bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel approach to imaging NO2 in the atmosphere
Authors: Kuhn Leon , Kuhn Jonas , Wagner Thomas , Platt Ulrich
Published: March 2022

Conventional spectroscopic methods have proven to be reliable and of high selectivity by utilizing the characteristic spectral absorption signature of a wide range of atmospheric trace gases, such as NO2. However, they typically lack the spatio-temporal resolution required to resolve fast processes, such as NO2 emissions from stacks or other point sources.

We present a novel fast imaging instrument for NO2: the NO2 camera based on Gas Correlation Spectroscopy (GCS) in the blue spectral range. Two gas cells (cuvettes) are placed in front of two camera modules. One gas cell is empty, while the other is filled with a high concentration of the target gas (i.e. NO2). The filled gas cell operates as a non-dispersive spectral filter to the incoming light, maintaining the two-dimensional imaging capability of the sensor arrays. NO2 images are generated on the basis of the light intensity ratio between the two images in the spectral window between 430 and 445 nm, where the NO2 absorption cross section has strong spectral structures. We report measurements taken at a large power plant, the Großkraftwerk Mannheim (GKM) in Baden-Württemberg, Germany. NO2 column densities in the stack plume of a GKM chimney are quantified at a spatio-temporal resolution of 1/12 frames per second (FPS) and 0.92m x 0.92m. A detection limit of 2·1016 molec cm-2 was reached. An NO2 mass flux of (7.4 ± 4.2) kg h-1 was estimated based on momentary wind speeds obtained from consecutive images using optical flow estimation. By comparison with a well-established model for plume chemistry (Janssen model), we demonstrate that the NO2/NOx ratio of stack plumes can be investigated using an imaging instrument like ours. The instrument prototype is highly portable and cost-efficient at building costs of below 2,000 Euro.
Effect of benzo(a)pyrene on the morphometric characteristics of tomato plants (Solanum Lycopersicum) under the conditions of a model experiment
Authors: Barbashev Andrey , Dudnikova Tamara , Minkina Tatiana , Sushkova Svetlana , Bakoeva Gulnora , Tikhonenko Elena , Chernikova Natalya , Rahman Md Mahfuzur , Amin Hazrat
Published: March 2022

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds of the benzene series, which differ in the number of benzene rings. Due to their carcinogenic and mutagenic properties, they have been included in the list of priority pollutants by the US Environmental Protection Agency and the European Community. Among all PAHs, there is a mutagen and a carcinogen of the 1st hazard class - benzo (a) pyrene (BaP), which is most often used as a marker of environmental pollution with PAHs. Up to 95% of the emitted pollutants are accumulated by the soil in various chemical forms. Since plants are inextricably linked with the soil, it becomes necessary to study the behaviour of PAHs in the formed plant-soil system. The aim of the study was to evaluate the effect of BaP on the morphometric characteristics of tomato plants under the conditions of a model experiment.

The studies were carried out under the conditions of a vegetation experiment. The soil was sifted through a sieve with a diameter of 1 mm and placed in 2 kg pots in 4 L pots. A BaP solution in acetonitrile was added to the soil surface based on the creation of a pollutant concentration in the soil of 400 and 1200 ng / g, which corresponds to 20 and 60 MPC of BaP. The original uncontaminated soil was used as a control. The soil was sown with tomato plants (Solánum lycopérsicum) of the early maturing variety White filling 241. The experiment was repeated three times. We analyzed such morphometric parameters as root length and stem height, as well as dry biomass of plants.

The root length and stem height in the control sample is set at 32 and 63 cm, respectively. In the samples contaminated with 20 MPC BaP, these indicators were lower, so the root length was 19 cm, and the stem height was 40 cm. In the samples with the introduction of 60 MPC BaP, the root length decreased to 14 cm and the stem height - to 27 cm.

In the control sample, the dry biomass of the roots was 10.3 g and the vegetative part was 80.2 g. When 20 MPC BaP was applied, these parameters decreased to 6.8 g of roots and 67 g of the vegetative part. In the samples with the introduction of 60 MPC BaP, the biomass of the roots was 3.1 g and the biomass of the vegetative part was 44 g, which is lower than the control values.

Thus, a decrease in the length of roots and the height of plant stems, as well as a decrease in their biomass relative to the control values, was established, which indicates that tomato plants are quite susceptible to soil pollution with BaP.

The research was financially supported by the Ministry of Science and Higher Education of the Russian Federation project on the development of the Young Scientist Laboratory (no. LabNOTs-21-01AB).
Deep subduction of continental crust contributes to mantle metasomatism and deep carbon cycle
Authors: Borghini Alessia , Nicoli Gautier , Ferrero Silvio , O'Brien Patrick J. , Laurent Oscar , Remusat Laurent , Borghini Giulio , Milani Sula
Published: March 2022

The garnet in the ultra-high pressure (UHP) eclogites of the Erzgebirge (Bohemian Massif, Germany) trapped primary inclusions of metasomatic melt originated by the partial melting of the continental crust. The study of these inclusions alow us to estimate the contribution of the subducted continental crust to mantle metasomatism and deep carbon fluxes. The inclusions are randomly distributed in the inner part of the garnet, they are micrometric and occur as both polycrystalline, i.e. nanogranitoids, and glassy, often with a shrinkage bubble. Nanogranitoids consist of kumdykolite, quartz, kokchetavite, biotite, white mica, calcite and rare graphite. The inclusions share their microstructural position in the garnet with inclusions of polycrystalline quartz interpreted as quartz pseudomorph after coesite that indicate the entrapment at UHP conditions. The melt composition, measured on glassy inclusions and rehomogenized nanogranitoids, is granitic. The melt is also hydrous, slightly peraluminous and the trace element enrichments observed are consistent with an origin from the continental crust, testified by the high amount of incompatible elements such as Cs, Pb, Th, U, Li and B. Similar signatures were also reported elsewhere in the Bohemian Massif, e.g. in other metasomatic melts hosted in HP mantle eclogites, in metasomatized mantle rocks and in post-collisional ultrapotassic magmatic rocks, suggesting that mantle metasomatism from melts originated in the continental crust is widespread in the orogen.

The melt H2O and CO2 contents were measured with the NanoSIMS. The CO2 values in particular were corrected reintegrating the vapor contained in the shrinkage bubble and are in average 19552 ± 772 ppm, the highest content of CO2 measured so far in crustal melt inclusions. The modelled endogenic carbon flux associated with the subduction of the continental crust of the Variscan Orogenic Cycle is 22 ± 8 Mt C yr-1. This flux within error is similar to the endogenic carbon fluxes in the serpentinized mantle (~ 14 Mt C yr-1) and to the exogenic fluxes in mid-oceanic ridges (~ 16 Mt C yr-1) and arc volcanoes (~ 24 Mt C yr-1). Hence, in collisional settings, deeply subducted continental crust carried a large amount of volatiles to the mantle and the lower crust. Due to the absence of post collisional arc volcanism, most of these volatiles remained trapped in the root of mountain belts. This long-term storage of the carbon in the orogen roots prevents ultimately the closure of the carbon cycle.
Extracting the most valuable information from multi-timescale hydrological forecasts for informing the operation of multipurpose water systems 
Authors: Castelletti Andrea , Zanutto Dennis , Ficchì Andrea , Giuliani Matteo
Published: March 2022

Given the ever-growing accuracy of forecast products over different lead times, it’s increasingly important to understand how to efficiently select and use the most valuable information to support adaptive and robust management of water resources under changing hydroclimatic conditions. In this study, we investigate how the most valuable information from multi-scale forecasts can be selected and used to inform the optimal operation of multipurpose water reservoirs. Our framework combines Input Variable Selection algorithms supporting the selection of the most informative policy inputs, including different forecast variables over diverse lead times, with the Evolutionary Multi-Objective Direct Policy Search method for designing Pareto optimal control policies conditioned on forecast information.

We test this approach on the Lake Como system, a regulated lake in Northern Italy which is operated for preventing floods along the lake shores, providing irrigation supply to downstream users and avoiding low lake levels. Our approach allows the identification of the best subset or combination of variables and metrics extracted from a suite of forecast products. In particular, the performance of the system is evaluated using short-term local deterministic forecasts as well as sub-seasonal and seasonal large-scale ensemble forecasts provided by the European Flood Awareness System (EFAS), part of the Copernicus Emergency Management Service. The candidate variables proposed as inputs for the IVS include different statistics extracted from these forecasts, including the accumulated inflow up to different lead times, the maximum daily flow over different temporal scales and spatial domains, the ensemble forecast variance and some skill scores. The performance of the designed forecast-informed operating policies is contrasted against various benchmarks, including perfect forecasts and the climatology. Beside improving the operating policy performance, results are expected to provide insights about the intrinsic bias of forecast products and to highlight the role of forecast uncertainty in policy design.
A worldwide assessment of the Jenkinson-Collison atmospheric circulation classification and observational uncertainty based on different reanalysis.
Authors: Fernández-Granja Juan Antonio , Brands Swen , Bedia Joaquín , Casanueva Ana , Fernández Jesús
Published: March 2022

Lamb Weather Types (LWT, 1972) are a classical method in synoptic climatology consisting in a subjective classification of atmospheric circulation based on an expert interpretation of sea-level pressure (SLP) fields centered on the British Isles. Jenkinson-Collison (1977) made a subsequent adaptation of the original LWT approach (JC-WT) to obtain an automated, objective method that is also applicable to other locations. In spite of its potential for an objective large-scale circulation typing in extratropical regions of the world, to date, JC-WT has been seldom used in the Southern Hemisphere, which requires a minor modification of its original formulation to this aim. This study sets the grounds for the adoption of the JC-WT classification worldwide by applying it centered in all cells of a 2.5º global grid (excluding a 10º wide equatorial band). We present an open, 6-hourly JC-WT catalogue on this grid for the period 1979-2005 built from five popular reanalysis products (https://doi.org/10.5281/zenodo.5761258). This catalogue is used to evaluate the observational uncertainty linked to the representation of atmospheric circulation in the different reanalyses.

Overall, we find empirical evidence of the suitability of the JC-WT classification for the regional assessment of atmospheric circulation outside the tropics, including the Southern Hemisphere. We also find important differences in the JC-WT representation by different reanalyses in some regions, such as the Tibetan Plateau, the Andes, Greenland and Antarctica, in light of the comparison of their respective occurrences and transition probabilities. These inconsistencies may compromise the robustness of circulation-based model assessments relying on a single reanalysis in these regions.
Experimental Measurements of Electric and Magnetic Fields in Simulated Dust Storms.
Authors: Reid David , Aplin Karen
Published: March 2022

Mars is the only planet in our solar system with an atmosphere for which there have been no observations of lightning. Despite this, it is expected to occur, with the planet known to have dust devils, which due to triboelectrification become charged. Terrestrially, dust storms generate electric fields of around 100 kV/m and there have been recordings of magnetic fields in the region of 0.4 nT. On Earth, the electric fields are not sufficient to cause breakdown. If dust devils generate similar fields on Mars, the field strength will exceed the breakdown field strength of approximately 20 kV/m, thus discharges can be expected – although these may not take the form of terrestrial discharges. The Kazachok surface platform of ExoMars 2022 will deliver the MAIGRET instrument (consisting of a search coil magnetometer, electric field antenna, and a flux gate magnetometer), which will put the capability to measure electric and magnetic fields onto Mars. To better understand the dust devils on Mars, and to aid with the interpretation of returned data from ExoMars, a series of experiments are planned to investigate the magnetic fields from charged dust.

In 2003 Krauss et al performed experiments to determine the necessary conditions for sufficient tribocharging to cause breakdown in a Mars-like atmosphere by first mixing dust to simulate wind speed, and then by dropping dust vertically at a range of pressures. Based upon Krauss’s work, two experiments will be performed with an electric field mill (CS110) and the engineering model of the MAIGRET search coil and thus two hypotheses will be tested. These are, firstly, that the vertical separation of charge is responsible for the electric field, and, secondly, that the spiralling motion of the charged particles is responsible for the magnetic field. The planned vertical drop and horizontal mixing experiments isolate these components of motion, allowing the predictions to be tested.
A palaeo-reconstruction of Devensian ice-flow phasing in the Vale of York. 
Authors: Jenkins Holly
Published: March 2022

Ice provenance and dynamic behaviour between the British-Irish ice sheet has been subject to controversy in recent years. Several studies of clast lithology and glacial morphology have alluded to the inland extension of the North Sea Lobe into northeast England and the Vale of York. However, the extent that the North Sea Lobe extends into the Vale of York, and its dynamic interactions with the Stainmore and Wensleydale ice masses is as yet unknown. This study aims to reconstruct the complex provenance of the Vale of York ice lobe through clast lithological and matrix geochemical analysis. Multivariate statistical methods were applied to the datasets in the form of a PCA and Cluster Analysis, to aid in the correlation of Vale of York tills to BIIS and NSL type sites. Indicator erratics for NSL (Cheviot volcanics and flint), Scottish (greywacke and metasedimentary lithologies), and Lake District (felsic tuff) provenance were found in several tills and were central to tracing till provenance. Major and trace metal, and clast lithological cluster analyses have identified at least two occasions where the NSL and Eden-Stainmore ice converges at Scorton Quarry in the north of the Vale of York. NSL ice has been traced as far south and west as Norton Mills. Deposits to the west (Marfield Quarry and Lightwater Quarry) are dominated by a local Wensleydale ice signature and lack evidence of North Sea ice.
MTD: a new powerful method to select urban-rural pairs for Urban Heat Island quantification applied to Turin, Italy
Authors: Bassani Francesca , Garbero Valeria , Poggi Davide , Ridolfi Luca , von Hardenberg Jost , Milelli Massimo
Published: March 2022

Since Howard (1833) first suggested that air temperatures recorded in urban areas are higher than in the surrounding countryside, there have been hundreds of studies of the Urban Heat Island (UHI) phenomenon, which is due to the different thermal properties between urbanized and natural lands, anthropogenic heat emissions, human-induced pollution and limited wind blowing among buildings. The impervious land cover type and the presence of sheltering constructions trap heat during the day and release it during the night,  resulting in higher night-time temperatures. The UHI intensity is commonly computed as the difference between an urban and a rural measurement site and, therefore, the definition of station pairs is a crucial task for its evaluation. To this end, we propose a powerful method capable of highlighting the thermal pattern typical of each weather station: the Mean Temperature Difference (MTD) method. Principal Component Analysis (PCA) is adopted to cluster similar thermal behaviours, allowing an objective classification of the stations. The strength and novelty of this data-based approach, which employs hourly temperature measurements, lays in the fact that any preliminary assumption about the landscape characterizing each station (i.e. urban or rural) is not needed, making it less arbitrary and more objective than other methods. The application of the proposed method to the metropolitan area of Turin (Italy) shows that the joint use of MTD with PCA yields reliable and easily interpretable results, also in an area with complex morphology (orographic and hydrographic heterogeneity, different land uses, etc.). Once the best urban and rural pairs have been identified, the characteristics of the Urban Heat Island are shown, highlighting its seasonal and daily properties.
The SAGE4CAN project: The use of shallow geothermal energy from oceanic volcanic islands 
Authors: García-Gil Alejandro , Santamarta Juan Carlos , Mejías Moreno Miguel , Baquedano Carlos , Garrido Schneider Eduardo , Alonso Sánchez Teresa , Rey Ronco Miguel Ángel , Sánchez-Navarro José Ángel , Marazuela Miguel Ángel , Andreu Gallego Alicia , Tiscar Cervero José Manuel
Published: March 2022

The use of shallow geothermal energy (SGE) resources in oceanic volcanic environments entails additional challenges when compared to continental sedimentary/plutonic settings. The efficiency of shallow geothermal heat exchangers heavily depends on the geology and hydrogeology of the terrain where are placed. Volcanic rocks in small oceanic islands (<5,000 km2) are the result of volcanism, erosion, and tectonic collapse. All these processes conform highly heterogeneous formations with complex hydrogeology whose thermal response to shallow geothermal systems requires a good understanding of heat transfer in such environments. The SAGE4CAN project will concentrate on SGE resource assessment taking into account heterogeneity characteristic of volcanic formations, both at local and insular scale. To this end, the Canary Islands are selected as representative volcanic oceanic islands, to define SGE implementation barriers including but not limited to (1) heterogeneities of thermal properties intrinsic to volcanic formations (volcanic dikes, red layers, landslides, etc.), (2) heat advection in the context of complex groundwater flow in the unsaturated (dominate in midlands and highlands) as well as in the saturated medium (coast), (3) enhanced geothermal gradients, (4) transient effects of urban and volcanic activity, (5) heating and cooling demand, (6) shallow geothermal energy installations design and optimization, as well as (7) energy transition strategies in energy-dependent islands. The SGE4CAN project will investigate novel approaches to overcome such boundary conditions of oceanic volcanic islands in the estimation of the renewability of the resources, developing novel procedures to conduct cost-efficient and open-access Thermal Response Tests (TRTs), investigate the performance of existent SGE systems, assessing environmental impacts associated with SGE use. The knowledge generated from this project will be used on its final stage to identify adequate strategies for the integration of SGE into heating and cooling policies and action plans, as well as to raise awareness about the technology so that it gets recognition.

 
Weather at Jezero, Mars from pressure measurements by the rover Perseverance
Authors: Sanchez-Lavega Agustin , del Rio-Gaztelurrutia Teresa , Hueso Ricardo , de la Torre Manuel , Harri Ari-Matti , Genzer Maria , Hieta Maria , Polkko Jouni , Rodríguez-Manfredi José Antonio , Tamppari Leslie K. , Newman Claire , Munguira Asier , Martínez Germán , Vicente-Retortillo Alvaro , Lemmon Mark , Pla-Garcia Jorge , Guzewich Scott , Toledo Daniel , Apéstigue Víctor , Viúdez-Moreiras Daniel ,   Additional Team members
Published: March 2022

We report the analysis of pressure measurements at Jezero crater, Mars by the MEDA instrument [1] onboard the rover Perseverance following its landing and covering the period from March 5, 2021 up to this meeting presentation (approximately from solar longitudes 15° to 200°). We identify a variety of atmospheric phenomena, spanning from local to global spatial and temporal scales that leave their imprint in the pressure data [2]. These comprises: Local turbulence (high frequency fluctuations), waves (short period oscillations 12-24 minutes), local vortices (sudden pressure drops from seconds to a minute), baroclinic waves (oscillation periods 4-5 sols) and up to six Fourier components of the thermal tides. The normalized amplitude of the diurnal and semidiurnal tides show a large variability along the studied period, but smaller changes are also noted in tidal components 3 to 6.  We report on the effects of the presence of water ice clouds and dust from storms on the tidal components. Finally, we present the main parameters that characterize each of the phenomena studied, their variability throughout this period, and a preliminary interpretation for all of them.

References:

[1] Rodríguez-Manfredi J. A. et al., Space Sci. Rev., 217.3, 1-86 (2021)

[2] Sánchez-Lavega A. et al., Perseverance/Mars2020 measurements of the daily pressure cycle at Jezero, P25A-03, AGU Fall Meeting (2021)
News about the EUMETNET statistical postprocessing benchmark
Authors: Demaeyer Jonathan
Published: March 2022

New postprocessing methods are sometimes introduced without proper comparison to other available techniques, and therefore the institutions responsible for the operational implementation of weather forecasts may struggle deciding the best choice for their particular usecase. With the goal of helping the weather community to make such decisions, the benchmark of different postprocessing methods on predefined datasets is an important topic and is a key deliverable of the current EUMETNET postprocessing module. This benchmark is also a collaborative effort from several meteorological institutions, members of EUMETNET, and academia to define common pratices and shape standards.

 

In this presentation, we will highlight the different aspects of the benchmark: (1) its current status and organization and (2) its objectives for the next 2 years. We will also detail the challenges ahead for this exercise, and the foreseen datasets and infrastructures needed to tackle them.
Investigating the convective origin of tropical tropopause layer cirrus with Lagrangian trajectories.
Authors: Johansson Erik , Legras Bernard , Podglajen Aurélien
Published: March 2022

High clouds play an important role in modulating Earth’s radiation budget by either trapping longwave radiation emitted from Earth or reflecting incoming shortwave radiation. Furthermore, several studies have pointed out the importance of high clouds in the mass transport between the troposphere and the stratosphere. Most of the upward mass transport from the troposphere into the stratosphere occurs in the tropical region. Here the transition zone between the thermally driven troposphere and the wave-driven stratosphere is usually referred to as the tropical tropopause layer (TTL), and it can extend over several kilometres.

High clouds in the tropics can form in different ways. They can be associated with convective clouds either by convective overshoots or remnants of convective clouds, and they can be created in situ, e.g., by the ascent of dry air, due to gravity waves, leaving a small quantity of water vapour that will undergo deposition into ice. The difference origin creates a vast variety of high clouds ranging from thin cirrus to thick anvils, all with different radiative properties. Due to the altitude and the extreme conditions, high clouds are hard to study. In situ measurements are often limited in either time or space, and high clouds are often masked by low clouds from the ground. Passive satellite instruments are limited to resolving the vertical distribution of clouds and cannot see the thinnest ones. The advent of active sensors onboard satellites has brought a wealth of detailed information on the distribution of high altitude clouds, including the thin ones. However, this information has not been fully used to study the genesis of such clouds.

In this study, we use the Lagrangian model TRACZILLA to do a climatological study of the origin of high clouds in the tropical region. To drive the Lagrangian model, we use a decade-long dataset from the cloud detecting lidar onboard the CALIPSO satellite, infrared brightness temperatures from geostationary satellites and reanalyse data (diabatic and kinematic vertical motions) from ERA5. We benefit from recent progress in the reanalysis that produces high-quality wind and heating rates in the tropopause region. The analysis aims to separate the clouds formed by in situ condensation in clear air from rising motion from those that are remains of anvils directly formed from convective towers. We describe the climatology of this cloud formation mechanism in the tropical band and its variability, with an accent on the summer monsoon season, which generates the largest amount of thin cirrus.
Seismological investigation of Mw=7.3 Karmedec Islands (New Zealand) earthquake occurred on June 15, 2019
Authors: Orlando Martina , Cianchini Gianfranco , De Santis Angelo , Perrone Loredana , Arquero Campuzano Saioa , D'Arcangelo Serena , Di Mauro Domenico , Marchetti Dedalo , Piscini Alessandro , Sabbagh Dario , Soldani Maurizio
Published: March 2022

An Mw=7.3 earthquake occurred on June 15, 2019 in New Zealand, Kermadec Islands (30.644° S, 178.100° W, 46 km depth), in correspondence with the Tonga-Kermadec subduction zone, and was characterized by a tectonic setting of shallow reverse faulting.

We investigated the preparatory phase from a seismological point of view, focusing on the analysis of seismic data in the period between January 1, 2018 and June 14, 2019 in an area limited by the Dobrovolsky strain radius. Specifically, the data from the global United States Geological Survey (USGS) and the national New Zealand (GEONet) earthquake catalogues are used in this study.

To characterize the seismicity trend in terms of magnitude distribution variations and strain release with time, we made a two-step analysis. The first one was to calculate the magnitude of completeness (Mc), which is an important parameter when estimating b-values (Wiemer and Wyss, B. Seism. Soc. Am., 2000). After this preliminary step, we observed that the seismicity accelerated during the preparation phase of the earthquake through the Revised Accelerated Moment Release (R-AMR) method (De Santis et al., Tectonophysics, 2015).

Finally, we found that the seismological research of the preparation phase of this earthquake helped to understand, together with other observations from ground and satellite, the so-called Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) phenomena prior to the mainshock.
A multidecadal model estimate of pan-Arctic coastal erosion rates and associated nutrient fluxes
Authors: Rynders Stefanie , Aksenov Yevgeny
Published: March 2022

Arctic coastal erosion is an environmental hazard expected to increase under climate change, due to decreasing sea ice protection along with increasing wave heights. In addition to the impact on land, this affects the marine environment, as coastal erosion is a source of organic matter, carbon and nutrients for the coastal waters and shelf seas in the Arctic. Following Barnhart et al., we adapted the White model for iceberg melt to calculate pan-coastal erosion rates. The approach combines ice, ocean and wave model output with permafrost model output and geological characteristics from observations. The calculated erosion rates show large spatial variability, similar to observations, as well as a large seasonal cycle. Additionally, it brings to light the increasing trend between the 1980s and 2010s, with a lengthening of the erosion season, plus inter-annual variability. Using observed nutrient ratios, the erosion rates are converted to biogeochemical sources, which can be used for marine ecosystem models. The approach could be used on-line in earth system models, providing both projections of future erosion rates as well as improved biogeochemistry projections. We acknowledge financial support from Advective Pathways of nutrients and key Ecological substances in the Arctic (APEAR) project (NE/R012865/1, NE/R012865/2, #03V01461), as part of the Changing Arctic Ocean programme, jointly funded by the UKRI Natural Environment Research Council (NERC) and the German Federal Ministry of Education and Research (BMBF), and from the European Union’s Horizon 2020 research and innovation programme under project COMFORT (grant agreement no. 820989), for which the work reflects only the authors’ view; the European Commission and their executive agency are not responsible for any use that may be made of the information the work contains.
Satellite-observed vegetation responses to intraseasonal rainfall variability
Authors: Harris Bethan L. , Taylor Christopher , Weedon Graham P. , Talib Joshua , Dorigo Wouter , van der Schalie Robin
Published: March 2022

The response of vegetation to changes in rainfall is a key factor in understanding terrestrial water availability, as well as land-atmosphere feedbacks that can occur as a result of the changes in evapotranspiration, albedo and surface roughness.

Studies of vegetation responses to rainfall have typically focused on variations at the seasonal timescale or longer. However, there is considerable rainfall predictability associated with atmospheric modes of intraseasonal (25 to 60 day) variability, for example the Madden-Julian Oscillation. An improved understanding of land surface predictability at the intraseasonal timescale could aid decision-making in areas such as water management or agriculture, as well as feeding back onto atmospheric predictability. Quantifying intraseasonal vegetation responses could also highlight required improvements in dynamic vegetation modelling for land surface models.

Here, we use satellite-based measurements of rainfall and Vegetation Optical Depth (VOD) to assess the relationships between the intraseasonal variability of rainfall and vegetation across the tropics and mid-latitudes. VOD is a proxy for vegetation water content and is also linked to biomass dynamics. Since it is derived from microwave observations, it can be retrieved under cloudy conditions, giving sufficient daily observations to permit the investigation of variations on the 25-60 day timescale in regions with frequent cloud cover such as the tropics. We use cross-spectral analysis to characterise the intraseasonal vegetation responses at a 0.25° pixel scale in each season.

Coherent intraseasonal relationships between rainfall and vegetation are typically found in arid or semi-arid regions, where vegetation is water-limited and hence sensitive to wet and dry spells. We also analyse the phase difference between rainfall and vegetation, i.e. by how many days one lags the other. Changes in vegetation are generally found to lag changes in rainfall, with increased rainfall followed by increased VOD. The results show that the observations capture distinct distributions of phase difference according to land cover type, with very fast (0-5 day) vegetation responses most likely in sparsely vegetated areas. Following strong intraseasonal wet events, the increase in VOD can persist for at least two months after the peak in rainfall.
Impact of erroneous station coordinates on the estimation of UT1-UTC with VLBI Intensive sessions
Authors: Kern Lisa , Schartner Matthias , Böhm Johannes , Böhm Sigrid , Nothnagel Axel , Soja Benedikt
Published: March 2022

So-called Intensives are one-hour-long VLBI sessions including mostly two stations, which are routinely observed to derive the Earth's phase of rotation expressed through the parameter UT1-UTC. Due to the limitation in time and participating stations, only a few parameters of interest can be estimated during the analysis, whereas others are fixed to their a priori values, such as the remaining Earth orientation parameters, as well as station and source coordinates. 

It is common knowledge that the impact of errors in the a priori station coordinates on the UT1-UTC results changes depending on the location, orientation and length of the baseline. In this presentation, we examine these effects for the first time in a systematic way covering the whole Earth. We performed Monte-Carlo simulations (MCS) with realistic noise models for a global 10° grid of artificial VGOS stations. The grid covers latitudes of -80° to 80° and longitudes of 0° to 180°. All possible and unambiguous baselines between these artificial telescopes are investigated. For every baseline, monthly schedules were generated over one year to eliminate source selection effects. In the MCS, the station coordinates are compromised with an error of 5 mm in either North-South, East-West or Up-Down direction. 

Thereby, we demonstrate that errors along the East-West direction tend to be less critical for long East-West baselines compared to errors in North-South direction. Furthermore, we show that errors in the station height are less critical compared to errors in North-South or East-West direction. The simulation results show that investigations of suitable locations for additional radio telescopes for UT1-UTC Intensive sessions cannot be selected by investigations in analytical equations such as the partial derivatives of the parameters alone but need more sophisticated analyses of error propagation.
Bridging the gap between GRACE and GRACE-Follow On by the combination of HLSST and SLR
Authors: Weigelt Matthias , Jäggi Adrian , Meyer Ulrich , Arnold Daniel , Meyer-Gürr Torsten , Vishwakarma Bramha Dutt , Devaraju Balaji , Steffen Holger , Sosnica Krzysztof , Ebadi Sahar
Published: March 2022

GRACE has been undoubtedly one of the most important sources to observe mass transport at global and regional scales. Within the COST-G project, GRACE and GRACE-Follow On gravity field solutions from various processing centers are being combined to further increase the spatial and temporal resolution. However, the GRACE and GRACE-Follow On time series suffer from a data gap of about one year. Thus, there is a need for an intermediate technique that will bridge the gap between the two missions and will allow 1) for a continued and uninterrupted time series of mass observations and 2) to compare, cross-validate and link the two time series. Here, we present a complete series that covers the gap period between the end of the GRACE mission in 2017 and the first available solutions of GRACE-Follow On in 2018. We will focus on the combination of high-low satellite-to-satellite tracking (hlSST) of low-Earth orbiting satellites by GNSS in combination with SLR. SLR is known to provide highest quality time-variable gravity for the very low degrees (2-5) and hlSST is able to provide a higher spatial resolution at a lower precision in the very low degrees. We discuss also the achievable spatial and temporal resolutions and possible applications in GIA and in interseasonal variation analysis. 
Optimization of pumping rates in an island freshwater lens considering parameter, observation, and climate uncertainty
Authors: Coulon Cécile , Lemieux Jean-Michel , Pryet Alexandre , Gatel Laura
Published: March 2022

Numerical models and optimization algorithms can be valuable tools for decision-making in coastal and island aquifers, where pumping wells are threatened by salinization. Yet, the implementation of pumping optimization under uncertainty remains limited in practice, because of long simulation times and challenges associated with uncertainty propagation through series of models. A method was developed to optimize pumping rates in an island freshwater lens considering parameter, observation, and climate uncertainty. It was implemented in an island aquifer in the Magdalen Islands (Québec, Canada). A seawater intrusion model with rapid simulation times was developed using MODFLOW-SWI2. The iterative ensemble smoother algorithm implemented by PESTPP-IES allowed for history matching and nonlinear uncertainty quantification. The model predictive uncertainties were coupled with climate uncertainties, including recharge uncertainty (derived from various global circulation models and emission scenarios) and sea-level rise uncertainty. Using PESTPP-OPT, the pumping rates in the freshwater lens were then maximized while avoiding the risk of well salinization and considering parameter, observation, and climate uncertainty. Results of the pumping optimization were compared with estimates of water demand uncertainty. This study used widely available, model-independent software and could be used to support groundwater management decision-making in other insular or coastal areas.
Influence of aerosol-radiation interactions on air pollution in East Asia
Authors: Hodnebrog Øivind , Stjern Camilla W. , Marelle Louis , Myhre Gunnar , Pisso Ignacio , Wang Shuxiao
Published: March 2022

Black carbon (BC) aerosol emission is an important contributor to particulate matter (PM) pollution in China, leading to adverse health effects and premature deaths. BC aerosols can also affect boundary layer meteorology by heating the atmosphere, due to the unique property of BC to absorb solar radiation. In contrast, sulphate aerosols reflect solar radiation and thus cool the surface. How individual aerosol pollutants influence boundary layer meteorology on a multi-year timescale is not well known. A particularly important aspect of this influence is a potential feedback process, where changed boundary layer conditions may influence present aerosol concentrations, potentially exacerbating near-surface pollution levels. In this work, we use the Weather Research and Forecasting model with Chemistry (WRF-Chem) at 45 km horizontal resolution covering East and South Asia, and at 15 km resolution covering East China. Simulations are driven by the ECMWF Reanalysis v5 (ERA5), and anthropogenic emissions are from the latest version of the Community Emissions Data System (CEDS). Multi-year simulations are evaluated against observations of meteorological parameters and air quality data for China. Preliminary results show that aerosol-radiation interactions due to BC lead to higher annual near-surface PM concentrations, underscoring the importance of mitigating black carbon aerosol emissions. The elevated PM concentrations can be explained by a shallower boundary layer and reduced turbulent mixing near the surface associated with BC. Possible effects of aerosol-radiation interactions on extreme pollution events, including not only extreme PM events but also extreme ozone (O3) events, will be examined.
Seasonal differences in the persistence of SST’s Response to the North Atlantic Jet Stream
Authors: Mecking Jennifer , Sinha Bablu , Harvey Ben , Robson Jon , Bracegirdle Tom
Published: March 2022

The North Atlantic Jet Stream is well known to leave an imprint on the North Atlantic SST in the form of a tri-polar pattern.  The majority of the existing research has focused on the winter jet stream position or strength of the jet stream.  Here we look at the response of the North Atlantic SSTs to the strength and position of the North Atlantic Jet Stream across all seasons in the CMIP6 piControl simulations.  For the case of both the strength and position of the jet stream the multi-model mean response is a tripolar SST pattern, with the response to the changes in strength showing a slight horseshoe pattern with the northern and southern most anomalies connected on the east and most evident in the summer.  The SST response to winter and spring jet stream changes persist the longest with the northern most imprint on the SSTs lasting up to 2 years.  The response to changes in the jet stream in the summer and fall leave an imprint on the SSTs lasting atmost into the following year.   Furthermore, we investigate at how these responses vary among the CMIP6 models and potential mechanisms leading to the persistence.
Multi-temporal elevation changes of Fedchenko Glacier, Tajikistan (1928-1958-1980-2010-2017-2019)
Authors: Brun Fanny , Lambrecht Astrid , Mayer Christoph , Berthier Etienne , Dehecq Amaury , Rezaei Janali , Deschamps-Berger César
Published: March 2022

Fedchenko Glacier, located in the central Pamir in Tajikistan, is the longest glacier in Asia. Due to its prominent location and its large size, it attracted scientific interest over the course of the twentieth and twenty first centuries, providing thus a rare legacy of historical data in Central Asia. In this study, we investigate a series of topographic data from 1928 to 2019. We use topographic maps collected during historical expeditions in 1928 and 1958. We take advantage of modern satellite data, such as KH-9 spy satellite (1980), SPOT5 (2010) and Pléiades (2017 and 2019). We also rely on ICESat campaign of 2003 and numerous GNSS surveys conducted in 2009, 2015, 2016 and 2019, which ensures a proper co-registration of the satellite data.

We calculate a mean rate of elevation change of -0.40 m/yr for 1928-2019, with a maximum thinning at the lowermost locations (approaching -0.90 m/yr). Despite this long-term thinning trend, we observe large contrasts between the sub-periods. The thinning rate of the tongue doubled for two sub-periods (1958-1980 and 2010-2017) compared to the long-term average. The ERA5 reanalysis (1950-2020) and the Fedchenko meteorological station records (1936-1991) reveal a dry anomaly in 1958-1980, followed by a wet anomaly in 1980-2010, which might have compensated for the temperature increase and thus mitigated mass losses. This wet anomaly could be an important feature of the “Pamir-Karakoram” anomaly, characterized by limited glacier mass losses in this region during the early twenty-first century. Our work contributes to better constrain the decadal glacier thickness changes, with unprecedented temporal resolution. This opens the way for more sophisticated approaches that link the glacier response to climate variability over decades.
Sensitivity of the simulation of thermally-driven circulations in an idealized valley to planetary boundary layer parameterizations
Authors: Giovannini Lorenzo , Zonato Andrea , Di Santo Dario , Bisignano Andrea , Zardi Dino
Published: March 2022

This contribution aims at presenting results from the project “Atmospheric boundary-layer modeling over complex terrain”, a collaboration between the University of Trento, the University of Bolzano and the University of Innsbruck with the objective to evaluate the performance of turbulence and land surface parameterizations over mountainous terrain and to identify potential issues that have a large impact on model results and consequently on the quality of weather forecasts.

A set of Reynolds-averaged Navier-Stokes (RANS) simulations at 1 km horizontal resolution is performed in an idealized three-dimensional valley-plain topography, using typical geometrical features of a north-south Alpine valley, with ridges up to 1500 m above the valley floor and a distance of 20 km from crest to crest. Simulations are initialized with a linear and stable vertical profile of potential temperature, dry air and an atmosphere at rest. The aim of the modeling experiment is to evaluate the sensitivity of model results to planetary boundary layer (PBL) parameterizations, exploring the performance of the PBL schemes implemented in the Weather Research and Forecasting (WRF) model, including a newly developed k-ε closure. Results from the RANS simulations are compared against a large-eddy simulation (LES) with a resolution of 100 m, which is taken as the benchmark. A full diurnal cycle has been considered for the evaluation of numerical results, focusing on the development of along- and cross-valley thermally-driven circulations and on the associated thermal field both in the nighttime and in the daytime phases. The sensitivity of model results to the change of the PBL scheme is assessed using as key metrics the strength and the timing of the thermally-driven circulations, as well as the vertical profiles of mean and turbulent quantities, when available. Results show that in most cases there is a good agreement between RANS simulations and the LES considering the main features of both along- and cross-valley circulations and the diurnal evolution of the thermal stratification. In particular, the intensity of the along-valley wind is generally well-reproduced by all the RANS simulations, while higher discrepancies are found for the timing of the evening transition. On the other hand, RANS simulations are in good agreement with the LES considering the timing of slope winds, whereas the simulation of their intensity presents much more variability, especially during nighttime.
Upstream-downstream asymmetries of drought impacts in major river basins of the European Alps
Authors: Dahlmann Heindriken , Stephan Ruth , Stahl Kerstin
Published: March 2022

Despite their considerable water availability, the European Alps are increasingly affected by droughts. Especially in recent decades, drought impacts have illustrated the regions’ vulnerability, so improved knowledge on the spatial distribution of drought impacts from high elevation headwater regions down to plateau and foothill areas is of tremendous importance. The region has an exceptional data availability including archived drought impact information. It is therefore a good test bed for the often-assumed general hypothesis that drought impacts become more severe downstream. The aim of this study was to investigate whether upstream-downstream differences in the distribution of drought impacts exist in the four major river basins of the European Alps - Rhine, Rhone, Po and Danube. Two different classifications were developed to divide these basins in up- and downstream areas. We based the first classification on the distances to the main sink, and the second classification on human influence. The EDIIALPS database provided quantitative data to analyse the distribution patterns of reported drought impacts from 2000-2020. The results suggest a strong regional variability regarding the temporal and spatial distribution of drought impacts within the individual basins. But they support the general hypothesis: for both classifications the number of drought impacts per area is higher in downstream regions. For the classification based on distances differences are statistically significant for the Rhine and Danube basin. The study provides insight into the spatial distribution of drought impacts in the four major river basins of the European Alps and proves the existence of upstream-downstream asymmetries. The integration of drought indices indicating drought conditions might further explain these differences. Climate change and enhanced cascading effects likely increase these asymmetries and consequently future drought management strategies need to move from emergency actions to better preparedness.