Over India, the heat waves occur during the months of April to June and can impact various sectors including health, agriculture, ecosystems and the national economy. In May 2015, a severe heat wave due to the delayed onset of southwest monsoon affected parts of south-eastern India, which claimed more than 2500 lives. Preliminary results show the prevalence of Heat events in six different regions of India during the pre-monsoon (March, April, May) and transitional (May, June, July) months.

We consider daily maximum temperatures and NOAA’s Heat Index (HI), a combination of temperature and relative humidity (also known as apparent temperature) which gives an insight into the discomfort because of increment in humidity. It is important to take HI along with temperature anomalies, since humidity also plays a role in transitional period.

Heatwaves over India are known to be linked with mortality and have indirect impacts on human health. To evaluate the heat related risk of mortality on Indian population, indicators and clusters of heat events were computed by taking into account population weighted temperature exposure.
The DEEP Project: Innovation for De-Risking Enhanced Geothermal Energy Projects
Authors: Lanza Federica , Wiemer Stefan ,   DEEP team
Published: March 2022

The Swiss Energy Strategy 2050 anticipates that by 2050 up to ~7% of the future energy production will come from deep geothermal energy. Likewise, many other countries worldwide are investigating the potential of harnessing deep geothermal energy as a renewable solution. However, seismic risk reduction and reservoir efficiency is the current major coupled problem faced by Enhanced Geothermal System (EGS) reservoirs. Balancing risk and economic output is a key requirement in all EGS projects. The DEEP (Innovation for De-risking Enhanced geothermal Energy Projects) project is an international collaboration whose research-goal is to establish a full-scale protocol for real-time monitoring and risk analysis of potential seismicity triggered by EGS operations. To this end, the project will employ innovative seismic sensors, improved event-cataloguing techniques, fully probabilistic data-driven seismicity forecasts, and loss assessment strategies. In DEEP we plan to apply the so-called Adaptive Traffic Light System (ATLS) where forecasts are continuously updated with real-time data-feeds, providing an integrated and dynamic assessment of the seismic risk to the operators. Field test sites include the Frontier Observatory for Research in Geothermal Energy (FORGE) in Utah (USA), as well as at EGS sites in Germany and France. Parallel to the technology development, the project aims also at defining the next-generation good-practice guidelines and risk assessment procedures in order to reduce commercial costs and enhance the safety of future projects. Here, we will present an overview of the DEEP project to provide a framework for other DEEP presentations. We will also showcase a selection of results from new event detection and location algorithms based on machine learning and using Distributed Acoustic Sensing (DAS), as well as the results from a pilot test of the ATLS workflow for seismicity forecast models for the upcoming FORGE stimulation strategy.
Future changes of average and extreme rainfall for the Bologna region
Authors: Guo Rui , Montanari Alberto
Published: March 2022

Simulation of daily rainfall for the region of Bologna produced by 13 climate models for the period 1850 - 2100 are considered. Data are compared with the historical series of daily rainfall observed in Bologna for the period 1850 - 2014. In particular, we focus on annual rainfall data, seasonality and extremes to derive information on the future development of water resources availability and flood risk. The results prove that rainfall seasonality is fairly well simulated by models, while the historical sequence of annual rainfall is not satisfactorily reproduced. Future projections for different emission scenarios allow to assess the impact of climate change on cumulative rainfall and extremes, therefore outlining important technical indications.
On the relation between the coefficient of friction of a fault and the variation of damage degree on the host rock: a numerical approach
Authors: Manna Ludovico , Dabrowski Marcin , Maino Matteo , Casini Leonardo , Reali Alessandro , Toscani Giovanni
Published: March 2022

We present a study on the dependence of the frictional properties of a fault rock on its degree of damage. The purpose is therefore to gain insight into frictional sliding, the governing force that controls earthquake nucleation, propagation and arrest. The focus on this topic is to try to find a reason for the experimental evidence that the friction coefficient seems to be almost independent on lithology. A possible explanation to investigate through the numerical modelling could be that the frictional properties of a realistic fault rock depend mostly on the concentration of micro- to macroscopic cracks and/or of lamellar phyllosilicates in the host rock, rather than on the composition of its bulk materials. The formalism of the Linear Elastic Fracture Mechanics (LEFM) can quantitatively reproduce the stresses and the strains on the interface propagating frictional rupture. The purpose is to use a Finite Element Method (FEM) numerical code in order to simulate the plane strain elastic deformation of a two-dimensional medium crossed by elliptical fractures and weak anisotropic inclusions. The analysis of the distribution and orientation of the stresses resulting from the interaction of a system of randomly oriented elliptical fractures under different loading conditions could provide information on the onset and propagation of frictional ruptures, such as real contact area reduction, slip velocity, number and length of global sliding precursors. The magnitude and orientation of the principal stresses around the tips of elliptical voids are crucial for the understanding of fracture coalescence and frictional reactivation of shear cracks in an elastic rock, which in turn is one of the main factors that govern the seismic cycle of natural faults. 
Modelling the Fenton reaction of amphibole asbestos
Authors: Tomatis Maura , Turci Francesco , Petriglieri Jasmine Rita , Campopiano Antonella , Cannizzaro Annapaola , Ballirano Paolo , Fantauzzi Marzia , Rossi Antonella , Bloise Andrea , Montereali Maria Rita , Nardi Elisa , Pacella Alessandro
Published: March 2022

In this work a sample of UICC crocidolite and a sample of fibrous tremolite were leached up to 1 week both in a simplified Gamble’s solution at acidic pH and in a phosphate buffered medium at neutral pH, in presence of H2O2. Surface chemical modifications were monitored by XPS spectroscopy. Subsequently, the generation of HO• radicals following reaction of both pristine and leached fibres with H2O2 (Fenton reaction) was investigated by spin trapping/EPR spectroscopy, with the aim of better clarifying the relationships between possible surface alteration occurring in vivo and chemical reactivity of amphibole asbestos. Moreover, the generation of HO• radicals was monitored on thermally treated fibres after leaching in phosphate buffered medium at neutral pH and in presence of H2O2 to investigate how chemical reactivity may be modulated by Fe oxidation state.

Results showed that, for both amphibole asbestos, the surface alteration following incubation in the modified Gamble’s solution does not alter HO• radical generation. Interestingly, leaching in phosphate buffered solution in presence of H2O2 induced a progressive increase in HO• release for crocidolite fibres, whereas a strong reduction was observed for asbestos tremolite. This behaviour is likely due to the quicker alteration of the crocidolite surface due to the interaction with H2O2, as indicated by XPS analysis. In particular, the oxidation induced by H2O2 promotes the dissolution of the first atomic layer of the crocidolite structure and the following occurrence on its surface of new reactive Fe centres, particularly under the form of Fe(II), of which the bulk is richer than the oxidized surface. Accordingly, the heated samples showed a reduced, but not suppressed by thermal oxidation, chemical reactivity, with no significant evolution following incubation in phosphate buffered medium at neutral pH and in presence of H2O2.
Improving understanding of nitrate sources in connected river and groundwater systems through linking nitrate isotopes and contaminants of emerging concern
Authors: Vystavna Yuliya , Soto David , Miller Jodie
Published: March 2022

Increased nutrient levels in aquatic systems can trigger issues such as eutrophication, water quality degradation, and algal blooms that have negative environmental and economic impacts. Nitrate contamination makes water unconsumable hence, reducing access to drinking water - a key factor of well-being as recognized in the UN Sustainable Development Goals. Nitrate source identification remains challenging using hydrochemical measurements, but the analysis of stable isotopes in nitrate (δ15N and δ18O) opened the possibility to track sources and processes. The efficiency of this isotopic approach lay in simple and precise field and analytical methods, with low cost and easy sample preparation. Despite the potential and usefulness, nitrate isotopes on their own cannot differentiate closely related sources of nitrate contamination with overlapping isotopic signatures, such as sewage (human sources) and manure (agricultural sources), as well as treated versus raw sewage inputs from the catchment. One solution is to combine isotopic techniques with analysis of compounds of emerging concern (CECs). Some CECs are ideal chemical markers of faecal contamination (sewage or manure) as they are usually linked to a specific source. They are ubiquitous in that source and are persistent and present at detectable concentrations in contaminated environmental samples. Their high solubility in water and low volatility facilitates their use as tracers for components originating in sewage and manure. Our study is focused on the innovative approach of combining stable isotopes with CECs in surface and groundwater to improve nitrogen source tracking and source delineation, and more precise quantification of groundwater/surface water interaction. As a proof of concept, we have combined stable isotopes of nitrate with CECs in surface water (large European river) and groundwater (shallow aquifer) case studies. Preliminary results provide a unique and versatile framework for expanding the use of isotopic techniques to tracing nitrate pollution sources and assessing water quality in the catchments worldwide.
Challenges in Storm Resolving Models: Biases and consistency in the representation of tropical precipitation in the coupled ICON model
Authors: Segura Hans , Hohenegger Cathy , Wengel Christian , Steven Bjorn
Published: March 2022

State-of-the-art Global circulation models (GCMs) are characterized by the use of parameterization of convection and low spatial resolution, resulting in persistent biases in the representation of tropical precipitation. Now, Storm Resolving Models (SRM), a new generation of global climates models which, due to their high spatial resolution (<10 km) do not rely on a convective parameterization, may allow bypass some of these well-known precipitation biases. In this study, we present results of coupled SRM simulations conducted with the ICON model and integrated on seasonal time scales (SRM-ICON). We consider three different versions of the model (SRM-ICON16, SRM-ICON29, SRM-ICON52). From SRM-ICON16 to SRM-ICON29, the scheme of the vertical mixing was changed (from TEE to Smagorinsky), along with its vertical length. In addition, a problem in the ocean-atmosphere coupling regarding momentum transfer was fixed. SRM-ICON52 differs from SRM-ICON29 in the vertical coordinates in the ocean (different discretization), land initialization, and a bug in the sensible heat flux calculation was solved. Using these three versions of SRM-ICON, we aim to understand which aspects of tropical precipitation are robust, even to model bugs, and are directly improved just by using an explicit representation of convection. We find that precipitation over land is well reproduced compared to observations and robust across the three versions.  Monsoon areas in the longest run of SRM-ICON are well represented when compared with GPM for the year 2020. Moreover, the meridional pattern of precipitation during the wet season of the North American, the South African, and the Australian monsoon systems, as well as the Maritime Continent in SRM-ICON, show similar characteristics to the observed in GPM. Also, the diurnal cycle of precipitation over land and ocean can be reproduced by SRM-ICON and is robust among the three versions. In contrast, the ITCZ structure over the ocean is highly sensitive to the model version and not necessarily improved compared to low-resolution simulation. Finally, we verified that changes in total tropical precipitation amounts among the three versions of SRM-ICON are consistent with differences in atmospheric radiative cooling, and can be mainly explained by the net longwave flux divergence. 
Sustainability issues of a Mediterranean semiarid irrigated piedmont inferred frommulti-decadal trends of water resources and land use
Authors: Ouassanouan Youness , Fakir Younes , Simonneaux Vincent , Kharrou Mohamed Hakim , Bouimouass Houssne , Chehbouni Abdelghani
Published: March 2022

Piedmonts around the Mediterranean are important hydro-agro-systems bridging between the mountains (upstream) where streamflow is generated, and the adjacent plains (downstream) where water is used. In Morocco, the piedmonts of the High-Atlas Mountains host secular irrigation channels (seguia) that divert the streamflow for irrigating a traditional agriculture since hundreds of years. These traditional hydro-agro-systems might be threatened by the effects of global change that requires in-depth study to identify the main causes and propose better sustainable management. The present study was carried out in the semi-arid piedmont of the High-Atlas mountains. A detailed analysis of hydro-climatological data was performed between 1965 and 2018 together with associated agricultural trends over the period 1984-2020. Statistical tests (Mann-Kendall and Pettitt) were used to assess whether there were significant trends or not in the long-term evolution of water resources. The findings revealed a significant decrease of the surface water and groundwater resource. The SPI meteorological drought index delineated three main droughts during 1982-1986, 1998-2008 and 2013-2017. Paradoxically, the scarcity and decrease trends in water resources are associated with an agricultural change from seasonal crops (cereals) to perennial crops (trees). The subsequent growing agricultural water demand exacerbates the water shortage and worsen the groundwater depletion.
Climate change impacts on Alpine hydropower in the context of environmental impacts and technical constraints
Authors: Wechsler Tobias , Hug Peter Dorothea , Zappa Massimiliano , Schaefli Bettina
Published: March 2022

Hydropower production affects different stakeholders, levels of administration and ecosystems, which makes the question of its sustainability complex. Hydropower delivers energy, storage capacity, jobs, economic value, but also involves altered streamflow, water temperature and sediment transport conditions, fractioning of aquatic habitats and modification of the landscape. Thus, an increasing demand for renewable and climate friendly energy from hydropower also results in more pressure on aquatic habitats, thereby potentially calling into question its sustainability.

In this work, we compare climate change impacts on the future energy production of 21 hydropower plants in Switzerland, to impacts related to environmental flow requirements and to site-specific technical optimisation potential. The simulation-based study corresponds to three future periods (2020–2049, 2045–2074 and 2070–2099) under three emission scenarios (RCP2.6, RCP4.5, RCP8.5), assuming unchanged environmental flow requirements and installed machinery. The results show an increase of winter production and a decrease of summer production, which in conjunction leads to an annual decrease. The simulated impacts strongly depend on the elevation and the plant-specific characteristics. The climate induced changes in production are of a similar order of magnitude as the production loss due to environmental flow requirements and the increase potential due to technical optimisations. A key result is that the climate induced reduction is not linearly related to the underlying streamflow reduction, but is modulated by environmental flow requirements, the design discharge and streamflow projections. Taken a step further, a change in production does not necessarily mean a linear change in financial revenue. The Water-Energy Nexus in terms of hydropower concerns more than just a m3s-1–kWh relationship: it is part of a complex framework that is namely sensitive to legal adjustments and to long lasting technical decisions taken in the past.
Combining POLDER-3 satellite observations and WRF-Chem numerical simulations to derive biomass burning aerosol properties over the southeast Atlantic region
Authors: Siméon Alexandre , Waquet Fabien , Péré Jean-Christophe , Ducos Fabrice , Thieuleux François , Peers Fanny , Turquety Solène , Chiapello Isabelle
Published: March 2022

Aerosol absorption is a key property to assess the radiative impacts of aerosols on climate at both global and regional scales. The aerosol physico-chemical and optical properties remain not sufficiently constrained in climate models, with difficulties to properly represent both the aerosol load and their absorption properties in clear and cloudy scenes, especially for absorbing biomass burning aerosols (BBA). In this study we focus on biomass burning (BB) particle plumes transported above clouds over the southeast Atlantic (SEA) region off the southwest coast of Africa, in order to improve the representation of their physico-chemical and absorption properties. The methodology is based on aerosol regional numerical simulations from the WRF-Chem coupled meteorology–chemistry model combined with a detailed inventory of BB emissions and various sets of innovative aerosol remote sensing observations, both in clear and cloudy skies from the POLDER-3/PARASOL space sensor. Current literature indicates that some organic aerosol compounds (OC), called brown carbon (BrOC), primarily emitted by biomass combustion absorb the ultraviolet-blue radiation more efficiently than pure black carbon (BC). We exploit this specificity by comparing the spectral dependence of the aerosol single scattering albedo (SSA) derived from the POLDER-3 satellite observations in the 443-1020 nm wavelength range with the SSA simulated for different proportions of BC, OC and BrOC at the source level, considering the homogeneous internal mixing state of particles. These numerical simulation experiments are based on two main constraints: maintaining a realistic aerosol optical depth both in clear and above cloudy scenes and a realistic BC-to-OC mass ratio. Modelling experiments are presented and discussed to link the chemical composition with the absorption properties of BBA and to provide estimates of the relative proportions of black, organic and brown carbon in the African BBA plumes transported over the SEA region for July 2008. The absorbing fraction of organic aerosols in the BBA plumes, i.e., BrOC, is estimated at 2 % to 3 %. The simulated mean SSA are 0.81 (565 nm) and 0.84 (550 nm) in clear and above cloudy scenes, respectively, in good agreement with those retrieved by POLDER-3 (0.85±0.05) at 565 nm in clear sky and at 550 nm above clouds) for the studied period.
floodGAN – A deep learning-based model for rapid urban flood forecasting
Authors: Hofmann Julian , Schüttrumpf Holger
Published: March 2022

Recent urban flood events revealed how severe and fast the impacts of heavy rainfall can be. Pluvial floods pose an increasing risk to communities worldwide due to ongoing urbanization and changes in climate patterns. Still, pluvial flood warnings are limited to meteorological forecasts or water level monitoring which are insufficient to warn people against the local and terrain-specific flood risks. Therefore, rapid flood models are essential to implement effective and robust early warning systems to mitigate the risk of pluvial flooding. Although hydrodynamic (HD) models are state-of-the-art for simulation pluvial flood hazards, the required computation times are too long for real-time applications.

In order to overcome the computation time bottleneck of HD models, the deep learning model floodGAN has been developed. FloodGAN combines two adversarial Convolutional Neural Networks (CNN) that are trained on high-resolution rainfall-flood data generated from rainfall generators and HD models. FloodGAN translates the flood forecasting problem into an image-to-image translation task whereby the model learns the non-linear spatial relationships of rainfall and hydraulic data. Thus, it directly translates spatially distributed rainfall forecasts into detailed hazard maps within seconds. Next to the inundation depth, the model can predict the velocities and time periods of hydraulic peaks of an upcoming rainfall event. Due to its image-translation approach, the floodGAN model can be applied for large areas and can be run on standard computer systems, fulfilling the tasks of fast and practical flood warning systems.

To evaluate the accuracy and generalization capabilities of the floodGAN model, numerous performance tests were performed using synthetic rainfall events as well as a past heavy rainfall event of 2018. Therefore, the city of Aachen was used as a case study. Performance tests demonstrated a speedup factor of 106 compared to HD models while maintaining high model quality and accuracy and good generalization capabilities for highly variable rainfall events. Improvements can be obtained by integrating recurrent neural network architectures and training with temporal rainfall series to forecast the dynamics of the flooding processes.
Swarm Fast Track spherical harmonic model of the external magnetic field to degree and order 3
Authors: Gomez Perez Natalia , Beggan Ciaran
Published: March 2022

The development of satellite measurements over the past four decades has allowed us to understand the magnetic field in the Earth environment at higher temporal and spatial resolution than before. This is most evident for satellite ensembles such as ESA’s Swarm constellation which allows simultaneous global coverage with three independent satellites.

Thanks to Swarm’s particular configuration, we can take advantage of the Local Time sampling difference between Swarm A/C and Swarm B in order to estimate the low degree variation of the external magnetic field in latitude and longitude. We separate the external and induced fields measured at satellite altitude, and obtain the spherical harmonic decomposition of each source to degree and order 3 twice per day. However, there is a trade-off between spatial and temporal resolution and clear disadvantages occur when the measured field varies rapidly during a geomagnetic storm, since the method used will result in coefficients of the averaged field over the chosen time interval rather than the peaks.

We compare our results with previous models of the external field during the St Patrick storm 2015, which used up to four different local time simultaneous coverage, as well as during quiet times and lesser storms using our own solutions. We find good agreement in each case.

In this talk we will describe the algorithm and methodology used and show results over the lifetime of the Swarm mission to date (2013-). A new daily product for the Swarm mission (MMA_SHA_2E) is being developed.
Comparison between Atmospheric Boundary Layer Height remote sensing-retrievals over a complex topography
Authors: Burgos Cuevas Andrea , Magaldi Hermosillo Adolfo , Adams David , Grutter de la Mora Michel , Garcia Franco Jorge L. , Ruiz Angulo Angel
Published: March 2022

The Atmospheric Boundary Layer (ABL) height is a key parameter in air quality research as well as in order to parametrize numerical simulations and forecasts. The identification of thermally stable layers has been one of the most common approaches in order to estimate this height. However, radiosonde's coarse temporal resolution is not enough to investigate the diurnal cycle of the ABL. Remote sensing has overcome this problem with a high temporal resolution. The backscatter retrieved by ceilometers elucidates the height that aerosols are able to reach and therefore has been used to estimate ABL height. Additionally, the implementation of Doppler lidars, and the velocity profiling provided by them, makes possible to investigate ABL via turbulence variables. However, different retrievals of ABL height are not usually coincident with each other and this issue becomes more evident over topographically complex terrain, such as Mexico City. It has been previously shown that the aerosol layer and the convective boundary layer height are generally not coincident over mountainous terrains. In this presentation we show that, at daytime hours, the convective boundary layer height (retrieved with Doppler lidar data) is lower than the aerosol layer height (retrieved with ceilometer data) during one year over Mexico City. Diurnal and monthly variabilities are discussed and the remote sensing-retrieved heights are compared with thermally stable layers estimated from radiosonde data. We show that multiple thermally stable layers develop, the upper ones are similar to the ceilometer retrieved heights and the lower ones are approximately as high as the Doppler lidar ones. Finally, the influence of radiation and precipitation over the retrieved heights is discussed over the year. The present research illustrates how the comparison between ceilometer backscatter and Doppler lidar ABL height retrievals can contribute to investigate the complexity of the ABL height over the mountainous terrain of Mexico City.

 
Modeling principal stress orientations in the Arabian plate using plate velocities
Authors: Pena Clavijo Santiago , Finkbeiner Thomas , Afifi Abdulkader M.
Published: March 2022

The Arabian Peninsula is part of a small tectonic plate that is characterized by active and appreciable deformations along its boundaries. Knowledge of the present-day in situ stress field in the Arabian plate and its variability is critical for earth science disciplines that require an understanding of geodynamic processes. In addition, it is essential for a range of practical applications that include the production of hydrocarbons and geothermal energy, mine safety, seismic hazard assessment, underground storage of CO2, and more.

This project aims at modeling the stress orientation field in the Arabian Plate using advanced computational tools together with a plate velocity model. We built a three-layer 3D model of the Arabian crust using digital elevation, basement depth, and Moho depth maps. Based on these data, we built a 3D unstructured finite element mesh for the whole Arabian plate, including the offshore area, with finer resolution at critical locations. The latter is a novel approach to this work.  To capture the deformation caused by the water bodies in the Red Sea, Gulf of Aden, and the Arabian Sea areas, we set a hydrostatic boundary condition as a function of bathymetry. Along the Zagros fold and thrust belt, we pinned the plate boundary to capture continental collision. Finally, the partial differential equation of force equilibrium (a linear static analysis) is solved using plate displacements (inferred from plate velocities) as boundary conditions for several displacement conditions.

The modeling results suggest NE-SW SHmax azimuths in northeastern Saudi Arabia and Kuwait while the Dead Sea transform areas show NW-SE to NNW-SSE azimuths, and the rest of the plate is characterized by predominant N-S SHmax azimuth. Due to pinned boundary conditions at the Zagros Mountains, SHmax azimuth changes from N-S at the Red Sea basin to NE-SW at the Zagros fold and thrust belt. We also notice significant stress concentrations in the transition from the Arabian shield to the sedimentary basins in the Eastern parts of the plate. This is in response to associated changes in rock properties. Hence, the simulated stress orientations corroborate the ongoing tectonic process and deepen our understanding of regional and local in situ stress variation drivers as well as the current elastic deformation in the Arabian plate.
What are the Maximally Possible Deviations from the Carbon Budget Approach?
Authors: Avakumović Vito , Brovkin Victor , Held Hermann
Published: March 2022

The carbon budget concept (TCRE; Transient Climate Response to cumulative carbon Emissions) emerged as a major concept in climate research since the late 2000s. Due to its simplicity, it is intensively utilized in the international policy arena. It is based on the claim that one can derive the global mean temperature increase solely from the knowledge of historical cumulative emissions by observing the linear relationship between the two, regardless of the emission pathway that preceded ('pathway independence').

Here, we ask for the maximally possible deviations from the TCRE ideal across emission scenario space. While there has been an extensive focus on quantifying the carbon budget using highly complex climate models, there seems to be a lesser focus on the pathway independence and possibly related deviations from the budget. Furthermore, few analytical examinations have been presented, for highly stylized settings only. This study contributes to filling that gap, utilizing the energy balance model FAIR. FAIR incorporates climate feedbacks and correctly emulates the temperature response to an emission pulse.

If the carbon budget approach was perfectly valid, the temperature response to an emitted unit of carbon should be a perfect step function. The actual temperature evolution following the emission pulse is reinterpreted as a Green's function and as such, utilized to calculate the total temperature increase at any given point. The novelty in this work is that the emission pathway is not assumed, but generated by maximizing (minimizing) the temperature output.

With the boundary conditions being the fixed total cumulative emissions and the maximal allowed mitigation efforts, two associated pathways are generated with the temperature increase in a given year acting as an objective value. The deviation from the budget is then extracted as a temperature difference between the upper and the lower bound of the optimization process. The results show that the absolute value of the deviation is less than the standard deviation of climate variability, confirming the fundamentals of the carbon budget approach. We also present an analytical upper bound of the deviation from path independence. The result shows that the deviation is a function of the allowed maximum emission slope.

The advantage of this method is that it can utilize the impulse response properties already published for highly complex models. The current limitation of the presented approach lies in the assumption that the pulse response is assumed constant even though the climate changes. The implications of a changing pulse remain to be explored. We see our work as a twofold contribution: (i) to predict maximally possible TCRE deviations from already published impulse response experiments, and (ii), to generate analytic understanding for the driving variables.
The effect of climate change on viniculture in the Western Cape of South Africa
Authors: Chauke Helga , Pongrácz Rita
Published: March 2022

There are many studies on global climate change, however, there is limited information on regional climate change and its effect on South Africa. This limits abilities to develop effective mitigation and adaptation strategies. It was projected that in the case of a global average temperature increase of 2 °C under optimistic conditions, South Africa was identified as one of the most vulnerable countries, and it was predicted that it will experience approximately 4 °C increase along the coast, and 7 °C in the interior by 2100.

The majority of viniculture is practiced in the Western Cape within South Africa, where the Mediterranean climate conditions resemble to the European Mediterranean regions (except the hemispherical differences). This area receives more rain than the inland regions, which makes it optimal for grape production. However, this region recently experienced an 18-month-long drought that threatened water resources and greatly affected agriculture.

For the present study, historic and future scenario simulation data were downloaded from the ESGF server of the CORDEX program, 10 and 9 simulations are available with 0.22° horizontal resolution for the RCP 8.5 and RCP 2.6, respectively. The reference period for this study is the 1981-2000 period, in addition, three different scenario periods are analysed: the near future (2021-2040), the mid-century (2041-2060), and the end of the century (2079-2098). Climate change maps project an increase (>100%) in precipitation at the end of the century under the pessimistic conditions, and an increase of 3 °C in the Western Cape region. However, some of the model simulations project these increases.

Such an increase in temperature will result in prolonged droughts and more frequent heat waves, thus resulting in alterations of ecosystem structures.Increased precipitation variability poses uncertainties for vine farmers, approximately 10,000 hectares of grapevine area has been lost in the past decade and more area could be lost due to climate change.The future of viniculture depends on the application of efficient mitigation and adaptation strategies against the fast changing climate.
Sequence of events at high resolution during deglaciations over the last 800ka from the EDC ice core
Authors: Grisart Antoine , Landais Amaelle , Stenni Barbara , Crotti Ilaria , Legrain Etienne , Masson-Delmotte Valérie , Jouzel Jean , Prié Fredéric , Jacob Roxanne , Fourré Elise
Published: March 2022

The EPICA Dome C (EDC) ice core has been drilled from 1996 to 2004. Its study revealed a unique 800 ka long continuous climatic record including 9 deglaciations. Ice cores contain numerous proxies in the ice and in the air trapped in bubbles (chronological constraints, greenhouse gases concentration, local temperature proxies, mid to low latitude climate proxies).

Here, we focus on the link between the high and low latitudes during the glacial/interglacial transitions provided by the isotopic composition of water and oxygen archived in both ice and gas matrix. On one hand, the water isotopic composition brings information on past temperatures and water cycle re-organizations:   dD records past temperature, whereas the combination of d18O with dD or d17O provide information on the past water cycle organization through d-excess and 17O-excess linked to climatic conditions of the evaporative regions. On the other hand, the elemental composition of oxygen expressed in the O2/N2 ratio provides key information for orbital dating over the last 800 ka in complement with the isotopic composition of atmospheric oxygen (d18O of O2 or d18Oatm) which is related as well to the low latitude water cycle.

In this study, we present new high resolution records of water isotopes of many proxies (d18O, d-excess and 17O-excess) as well as high resolution measurements of O2/N2 and d18Oatm over the last 9 deglaciations on the EDC ice core. We detail the coherent low to mid-latitude orbital patterns obtained using our multiproxy approach with a focus on Termination II, Termination V and the 800 – 500 ka. deglaciations. We look at the similar patterns between terminations and between the different proxies presented.
High-resolution meteorological simulations in Heidelberg using GRAMM/GRAL model
Authors: Maiwald Robert , Wald Simone , Suter Ivo , Brunner Dominik , Butz André , Vardag Sanam
Published: March 2022

More than 60% of global greenhouse gases are produced in urban areas. Urban areas therefore exhibit an immense mitigation potential, which needs to be fully exploited to limit climate change.  In order to monitor the effectiveness of mitigation measures, local decision makers require sub-urban data on the spatio-temporal distribution of greenhouse gases. The GRAMM/GRAL model is capable of calculating high-resolution (10m) wind fields over long time periods by using a “catalogue approach”. The model is therefore well suited to support mitigation efforts in cities.

GRAMM/GRAL is composed of the mesoscale model GRAMM and a coupled computational fluid dynamics (CFD) model GRAL. GRAMM calculates meteorological wind fields by solving the Reynolds-Averaged-Navier-Stokes (RANS) equation. In the catalogue approach, the model GRAMM calculates about 1000 wind fields with 100 m resolution each with a different set of atmospheric stabilities, wind speeds and directions. The CFD model GRAL uses these wind fields as input at the boundaries and calculates higher resolution (10m) wind fields taking the flow around buildings into account. Passive tracers may be released within the GRAL model to simulate their dispersion using a Lagrangian particle dispersion approach. A time series of wind fields and concentrations can be obtained by matching measured and simulated wind fields. This matching procedure saves computational costs and therefore enables the analysis of longer time periods.

In this study, we characterize the GRAMM/GRAL model performance in Heidelberg and compare modelled and measured wind fields in an urban setting for a period of three months. In general, we find a good agreement between modelled and simulated wind direction. Wind speeds can be simulated with a root-mean square difference of about 1.0 m/s and a mean bias of about 0.6 m/s. We find that the number of wind stations influences the overall model performance, which is in accordance to Berchet et al. (2017).

We further present an outlook on possible set-ups of an inversion scheme to estimate greenhouse gas fluxes from a hypothetical measurement network. To this end, we utilize the high-resolution model GRAMM/GRAL to simulate CO2 concentration in the urban atmosphere and plan to approximate CO2 fluxes using regularized least-square approaches as well as machine-learning methods. We discuss remaining challenges such as background CO2 and biogenic CO2 fluxes.