bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating the Impact of Topography on Satellite-Derived Evapotranspiration Estimates in the High Atlas Mountains of Morocco
Authors: Sebbar Badr-eddine , Merlin Olivier , Khabba Saïd , Pénot Victor , Simonneaux Vincent , Bouchet Marine , Chehbouni Abdelghani
Published: February 2023

Accurate evapotranspiration (ET) estimates in mountainous regions are needed for better understanding the hydrological cycle and managing water resources within watersheds. However, the complex topography of these areas can have significant effects on ET, making it challenging to monitor at all scales. In this study, we sought to improve the accuracy of thermal remote sensing-based ET estimates in the High Atlas region of Morocco by taking into account the effect of topography. To do this, we used two ET models, both driven by LANDSAT optical/thermal data: the Two-Source Energy Balance (TSEB) model and the contextual Water Deficit Index (WDI) model. The meteorological data (such as air temperature, wind speed, and humidity) used to force the models were taken from ERA5-Land reanalysis products and specifically disaggregated at 30 meters to account for elevation effects, while the solar radiation data were obtained using the Samani et al. method to consider sun exposure effects. We compared the ET estimates produced by both models to measurements taken at two Eddy covariance towers in the mountains at different elevations (900 and 3850 m.a.s.l). Our results showed that the TSEB model was able to accurately estimate ET in the region, with a high level of consistency (r² = 0.72, rmse = 43 Wm-2). The relative performance of both TSEB and WDI models was assessed. We also found that topography significantly influences ET in the High Atlas Mountains, emphasizing the importance of considering it when estimating ET at the watershed scale. This outcome can be used to better understand the hydrological cycle and manage water resources in mountainous areas.
Contribution of small coastal rivers to copper export to the Gulf of Lions
Authors: Machu Yann , Aubert Dominique , Ludwig Wolfgang , Charrière Bruno , Sola Jennifer , Sotin Christine
Published: February 2023

Soils in the Gulf of Lions region (NW Mediterranean) show some of the highest copper (Cu) levels in Europe (Ballabio et al, 2018). The episodic and erosive nature of rainfall in the Mediterranean area (González-Hidalgo et al, 2007), historical intensive agricultural practices using Cu to fight the downy mildew and its relatively high solubility make the study of its transfer and consequences along the land-sea continuum a major issue. The main objective is to quantify the Cu fluxes from coastal rivers discharging in the Gulf of Lions and characterise their temporal variability highlighting the importance of floods on the transfer processes of matter and associated contaminants in the Mediterranean region.Since 2006, the SNO MOOSE, a multi-platform and multi-site observation network designed to monitor the evolution of the Mediterranean basin in a context of global change, has been carrying out. Therefore, on a monthly monitoring basis, trace metal concentrations in suspended particulate matter (SPM) have been estimated in the five main small coastal rivers of the Gulf of Lions as well as the Rhone River.These observations coupled with a sediment flux model (Sadaoui et al, 2016) allow the estimation of elemental fluxes. Small rivers have the highest average Cu content in suspended matter (80.3 µg/g) and in the soils of the catchment areas (79.7 µg/g) (approximatively a factor of 2 compared with the Rhone). Mean annual estimation of Cu fluxes are about 316T/year with an interannual variability of 36%. The Rhone River is by far the major contributor to the fluvial exports of particulate copper to the Gulf of Lion. However, although small coastal rivers account only for 6% of SPM inputs, their contribution to particulate Cu fluxes averages 9.7%.Interannual variability of fluxes is controlled by the occurrence of episodic flash floods on coastal rivers typical of the functioning of Mediterranean watercourses (Roussiez et al, 2011, 2012).The SPM transport originating from surface soil erosion and associated copper mainly takes place during these brief events for small coastal rivers (annual average of 66% of total Cu export against 19% for the Rhone). According to the number of events occurring each year their relative contribution of Cu fluxes compared to the Rhone is highly variable (from 2 % in 2012 up to 41% in 2011). Thus, the influence of coastal rivers on the global Cu budget to the Gulf of Lions is not negligible.Moreover, copper transferred in rivers from the erosion of wine-growing soils is mainly in extractable form, which is more hazardous for the environment because it is both mobile and potentially assimilable by organisms.
Temporal variability of gamma radiation and aerosol concentration over the North Atlantic ocean
Authors: Dias Nuno , Amaral Guilherme , Almeida Carlos , Ferreira António , Camilo António , Silva Eduardo , Barbosa Susana
Published: February 2023

Gamma radiation measured over the ocean is mainly due to airborne radionuclides, as gamma emission by radon degassing from the ocean is negligible. Airborne gamma-emitting elements include radon progeny (Pb-2114, Bi-214, Pb-210) and cosmogenic radionuclides such as Be-7. Radon progeny attaches readily to aerosols, thus the fate of gamma-emitting radon progeny, after its formation by radioactive decay from radon, is expected to be closely linked to that of aerosols.Gamma radiation measurements over the Atlantic Ocean were made on board the ship-rigged sailing ship NRP Sagres in the framework of project SAIL (Space-Atmosphere-Ocean Interactions in the marine boundary Layer). The measurements were performed continuously with a NaI(Tl) scintillator counting all gamma rays from 475 keV to 3 MeV.  The counts from the sensor were recorded every 1 second into a computer system which had his time reference corrected by a GNSS pulse per second (PPS) signal. The GNSS was also used to precisely position the ship. The measurements were performed over the Atlantic ocean from January to May 2020, along the ship’s round trip from Lisboa - Cape Verde – Rio de Janeiro – Buenos Aires – Cape Town – Cape Verde - Lisboa.The results show that the gamma radiation time series displays considerable higher counts and larger variability in January compared to the remaining period. Reanalysis data also indicate higher aerosol concentration. This work investigates in detail the association between the temporal evolution of the gamma radiation measurements obtained from the SAIL campaign over the Atlantic Ocean and co-located total aerosol concentration at 550 nm obtained every 3 hours from EAC4(ECMWF Atmospheric Composition Reanalysis 4) data.
BepiColombo second Mercury flyby : Ion composition measurements from the Mass Spectrum Analyzer (MSA)
Authors: Delcourt Dominique , Hadid Lina , Saito Yoshifumi , Fränz Markus , Yokota Shoichiro , Fiethe Björn , Verdeil Christophe , Katra Bruno , Leblanc Frédéric , Fischer Henning , Harada Yuki , Fontaine Dominique , Krupp Norbert , Michalik Harald , Illiano Jean-Marie , Berthelier Jean-Jacques , Krüger Harald , Murakami Go , Matsuda Shoya
Published: February 2023

On June 23rd 2022, BepiColombo performed its second gravity assist maneuver (MFB2) at Mercury. Just like the first encounter with Mercury that took place on October 1st 2021, the spacecraft approached the planet from dusk-nightside to dawn-dayside down to an extremely close distance (within about 200 km altitude from the planet surface). Even though BepiColombo is in a so-called “stacked configuration” during cruise, meaning that the instruments cannot be fully operated yet, these instruments can still make interesting observations. Particularly, despite their limited field-of-view, the particle sensors allow us to get a hint on the ion composition and dynamics very close to the planet well before the forthcoming orbit insertion around Mercury in December 2025. In this study, we present observations of the Mass Spectrum Analyzer (MSA) at Mercury during MFB2. MSA is part of the low energy sensors of the Mercury Plasma Particle Experiment (MPPE) consortium (PI: Y. Saito), which is a comprehensive instrumental suite for plasma, high-energy particle and energetic neutral atom measurements (Saito et al., 2021) onboard the Mercury Magnetospheric Orbiter (Mio). MSA is a “reflectron” time-of-ﬂight spectrometer that provides information on the plasma composition and the three-dimensional distribution functions of ions with energies up to ~ 38 keV/q and masses up to ~ 60 amu (Delcourt et al., 2016). In this study, we show that both H+ and He2+ ions in the 1-10 keV range are present throughout the innermost magnetosphere near closest approach. In addition, during this MFB2 sequence, MSA observations provide evidences of He+ ions with energies of several hundreds of eVs. These ions likely originate from the planet exosphere and are rapidly circulated within the magnetosphere. During the outbound sequence of MFB2, MSA measurements also reveal copious amounts of keV protons of solar wind origin that propagate upstream after being reflected from the bow shock.
Spatio-Temporal Scales of Plasma Density in Topside Ionosphere
Authors: Urbar Jaroslav , Spogli Luca , Cicone Antonio , Clausen Lasse , Jin Yaqi , Wood Alan , Donegan-Lawley Elizabeth , Alfonsi Lucilla , Cesaroni Claudio , Kotova Daria , Høeg Per , Miloch Wojciech
Published: February 2023

Non-linear couplings of the Earth’s ionosphere with the geospace environment occur in a largely varying range of spatial and temporal scales. As some radio remote sensing techniques like GNSS measurements suffer from artificial radio frequency interference (RFI) at the smallest scales representing ionospheric scintillation, is it advantageous to have ionospheric scales observations based on in-situ measurements.We investigated the variability of the in-situ plasma density and magnetic field measured by Swarm satellites creating the climatology of their scales by leveraging the Fast Iterative Filtering (FIF) technique.FIF is able to provide a very fine time-frequency representation decomposing any non-stationary, nonlinear signals, into oscillating modes, called intrinsic mode components or functions (IMCs or IMFs), characterized by their specific frequency.The results are obtained by time-integrating the instantaneous time-frequency representations, provided through the so-called “IMFogram”. These IMFograms have the potential to show the greater details of the scale sizes and their variations, illustrating the time development of the multi-scale processes during various disturbances of geospace.
Number of Chamber Measurement Locations for Accurate Quantification of Landscape-Scale Greenhouse Gas Fluxes: Importance of Land Use, Seasonality, and Greenhouse Gas Type
Authors: Wangari Elizabeth , Mwanake Ricky , Kraus David , Werner Christian , Gettel Gretchen , Kiese Ralf , Breuer Lutz , Butterbach-Bahl Klaus , Houska Tobias
Published: February 2023

Accurate quantification of landscape soil greenhouse gas (GHG) exchange from chambermeasurements is challenging due to the high spatial-temporal variability of fluxes, which results in largeuncertainties in upscaled regional and global flux estimates. We quantified landscape-scale (6 km2 in centralGermany) soil/ecosystem respiration (SR/ER-CO2), methane (CH4), and nitrous oxide (N2O) fluxes atstratified sites with contrasting landscape characteristics using the fast-box chamber technique. We assessedthe influence of land use (forest, arable, and grassland), seasonality (spring, summer, and autumn), soiltypes, and slope on the fluxes. We also evaluated the number of chamber measurement locations required toestimate landscape fluxes within globally significant uncertainty thresholds. The GHG fluxes were stronglyinfluenced by seasonality and land use rather than soil type and slope. The number of chamber measurementlocations required for robust landscape-scale flux estimates depended on the magnitude of fluxes, which variedwith season, land use, and GHG type. Significant N2O-N flux uncertainties greater than the global meanflux (0.67 kg ha−1 yr−1) occurred if landscape measurements were done at <4 and <22 chamber locations(per km2) in forest and arable ecosystems, respectively, in summer. For CO2 and CH4 fluxes, uncertaintiesgreater than the global median CO2-C flux (7,500 kg ha−1 yr−1) and the global mean forest CH4-C uptake rate(2.81 kg ha−1 yr−1) occurred at <2 forest and <6 arable chamber locations. This finding suggests that morechamber measurement locations are required to assess landscape-scale N2O fluxes than CO2 and CH4, based onthese GHG-specific uncertainty thresholds.
Refining Estimates of Antarctic Geothermal Heat Flow Using Seismological Constraints on Crustal Composition and Lithospheric Thermal Structure
Authors: Hazzard James , Richards Fred , Roberts Gareth
Published: February 2023

Geothermal Heat Flow (GHF) is a crucial boundary condition governing ice sheet stability, due to the positive relationship between thermal input into the ice sheet and basal sliding rates. Tectonic history biases the crustal distribution of heat-producing elements, and the pattern of mantle convection influences regional thermal structure, leading to significant intracontinental variations in Antarctic GHF of order 100 mW/m2.  However, extensive ice cover across Antarctica severely limits the ability to directly measure GHF or crustal composition. Geophysical proxies are therefore required to access information pertaining to the lateral structure of GHF and its potential impact on ice sheet dynamics.Previous studies have used geomagnetic data to infer the depth above which ferromagnetic structure is locked in, corresponding to the ~850 K isotherm. Others have relied on the sensitivity of seismic velocity to thermal structure to model local variations in surface temperature gradient. Both approaches require assumptions on crustal properties, which are typically chosen ad-hoc, and may affect GHF estimates in a significant and non-systematic manner. Other studies have used the observed covariation between lithospheric seismic velocity and GHF in regions with high measurement densities (e.g., continental USA) to map Antarctic seismic structure into GHF. This introduces a dependency of inferred Antarctic GHF on the range of tectonic environments sampled by the continental region used to derive the empirical relationship.Here, we adopt a distinct approach, in which Monte Carlo sampling is used to include crustal conductivity and heat production as free parameters in a numerical modelling procedure that fits theoretical geotherms to new probabilistic seismic inferences of upper mantle temperature structure beneath Antarctica. By integrating empirical constraints on crustal conductivity derived from P-wave velocity data, we are able to build distributions of covarying crustal conductivity, heat production, and GHF. This allows us to generate a model of Antarctic GHF which is complementary to that of other studies, and includes an estimate of lateral uncertainty structure based on the sensitivity of thermal gradients to crustal composition and anelastic deformation at seismic frequencies.
Challenges and ways forward in ecological impact attribution
Authors: Bastos Ana , Sippel Sebastian , Frank Dorothea , Mahecha Miguel , Zaehle Sönke , Zscheischler Jakob , Reichstein Markus
Published: February 2023

Weather extremes have multiple impacts on ecosystems, either through direct influence on plant functioning and health, or indirect and lagged impacts through disturbances such as fires, insects or pest outbreaks. Recent decades have seen an increase in high-impact extreme events, such as large-scale drought-induced mortality, crop failure, mega-fires, and widespread tree mortality events.Understanding to which degree these events are already signs of human-driven climate change requires establishing a reference of natural climatic and ecological variability and formal attribution frameworks. Attribution of single weather extremes is challenging, but feasible through large ensembles of climate model simulations and by advanced statistical techniques. Attribution of high-impact ecological events is, however, complicated by the fact that impacts are not only driven by climate but also by internal ecological dynamics (mortality, gap dynamics, competition, succession) and human influence on the landscape and ecosystem composition (e.g., through land cover change, management, landscape fragmentation, etc.).Here, we present a systemic framework that brings together climate risk and disturbance ecology perspectives to analyse the causal links between climate extremes, disturbances, and ecosystem dynamics. We propose an extended attribution approach that considers not only anthropogenic effects via climate change but also anthropogenic influences on ecological factors that modulate impacts. Based on this framework and on dedicated simulations by an Earth System Model, we exemplify how eco-climatic storylines can be used for robust attribution of high-impact events.  
Global modeling of the mesoscale buildup of the ring current and its role in magnetosphere-ionosphere coupling
Authors: Sorathia Kareem , Michael Adam , Sciola Anthony , Bao Shanshan , Lin Dong , Merkin Slava , Ukhorskiy Sasha , Roedig Constanze , Garretson Jeffrey
Published: February 2023

During geomagnetically active periods plasma is transported from the magnetotail into the inner magnetosphere to become the ring current. The transpot of plasma into the ring current occurs at different spatial and temporal scales, from global quasi-steady convection to bursty bulk flows (BBFs), with typical cross-tail extents of 1-3 Earth radii. During its enhancement, the ring current plays a critical role in magnetosphere-ionosphere coupling. Ring current ions build up plasma pressure in the inner magnetosphere and will drive field-aligned currents which must close in the ionosphere, while electrons will lead to diffuse precipitation and enhanced ionospheric conductance which shape the ionospheric path of current closure. Current closure in the ionosphere will couple to the thermospheric neutral population, via Joule heating, and alter the dynamics of the plasmasphere, via the penetration electric field in the inner magnetosphere. Understanding the relative role of convection at different spatial scales in both the buildup of the ring current and its broader effects on geospace coupling is an area of active interest and one of the core science questions of the Center for Geospace Storms. In this talk I will describe how addressing this question has informed the development of the Multiscale Atmosphere Geospace Environment (MAGE) model and highlight several recent modeling studies which illustrate the central role of mesoscale processes.
Absolute gravimetry in South Patagonia for geodynamic applications
Authors: Gebauer André , Pasquaré Alfredo , Lothhammer Alexander , Rülke Axel , Scheinert Mirko , Richter Andreas , Döhne Thorben , Marderwald Eric , Romero Abelardo , Brunini Claudio , Gende Mauricio , Falk Reinhard , Connon Gerardo , Cimbaro Sergio , Piñón Diego , Guagni Hernán
Published: February 2023

The project “Gravimetric determination of the solid earth reaction due to mass changes in south Patagonia”, funded by the German Research Foundation (DFG), focuses on the viscoelastic characteristics of the upper mantle and its ongoing response to past and present changes in stress caused by the surface loading of the changing ice masses of the Patagonian ice fields. Such in-situ data form an important pre-requisite to constrain the information on present-day ice mass balance obtained by the GRACE and GRACE-Follow On satellite missions.The GNSS observations carried out by the TU Dresden group in southern Patagonia in the recent decade have shown high uplift rates but at a relatively small spatial scale. These uplift rates are mainly due to glacial mass loss for the time period from the little ice age to present. However, the GNSS data used to determine the surface deformation cannot unambiguously separate elastic and viscoelastic processes. This project seeks to add absolute gravimetry at selected locations which are both situated close to the southern Patagonian ice field and further radiate from the maximum observed uplift. Due to the east-west asymmetry of the observed uplift rates, the measurement range has been extended by stations up to the coast of the Atlantic Ocean. It is well established but little applied in practice, that using GNSS together with absolute gravity time series allows these two processes to be separated. Combining the gravimetric and GNSS observations with seismic measurements and with modelling we hope to improve the observational evidence in this region undergoing rapid viscoelastic deformation. Thus, we aim to yield new insights into the physical properties of the Earth’s interior, especially of the rheology of the mantle, to be later combined with GIA modelling.We will present the observations covering the working area between the Atlantic coast in the east and the southern Patagonian ice field in the west. In 2020 and 2022 two observation campaigns were performed including absolute gravimetry, relative gravimetry, GNSS, precise leveling and particular water level observations. In this presentation we will focus on the absolute gravity measurements which have been performed at eight locations in southern Patagonia using a micro-g LaCoste FG5 absolute gravimeter. We will discuss the observational setup, the instrumental performance and the results obtained so far together with the uncertainties of the observations.
Assimilation of satellite temperature and chlorophyll observations for improved ecosystem predictions in the Baltic Sea
Authors: Sun Yuchen , Nerger Lars
Published: February 2023

The CMEMS Monitoring and Forecasting Center for the Baltic Sea (BAL-MFC) uses NEMO coupled to ERGOM to compute reanalysis and forecasts for the Baltic Sea. Operationally, in situ observations of nutrients and oxygen are assimilated using the parallel data assimilation framework (PDAF, https://pdaf.awi.de) using a fixed ensemble read from model snapshots. In the EU-project SEAMLESS, the operational model setup build the basis for enhancements by a fully dynamical data assimilation approach. For this, the coupled NEMO-ERGOM model system is augmented by the data-assimilation functionality of PDAF and NEMO-ERGOM is run in ensemble mode. Using an ensemble of 30 members, satellite surface temperature and chlorophyll observation are assimilated daily. We assess the impact of the assimilation on the forecast skill with a focus on the biogeochemical variables. In addition, additional ecosystem indicators, like trophic efficiency, pH, and phytoplankton community structure are analyzed. The developments on the data assimilation system are in wide parts generic an can also be applied with other model configurations or components. While the developments in SEAMLESS are independent from the BAL-MFC operational developments, it is planned to make them available to the operational service.
Preliminary assessment and comparison of sediment connectivity indexes in a small catchment area: A case study in Tuscany
Authors: Barbadori Francesco , Pelacani Samuel , Raspini Federico , Segoni Samuele
Published: February 2023

The problem of soil erosion is a current issue, especially in hilly and mountainous areas where the driving force is surface runoff, able to mobilize large amounts of sediment that may be delivered to rivers. This process must be considered in a context of climate change, where the number of extreme rainfall events is observed to increase, and their temporal distribution is bound to concentrate in very short periods between long dry intervals of time. The potential soil erosion and degradation can be assessed through the study of the linkages between sources and sinks in a watershed, typically called sediment connectivity assessment. The evaluation of sediment connectivity allows to identify areas prone to the delivery of sediments through the catchment and local depressions that may disconnect land units. The quantitative assessment of sediment connectivity can be evaluated by the using of indexes (e.g. Index of connectivity – IC) with a pixel by pixel procedure in a GIS environment. It is also possible to differentiate structural connectivity, which is evaluated with a geomorphological view, and functional connectivity, which consider the forcing processes and antecedent conditions (e.g. soil moisture). In this study we applied two well established approaches for calculating ICs that use geomorphological and driving force approaches in a small catchment area located in Tuscany. The area was mapped using LiDAR technology to have a high resolution digital terrain model and was affected by recent extreme rainfall events. The application of these two approaches to a small catchment area permitted to concentrate in a nearly homogenous site in terms of land use and focus on geomorphological features that contribute to a connection or a disconnection of catchment’s land units with high spatial resolution. Furthermore, the use of two different indexes allows to study the topic of sediment connectivity and associated soil erosion potential from two points of view with, considering both land management and future warning systems development. Further activities are focusing on the validation of the connectivity indexes, at the rainfall event scale, by monitoring the river suspended sediment transport at the outlet of the watershed in order to relate GIS calculated indexes with the amount of sediments delivered in the riverbed during each rainfall event.
Intensification of Global Hydrological Droughts Under Anthropogenic Climate Warming
Authors: Gu Lei , Yin Jiabo , Slater Louise , Do Hong Xuan
Published: February 2023

Anthropogenic climate warming is expected to accelerate the hydrological cycle with significant consequences for hydrological droughts. However, a systematic understanding of climate warming impacts on the global hydrological droughts and their driving mechanisms is still lacking. Here, we integrate bias-corrected climate experiments, multiple hydrological models (HYs), and a multivariate analysis of variance (ANOVA) with a machine learning modeling framework, to examine the evolving frequency and multivariate characteristics of hydrological droughts and their mechanisms under climate warming for 6,688 catchments in the five principal Köppen-Geiger climate zones. Results show that the total frequency of hydrological droughts is likely to stay unchanged while extreme hydrological droughts (e.g., events with a 30 yr joint return period, JRP) are projected to occur more frequently across the 21st century. The historical 30 yr JRP events assessed during the historical baseline period of 1985–2014 could become twice as frequent over ∼60% of global catchments by 2071–2100 under the middle and high emission scenarios (ESs). Climate uncertainty (i.e., from global climate models and ESs) is the major source of uncertainty over temperate and tropical catchments, versus HY uncertainty in arid catchments with locally complex runoff regimes. Our machine learning framework indicates that precipitation stress controls the development of historical droughts over ∼87% of global catchments. However, with climate warming, air temperature variations are expected to become the new primary driver of droughts in high-latitude cold catchments. This study highlights an increasing risk of global extreme hydrological droughts with warming and suggests that rising temperatures in high latitudes may lead to more extreme hydrological droughts.
Heat waves monitoring over West African cities: uncertainties, characterization and recent trends
Authors: Ngoungue Langue Cedric Gacial , Lavaysse Christophe , Vrac Mathieu , Flamant Cyrille
Published: February 2023

Heat waves can be one of the most dangerous climatic hazards affecting the planet; having dramatic impacts on the health of humans and natural ecosystems as well as on anthropogenic activities, infrastructures and economy. Based on climatic conditions in West Africa, the urban centers of the region appear to be vulnerable to heat waves. The goals of this work is firstly to assess the potential uncertainties encountered in heat waves detection; and secondly analyze their recent trend in West Africa cities during the period 1993-2020. This is done using two state-of-the-art reanalysis products, namely ERA5 and MERRA, as well as two local station datasets, namely Yoff Dakar in Senegal and Aéroport Félix Houphouët Boigny Abidjan in Ivory Coast. An estimate of station data from reanalyses is processed using an interpolation technique : the nearest neighbor to the station with a land sea mask >=0.5; the interpolated temperatures from local station in Dakar and Abidjan, show slightly better correlation with ERA5 than MERRA. Three types of uncertainties are discussed: the first type of uncertainty is related to the reanalyses themselves, the second is related to the sensitivity of heat waves frequency and duration to the threshold values used to monitor them; and the last one is linked to the choice of indicators and the methodology used to define heat waves. Three sorts of heat waves have been analyzed, namely those occurring during daytime, nighttime and both daytime and nighttime concomitantly. Four indicators have been used to analyze heat waves based on 2-m temperature, humidity, 10-m wind or a combination of these. We found that humidity plays an important role in nighttime events; concomitant events detected with wet-bulb temperature are more frequent and located over the north Sahel. For all indicators, we identified 6 years with a significantly higher frequency of events (1998, 2005, 2010, 2016, 2019 and 2020) possibly due to higher sea surface temperatures in the equatorial Atlantic ocean corresponding to El Nino events for some years. A significant increase in the frequency, duration and intensity of heat waves in the cities has been observed during the last decade(2012-2020); this is thought to be a consequence of climate change acting on extreme events
Ocean heat increase and sea ice reduction in the Fram Strait conveys Arctic Ocean change
Authors: de Steur Laura , Sumata Hiroshi , Divine Dmitry , Granskog Mats , Pavlova Olga
Published: February 2023

The sea ice extent in the Arctic Ocean has reduced dramatically with the last 16 years (2007-2022) showing the 16 lowest September extents observed in the satellite era. Besides a declining sea ice cover and increase in ocean heat content in summer, the winter sea ice concentration and thickness have also become more vulnerable to changes. We present results from the Fram Strait Arctic Outflow Observatory showing that the upper ocean temperature in the East Greenland Current in the Fram Strait has increased significantly between 2003 and 2019. While the cold Polar Water now contains more heat in summer due to lower sea ice concentration and longer periods of open water upstream, the warmer returning Atlantic Water has shown a greater presence in winter the central Fram Strait, impacting the winter sea ice thickness and sea ice extent. These processes combined result in a reduced sea ice cover downstream along the whole east coast of Greenland both in summer and winter, which has consequences for winter-time ocean convection in the Greenland Sea.
Report on selected measurements in the canopy of a Rambouillet forest site during the ACROSS field campaign
Authors: Kukui Alexandre , Xue Chaoyang , Houny Jérôme , Mcgillen Max , Bachelier Fanny , Grosselin Benoit , Daële Véronique , Mellouki Wahid
Published: February 2023

In this contribution we report on a subset of ground-based measurements performed by LPC2E and ICARE at a forest site of Rambouillet during June-July of 2022 in the frame of the project ACROSS (Atmospheric ChemistRy Of the Suburban foreSt). In particular, we present the following time-concentration profiles:-    OH and sum of peroxy radicals (CIMS , LPC2E);-    gaseous H2SO4 (CIMS, LPC2E);-    large number of volatile organic compounds (VOCs) and their oxidation products, including  N-containing oxygenated organic molecules (OOMs) (Orbitrap High Resolution CIMS, LPC2E);-    directly emitted VOCs and their oxidation products measured by GC-MS/FID (ICARE)-    HONO (LOPAP, ICARE)-    NO and NO2 (ICARE)Based on a first analysis of this reduced data-set some preliminary conclusions are made about an influence of VOCs emissions and NOx variability on the composition of OOMs oxidation products, HONO formation and oxidation capacity in the forest canopy.
The FAAM large atmospheric research aircraft: a brief history and future upgrades
Authors: Lee James
Published: February 2023

The UK’s large atmospheric research aircraft is a converted BAe 146 operated by the Facility for Airborne Atmospheric Measurements (FAAM). With a range of 2000 nautical miles, the FAAM aircraft is capable of operating all over the world and it has taken part in science campaigns in over 30 different countries since 2004. The aircraft can fly as low as 50 feet over the sea and sustain flight at 100 feet high. The service ceiling is nearly 11 km high. Typically, flights will last anywhere between one and six hours, and we will carry up to 18 scientists onboard, who guide the mission and support the operation of up to 4 tonnes of scientific equipment. Currently, the aircraft is undergoing a £49 million mid-life upgrade (MLU) program, which will extend its lifetime to at least 2040. The three overarching objectives of the MLU are to:Safeguard the UK’s research capability – allowing the facility to meet the needs of the research community, enhance the range of services available, and respond to environmental emergencies.Provide frontier science capability – meeting new and existing research needs and supporting ground-breaking science discoveries, with a flexible and world-class airborne laboratory.Reduce environmental impact – maintaining and improving the performance of the facility, and minimising emissions and resource use from aircraft operation.Presented here will be a brief history of the aircraft operations, including example science outcomes from all flights all over the world. In addition, detail of the ongoing upgrades, in particular the new and cutting-edge measurement capability for gases, aerosols, clouds, radiation and meteorology. Also presented will be the expected reductions in environmental impact of the aircraft and how these will be monitored.
Self-consistent modelling of nanoflares: generation of heating and thermodynamic response in 3D MHD
Authors: Reid Jack , Johnston Craig D. , Threlfall James , Hood Alan W.
Published: February 2023

Resolving thermodynamic transport in three-dimensional models of stratified coronal loops is a long-standing challenge that limits progress in solving the coronal heating problem.Since three-dimensional thermal conduction in MHD has been computationally too expensive to resolve the steep temperature gradients in the transition region, two simpler approaches have been adopted: one-dimensional, field-aligned models following the thermal response to imposed forms of heating, and three-dimensional MHD models that produce the forms of Ohmic and viscous heating self-consistently but cannot consider the consequent thermodynamic response.Now, using a novel numerical technique, TRAC, we can resolve energetic transport in the transition region in fully three-dimensional MHD models.In a model of a multi-stranded coronal loop in a curved arcade, we investigate the heating produced in an 'avalanche'-like process.In such, a chain reaction of reconnection-induced local events occurs, with each event disturbing wider plasma and triggering other processes, such as shocks, jets, and turbulence, that generate heating, which we analyse with particular attention to the spatio-temporal distribution of nanoflares.At the same time, we treat the thermodynamic response of the plasma self-consistently, and study the evolving temperature profiles.Avalanches successfully propagate in curved arcades and appear capable of maintaining a hot corona with realistic temperatures and densities in heated loops.One novelty of interest lies in `campfire'-like events, with simultaneous reconnection events at disjoint sites along coronal strands, akin to recent results from Solar Orbiter.
The controlling effect of the cold plasma density over the acceleration and loss of ultra‐relativistic electrons
Authors: Shprits Yuri , Allison Hayley , Drozdov Alexander , Wang Dedong
Published: February 2023

Novel analysis of phase space densities at multiple energies allows for differentiation between various acceleration mechanisms at ultra‐relativistic energies. This method allows us to trace how particles are being accelerated at different energies and show how long it takes for acceleration to reach particular energy. This method clearly demonstrates the importance of local acceleration and also demonstrates the importance of outward radial diffusion in transporting electrons to GEO.Acceleration to such high energies occurs only when cold plasma in the trough region is extremely depleted, down to the values typical for the plasma sheet. We perform event and statistical analysis of these depletions and show that the ultra‐relativistic energies are reached for each such depletion that is accompanied by the intensification of ~2MeV. VERB‐2D simulations are then used to explain these observations. There is also a clear difference between the loss mechanisms at MeV and multi‐MeV energies due to EMIC waves that can very efficiently scatter ultra‐relativistic electrons but leave MeV electrons unaffected.Modelling and observations clearly show that cold plasma has a controlling effect over the ultra‐ relativistic electrons that are 10^6‐10^7 times more energetic. We also present how the new understanding gained from the Van Allen Probes mission can be used to produce the most accurate data assimilative forecast. Under the recently funded EU Horizon 2020 Project Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation (PAGER) we study how ensemble forecasting from the Sun can produce long‐term probabilistic forecasts of the radiation environment in the inner magnetosphere.
Controls on valley-floor width across the Himalayan orogen
Authors: Clubb Fiona , Mudd Simon , Schildgen Taylor , van der Beek Peter , Devrani Rahul , Sinclair Hugh
Published: February 2023

Himalayan rivers transport approximately 103 Mt of sediment annually from their source in the steep topography of the High Himalaya to ocean basins. However, the journey from source to sink is not necessarily a smooth one: on the way, sediment can become trapped in montane storage systems, such as river valleys or floodplains. While sediment is stored in valleys, climate and erosional signals that we may wish to read from the final sedimentary record can be modified or even destroyed. We therefore need to understand the spatial distribution, volume and longevity of these valley fills. However, controls on Himalayan valley location and geometry are unknown, and sediment volume estimates are based on relatively untested assumptions of valley widening processes.In this work we use a new method of automatically detecting valley floors to extract 1,644,215 valley-floor width measurements across the Himalayan orogen. We use this dataset to explore the dominant controls on valley-floor morphology, and to test models of valley widening processes. We use random forest regression to estimate the importance of potential controlling variables, and find that channel steepness, a proxy for rock uplift, is a first-order control on valley-floor width. We also analyse a newly compiled dataset of 1,797 exhumation rates across the orogen and find that valley-floor width decreases as exhumation rate increases. We therefore suggest that valley-floor width is adjusted to long-term exhumation, controlled by tectonics, rather than being controlled by water discharge or bedrock erodibility. We also hypothesise that valley widening predominantly results from sediment deposition along low-gradient valley floors, controlled by the ratio of sediment to water discharge, rather than lateral bedrock erosion.
Understanding the role of coal in CO2 geological sequestration
Authors: Vieira da Silva José , Rodrigues Cristina , Pimenta Celeste , Lemos de Sousa Manuel J.
Published: February 2023

Nowadays, to understand and, ultimately, to control climate changes, considered one of the main international current topics, it is imperative to reduce the CO2 concentration in the atmosphere, otherwise the environmental, economic, and social consequences will be enormous. The reduction of CO2 can be carried out using several options, each one having technological, environmental, and economic advantages and/or disadvantages. In this regard, the CO2 geological sequestration represents itself as an alternative, which is technologically feasible in depleted conventional deposits of oil and natural gas, in abandoned collieries and/or deep unexploited coal seams, and in deep saline aquifers. In the current state of knowledge, the geological sequestration of CO2 in Portugal, among all available options, will only be possible in existing coal abandoned mines, and deep saline aquifers.In 2022, a highly interactive work was carried out by secondary school students from Dr. Machado de Matos School Grouping, and researchers from the Fernando Pessoa University – Porto, the main goal being to study and understand the role of coal, in layers in abandoned Portuguese mines, in CO2 geological sequestration. For this purpose, the students were confronted with different data published in scientific journals and, ultimately, they tried to understand which coals and which Portuguese mines are more suitable to the CO2 sequestration. Additionally further work will be developed regarding air quality of the place where the school is located.
Polygonal impact craters on Ganymede
Authors: Baby Namitha Rose , Kenkmann Thomas , Stephan Katrin , Wagner Roland J.
Published: February 2023

Polygonal impact craters (PIC) are impact craters that have at least one straight rim segment in planform [1-8]. Among all impact craters, PICs represent a small percentage. They exist on both rocky and icy planetary bodies [9]. To our knowledge no studies on PICs have been carried out for Ganymede. Here we are examining the straight segments of PICs and their relationship with adjacent lineaments or fractures. We use the global mosaic prepared by [10], which combines the best high-resolution images from Voyager 1, Voyager 2, Galileo and Juno spacecrafts. Despite the resolution limits and different illumination angles, we identified and mapped 459 PICs across Ganymede whose diameter range from 5 km to 153 km.  PICs, which were superimposed by other craters or terrains are not considered for this study. The number of straight segments possessed by PICs ranges from 1 to 9 with quadrangular, hexagonal and octagonal shapes being most common. Most of these PICs exhibit a central peak or a pit, with a minor fraction of them showing a dome. Straight rim segments of PICs align with the linear features adjacent to them and indicate that such lineaments are not exclusively surface features but lead to a localization of deformation and influence the cratering process. Straight rim segments of PICs in the dark cratered terrain (dc) are oriented along fractures and furrows. For instance, Galileo Regio have many PICs because of the NW-SE trending furrows and a high density of faults and fractures.  Here, most of the PICs have hexagonal shape with two of the straight segments parallel to the orientation of furrows and rest of the segments are at approximately perpendicular angle. Also, the presence of PICs suggests that they formed after formation of the linear features. The majority of linear features on anti-Jovian hemisphere trends in NW-SE direction while the preferred orientation of linear features on sub-Jovian hemisphere is in NE-SW direction [11]. However, the preliminary orientation analysis of straight segments of PICs using rose diagrams does not show a preferred orientation for the anti-Jovian and sub-Jovian hemispheres.REFERENCES: [1] Fielder, G. (1961) PSS. 8(1), 1-8. [2] Kopal, Z. (2013) Springer. [3] Shoemaker, E.M. (1962) Physics and Astronomy of the Moon, Academic Press, New York, pp. 283-359. [4] Roddy, D.J. (1978) Lunar Planet. Sci. Conf. Proc. 9, 3891-3930. [5] Öhman et al. (2005) Impact Tectonics. Springer, Berlin, pp. 131–160. [6] Öhman et al. (2008) Meteorit. Planet. Sci. 43, 1605–1628. [7] Beddingfield et al. (2016) Icarus 274, 163-194. [8] Beddingfield and Cartwright (2020) Icarus 343, 113687. [9] Öhman et al. (2010) Geolog. Soc. Am. Special Papers 465, 51–65. [10] Kersten et al. (2022) pp. EPSC2022-450. [11] Rossi et al (2020) Journal of Maps, 16(2), 6-16.
Disentangling human influences on hydrological drought
Authors: Coxon Gemma , Bloomfield John P , McMillan Hilary , Oldham Louisa , Pianosi Francesca , Salwey Saskia , Wendt Doris , Zheng Yanchen
Published: February 2023

Human influences can both intensify or mitigate hydrological droughts significantly altering their severity, duration, and frequency via non-linear and dynamic feedbacks. Despite their large influence, current understanding of when, where and to what degree, human-water interactions modify hydrological drought is lacking. One of the key reasons for this is the scarce availability of quantitative human water use data as they are typically considered commercially sensitive and hard to obtain. Consequently, we often rely on static, low-resolution indicators of human water use (such as global water use databases) or qualitative information on human water use, when in reality human-water interactions are highly place-specific and non-stationary over time due to changes in water management and policies.In this study, we will disentangle human influences on hydrological droughts using observational hydro-meteorological and groundwater data and a unique dataset of spatially explicit, time-varying abstractions and discharges for a large sample of catchments across England. Building on recent work to quantify and detect human influences, we will use a suite of hydrological signatures to characterise deviations in droughts and low flows from a large sample of benchmark (i.e. near-natural) catchments. We will link these deviations to different characteristics of the abstractions data (e.g. seasonal catchment averages, abstraction purpose) and to key water management schemes (e.g. low flow alleviation schemes). In doing so, we will advance our current understanding of how humans influence hydrological droughts and how we can improve the collection of human-water use data for future environmental analyses.