bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterizing the rupture extent of creep events along the Central San Andreas Fault.
Authors: Gittins Daniel , Hawthorne Jessica
Published: March 2022

The San Andreas Fault has been observed to creep at the surface along the creeping section between San Juan Bautista and Cholame. Slip along this creeping section accumulates at a slow background rate that is punctuated by creep events: few-mm bursts of slip that occur every few weeks to months. Despite observations of these events dating back to the 1960s, we still do not know the rupture extent of these events or the forces that drive them, as previous estimations are confined to short observation periods or one location. So in this study, we systematically characterize creep events in terms of their along-strike rupture extent and determine the depth at which these events occur.

We detect and analyze creep event rupture extent using 18 USGS creepmeters and PBO strainmeters along the San Andreas fault. Using a cross-correlation approach, we systematically detect 2120 creep events in the creepmeter record spanning 1985 - 2020. Comparing the start times of these events, we identify 306 potential multi-creepmeter events and determine their potential along-strike rupture extent. Through both visual inspection and statistical analysis, we identify five creep event types, including single-creepmeter events, small (<2 km) events, medium-sized (3-6 km) events, large (>10 km) events and events that rupture multiple fault strands. We also repeated this analysis after removing events that may be driven by rainfall, and we find that only the correlation of the very largest creep events diminishes. This suggests that these kilometer-long events are not small rainfall-associated perturbations; they are likely to be driven by complex or heterogeneous frictional weakening at depth.

We are exploring more of the properties of creep events to understand better the driving physics, primarily depth, duration, slip and slip evolution. By determining these properties, we may be able to better discriminate between the driving models of creep events and provide a window into the dynamics of larger-scale slip on the San Andreas Fault.
The timescales of climate responses to carbon dioxide and aerosols
Authors: Myhre Gunnar , Stjern Camilla , Samset Bjørn , Forster Piers , Quaas Johannes , Takemura Toshi , Voulgarakis Apostolos , Jia Hailing , Jouan Caroline , Sand Maria , Olivie Dirk
Published: March 2022

Enhanced emissions of both greenhouse gases and aerosols generate climate responses on a wide range of time scales. An initial radiative response triggers a set of rapid adjustments, which are eventually followed by surface-temperature-driven feedbacks. While a lot happens during the first days and months after a perturbation, the monthly mean data typically used in climate studies are too coarse to show the temporal evolution of responses. In these analyses, we take a closer look at how the climate system responds during the very first hours and days after a sudden increase in carbon dioxide (CO2), in black carbon (BC) or in sulfate (SO4). Five models have performed PDRMIP simulations with hourly output, and we also compare results to monthly PDRMIP and CMIP6 results. We find that the effect of increasing ocean temperatures kicks in after a couple of months. Rapid precipitation reductions are for all three climate perturbations established after just a couple of days, and does for BC not differ much from the full-time response.  For CO2 and SO4, the magnitude of the precipitation response gradually increases with surface warming, and for CO2 the sign of the response changes for negative to positive after two years. Rapid cloud adjustments are typically established within the first 24 hours and while the magnitude of cloud feedbacks for CO2 and SO4 increases over time, the latitude-height pattern of the total cloud changes is clearly present after one year. While previously known that climate responses to BC are dominated by rapid adjustments, this work underlines the swiftness of the processes involved.
Estimating Water Surface Slope of Rivers Using ICESat-2 Observations
Authors: Scherer Daniel , Schwatke Christian , Dettmering Denise
Published: March 2022

The water surface slope of rivers is an essential variable for estimating river discharge. It is also helpful as a correction applied to range measurements of satellite altimetry missions to derive water level time series at a virtual station. Still, only rough and mean estimates of water surface slope are obtainable using classical satellite altimetry because of its coarse time and space resolution.

Using the unique measurement geometry of ICESat-2 with six parallel laser beams, we derive instantaneous reach-scale water surface slope along and across the satellite's ground track. The method can be applied globally and provides extending insights into the time- and space-variability of the water surface slope of any river with increasing mission duration.

We compare the ICESat-2 water surface slope estimates with time-variable slopes derived from in-situ data from multiple gauging stations and with static datasets (e.g., from SWORD). We also show the possible performance gain at multiple virtual stations in the "Database for Hydrological Time Series of Inland Waters" (DAHITI, https://dahiti.dgfi.tum.de) applying the water surface slope estimates as a correction of the orbit-drift which can be a few kilometers for repeat missions such as Jason-2/3. However, the largest impacts are expected for non-repeat orbit missions such as CryoSat-2 or Saral (after July 2016).
Acoustic Precursors to Laboratory Induced Fault Slip and Failure
Authors: Veltmeijer Aukje , Naderloo Milad , Barnhoorn Auke
Published: March 2022

With human activities in the subsurface increasing, so does the risk of induced seismicity. For mitigation of the seismic hazard and limiting the risk, monitoring and forecasting are essential. A laboratory study was performed to find precursors to fault failure. In this study, Red Pfaelzer sandstones samples were used, which are analog to the Groningen gas reservoir sandstones. A saw-cut fault was cut at 35 degrees, and the samples were saturated. Fault slip was induced by loading the sample at a constant strain rate, and simultaneously active acoustic transmission measurements were performed. Every 3 seconds 512 S-waves were sent, recorded, stacked to reduce the signal-to-noise ratio, and analyzed. The direct seismic wave velocity, coda wave velocity, and transmissivity were monitored before and during the reactivation of the faulted samples. Different loading patterns and confining pressures were investigated in combination with active acoustic monitoring. Velocity and amplitude variations were observed before the induced fault slip and can be used as precursory signals. Two methods to determine changing velocities were used. Direct S-wave velocities are compared to velocity change obtained by coda wave interferometry. Both analyses gave similar precursory signals, showing a clear change in slope, from increase to decreasing velocities and amplitudes prior to fault reactivation. Fault reactivation is preceded by fault creep and the destroying of some of the asperities on the fault plane, causing the seismic wave amplitude and velocity to decrease. Combining all precursors, the onset of fault slip can be determined and therefore upcoming slip can be forecasted in a laboratory setting. Our results show precursory changes in seismic properties under different loading situations and show a clear variation to the onset of fault reactivation. These results show the potential of continuous acoustic monitoring for detection and forecasting seismicity and help the mitigation of earthquakes.
Numerical modelling of passive tracer dispersion from a continuous point source in a steady thermally driven slope wind
Authors: Farina Sofia , Bisignano Andrea , Zardi Dino
Published: March 2022

An Eulerian model for the dispersion of a passive tracer over a simplified slope driven by a thermally driven circulation is presented here. The source of the tracer is point-like and the emission continuous, the local circulation is a pure anabatic flow modelled following Prandtl’s (1942) steady-state model. The eddy diffusivity is considered constant along the vertical direction. The incapability of a classical Gaussian model to forecast the concentration field is shown through a comparison between the results of the Gaussian and Eulerian models. A study of the sensitivity of the concentration field to the position of the source and to the characteristics of the wind field is proposed. Moreover, a relationship between the position and the intensity of the ground concentration field, together with its dependence on the environmental parameters is found. 

Prandtl L. 1942. Führer durch die Strömungslehre, Chapter 5. Vieweg und Sohn: Braunschweig, Germany. [English translation: Prandtl L. 1952. Mountain and valley winds in stratified air, in Essentials of Fluid Dynamics: 422–425. Hafner Publishing Company: New York, NY]

 
Total phosphorus removal in multi-soil-layering nature-based technology: assessment of influencing factors and prediction by data driven methods
Authors: Sbahi Sofyan , Ouazzani Naaila , Hejjaj Abdessamed , Lahrouni Abderrahman , Mandi Laila
Published: March 2022

Excess phosphorus (P) in wastewater can produce eutrophication, posing a serious risk to the safety of water resources and ecosystems. Therefore, effective pollutant removal including P from wastewater is the key strategy to save the environment and public health. Multi-soil-layering (MSL) is a promising nature-based technology that mainly relies on a soil mixture containing iron to remove P-pollution from wastewater. Fifteen water quality parameters were monitored in the MSL influent to determine which ones have the strongest relationship with total phosphorus (TP) removal. The influence of hydraulic loading rate (HLR) and climatic variables on the removal of TP was investigated. Three data-driven methods including multiple linear regression (MLR), k-nearest neighbors (KNN), and random forest (RF) were conducted to predict TP removal at the MSL system outlet. In contrast to climatic variables, the results reveal that the HLR has a significant impact (p <0.05) on TP removal (47%-90%) in the MSL system. Furthermore, using a feature selection technique, the HLR, pH, orthophosphate, and TP were suggested as the relevant input variables affecting TP removal in the MSL system, while an examination of accuracy shows that the RF model achieves good prediction accuracy (R2 = 0.94).
Is planetary resurfacing a key factor for outgassing and gas speciation on rocky planets?
Authors: Noack Lena , Brachmann Caroline
Published: March 2022

Accurate measurements of a planet's mass, radius and age (provided for example by the PLATO mission and follow-up measurements) together with compositional constraints from the stellar spectrum can help us to deduce potential evolutionary pathways that rocky planets can evolve along, and allow us to predict the range of likely atmospheric properties that can then be compared to observations.

However, for the evolution of composition and mass of an atmosphere, a large degeneracy exists due to several planetary and exterior factors and processes, making it very difficult to link the interior (and hence outgassing processes) of a planet to its atmosphere. The community therefore thrives now to identify the key factors that impact an atmosphere, and that may lead to distinguishable traces in planetary, secondary outgassed atmospheres. Such key factors are for example the planetary mass (impacting atmospheric erosion processes) or surface temperature (impacting atmospheric chemistry, weathering and interior-atmosphere interactions).

Here we investigate the signature that a planet evolving into plate tectonics leaves in its atmophere due to its impact on volcanic outgassing fluxes and volatile releases to the atmosphere - leading possibly to distinguishable sets of atmospheric compositions for stagnant-lid planets and plate tectonics planets. These preliminary findings will need to be further investigated with coupled atmosphere-interior models including various feedback mechanisms such as condensation and weathering as well as atmospheric escape to space.
Identification of flocculation during large-river estuarine mixing
Authors: Ming Yue
Published: March 2022

The flocculation, triggered during estuarine mixing and having an important role on land-to-sea interactions, is a fundamental issue in near-shore oceanographic studies. Identifying the in situ flocculation in large-river estuaries is quite a challenging work, because of the complex seawater circulation and heterogeneous SPM composition in those areas. In this study, three cruises were conducted in the Changjiang (Yangtze) River Estuary and the adjacent area in March, May, and July 2016. Vertical profiles of suspended particulate matter (SPM) total volume, mean size, and size spectra were determined using laser in situ scattering and transmissometry (LISST) measurements at 66–89 stations during the three cruises. Stable isotopic ratios of δ13C were also measured in the organic carbon contents of SPM collected at the surface, middle, and bottom layers of the sampling stations. The LISST data were used to successfully identify flocculation occurring in the field as well as to trace SPM size spectrum changes before and after the flocculation process. The δ13C values were utilized to study the response of biogeochemical parameters to the flocculation. Phytoplankton blooms occurring in May largely resulted in the discontinuous variations of LISST parameters and δ13C from March to July. Although SPM size spectra involved in flocculation showed different patterns in different seasons, however, the flocculation processes were always contributed by smaller particles with sizes of several tens of µm aggregating into larger ones > 300 µm. Using LISST and δ13C measurements together greatly improves our understanding of SPM dynamics in estuarine and coastal areas, in which estuarine flocculation is a critical component.
Statistics of broadband low-frequency waves at the magnetopause
Authors: Steinvall Konrad , Khotyaintsev Yuri , Graham Daniel
Published: March 2022

Broadband waves near and below the lower-hybrid frequency have been observed at the magnetopause for a long time. In recent years NASA's multi-spacecraft mission Magnetospheric Multiscale (MMS) has enabled the waves to be analysed in much greater detail.
Previous case studies have shown that these waves can cause plasma diffusion across the magnetopause, leading to the broadening of current layers. It has also been argued that the waves might contribute to parallel electron heating and anomalous resistivity.

In this study we analyze the aforementioned waves at the magnetopause using multi-spacecraft analysis methods and data from the MMS mission. We investigate the properties of these waves on a statistical level, using several months of data. In particular, we present the relation between the waves and ambient plasma properties such as density gradients and the corresponding gradient length-scale, and to magnetic reconnection.
Iron and steel-making slags as an environmentally-beneficial resource; a UK perspective.
Authors: Riley Alex , Onnis Patrizia , Gandy Catherine , MacDonald John , Burke Ian , Renforth Phil , Jarvis Adam , Hudson-Edwards Karen , Mayes William
Published: March 2022

The production of iron and steel has generated substantial volumes of slag as waste, with estimates of up to 384 million tonnes (Mt) of iron slag and 280 Mt of steel slag produced globally, to date. Whilst the majority of these by-products (approximately 70 %) have seen bulk re-use in a number of applications (e.g. as ballast in construction applications), a significant volume of slag has been disposed of in environmental settings, where the release of metal-rich alkaline leachates can cause enduring pollution. However, the mineralogical and physical properties of slags also offer opportunity for environmental benefits, namely; through sequestration of atmospheric carbon dioxide, by acting as stockpiles of critical raw materials, and in certain situations performing as incidental coastal defences.

Findings are presented from national-scale field investigations, laboratory experiments, and spatial data analyses, which aim to explore the resource potential of iron and steel slags in the United Kingdom (UK). Within the 236 Mt of slags disposed of in the UK environment, projected carbonation rates revealed a potential for uptake of 138 Mt CO2 under enhanced weathering conditions. Notable masses of technologically-critical elements were also estimated within UK slags, with reserves in the region of 1.55 Mt of V2O5, 1.58 Mt of TiO2, and 1.26 Mt of Cr2O3 estimated. Further to acting as a resource, in areas of coastal deposition, slag banks were observed to offer tidal protection. At a number of sites this allowed the development of nationally-significant ecological communities, whilst laboratory leaching experiments reveal a very low risk of chemical leaching in saline conditions. The integration of spatial analyses with chemical composition and leaching data can help to inform decisions on maximising resource potential whilst minimising the potential environmental risks associated with slag reworking.
Magnetic topology of actively evolving and passively convecting structures in the turbulent solar wind
Authors: Hnat Bogdan , Chapman Sandra , Watkins Nick
Published: March 2022

Multipoint in-situ Cluster observations of the solar wind are analysed to identify the magnetic field line topology and current density of turbulent structures using magnetic field gradient tensor invariants. Identified structures are classified as actively evolving if their magnetic field varies significantly from the force-free configuration. We find that at least 35% of all structures are both actively evolving and carrying the strongest currents, actively dissipating, and heating the plasma. These structures are comprised of 1/5 3D plasmoids, 3/5 flux ropes, and 1/5 3D X-points consistent with magnetic reconnection. Actively evolving and passively advecting structures are both close to log-normally distributed. This provides direct evidence for the significant role of strong turbulence, evolving via magnetic shearing and reconnection, in mediating dissipation and solar wind heating.
Temporal variability in central European climate reconstructions, 1501–2020 CE, and its attribution
Authors: Mikšovský Jiří , Brázdil Rudolf , Dobrovolný Petr , Pišoft Petr , Trnka Miroslav , Možný Martin , Balek Jan
Published: March 2022

Despite their pivotal role in climate research, direct instrumental records of meteorological variables are only available for the most recent part of climate history. Even in regions with longest tradition of weather measurements, such as central Europe, the existing series rarely comprise more than two centuries of reliable data. However, documentary sources, both quantitative and qualitative, can be employed to substantially extend the available records. Using the resulting multi-centennial data, previously unexplored features of climate system’s evolution can then be studied.

In this analysis, temporal variability in annual and seasonal series of temperature, precipitation and drought indices (Standardized Precipitation Index - SPI, Standardized Precipitation Evapotranspiration Index - SPEI, Z-index), pertaining to the territory of contemporary Czechia, has been studied over the 1501–2020 CE period. The series under investigation were reconstructed from multitude of Czech documentary data sources, combined with instrumental observations. Phenoclimatic temperature and SPEI reconstructions, derived from historical records of cereal and grape harvest dates, were also employed and compared to their documentary-based counterparts.

Statistical attribution analysis, utilizing multiple linear regression, confirmed the influence of covariates related to volcanic activity (prompting temporary temperature decreases, especially during summer) and the North Atlantic Oscillation (influential in all seasons except summer for all target variables) in the Czech climate reconstructions. Statistically significant components correlated with multidecadal variability in the northern Atlantic and northern Pacific (represented by multiproxy-reconstructed AMO and PDO indices) were identified in the Czech temperature and precipitation series as well as in all drought indices. Additionally, using wavelet and cross-wavelet analysis, notable oscillations shared by the AMO/PDO variations and the Czech climate series were found, particularly at periods of approximately 70–100 years.
Oceanic restratification processes associated with tropical cyclone intensification
Authors: Kaouah Mohamed , Lee Keun-Ok , Bielli Soline , Lapeyre Guillaume
Published: March 2022

Tropical Cyclones (TC) are strongly coupled systems as the underlying warm ocean serves as an energy source for the TC while the strong cyclonic winds modify the ocean state. Good predictions of the TC development are dependant on our knowledge of the ocean heat content which may favor or inhibit the TC. Understanding how the ocean stratification evolves at the same time the TC does is thus crucial to improve TC forecasts.

The 2018-2019 cyclonic season of the South Western Indian Ocean was active and saw the development of nine intense TCs. These cyclones went through regions with different oceanic properties in terms of stratification and heat content. The aim of this study is to understand how such ocean properties affect TC evolution.

To this end, we conducted several idealized simulations of TC using the same atmospheric state but with different oceanic profiles (temperature, salinity) derived from 5-month MERCATOR analysis data (from November 2018 to March 2019). The experiments were conducted using a state of the art coupled modelling system with CROCO (for the ocean) and Meso-NH (for the atmosphere) models with a grid spacing of 4 km.

The TC lifecycle (i.e intensity, structure) as well as the ocean response (i.e. sea surface cooling, advection and mixing processes) are investigated with a particular emphasis on the heat budget analysis. We found that a rapid TC intensification phase occurred due to the warm oceanic surface layers (the first 40 meters) and a strong decaying phase occurred due to the cooler underlying ocean. Moreover we highlight the chronology of the cooling processes in the oceanic mixed layer and the importance of the advection processes within it, which are then relayed by vertical mixing.
Cloud radiative impact on the dynamics and predictability of an idealized extratropical cyclone
Authors: Keshtgar Behrooz , Voigt Aiko , Hoose Corinna , Riemer Michael , Mayer Bernhard
Published: March 2022

Extratropical cyclones drive midlatitude weather, including extreme events, and determine midlatitude climate. Their dynamics and predictability are strongly shaped by cloud diabatic processes. While the cloud impact due to latent heating is well known and much studied, little is known about the impact of cloud radiative heating (CRH) on the dynamics and predictability of extratropical cyclones. Here, we address this question by means of baroclinic life cycle simulations performed at a convection-permitting resolution of 2.5 km with the ICON model. The simulations use a newly implemented channel setup with periodic boundary conditions in the zonal direction. Moreover, they apply a new modeling technique for which only CRH interacts with the cyclone, which circumvents changes in the mean state due to clear-sky radiative cooling. To understand the CRH impact on the upper-tropospheric circulation, we diagnose sources and the evolution of differences in potential vorticity (PV) between a simulation with and without CRH.

We find that CRH increases the intensity of the cyclone with the impact being more prominent at upper levels. The mechanism by which CRH affects the cyclone operates mostly via a modification of other diabatic processes, in particular an intensification of the latent heating associated with cloud microphysical processes. This changes PV tendencies, and these changes are then advected by the upper-tropospheric divergent flow to the tropopause region, where the large-scale rotational flow further changes the tropopause structure.

Our results indicate that although CRH is comparably small in magnitude, it can affect extratropical cyclones by changing cloud microphysical heating and subsequently the large-scale flow similar to a previously identified multi-stage upscale error growth mechanism. Our results further indicate that CRH can impact the predictability of the cyclones. This impact may be especially important in storm-resolving models, for which simplified radiative transfer calculations might bias CRH. 
Pan-European high-resolution groundwater recharge mapping – combining satellite data and national survey data using machine learning
Authors: Stisen Simon , Martinsen Grith , Bessiere Helene , Caballero Yvan , Koch Julian , Juan Collados-Lara Antonio , Mansour Majdi , Sallasmaa Olli , Pulido Velázquez David , Hunter Williams Natalya , Jan Zaadnoordijk Willem
Published: March 2022

Groundwater recharge quantification is essential for sustainable groundwater resources management, but typically limited to local and regional scale estimates. A high-resolution (1 km x 1 km) dataset consisting of long-term average actual evapotranspiration, effective precipitation, a groundwater recharge coefficient, and the resulting groundwater recharge map has been created for all of Europe using a variety of pan-European datasets and seven national gridded recharge estimates. As an initial step, the approach developed for continental scale mapping consists of a merged estimate of actual evapotranspiration originating from satellite data and the vegetation controlled Budyko approach to subsequently estimate effective precipitation.  Secondly, a machine learning model based on the Random Forest regressor was developed for mapping groundwater recharge coefficients, using a range of covariates related to geology, soil, topography and climate. A common feature of the approach is the validation and training against effective precipitation, recharge coefficients and groundwater recharge from seven national gridded datasets covering the UK, Ireland, Finland, Denmark, the Netherlands, France and Spain, representing a wide range of climatic and hydrogeological conditions across Europe.  The groundwater recharge map provides harmonised high-resolution estimates across Europe and locally relevant estimates for areas where this information is otherwise not available, while being consistent with the existing national gridded estimates. The Pan-European groundwater recharge pattern compares well with results from the global hydrological model PCR-GLOBWB 2. At country scale, the results were compared to a German recharge map showing great similarity. The full dataset of long-term average actual evapotranspiration, effective precipitation, recharge coefficients and groundwater recharge is available through the EuroGeoSurveys’ open access European Geological Data Infrastructure (EGDI).
Morphodynamic model of the Yichang-Chenglingji Reach: migration of erosion centers downstream of the Three Gorges Dam
Authors: Wang Hualin , Zheng Shan , An Chenge
Published: March 2022

Abstract: Many rivers worldwide have suffered great degradation after large reservoirs construction. By investigating the Yichang-Chenglingji reach downstream of the Three Gorges Dam, we identified and analyzed the erosion centers (sub-reach with most severe erosion intensity) which migrated downstream along the river with the rate of 7.5 km/yr. To simulate the phenomenon and study the factors influencing the migration rate of erosion centers, a one-dimensional river morphodynamic model is implemented using field data (including water and sediment regimes and grain size of bed material) of Yichang-Chenglingji reach based on the active layer theory. We set three values for the thickness of active layer and designed four groups of grain size distribution of the sub-layer based on the drill data and the grain size distribution of bed surface material at Yichang station. The simulation results show that the main cause of the erosion centers is bed armoring. A high-speed bed armoring process is instrumental in the formation and migration of erosion centers, as the armoring of bed surface inhibits the further degradation in the upper reach. The thinner the active layer and the coarser the sub-layer, the faster the process of bed armoring. Under the condition that the thickness of the active layer is 1.5m and the sediment of sub-layer is the field data of bed surface material at Yichang station in 2020, the migration rate (13km/yr.) of erosion centers in simulation results are most in agreement with the actual erosion centers. Our results may deepen the understanding of the river evolution after the abrupt sediment reduction.

Key words: Three Gorges Dam; Yichang-Chenglingji Reach; Morphological evolution; Erosion centers; Spatial clustering; Numerical model
Atmospheric rivers responses to climate change in the Mediterranean Region
Authors: Ramos Alexandre M. , Sousa Pedro M. , Trigo Ricardo M.
Published: March 2022

Moisture transport over the northeastern Atlantic Ocean is one of the processes governing precipitation distribution and variability over Southern Europe. This moisture transport mainly occurs in the so-called Atmospheric Rivers (ARs). ARs are relatively narrow and elongated filaments of high-water vapor transport, which are associated with tropical moisture exports and often occur in combination with the passage of strong extratropical cyclones. Such structures transport more than 90% of the total mid-latitude vertically integrated water vapor, that on landfall, produce precipitation which can be both beneficial and destructive due to its interaction with topography or ascent in the Warm Conveyor Belt.

Understanding how AR characteristics will respond to a warming climate is, therefore, critical to mitigate changes in the intensity of AR-related precipitation and related hydrological extremes.

ARs reaching Southern Europe are analyzed using CMIP5 and CMIP6 simulations and on a high resolution transient simulation between 850 CE to 2100. The projected IVT for 2070–99 significantly exceeds the range given by interannual–interdecadal variability of the last millennium. Changes in IVT are in line with significant increases in tropospheric moisture content, driven by the concurrent rise in surface temperatures associated with the anthropogenic climate trend. On regional scales, recent and projected precipitation changes over the British Isles follow the global positive IVT trend, whereas a robust precipitation decrease over Iberia is identified in the twenty-first century, particularly during autumn. This indicates a possible extension of stable and dry summer conditions and a decoupling between moisture availability and dynamical forcing. The investigation of circulation features reveals a mean poleward shift of moisture corridors and associated atmospheric rivers.

 

Acknowledgments

The financial support for this work was possible through the following FCT project: HOLMODRIVE—North Atlantic Atmospheric Patterns Influence on Western Iberia Climate: From the Late Glacial to the Present (PTDC/CTA-GEO/29029/2017).
Lightning activity accompanying tropical cyclones
Authors: Rosická Kateřina , Kolmašová Ivana , Santolík Ondřej
Published: March 2022

We used the World Wide Lightning Location Network and cyclones tracks from the International Best Track Archive for Climate Stewardship to study properties of lightning strokes occurring in tropical cyclones. We studied 429 cyclones occurring from 2012 to 2017 in both hemispheres with more than 11 million lightning strokes found within a distance of 600 km from the cyclone eye. For purposes of our study, we divided the cyclones into 6 basins: Indian Ocean, North Atlantic, Northeast Pacific and Northwest Pacific in the northern hemisphere and Indian Ocean and Southern Pacific in the southern hemisphere. We found differences in the numbers, energies and multiplicities of lightning strokes occurring in the cyclones in the northern and southern hemispheres. We calculated the median stroke energy for each cyclone. We used Saffir-Simpson scale for classifying the intensity of tropical cyclones and found a tendency of decreasing median stroke energies with an increasing cyclone intensity. We compared the evolution of lightning activity accompanying the cyclones with the evolution of their central pressure and wind speed to examine the possibility of using the lightning activity for prediction of cyclone intensity changes. In the northern hemisphere, there was on average about 28 thousands of strokes per cyclone with a median energy of 1.7 kJ, while in the southern hemisphere, there was on average 24 thousands of strokes per cyclone with a median energy of 2.7 kJ. The difference in multiplicity is not really noticeable with an average of 1.39 strokes per flash in the northern hemisphere and 1.34 strokes per flash in the southern hemisphere. In our dataset, we found 28 strokes with an energy over 1 MJ (superbolts), which occurred in a short period during the winter 2013-14, which was the winter exhibiting the largest SOI (Southern oscillation index).

 
Mass loss of mountain glaciers does not translate directly to sea level rise
Authors: Kraaijenbrink Philip , Sutanudjaja Edwin , van de Wal Roderik , Bierkens Marc , Immerzeel Walter
Published: March 2022

The excess meltwater that results from climate change induced mass loss of mountain glaciers is an important contributor to sea level rise (SLR). Up to now, large scale glacier observations and models have been used to estimate the amount of generated excess meltwater and its transient contribution to SLR under the assumption that meltwater is added to the ocean instantaneously and in its entirety. However, hydrological processes and water consumption during the transit from glacier to the ocean may affect the amount and timing of glacier runoff that eventually drains into the ocean. We hypothesize that some of the lost glacier ice may not reach the ocean at all or only at a much later stage.

In this study, we assessed the impacts of the hydrological pathway of meltwater from the glacier snouts to the ocean in the Indus Basin. With its large glacier ice reserves, relatively arid climate and large irrigation scheme, this basin provides the optimal case study for such an assessment. We coupled output from a detailed glacier model to the fully distributed hydrological model PCR-GLOBWB 2, and forced the models with bias-corrected historical and future climate data from the third phase of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3).

Our findings show that, particularly in (periods of) dry years, considerable fractions of excess glacier meltwater do not enter the ocean. The changes in hydrological stores indicate that much of it is withdrawn for surface water irrigation of cropland and eventually evaporates as a result. The increased surface water availability due to the presence of excess glacier meltwater leads to a lowering of groundwater irrigation and a reduction of the unsustainable depletion of the basin’s groundwater store. In the future, increased availability of excess glacier meltwater and increased water withdrawals due to continued climate change and socioeconomic developments exacerbate these effects. Up to the end of century, depending on the specific climate scenario, around 12% of excess glacier meltwater does not enter the ocean directly.

We conclude that not all glacier mass loss can be assumed to contribute (directly) to SLR, which may lead to overestimation of future sea level rise. Further research is necessary to estimate the breadth of these effects at a global scale, but we hypothesize that this may also play a role in other glacierized basins with semi-arid downstream regions and considerable distances between the glaciers and the ocean.
Extending Rapid Image Classification with the Picture Pile Platform for Citizen Science
Authors: Sturn Tobias , See Linda , Fritz Steffen , Karanam Santosh , McCallum Ian
Published: March 2022

Picture Pile is a flexible web-based and mobile application for ingesting imagery from satellites, orthophotos, unmanned aerial vehicles and/or geotagged photographs for rapid classification by volunteers. Since 2014, there have been 16 different crowdsourcing campaigns run with Picture Pile, which has involved more than 4000 volunteers who have classified around 11.5 million images. Picture Pile is based on a simple mechanic in which users view an image and then answer a question, e.g., do you see oil palm, with a simple yes, no or maybe answer by swiping the image to the right, left or downwards, respectively. More recently, Picture Pile has been modified to classify data into categories (e.g., crop types) as well as continuous variables (e.g., degree of wealth) so that additional types of data can be collected.

The Picture Pile campaigns have covered a range of domains from classification of deforestation to building damage to different types of land cover, with crop type identification as the latest ongoing campaign through the Earth Challenge network. Hence, Picture Pile can be used for many different types of applications that need image classifications, e.g., as reference data for training remote sensing algorithms, validation of remotely sensed products or training data of computer vision algorithms. Picture Pile also has potential for monitoring some of the indicators of the United Nations Sustainable Development Goals (SDGs). The Picture Pile Platform is the next generation of the Picture Pile application, which will allow any user to create their own ‘piles’ of imagery and run their own campaigns using the system. In addition to providing an overview of Picture Pile, including some examples of relevance to SDG monitoring, this presentation will provide an overview of the current status of the Picture Pile Platform along with the data sharing model, the machine learning component and the vision for how the platform will function operationally to aid environmental monitoring.
LatHyS hybrid simulation of the August, 10 2021 BepiColombo Venus flyby
Authors: Aizawa Sae , Persson Moa , Menez Thibault , Andre Nicolas , Modolo Ronan , Barthe Alain , Penou Emmanuel , Fedorov Andrei , Sauvaud Jean-Andre , Leblanc Francois , Chaufray Jean-Yves , Saito Yoshifumi , Yokota Shoichiro , Murakami Go , Genot Vincent , Sanchez-Cano Beatriz , Heyner Daniel , Horbury Tim , Louarn Philippe , Owen Christopher
Published: March 2022

The 2nd Venus flyby of BepiColombo has been examined and compared by the newly developed global hybrid simulation LatHyS for the Venusian environment. The LatHyS has been first validated by comparison with Venus Express observations, then using the observation from Solar Orbiter, which was located in the upstream region and both observed the same solar wind, it is applied for the Venus flyby. The simulation successfully reproduced the observed signatures and it shows that BepiColombo passed through the stagnation region of Venus, which supports the results obtained by data-analysis. In addition, we have sampled the plasma information along the trajectory and constructed the energy spectrum for three species (solar wind proton, planetary proton, and planetary oxygen ion) and possible effect due to the limited field of view is discussed. Moreover, ion escape from Venus for planetary species have been discussed and the escape rate is estimated. 
The large-scale structure of the solar wind: flux conservation, radial scalings, Mach numbers, and critical distances 
Authors: Verscharen Daniel , Bale Stuart D. , Velli Marco
Published: March 2022

One of the key challenges in solar and heliospheric physics is to understand the acceleration of the solar wind. As a super-sonic, super-Alfvénic plasma flow, the solar wind carries mass, momentum, energy, and angular momentum from the Sun into interplanetary space. We present a framework  based on two-fluid magnetohydrodynamics to estimate the flux of these quantities based on spacecraft data independent of the heliocentric distance of the location of measurement.

Applying this method to the Ulysses dataset allows us to study the dependence of these fluxes on heliolatitude and solar cycle. The use of scaling laws provides us with the heliolatitudinal dependence and the solar-cycle dependence of the scaled Alfvénic and sonic Mach numbers as well as the Alfvén and sonic critical radii. Moreover, we estimate the distance at which the local thermal pressure and the local energy density in the magnetic field balance.

These results serve as predictions for observations with Parker Solar Probe, which currently explores the very inner heliosphere, and Solar Orbiter, which will measure the solar wind outside the plane of the ecliptic in the inner heliosphere during the course of the mission.
Spectral variations of the cancellation factor for temperature investigation in the mesospheric nightglow layer
Authors: Bellisario Christophe , Simoneau Pierre , Hauchecorne Alain , Keckhut Philippe , Chane-Ming Fabrice , Listowski Constantino
Published: March 2022

The infrared emission lines observed between 80 and 100 km known as nightglow allow the investigation of dynamic phenomena such as gravity waves. These perturbations act on local temperature and density. However, the observation of the local perturbations in the nightglow layer is mainly performed by spectrally broad cameras. Swenson and Gardner (1998) introduced the cancellation factor linking relative variations of intensity with relative variations of temperature. The cancellation factor is a function of the perturbation vertical wavelength estimated from simulation that do not include spectral variations. In this study, we intend to estimate the spectral variability of the cancellation factor, in particular within the range 0.9-1.7 µm corresponding to infrared InGaAs camera, used during measurement campaigns. We describe briefly the model that resolves the vibrational states of the nightglow main source (OH). Then vertically propagating gravity waves are applied on a 1D scheme and the cancellation factor is computed based on the impact on both temperature and intensity. Spectral variations of the cancellation factor are observed and compared along the variation of the vertical wavelength.
Paleoclimate archive potential of the possibly former sub-glacial Lake Manicouagan (Canada)
Authors: Lenz Kai-Frederik , Gebhardt Catalina , Lajeunesse Patrick , Lohrberg Arne , Gross Felix , Krastel Sebastian
Published: March 2022

Lakes in formerly glaciated areas are prone to provide valuable paleoclimate archives, which contain information about the glacial processes influencing the region in which the lakes formed. The eastern Canadian provinces Québec, Newfoundland and Labrador are key areas to understand climate changes since the Cenozoic. Lake Manicouagan is a 214 Myr old impact crater lake located in the province of Québec, 220 km north of the Saint Lawrence River. This area was directly affected by the waxing and waning of the Laurentide Ice Sheet at least during the last glaciation. Here, we present high-resolution seismic data imaging the glacially excavated thalweg of Lake Manicouagan and a sedimentary sequence filling it. On that basis, we assess the potential of this sedimentary sequence as a paleoclimate archive. Our high-resolution seismic data reveal a varying shape of the valley throughout the lake. A U-shape of the valley suggests that grounded glacial erosion excavated the thalweg, whereas a narrow V-shape in some areas is indicative of pressurized subglacial meltwater erosion. We discuss three different scenarios regarding the deposition of sediment and the evolution of Lake Manicouagan during the Upper Pleistocene and Holocene: (1) the entire sedimentary sequence was deposited during and after the final retreat of the Laurentide Ice Sheet or (2) the deposits are the result of multiple glacial-interglacial cycles or (3) Lake Manicouagan was a subglacial lake during the last glaciation. We favor the third scenario because it explains missing interglacial units and erosional ice contact surfaces in the sedimentary sequence. Lake Manicouagan holds a valuable paleoclimate archive regardless of the scenario. Either the lake is a high-resolution paleoclimate record of the last 7.5 kyr, or the lake sediments contain pre-deglacial information, located in an area which was directly affected by advance and retreat of the Laurentide Ice Sheet during the Wisconsin glaciation.
Numerical modeling of a granodioritic MD-BTES test-site
Authors: Seib Lukas , Bossennec Claire , Julian Formhals , Bastian Welsch , Frey Matthis , Sass Ingo
Published: March 2022

Geothermal energy and thermal energy storages can significantly reduce the consumption of fossil energy resources by storing large amounts of heat in the subsurface, which is especially valuable when dealing with fluctuating renewable energy sources. Crystalline rocks with low hydraulic conductivity are a suitable target for such storage systems due to reduced convective heat losses. In the frame of the research project SKEWS (Seasonal Crystalline Borehole Thermal Energy Storage), a medium deep borehole thermal energy storage demonstrator with four 750 m deep borehole heat exchangers will be built at the Technical University of Darmstadt, Germany. In the preparation phase of this project, an extensive geophysical, petrophysical and structural dataset is gathered for the characterization of the project site’s subsurface.

This multi-disciplinary dataset is used for the creation of a first-order finite element method (FEM) model of the storage reservoir for thermo-hydraulic modelling. The input data includes a large petrophysical dataset for crystalline rocks and a stress-dependent Discrete Fracture Network (DFN) for the hydraulic characterization of the fractured granodioritic basement rock. For numerical analysis of the storage operation cycles, a novel co-simulation approach, using the FEM suite FEFLOW and the Modelica library MoSDH, is used to consider the interconnection between the subsurface heat-exchangers and the surface heating grid. This approach allows for detailed FEM modelling of the subsurface, while being able to take the complexity of the surface heating network into account at the same time. The model will be updated continuously by additional data during the building process of the pilot and the following experiments, to generate a highly detailed and validated numerical model of a heat storage system in a granodioritic reservoir. Ultimately, the presented workflow can serve for the accurate prediction of the performance of upscaled systems and therefore support a well-founded design process of this novel storage technology.