bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence of Rapidly Increasing Dangerous Humid-Heat Risk in Africa's Great Green Wall
Authors: Tuholske Cascade , Ivanovich Catherine , Horton Radley , Shukla Shraddhanand , Brooks Nina , Andam Kwaw , Williams Emily , Funk Chris
Published: February 2023

Since the 1980s, air temperatures have precipitously risen across the African Sahel due to climate change. Currently, the Sahel has rapidly greened. While the drivers of such land-cover and land-use change (LCLUC) across this dryland region are debated, development organizations, governments, and multinational organizations have heralded the greening of the Sahel as a solution to land-degradation and as an impetus to improve human health and well being for low-income peoples across the region. Indeed, the Great Green Wall has garnered significant global attention and investment. Yet, the Great Green Wall may increase available moisture across this normally dryland region, which combined with increased air temperatures, can increase the likelihood of dangerous humid-heat conditions that harm human health and reduce economic activity. Despite the implications of the amplification of hot-humid heat extremes due to interactions between LCLUC and climate change along the Great Green Wall, no longitudinal and fine-grained synthesis of these processes exists for the Sahel.

Here we merge the highest resolution and most accurate global temperature record – CHIRTS-daily – and down-scaled reanalysis relative humidity estimates with the Long-term Global Land Change dataset to identify where LCLUC converges with increases in dangerous humid-heat events across the Sahel from 1983 - 2016. We find that Sahelian regions that are greening the fastest are significantly more likely to have an increase in dangerous humid-heat compared to non-greening regions. Our initial results suggest that the Great Green Wall may be creating hot-humid heat conditions that may curtail economic growth and that may approach the limits of human survivability as we continue to warm the climate and green the Sahel.
Morphotectonic and seismological evidence of active tectonics in the Umbria-Marche Apennines, central Italy
Authors: Invernizzi Chiara , Teloni Simone , Ascione Alessandra , Mazzoli Stefano , Pierantoni Pietro Paolo , Costa Mario , Valente Ettore
Published: February 2023

During the last millennium, several moderate to strong earthquakes occurred in the Umbria-Marche Apennines and Marche foredeep, making this region one of the most seismically active areas of Europe. Seismic activity is mainly clustered in the southern part of the region. Nevertheless, beside the presence of high magnitude historical earthquakes, the lack of significant instrumental seismicity (i.e. ML > 2.5 earthquakes) makes the northern sector of the study area as a prominent seismic gap. Such a northern area is highly challenging for the detection of active, often blind, faults that are essential to a reliable seismic hazard assessment of the region. To tackle this issue, we test an integrated methodological approach based on available geological information together with the analysis of high-resolution seismological data and stress inversion analysis. Furthermore, GIS-based morphotectonic analyses are also used to study the correlation between the identified structures and neotectonic processes. Topography analysis includes the creation of seven swath profiles (20 km in width) and of maximum, minimum, mean elevation and relief maps. River network analysis is carried out using river long profiles and transformed (𝝌) long profiles coupled with slope/area diagrams. The former allowed the location of knickpoints/knickzones, whereas the latter allowed the spatial distribution of the Ksn (normalized steepness) index to be obtained. Combined data from topography and river network mark the different neotectonic behaviour of the northern and southern sectors of the Umbria-Marche Apennines. In fact, the southward increase of (i) mean and minimum elevations, (ii) local relief, (iii) abundance of non-lithology controlled knickpoints, and (iv) Ksn values, suggest the presence of a locus of enhanced vertical motion (i.e., surface uplift) in the south. Here, the largest historical earthquakes and the strongest instrumental seismicity also occur, thus suggesting active tectonics is more intense in this area of stronger uplift.The results of our multidisciplinary analysis are consistent with evidence of along-strike segmentation of the fold and thrust belt where each sector is characterised by different active tectonic behaviour and thickness of Pliocene deposits. Boundaries of sectors roughly coincide with major transversal fault systems, segmenting the outer portion of the fold and thrust belt in the Marche foothills. Such transversal systems are accompanied by diffuse seismicity (< M= 5.5) and probably mark the loci of long-lived, deep-seated fault zones that exert a major control on the active tectonic behaviour of large crustal blocks also compartmentalizing the axial zone of the chain. 
Origin of S-type granites in the forearc accretionary complex of the East Kunlun Orogenic Belt, northern Tibetan Plateau
Authors: Ren Xiang , Dong Yunpeng , He Dengfeng , Hauzenberger Christoph
Published: February 2023

A forearc environment is usually characterised by a relatively low geothermal gradient and hence little magmatic activity occurs. However, S-type granites were discovered within the forearc accretionary complex of the East Kunlun Orogenic Belt. The S-type granites intruded into an upper amphiolite facies partially migmatitic crystalline basement in form of dikes and sills at ca. 440 Ma which corresponds to the transition of the Proto-Tethyan to the Paleo-Tethyan realm in the northern Tibetan Plateau. The observed granites contain either garnet + biotite + muscovite or garnet + muscovite: (1) muscovite granite is strongly peraluminous with an aluminous saturation index (ASI) of more than 1.1 (ASI = molar [Al2O3/(Na2O+K2O+CaO]) and has high-K calc-alkaline characteristics, low Sr/Y (1.9–16.1) and LaN/YbN (1.85–13.2) ratios. (2) Two-mica granite is moderately peraluminous (ASI = 1.02–1.09), has high Ca and low K contents as well as high Sr/Y (16.8–67.7) and LaN/YbN(10.9–33.3) ratios. Other trace element contents and their ratios also show striking differences with high Sr (207–324 ppm) content and CaO/Na2O (0.47–0.96) ratio, and a low Rb/Sr (0.04–0.32) ratio for two-mica granite, but low Sr (63–126 ppm) content and CaO/Na2O (0.08–0.20) ratio, and a high Rb/Sr (0.56–2.53) ratio for muscovite granite. The observed differences are due to different protolith chemistries and melting mechanisms. Based on melting experiments of metasedimentary rocks (Patiño Douce and Harris, 1998), muscovite granite was most likely produced by dehydration melting of a metapelitic source and the two-mica granite by H2O-fluxed melting of a metagreywacke. Zircon Hf isotopes of the two S-type granites have εHf(440 Ma) values of -6.85 to +12.02 indicating the involvement of a mantle-derived magma which probably triggered the anatexis of supracrustal rocks deposited in a forarc regime. Coveal adakites with a younging westward trend as well as mafic rocks have been reported in this accretionary complex, which together with anatexis and metamorphism of accreted material support the occurrence of a slab window beneath the forearc accretionary complex of the East Kunlun Orogenic Belt during subduction of the Tethyan oceanic slab. ReferencesPatiño Douce, A.E., Harris, N., 1998. Experimental constraints on Himalayan anatexis. Journal of Petrology 39, 689–710.
The Jura Fold-Thrust Belt, Switzerland – a contractional deformation setting for nuclear waste disposal
Authors: Bond Clare , Robledo Francisca , Butler Robert
Published: February 2023

The Jura, on the outer margin of the NW Alps, is classically interpreted as a “thin-skinned” fold-thrust belt, detached along Triassic evaporites. It includes the Opalinus Clay (Toarcian-Aalenian), the designated host formation for a radioactive waste repository in Switzerland. We develop a case study to illustrate how methods and approaches in cross-section balancing and restoration, based on seismic imagery, can be applied to assess risks and uncertainties for the integrity of the Opalinus Clay. We focus on the Nördlich Lägern area, announced in 2022 as the preferred site for nuclear waste disposal in Switzerland.  Between northern and southern fold-thrust structures, 3D seismic mapping defines a largely unfaulted domain within which there is no seismic indication of deformation in the Opalinus Clay. It is however seismically transparent. Bounded to the north and south by domains of strongly-faulted Mesozoic strata the low-strain zone has been translated tectonically and is underlain by a seismically resolved Permo-Carboniferous basin. Here we consider multiple interpretations of key section lines with varying degrees of structural linkage and several conceptual models for the timing of the contractional deformation structures. By exploring multiple interpretations, we consider the key uncertainties in structural understanding and risks that might compromise the structural integrity of the waste repository site. Key questions include: were the thin-skinned thrust structures influenced by deep basement structures (that might reactivate in the future)? Has the Opalinus acted as an intraformational detachment that connects kinematically the northern and southern fold-thrust structures? Section balancing and restoration are used to assess whether strain in the two deformation domains can be matched on both sides of the Opalinus Clay. If not, then there is an increased risk of the Opalinus having acted as a detachment passing through the low strain domain, the candidate repository site. A combination of line-length and formation area balancing have been applied to the adjacent, upper and lower, units to the Opalinus Clay, evoking different interpretations of fault trajectories in the bounding fold-thrust domains. In all these interpretations, a balance in tectonic contraction can be achieved without involving distributed strain or requiring detachment within the Opalinus. On this basis, the structural integrity of the prospective repository site is not compromised; an inference consistent with borehole evidence. No significant layer-parallel fault zones have been identified in the four borehole penetrations in the Nördlich Lägern area. The work highlights the importance of structural interpretation and restoration techniques in assessing risks for energy and waste storage projects in contractional settings, even when searching for low strain zones.
The Tipping Points of the Atlantic Meridional Overturning Circulation in Warm and Cold Climates
Authors: Curtis Paul Edwin , Fedorov Alexey
Published: February 2023

In response to abruptly increasing atmospheric CO2 concentrations, general circulation model experiments typically evidence a rapid reduction or full collapse of the Atlantic Meridional Overturning Circulation (AMOC) from its current, strongly overturning state, into one characterized by weak overturning and reduced northward oceanic heat transport. This tipping point is frequently discussed in the context of present and past global climate changes. Less understood, however, is the evolution of the circulation towards a new equilibrium state, which occurs over many centuries or millennia following the initial AMOC response. To revisit this problem, we have performed multi-millennial simulations of the Community Earth System Model version 1 (CESM1) in a low-resolution configuration (T31 gx3v7), appropriate for paleoclimate studies. We consider a pre-industrial control (284.7ppm) simulation, as well as abrupt 2x, 4x, 8x, 16x, and 0.5x pre-industrial control atmospheric CO2 concentrations whereby atmospheric concentrations are increased at the start of integration and held constant for the duration of the experiment. In all global warming scenarios, we observe a rapid collapse to the AMOC within the first 250 years, attributed mechanistically to the complex interplay between surface salinity and temperature which inhibits deep-water formation in the sub-polar North Atlantic. Then, in our abrupt doubling and quadrupling of atmospheric CO2 experiments we observe a recovery to the circulation after some 1,000 years, and 3,500 years, respectively. After initially collapsing, our 8xCO2 experiment remains in this weakened state even after 10,000 years of integration have been performed, potentially indicating that a new equilibrium may have been met in this very warm climate. We have further observed other intriguing bifurcations which arise stochastically in the forced system. First, in our abrupt 4xCO2 experiment, with the AMOC in a collapsed state we observe a spontaneous activation of the Pacific Meridional Overturning Circulation (PMOC) some 2,500 years following the initial forcing. The circulation persists for 1,000 years and has a notable effect on climate in the North Pacific region, for instance raising surface temperatures through the associated increase in Pacific Ocean northward heat transport. At 3,500 years the circulation collapses concomitantly with an AMOC recovery in the experiment, demonstrating a AMOC/PMOC seesaw. Secondly, in our abrupt global cooling experiment, we observe a spontaneous collapse of the AMOC after 2,000 years, which precedes a recovery over the next 1,500 years, before a secondary, rapid collapse to the circulation at 3,500 years. The behavior resembles a Dansgaard-Oeschger Event. Overall, our results highlight the rich quasi-equilibrium dynamical behavior of the Global Meridional Overturning Circulation in past climates for which atmospheric CO2 concentrations were markedly different.
Quantification and Restoration of the Pre-Drift Extension Across the NE Atlantic Conjugate Margins During the Mid-Permian-Early Cenozoic Multi-Rifting Phases
Authors: Abdelmalak Mansour M. , Gac Sébastien , Faleide Jan Inge , Shephard Grace E. , Tsikalas Filippos , Polteau Stéphane , Zastrozhnov Dmitry , Torsvik Trond H.
Published: February 2023

The formation of the NE Atlantic conjugate margins is the result of multiple rifting phases spanning from the Late Paleozoic and culminating in the early Eocene when breakup was accompanied with intense magmatic activity. The pre-breakup configuration of the NE Atlantic continental margins is controlled by crustal extension, magmatism, and sub-lithospheric processes, all of which need to be quantified for the pre-breakup architecture to be restored. Key parameters that need to be extracted from the analysis of crustal structures and sediment record include stretching factors, timing of rifting phases, and nature of the deep crustal structures. The aim of this study is to quantify the pre-drift extension of the NE Atlantic conjugate margins using interpreted crustal structure and forward basin modeling. We use a set of eight 2D conjugate crustal transects and corresponding stratigraphic models, constrained from an integrated analysis of 2D and 3D seismic and well data. The geometry and thickness of the present-day crust is compared to a reference thickness which has experienced limited or no crustal extension since Permian time allowing the quantification of crustal stretching. Based on the eight conjugate crustal transects, the total pre-drift extension is estimated to range between 181 and 390 km with an average of 270–295 km. These estimates are supported by the results of forward basin modeling, which predict total extension between 173 and 325 km, averaging 264 km. The cumulative pre-drift extension estimates derived from basin modeling are in turn used to calculate the incremental crustal stretching factors at each of the three main rifting phases between the conjugate Greenland-Norwegian margins. The mid-Permian early Triassic rifting phase represents 32% of the total extension, while the equivalent values are 41% for the mid-Jurassic to mid-Cretaceous and 27% for the Late Cretaceous-Paleocene rifting phases. These values are used to establish and present at first, a full-fit palinspastic plate kinematic model for the NE Atlantic since the mid-Permian and will be the base for future work on more elaborated models in order to build accurate paleogeographic and tectonic maps.
Profiling households with their flood response measures in Ho Chi Minh City, Vietnam
Authors: Yang Liang Emlyn , Garschagen Matthias
Published: February 2023

Diverse flood response measures and adaptation actions have been carried out worldwide by various stakeholders, especially the various kinds of responses at household level. However, there is a lack of substantial understanding on the profiles of different households regarding their flood response measures, the driving factors, particularly with regards to dynamically changing socio-economic groups and the question of individual vs. collective action for flood risk reduction. Ho Chi Minh City (HCMC) with characterizations of rapid urbanization, socio-economic transitions and significant climate/environment influences at a low lying flood prone area, is increasingly suffering from more frequent and intense floods. Based on a large scale household survey conducted in September and October 2020, the study classifies different flood coping/adaptation measures in HCMC.A cluster analysis of multiple factors is carried out to clarify the major factors and to identify the features of households and their networks in each cluster. Specific data analysis indicates: 1) Majority of local people don’t receive external supports, due to the fact of moderate flood events and that they subjectively don’t concern much to the impacts (have got used to floods). 2) The most vulnerable groups did receive various supports, which indicates the existence of a basic flood-safe system in HCMC. 3) Long-term adaptation measures are not often applied, because vulnerable groups are not able to while rich people don’t need to. Findings of the study help to better understand the local status of flood responses against the backdrop of underlying socio-economic transformations. 
Tropospheric tomography – integration of ground- and space-based GNSS observations
Authors: Hanna Natalia , Weber Robert
Published: February 2023

On the way transmitter-receiver, the Global Navigation Satellite Systems (GNSS) signal is attenuated and delayed by the presence of water vapor. This information serves as the input to the GNSS tomography - a robust technique in water vapor estimation concerning its amount and distribution in the troposphere.GNSS rays pass through the tomographic grid built over a dense network of ground-based GNSS stations. Due to the constant movement of the GNSS satellites influencing their elevation angle and visibility, the measurement geometry varies in time. The model elements are either over or under-determined during the chosen time span within the area of interest; hence, the system of observation equations is mixed-determined.However, to enhance the tomographic solution, the model can be supplied with additional data, e.g., from the radio occultation (RO). The RO technique provides the space-based signal delay between the low Earth orbit (LEO) and GNSS satellites. Products obtained from the RO measurements consist of bending angles and vertical dry- and wet-atmosphere data.In this study, we analyze the COSMIC-1 radio occultation events in the tomographic domain located in the Netherlands in February 2018. The observation system in the ATom GNSS software was extended with the space-based wet refractivity profiles (level 2 data). We compare the obtained 3D wet refractivity field to the GNSS ground-based-only tomographic solution and the radiosonde measurements. The drawbacks and potential development of the applied solution are also discussed.
Hydroxylation of Lunar Soil with Solar Wind
Authors: Yeo Li Hsia , McLain Jason , Killen Rosemary
Published: February 2023

Introduction:  Solar wind, which comprises high energy hydrogen ions, continuously strikes the lunar surface, which is rich in oxygen. This presents an opportunity for hydroxylation - the creation of OH on lunar soil. Both OH and H2O have been detected on the lunar surface, with some variability in abundance throughout the lunar day. It is important to understand how space weathering contributes to the production and proliferation of hydrogen-bearing resources such as water within the lunar environment.OH shows a distinct absorption feature in the infrared (IR) at ~3 µm-1 that can be readily studied. Fourier Transform Infrared (FTIR) Spectroscopy is a fast and accurate way to detect changes in the infrared spectra of lunar soil. Previous studies have examined the changes in IR spectra of amorphous silica and olivine, as well as lunar soil before and after hydrogen irradiation. However, the evolution of the OH band and other IR features has not been studied during hydrogen radiation itself. It is especially important to not expose the samples to terrestrial air, which will contaminate the samples with water. Method and Results: We present FTIR spectra on Apollo-era soil samples obtained simultaneously with high energy hydrogen plasma irradiation, similar to the solar wind. Samples are first prepared by baking under vacuum to drive off any surface water. Samples are also brought through thermal cycling and heated to 400K (lunar dayside maximum temperature) in-situ, and changes in their IR spectra are reported. Comparisons between Apollo samples with different minerology and with a control of crushed SiO2 are also provided. Results show broad but distinct growths in the 3 µm-1 absorption band for lunar samples compared to a sharper peak for SiO2. Since the samples are not exposed to terrestrial water during measurements, the evidence of hydroxylation presented is likely due to hydrogen irradiation. 
How well do we understand Phanerozoic hyperthermals? Investigations with a climate-biogeochemical model
Authors: Mills Benjamin
Published: February 2023

The Phanerozoic Eon is littered with high temperature perturbations which relate to large igneous province (LIP) volcanism. Each of these events occurred against a different climatic and biogeochemical backdrop, and had biotic effects ranging from negligible to extreme. In this talk I will cover the progress we have made with the climate-biogeochemical model SCION, which aims to reconstruct the long-term Phanerozoic climate state as well as these individual hyperthermal events. I will investigate the differences in the amount of carbon that is required to drive the events in the model, versus what is known from the geology of the LIPs themselves. I will then try to suggest solutions to these problems, which may lie in the biotic or biogeochemical responses to climate warming.
Enhanced Quantification and Source Apportionment Capabilities of a New Higher-Resolution Aerosol Chemical Speciation Monitor for Long-Term Measurements of Non-Refractory Aerosol
Authors: Croteau Philip , Nault Benjamin , Canagaratna Manjula , Fortner Edward , Lambe Andrew , Stark Harald , Sueper Donna , Werden Benjamin , Williams Anandi , Williams Leah , Worsnop Douglas , Jayne John
Published: February 2023

Long-term measurements of the composition and mass concentration of particulate matter (PM) are essential for source apportionment, epidemiological studies, and air quality trends. Over the past ten years, the Aerosol Chemical Speciation Monitor (ACSM) has been widely used for long-term, in situ, high time resolution measurements. However, to date there are limited measurements with these instruments in Africa and South/Southeast Asia. The measurements that have been made in these regions suggest the presence of varied and complex sources. Current ACSMs have unit mass resolution (UMR), which impacts detection limits and separation and identification of ions, limiting source apportionment. Here, we present a new instrument, the Time-of-Flight ACSM with eXtended resolution (TOF-ACSM-X) with updated analysis software (Tofware) to allow for high-resolution peak fitting. The TOF-ACSM-X has a mass resolution of ~2000 m/Δm, which is approximately an order of magnitude higher than the other versions of the ACSM. This enhanced resolution improves ammonium detection limits by approximately 2-orders of magnitude, from ~0.200 μg m-3 to ~0.008 μg m-3 (TOF-ACSM versus TOF-ACSM-X, respectively), for 15-minute integration times. Intercomparisons of the TOF-ACSM-X with other measurements show improved performance in source apportionment and elemental analysis.
3D Deep electrical resistivity structure of a geyser-hosting hydrothermal field, Haukadalur, Iceland.
Authors: Lupi Matteo , Collignon Marine , Fischanger Federico , Carrier Aurore , Trippanera Daniele , Pioli Laura
Published: February 2023

Despite being among the most fascinating geological processes on Earth, little is still known about the charging and discharging processes taking place at geysers. We conducted a 3D geoelectrical campaign in the Haukadalur hydrothemal field, Iceland, to investigate the spatial relationships between geysers and the aquifers feeding them. We deployed 24 IRIS Fullwavers to measure the 3D resistive structure of this geyser-hosting hydrothermal field. In addition to DC resistivity measurements and induced polarization methods, we also recorded temperature variations inside Strokkur and Great Geysir geysers. We lowered multiple thermometers at different depths highlighting temperature fluctuations that point out a marked oscillatory behaviour at depth.The electrical study is complemented with a semi-quantitative temperature distribution of the thermal springs across the hydrothermal field that has been acquired through several unmmanned aerial vehicle surveys. This combined approach highlights the strong control that extensional tectonics has on the distribution of fluids across the hydrothermal field. The inverted geoelectrical data suggest the possible occurrence of a common deep groundwater reservoir from which fluids feeding Strokkur and Great Geysir upwell. Induced polarization data are particularly effective in showing water-filled pipes, that we interpret as sub-vertical fracture zones. The geysers are located at the borders of highly resistive regions that we interpret as being vapour-saturated domains. The study shows to the best of our knowledge the first full 3D electrical structure of a geyser-hosting hydrothermal field and helps us understanding the intreplay between boiling fluids and eruption dynamics at geysers.
Towards robust seasonal streamflow forecasts in mountainous catchments: impact of calibration metric selection in hydrological modeling
Authors: Mendoza Pablo A. , Araya Diego , Muñoz-Castro Eduardo , McPhee James
Published: February 2023

The ensemble streamflow prediction (ESP) method has been widely used to produce seasonal streamflow forecasts, especially in snow-influenced basins. Because the approach relies on the assumption of perfect initial conditions that are obtained from hydrological models, choices related to their implementation may have considerable impacts on forecast attributes. Here, we investigate the extent to which the choice of calibration objective function (OF) affects the quality of seasonal (Spring-Summer) streamflow forecasts in mountainous regions, and also explore possible connections between forecast skill and hydrological consistency - measured in terms of biases in hydrological signatures - obtained from the model parameter sets. To this end, we calibrate three conceptual rainfall-runoff models (GR4J, TUW, and Sacramento) using 12 different calibration metrics, including seasonal objective functions that emphasize errors during the snowmelt period, and produce hindcasts for five initialization times over a 33-year period (April/1987 - March-2020) in 22 mountain catchments that span diverse hydroclimatic conditions along the semiarid Andes Cordillera. The results show that seasonal objective functions generate satisfactory performance in terms of probabilistic skill, reliability, and correlation compared to classic OFs like the Nash-Sutcliffe Efficiency (NSE). Nevertheless, commonly used OFs provide more realistic simulations in terms of simulated hydrological signatures. Among the options tested, an OF that combines the Kling-Gupta Efficiency (KGE) and NSE(log(Q)) provides the best compromise between hydrologically consistent model simulations and good forecast performance. Overall, we do not find direct relationships between hydrologically consistent model parameter sets and the quality of seasonal ESP forecasts. Finally, the results show that ESP is most skillful in catchments with high baseflow index and high interannual runoff variability. 
Mapping storm damage across the world’s forests
Authors: Acil Nezha , Wayman Joseph , Suvanto Susanne , Senf Cornelius , Sadler Jonathan , Pugh Thomas
Published: February 2023

Storms are natural weather events, varying greatly in frequency and intensity across the world. They are characterised by strong winds that can disturb forests via tree defoliation, breakage and uprooting. Despite close monitoring of forest disturbance occurrences in recent years, we still lack information on the contribution of storms in driving forest dynamics worldwide. Here, we build a machine learning classification model to identify wind-related forest disturbances at the global scale. Forest disturbance patches detected between 2002 and 2014 were associated with multiple covariates as potential indicators of wind damage. These covariates include structural metrics inherent to the disturbances, such as patch size, elongation and spatiotemporal clustering, as well as environmental variables describing topography, weather, and soil conditions. We used these data for 20,000 reference patches (10,000 wind and 10,000 non-wind), widely distributed across forest biomes, to train a random forest classifier. Cross-validation with 20,000 other reference patches over 10 runs showed that the model achieved satisfactory performance scores. It yielded omission errors of ca. 20% and commission errors of ca. 5%, mostly associated with harvest, selective logging and biotic outbreaks.  The most important variable was maximum wind speed, followed by patch temporal clustering. Model deployment at the global scale will provide quantitative insights into storm damage biogeography, regime characteristics and relative contributions to global carbon fluxes and forest dynamics.
OSCAR: a new airborne instrument to image ocean-atmosphere dynamics at the sub-mesoscale: instrument capabilities and the SEASTARex airborne campaign
Authors: Martin Adrien , Macedo Karlus , Portabella Marcos , Marié Louis , Marquez José , McCann David , Carrasco Ruben , Duarte Rui , Meta Adriano , Gommenginger Christine , Martin-Iglesias Petronilo , Casal Tania
Published: February 2023

OSCAR (Ocean Surface Current Airborne Radar) is a new airborne instrument which provides unique 2D synoptic views of ocean and atmosphere dynamics (currents, waves, winds) below km-scale. OSCAR is the airborne demonstrator of SeaSTAR, an innovative satellite mission concept currently under study in Phase 0 of ESA Earth Explorer 11. SeaSTAR aims to observe ocean submesoscale dynamics and small-scale atmosphere-ocean processes in all coastal, shelf and polar seas by providing simultaneous measurements of current and wind vectors at 1 km resolution with accuracy better than 0.1 m/s and 2 m/s respectively. A key objective of SeaSTAR is to characterize, for the first time, the magnitude, spatial structure, regional distribution and temporal variability of upper ocean dynamics on daily, seasonal and multi-annual time scales, with particular focus on coastal seas, shelf seas and Marginal Ice Zone boundaries.OSCAR was flown over the Iroise Sea (West of Brittany, France) in May 2022 during the SEASTARex campaign. The OSCAR operations and products are representative of the spaceborne concept, with geophysical parameters and accuracies that directly relate to those of the SeaSTAR satellite mission. In itself, OSCAR provides a new observing capability that will improve our understanding of microwave Doppler sensing of the ocean thanks to its unique Doppler and scatterometry capabilities in three azimuth directions. OSCAR’s high-resolution images (8 metres pixels resolution) over a 5km swath provide 2D synoptic views of ocean and atmosphere dynamics below km-scales that are highly relevant to support and complement scientific investigations of fine-scale ocean-atmosphere processes based on in-situ, satellite and model data.In this paper, we give an overview of the OSCAR system, of the SEASTARex campaign over the Iroise Sea in May 2022 and present the main preliminary results about the performance and imaging capability of the instrument.
Improving ecosystem model development with machine learning: a full hybrid approach
Authors: Papastefanou Phillip , Esquivel-Muelbert Adriane , Suvanto Susanne , Olin Stefan , Crowther Thomas , Schelhaas Mart-Jan , Pugh Thomas
Published: February 2023

Making projections of ecological systems under environmental change is central to many disciplines. Process-based models aim to represent core ecological mechanisms governing ecosystem dynamics, which can then be valuable for projecting change under novel environmental conditions. Yet, as our ecological understanding evolves, updating parameter information can be challenging. In addition, classical statistical approaches to fitting functional relationships often miss the complexity of interacting, non-linear dynamics, which can limit the predictive capacity of models. As such, a growing body of work suggests that the integration of modern machine learning might help to improve the representation of key ecological dynamics within such process-based models.  Here, we present a case study, using machine learning to identify key relationships between relative growth, biomass and mortality compared to classical regression methods. Our results suggest that the inclusion of a deep neural network (DNN) into a “theory-driven” process based global vegetation model can greatly improve model predictions of patch level forest structure and vegetation dynamics. This hybrid approach offers both the benefits of interpretability and physically-realistic structure, combined with the depth of information contained in big datasets and the flexibility of model machine learning.
Using observation data to improve simulation of man-made reservoirs in a global hydrological model
Authors: Hosseini-Moghari Seyed-Mohammad , Döll Petra
Published: February 2023

Reservoir operation modeling is challenging since it directly depends on human decision-making that varies from dam to dam. Large-scale reservoir modeling is even more difficult due to the lack of observed operation data. Therefore, generic reservoir operation models are used to model large-scale reservoir operations focusing on a specific purpose, rather than real operations. One of the well-known generic schemes for reservoir operation is Hannsaki et al. (2006) algorithm which is currently used in several global hydrological models including the Water Global Assessment and Prognosis (WaterGAP) model. This algorithm improves hydrological process modeling compared to natural lake methods; however, its performance still needs to be improved, particularly for storage simulations. In this study, a new approach is implemented in the WaterGAP model to improve Hannsaki’s algorithm by using different one-parameter linear operation rules for different reservoir storage levels i.e., above 70 %, between 40 % and 70 %, and below 40 % of reservoir capacity (in total three equations). As a result, we can model each reservoir individually. In addition, we use storage at each time step for estimating the release coefﬁcient instead of the storage at the beginning of the operational year in Hannsaki’s algorithm. The ResOpsUS dataset (historical reservoir inflow, storage, and outflow of major reservoirs across the US) is used to estimate the best parameters for each reservoir and evaluate the results over the US. The results of the new approach show an improvement compared to Hannsaki’s algorithm e.g., when the inflow has a good quality (the Kling-Gupta Efficiency (KGE) greater than 0.50), the median of KEG for storage (outflow) of the new approach reaches 0.23 (0.49) compared to -0.71 (0.25) for Hannsaki’s algorithm.
Climate tipping risks under policy-relevant overshoot temperature pathways
Authors: Möller Tessa , Högner Ernest Annika , Bien Samuel , Schleussner Carl-Friedrich , Rockström Johan , Donges Jonathan F. , Wunderling Nico
Published: February 2023

The risk of triggering multiple climate tipping points if global warming levels were to exceed 1.5°C has been heavily discussed in recent literature. Current climate policies are projected to result in 2.7°C warming above pre-industrial levels by the end of this century and will thereby at least temporarily overshoot the Paris Agreement temperature goal.Here, we assess the risk of triggering climate tipping points under overshoot pathways derived from emission pathways and their uncertainties from the PROVIDE ensemble using PyCascades, a stylised network model of four interacting tipping elements including the Greenland Ice Sheet, the West Antarctic Ice Sheet, the Atlantic Meridional Overturning Circulation, and the Amazon Rainforest.We show that up until 2300, when overshoots are limited to 2°C, the upper range of the Paris Agreement goal, the median risk of triggering at least one element would be less than 5%, although some critical thresholds may have been crossed temporarily. However, the risk of triggering at least one tipping element increases significantly for scenarios that peak above the Paris Agreement temperature range. For instance, we find a median tipping risk in 2300 of 46% for an emission scenario following current policies. Even if temperatures would stabilize at 1.5°C after having peaked at temperatures projected under current policies, the long-term median tipping risks would approach three-quarters.To limit tipping risks beyond centennial scales, we find that it is crucial to constrain any temperature overshoot to 2°C of global warming and to stabilize global temperatures at 1.0°C or below in the long-term.
Improving the operational coverage of MISR aerosol retrievals over shallow, turbid, and eutrophic waters
Authors: Nelson Robert , Witek Marcin , Garay Michael , Bull Michael , Limbacher James , Kahn Ralph , Diner David
Published: February 2023

Shallow coastal waters are often biologically productive (eutrophic), turbidity from runoff is common, and the atmosphere above is typically more aerosol-laden than over open ocean waters. Although the NASA Earth Observing System’s Multi-angle Imaging SpectroRadiometer (MISR) onboard the Terra satellite has been observing aerosols for 23 years, the current operational retrieval algorithm (V23) does not report results over shallow waters (< 50 m in depth or < 5 km from land), due to the complexity of accounting for water-leaving radiance under these conditions. However, MISR measures radiances at four wavelengths and nine view angles, which makes it possible to distinguish atmospheric from ocean surface contributions to the top-of-atmosphere signal. Here, we implement and validate a "Shallow Water" aerosol retrieval algorithm, following Limbacher and Kahn (2019), which constrains a Lambertian surface reflectivity term to account for water-leaving radiance from shallow, turbid, and eutrophic waters. We develop custom quality filtering and find that this modified retrieval algorithm compares well to independent surface-based observations and is better suited for use over shallow waters than the operational Dark Water retrieval algorithm. Globally, retrieving aerosols over shallow waters increases the number of over-water measurements by more than 7%, preferentially in some of the most biologically active coastal regions of the ocean.
Recharge from Reservoirs, Groundwater Flow, and Response to Climate Variability in Arid Basins: Revelations from GRACE Observations
Authors: Sultan Mohamed , Abdelmohsen Karem , Saleh Hassan , Karimi Hadi
Published: February 2023

The Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow On (GRACE-FO) when combined with traditional data sources (geochronology, geochemistry, hydrology, modelling) can enhance our understanding and monitoring of elements of hydrologic systems including recharge of reservoirs, groundwater flow direction and rates, and the impacts of climate change on watersheds worldwide.  We cite a few examples. Large seasonal fluctuations (peak: Nov./Dec.; trough: July/Aug.) in Lake Nasser's surface water levels are accompanied by an increase in GRACETWS (average: 50 ± 13 mm/yr, up to 77 ± 18 mm/yr) over Lake Nasser in Upper Egypt and by a progression of a front of increasing GRACETWS values (> 50 ± 13 mm) away from the lake reaching distances of up to 700 km some 3 to 5 months following peak lake level periods. Those patterns are consistent with rapid turbulent groundwater flow from Lake Nasser along preferred flow directions (networks of faults and karst topography). The Tigris Euphrates watershed (30 dams) showed an impressive recovery following a prolonged drought (2007–2018; Average Annual Precipitation [AAP]: ~400 km3) by an extreme precipitation event in 2019 (726 km3) with no parallels in the past 100 years. This recovery (113±11 km3) compensated for 50% of the losses endured during drought by impounding a large portion of the runoff within the reservoirs (capacity: 250 km3). The Aswan High Dam, with its storage capacity of 150 km3 represents one of the best-engineered systems that enabled Egypt to ride out droughts and avoid extreme flooding events that affected neighboring Sudan. Additional engineering structures are recommended to take advantage of the excess Lake Nasser waters (35 km3), now residing in the Tushka lakes. In basins lacking artificial reservoirs, a different response to extreme precipitation events is observed from temporal GRACE solutions. Extreme precipitation events (2011-2022) over northern Arabia (PPT: Hail: 8.43 km3; Ad-Dahna: 2.22 km3 and Medina: 3.71 km3) and central Arabia (PPT: Riyadh: 4.66 km3 and Mecca: 0.21 km3) produced an increase in GRACETWS that lasted for a few months only. Cyclones over Oman (2011and 2015; PPT: 6 and 6.6 km3, respectively) had a similar effect. Findings demonstrate that highly engineered watersheds are better prepared to deal with the projected increase in the frequency and intensity of extreme rainfall and drought events in the 21st century.
One Martian year of MEDA HS humidity sensor observations and comparisons with models
Authors: Polkko Jouni ,   One Martian year of MEDA HS humidity sensor observations and comparisons with models
Published: February 2023

The Mars 2020 mission rover “Perseverance”, launched on 30 July 2020 by NASA, landed successfully 18th Feb. 2021 at Jezero Crater, Mars (Lon. E 77.4509° Lat. N 18.4446°). The landing took place at Mars solar longitude Ls = 5.2°, close to start of the northern spring. Perseverance’s payload includes the relative humidity sensor MEDA HS (Mars Environmental Dynamics Analyzer Humidity Sensor), which almost one Martian year of observations are described here. The relative humidity measured by MEDA HS is reliable from late night hours to few tens of minutes after sunrise when the measured relative humidity is greater than 2% (referenced to sensor temperature). Observations show seasonal and diurnal trends and short term temporal fluctuations, which are discussed.Nighttime observations are compared with the Finnish Meteorological Institute and Helsinki University adsorptive Single Column Model in various conditions and seasons. The model allows estimating daytime humidity levels. Model comparisons suggest water vapor nighttime adsorption into the soil.Short period fluctuations in the surface humidity data may be due to turbulence caused by downslope winds and nighttime jets. These turbulences break nighttime boundary layer and bring humid air from above. Observed data is compared with the numerical simulations of turbulence over Jezero given by Mars Regional Atmospheric Modeling System (MRAMS).Data is also compared with the Mars Science Laboratory rover Curiosity humidity instrument data. 
Morphometrical analysis of the Aspidolithus/Broinsonia group around the Santonian–Campanian boundary in the Loibichl section (Austrian Eastern Alps)
Authors: Granero Ordóñez Paula , Wierzbicki Adam , Wagreich Michael
Published: February 2023

The first occurrence of large Aspidolithus parcus parcus (Stradner 1963) Noël 1969 or Broinsonia parca subsp. parca (Stradner, 1963) Bukry, 1969 (of Nannotax3) defines the base of the Campanian. This bioevent is generally near the paleomagnetic reversal from C34n (Long Cretaceous Normal Superchron) to C33r, the primary marker for the base of the Campanian, with a proposed GSSP at Bottachione/Gubbio (Miniati et al., 2021). Changes in coccolith morphometry of the Aspidolithus/Broinsonia group are used to identify subspecies of the group relevant in the Upper Cretaceous. However, there is a taxonomic problem in the generic attribution of Aspidolithus (without central cross) or Broinsonia (with central cross) (see also Nannotax 3 and Miniati et al., 2020).The present study focuses on the light-microscope morphometric analysis of Broinsonia/Aspidolithus group, around the Santonian–Campanian boundary (UC13-UC14a-UC14b) in the Loibichl section (Austrian Eastern Alps). A total of 1021 specimens with a moderate to good state of preservation of Broinsonia/Aspidolithus spp. have been measured using JMicroVision software. For each specimen, the length (L) and width (W) of the coccolith, the b/a ratio of the width of the outer rim/shield (b) versus the small diameter of the central area (a) (e.g. Gardin et al., 2001), as well as the number of perforations in the central area (e.g. Lauer, 1975) have been measured.Five morphotypes were distinguished at Loibichl section as well as Wolfgring et al. (2018, Postalm section). Including the number of perforations: (1) Broinsonia enormis subs. 1 (L < 9 µm, b/a ≥ 2 and 8-16 perforations); (2) Broinsonia enormis subs. 2 (L < 9 µm, b/a < 2 and 4-12 perforations); (3) A. parcus expansus (Wise & Watkins in Wise 1983) Perch-Nielsen 1984 (L > 9 µm, b/a ≥ 2 and 8-16 perforations); (4) A. parcus parcus (L > 9 µm, b/a < 2 to ≥ 1 and 4-16 perforations; (5) A. parcus constrictus (Hattner et al., 1980) Perch-Nielsen 1984 (L > 9 µm, b/a <1 and 4-8 perforations). Throughout the section a trend in the distribution of morphospecies is observed, marked by an increase in the abundance of Aspidolithus parcus parcus and a decrease in the abundance of Aspidolithus parcus expansus in the upper part of the section.Gardin, S., et al. 2001. Developments in Palaeontology and Stratigraphy 19, 745–757.Lauer, G. 1975. Archives des Sciences de Genève 28, 259–262.Miniati, F., et al. 2020. Rivista Italiana di Paleontologia e Stratigrafia 126, 783–801.Wolfgring, E., et al. 2018.. Newsletters on Stratigraphy 51.Young, J.R., et al. 2017. Nannotax3 website. Accessed 2 May 2021. URL: https://www.mikrotax.org/Nannotax3.