bluuebunny/crossref_metadata_2025 huggingface dataset:
SOFT-IO-LI: a new tool merging space and ground based lightning observations and aircraft NOx measurements.
Authors: Mackay Catherine , Sauvage Bastien , Wolff Pawel , Defer Eric , Mahnke Christoph , Petzold Andreas , Bundke Ulrich , Kennert Marcel
Published: March 2022

SOFT-IO-LI is a new tool merging space and ground based lightning observations and aircraft NOx measurements to provide a database of new parameters characterizing lightning-NOx air masses observed at the global scale, to the scientific community.

The tool takes lightning-NOx air masses measured by IAGOS (In-service Aircraft for a Global Observing System) a European Research Infrastructure for global observations of atmospheric composition using commercial aircraft. FLEXPART the Lagrangian transport and dispersion model is used, together with ERA5 reanalysis weather data from ECMWF, to perform a backward trajectory of these air masses, resulting in hourly mass residence times for lightning-NOx particles for the days prior to the flight measurements.

We will present, for IAGOS transatlantic flights, the comparison of these mass residence times with ground based NLDN (National Lightning Detection Network) and space based GLM (Global Lightning Mapper) lightning observations, as well as with ABI (Advanced Baseline Imager) cloud data. We will show that SOFT-IO-LI is capable of relating lightning events and chemical species observed in situ, in order to determine characteristics of the different lightning-related air masses.
Different microstructures in low grade shear zone formed at comparable temperatures: effect of pre and syn-kinematic fluid-rock interactions
Authors: Airaghi Laura , Alaoui Khadija , Dubacq Benoit , Rosenberg Claudio , Bellahsen Nicolas
Published: March 2022

Different microstructures and quartz recrystallization mechanisms can be observed in shear zones of granites that formed in similar greenschist-facies conditions. It is generally assumed that temperature plays a major role on quartz rheology and recrystallization. However, at low-grade conditions, fluid percolation also controls strain accommodation, by favouring the growth of weak phases as phyllosilicates. The relative importance of temperature over fluid-induced softening reactions on microstructures remains however poorly constrained mainly because comparative studies among low-grade shear zones are lacking.

The present work focusses on two granitic massifs of the central Pyrenees deformed at greenschist-facies conditions but showing different structural styles. While in Bielsa granitoid, shear zones are spaced of ~ 100-200 m, in Maladeta strain is localised in shear zones spaced of ~ 1.5 km. The Bielsa granitoid, is pervasively altered at late-Variscan time, as suggested by petrography and trace elements variations uncorrelated to strain gradients, and then at Alpine time. Alpine mylonites are made of white mica at ~ 50 % vol. Quartz poorly recrystallizes by bulging. Geochemical whole-rock analyses show systematic variations of alkali, fluid and volume with increasing strain. These results point to a pervasive fluid-rock interaction before and during deformation in Bielsa.  In contrast, in high strain rocks of Maladeta, the magmatic mineral assemblage is largely preserved. Quartz pervasively recrystallizes by sub-grain rotation and white mica is less abundant (20% vol). Consistently, geochemical whole-rock analyses show no or little major element transfer across Maladeta shear zone at constant volume. This point to a lower pre and syn-kinematic fluid-rock interaction in Maladeta than in Bielsa. Thermometry on metamorphic chlorite show similar temperature ranges for deformation in the two massifs (280-350°C).

Variations of pre-kinematic hydrothermal alteration therefore strongly affect quartz recrystallisation mechanisms and microstructures, by controlling the abundance of weak phases as white mica. This process is observed despite very similar temperature ranges. Such variations may also explain the difference of structural style in the two massifs (distributed vs localised deformation) up to an outcrop scale.
Reversibility experiments of present-day Antarctic grounding lines: the short-term perspective
Authors: Hill Emily A. , Urruty Benoit , Reese Ronja , Garbe Julius , Gagliardini Olivier , Durand Gael , Gillet-Chaulet Fabien , Gudmundsson G. Hilmar , Winkelmann Ricarda , Chekki Mondher , Chandler David , Langebroek Petra
Published: March 2022

The stability of the grounding lines of Antarctica is a fundamental question in glaciology, because current grounding lines in some locations are at the edge of large marine basins, and have been hypothesized to potentially undergo irreversible retreat in response to climate change. This could have global consequences and raise sea levels by several metres. If the Antarctic grounding lines in their current configuration are close to being unstable, a small change in external forcing, e.g. a reduction in ice shelf buttressing resulting from an increase in ice shelf melt rates, would lead to continued retreat of the grounding line due to the marine ice sheet instability hypothesis, even after the melt perturbation is reverted. Alternatively, if the system state reverts to its previous value after the perturbation is removed, we can consider the current grounding line positions to be reversible. 

Here, we initialise the ice sheets models Úa and Elmer/Ice to closely replicate the current configuration of the Antarctic Ice Sheet, in particular, the current position of the grounding lines. Under control conditions, state fluxes and ice volume changes are forced to be in balance. Using these quasi-steady state ice sheet configurations, we apply a small amplitude perturbation in ice shelf melt rates by imposing an increase for 20 years in the far-field ocean temperature. After 20 years the melt rate perturbation is returned to zero, and model simulations are continued for a further 80-year recovery period. During this recovery period we examine the trend in ice flux and grounding line position, i.e. do they tend towards their previous values, or do they move further away from their initial state? Our results suggest that the global grounding line around Antarctica begins to reverse to its former state after the perturbation is removed. However, we find the reversibility and response times of grounding lines to a small perturbation in ice shelf buttressing varies between individual basins across the ice sheet.

This work is part of the TiPACCs project and complements an overview presentation on the reversibility of present-day Antarctic grounding lines (EGU22-5176) as well as a presentation exploring long-term reversibility experiments (EGU22-7885).
On the dynamics of rock glaciers in marginal mountain permafrost (Retezat Mountains, Romania).
Authors: Sirbu Flavius , Poncos Valentin , Strozzi Tazio , Onaca Alexandru , Teleaga Delia , Birtas Dan
Published: March 2022

Active rock glaciers (RG) are associated with mountain permafrost occurrence, and in the last years, remote sensing has been widely used to assess their dynamics. However, the use of remote sensing in determining the dynamics of slow-moving rock glaciers, from areas with patchy permafrost, controlled by site-specific conditions still remains a significant challenge. One such area is the central part of Retezat Mountains in the Southern Carpathians, Romania.

Here we present and discuss the results obtained by using Persistent Scatterer Interferometry (PSI) on Sentinel-1 images between 15.5.2015 and 27.10.2020. The results were validated with 26 in situ measurements with a Topcon Hiper V Differential GPS connected to the ROMPOS network for real-time corrections and millimetric accuracy. Also, the spatial distribution of RG dynamics was compared with a predicted map of permafrost distribution.

The results show that the displacement rates are low, at around 10mm/year. Out of the 48 investigated RGs, only two have displacement rates between 10 and 20mm/year, 14 show displacement of up to 10mm/year, and 32 don’t show any (measurable) displacement. However, the displacement rates are found to cover only part of the RGs, with stable areas being identified on all of them. When comparing the distribution pattern of the displacement rates, there is a good overall agreement with the modelled permafrost distribution, further suggesting that rock glacier dynamics are influenced by permafrost occurrence in marginal conditions.
A century-long homogenized dataset of near-surface wind speed observations since 1925 rescued in Sweden, HomogWS-se
Authors: Zhou Chunlüe , Azorin-Molina Cesar , Engström Erik , Minola Lorenzo , Wern Lennart , Hellström Sverker , Lönn Jessika , Chen Deliang
Published: March 2022

The main reasons for the lack of data rescue and homogenization of early near-surface wind speed (WS) observations before the 1960s are insufficient manpower and lack of funding. Funding from the Swedish Research Council for Sustainable Development (FORMAS) for a joint project (ref. 2019-00509) ‘Assessing centennial wind speed variability from a historical weather data rescue project in Sweden (WINDGUST)’ among the Swedish Meteorological and Hydrological Institute, the University of Gothenburg, and the Spanish National Research Council, presents a great opportunity to rescue and homogenize the early paper-based WS data in Sweden, for creating a century-long homogenized WS dataset.

Here, we rescued paper-based WS records dating back to the 1920s at 13 stations in Sweden and established a four-step homogenization procedure to generate the first 10-member centennial homogenized WS dataset (HomogWS-se) for community use. First, background climate variation in the rescued WS series was removed, using a verified reanalysis series as a reference series to construct a difference series. A penalized maximal F test at a significance level of 0.05 was then applied to detect artificial change-points. About 38% of the detected change-points were confirmed by the known events recorded in metadata, and the average segment length split by the change-points is ~11.3 years. A mean-matching method using up to five years of data from two adjacent segments was used to adjust the earlier segments relative to the latest segment. The homogenized WS series was then obtained by adding the homogenized difference series back onto the subtracted reference series. Compared with the raw WS data, the homogenized WS data is more continuous and lacks significant non-climatic jumps. The homogenized WS series presents an initial WS stilling and subsequent recovery until the 1990s, whereas the raw WS fluctuates with no clear trend before the 1970s. The homogenized WS shows a 25% reduction in the WS stilling during 1990-2005 than the raw WS, and this reduction is significant when considering the homogenization uncertainty from reference series. The homogenized WS exhibits a significantly stronger correlation with the North Atlantic Oscillation (NAO) than that of the raw WS (0.54 vs 0.29). These results highlight the importance of the century-long homogenized WS series in increasing our ability to detect and attribute multidecadal variability and changes in WS. HomogWS-se will be released on an open-access data repository for community uses, including studying WS changes, assessing model simulations, and constraining future projections of WS and wind energy potential. The proposed homogenization procedure enables other countries or regions to rescue their early climate data and jointly build global long-term high-quality datasets.
Fracture energy variations of rocks: a mechanical investigation
Authors: Guggisberg Antoine , Lebihain Mathias , Violay Marie
Published: March 2022

Crack propagation is critical for the assessment of the strength of rocks. Linear Elastic Fracture Mechanics (LEFM) theory is commonly used to describe its propagation. However, the variation of the fracture energy, its key parameter, is generally poorly understood as its experimental measurements are influenced by temperature, stress biaxiality, and rupture velocity. This indicates other dissipative processes may occur in the vicinity of the crack.

We conduct Modified Ring Tests (MRT) on Carrara marble to investigate these mechanisms. MRT provides stable mode I crack propagation under controlled velocity and stress biaxiality conditions. Coupled with a compliance method calibrated through Finite Element Method (FEM), we obtain multiple local measurements of the fracture energy within a single test. FEM also provides estimation of stress biaxiality levels as well as higher order terms of the Williams’ expansion of the stress field.

The method is validated on PMMA through Digital Image Correlation (DIC) techniques. Experiments on Carrara marble show that the stress biaxiality can directly influence the fracture energy measurements. A microscopic investigation on marble is performed to look for micro-mechanisms which may cause observed variations of fracture energy.
Root water uptake recovers during the night likely due to micorscopic redistribution of water
Authors: van Dusschoten Dagmar , Muellers Yannik
Published: March 2022

Root water uptake (RWU) is a dynamic process that depends on the interplay of evaporative demand by the shoot and water availability for the roots in the soil. Water availability may be limited due to negative bulk water potentials but potentially even more so by highly negative soil water potentials close to the roots when the water around the roots is depleted more rapidly than can be supplied by the bulk soil. Additionally, root-soil contact may be reduced due to root shrinkage, or uptake may be reduced because of decreased internal conductivity.

Whereas flows in the bulk of the soil can generally respond slowly to changes, on a microscopic scale (<1 cm3) flows can respond faster. Here we performed experiments using the Soil Water Profiler (van Dusschoten, 2020) which can monitor changes of the soil water content with a vertical resolution of 1cm and a sensitivity of about 5 µl. These measurements were combined with a psychrometer such that the development of water potential gradients between the shoot and the bulk soil could be followed dynamically. Our experiments show that root water uptake responds rapidly to light changes, here induced by a programmable, high intensity LED panel and that the shoot driven uptake causes depth dependent soil water depletion that becomes  highly dependent on the local bulk soil water content and root distribution when the soil dehydrates. However, this does not seem to fully explain our results which would benefit from knowledge of the water potentials close to the root. These can be estimated using the matrix flux concept.

One of the interesting aspects that can potentially be explained using this approach is what happens during the night. Whereas we can observe a small upward movement of water in a soil column with a plant, this causes only minimal changes of the average, vertical soil water potentials. However, horizontal movement along the soil water gradients towards the roots would flatten the local, radial gradients and cause a much more significant increase of the soil water potential close to the roots. The next morning, initial RWU is significantly higher than at the end of the prior day, but rapidly decreases again, sometimes within an hour. This would indicate that local water availability, which can be rapidly reduced, is the main driver of this process. Alternatively, root shrinkage or other dynamic, plant characteristics come into play.

We will show data acquired on maize and Faba beans over periods spanning a few days during in which the plants slowly deplete water resources and constantly change their water uptake profiles and rates depending on above ground and below ground conditions. Focus will be on what happens during the night.
The potential of urban soils for carbon neutral cities
Authors: Karvinen Esko , Järvi Leena , Viskari Toni , Havu Minttu , Kuuri-Riutta Olivia , Rauhamäki Pinja , Soininen Jesse , Kulmala Liisa
Published: March 2022

Urban areas are notable sources of atmospheric CO2 and cities are currently setting up climate programs with the aim of carbon neutrality in the near future. For example, two major cities in Southern Finland, Helsinki and Turku, have set their targets for 2035 and 2029, respectively. Carbon neutrality can be achieved by reducing carbon emissions, compensating them, and / or strengthening carbon sinks in urban vegetation and soils, the last of which is often deemed the most cost-efficient option. However, the current understanding of biogenic carbon cycling in urban environments is based on dynamics observed in more well-known ecosystems such as forests and agricultural lands. Urban ecosystems differ from non-urban areas in terms of temperature, precipitation and water cycling, pollution, and the level of human-induced disturbance. Thus, there is a need for observations on urban carbon to accurately model and estimate the carbon sinks and stocks in urban green space.

We aimed to monitor urban biogenic carbon cycle with an extensive field campaign carried out around the SMEAR III ICOS station in 2020–2022, accompanied by a few satellite sites around the capital region of Finland. In this presentation, we will show soil carbon pools and the dynamics of soil respiration at five different types of urban green space: a managed park lawn with and without trees, small urban forest, apple orchard, and street tree site. Soil respiration was measured with both regularly repeated manual chamber measurements and automatic chambers throughout two growing seasons. Soil carbon stock was estimated by soil samplings conducted in 2020 and 2021. We investigate the role of different drivers in soil CO2 emission at the various urban green space types and compare those to corresponding metrics measured in non-urban areas. In addition, we test the applicability of Yasso model to simulate the soil carbon dynamics in urban areas.
Accuracy of the relative humidity sensor MEDA HS onboard Perseverance rover
Authors: Hieta Maria , Polkko Jouni , Jaakonaho Iina , Genzer Maria , Tabandeh Shahin , Rodríguez Manfredi José Antonio , Tamppari Leslie , de la Torre Juarez Manuel
Published: March 2022

MEDA HS is the relative humidity sensor on the Mars 2020 Perseverance rover provided by the Finnish Meteorological Institute (FMI). The sensor is a part of Mars Environmental Dynamic Analyzer (MEDA), a suite of environmental sensors provided by Centro de Astrobiología in Madrid, Spain.

The accuracy requirement for MEDA HS relative humidity was ±10% RH for temperatures above -70 ºC, and ±20% RH for temperatures between -83...-73 ºC. Dynamic range from 0 to 100% RH shall cover the whole Martian temperature range from -83 ºC to -3 ºC. However it must be noted that during the daytime when the relative humidity drops close to zero, the readings are not scientifically meaningful due to the large relative uncertainty.

MEDA HS flight model was tested and calibrated in Mars-like dry environment at FMI together with flight spare and ground reference models from +22 ºC to -70 ºC and in saturation conditions from -40 ºC down to -70 ºC. Further, the MEDA HS flight model final calibration is complemented by calibration data transferred from an identical ground reference model which has gone through extensive humidity calibration test campaign at DLR PASLAB. The MEDA HS has been calibrated to full relative humidity range between -70 to -40 ºC in CO2 in the pressure ranges from 5.5 to 9.5 hPa, representative of Martian surface atmospheric pressure, and partial range up to +22 ºC. For lower temperatures the results are extrapolated.

The complex analysis of the MEDA HS measurement uncertainty has now been finalized and the results are presented in the conference. It has been found that the sensor exceeds the design requirements and will provide high accuracy relative humidity measurements from the Martian surface to provide important meteorological observations and to support MEDA and other M2020 investigations.
Most effective measures to combat heat indoors
Authors: Corpel Lisanne , Solcerova Anna , de Vries Samuel , Kluck Jeroen , van der Strate Edwin , Mesdaghi Batoul , van Walsum Ronald
Published: March 2022

Due to climate change, homes are increasingly becoming unacceptably hot, especially during heat waves and therefore create health risks for citizens. To combat heat indoors, active cooling systems, such as air conditioning, are very effective. However, this also comes with negative effects such as increasing energy demand, the use of cooling liquid and releasing heat into the surrounding outdoor environment. Housing associations in particular want to know how they can take possible overheating into account when renovating homes (e.g., for the energy transition). That is why, on behalf of the national government, it was investigated which characteristics on three different levels (the urban area, the building, and the inhabitant) make homes especially vulnerable to heat and which measures can limit that heat.

Desk research (literature study, simulation study and panel discussion) has been carried out in which different situations and the effectiveness of heat-reducing measures have been compared and ranged. For two common housing types in the Netherlands that cover a substantial part of the Dutch housing stock owned by housing corporations, the hourly temperature has been simulated for a representative summer. This was done for many combinations of factors like: green surroundings or urban heat islands effects, solar heat gain (windows, sunscreens), insulation, green roofs, ventilation and use of curtains.

The research shows that the entrance of sun in particular determines overheating of houses and that measures that reduce solar heat gain therefore have the greatest positive effect. Orientation of the house, location and size of windows, and sunscreens are key factors in preventing heat gain. Purge ventilation during the night is the second most important measure, as this helps cooling the house. For this reason night time city temperatures are important. Better insight in those urban night time temperatures is required. The study also showed that human behaviour is an important factor. Correct ventilation and use of sunscreen have a large impact on overheating of houses. Finally, the focus on thermal insulation without sufficient attention on ventilation greatly increases the risks of overheating. The outcome of the research is presented in a guideline for housing associations that ranges the measures in very effective, medium effective and undesirable actions.
Transferable surrogate models based on inductive biases of graph neural networks for water distribution systems
Authors: Kerimov Bulat , Tscheikner-Gratl Franz , Steffelbauer David
Published: March 2022

Water utilities tackle various problems in planning and operating their systems with complex and computationally expensive hydraulic models, i.e., maximizing system resilience, fault isolation, risk assessment, optimal pump scheduling, or water loss reduction via pressure management. To meet limited computational budgets, engineers employ less resource-intensive surrogate models. Current surrogate models based on artificial neural networks deliver similar accuracies as hydraulic models with lower computational costs. However, they require retraining when applied to an unknown water distribution system, which increases their computational load and limits their general applicability. Recent advancements in graph-based machine learning address these limitations. Graph neural networks (GNNs) naturally connect with the network elements (e.g., pipes and valves with edges, junctions, and tanks with vertices)  of water distribution systems, proving themselves to be a promising candidate for surrogate modeling. Once trained on a specific network to be a surrogate model, GNNs possess inductive biases that allow transferability to an unseen topology. In this work, we adopted a demand-driven simulation of a water distribution system in a graph machine learning setting. We built a synthetic dataset of demand-driven simulation with EPANET, founded on the example of real-world water distribution systems, and trained an attention-based GNN to emulate the hydraulic simulator. The accuracy was evaluated inductively on an unseen larger-sized water distribution network. We observed that the model showed promising transferability results to a larger network without the need for additional re-training on the unseen topology.
Cloud albedo's hemispheric asymmetry: why is the Southern Ocean cloudier?
Authors: Blanco Joaquin , Caballero Rodrigo , Bony Sandrine , Datseris George , Stevens Bjorn , Kaspi Yohai , Hadas Or
Published: March 2022

Recent work has shown that the hemispheric asymmetry in cloud albedo is maximized over extratropical oceans: the Southern Ocean exhibits greater climatological cloud albedo than its northern counterpart. We investigate the dynamical causes of such asymmetry by evaluating how albedo responds to a series of cloud controlling factors, namely: sea surface temperature (SST), pressure velocity at 500mb (ω500), Estimated Inversion Strength (EIS), Marine Cold Air Outbreak (MCAO) index, SST-T2m (ΔTsfc), and surface wind (Vsfc). A cloud albedo parameterization applied to MODIS optical thickness and fractional cloud cover is used in conjunction with ERA-Interim reanalysis products over oceanic points in the 50°–65° bands and for a 15-year period. Cloud properties are bin-averaged according to the range of variability of each predictor, using a 1-day timescale. We find that although ω500 strongly controls cloud albedo, it cannot explain the observed hemispheric asymmetry. Instead, we find that surface wind most skillfully explains the hemispheric albedo difference, due to the much greater winds in the Southern Ocean. We further show that Vsfc is not only a predictor of cloud albedo but it also controls physical processes in the boundary layer such that stronger winds ultimately lead to thicker and more horizontally extended cloud decks. The interhemispheric albedo asymmetry is significantly reduced in winter, responding to a strengthening of winds in the North Atlantic and Pacific Oceans during this season. Our findings have significant implications regarding GCM cloud biases over the Southern Ocean for the current climate, as well as for cloud feedback in a warming planet.
The long-term sea-level commitment from Antarctica
Authors: Klose Ann Kristin , Coulon Violaine , Pattyn Frank , Winkelmann Ricarda
Published: March 2022

With a sea-level rise potential of 58 m sea-level equivalent, the future evolution of the Antarctic Ice Sheet under progressing warming is of importance for coastal communities, ecosystems and the global economy. Short-term projections of the sea-level contribution from Antarctica in the recent ice sheet model intercomparison ISMIP6 range from a slight mass gain (-7.8 cm) to a mass loss of up to 30.0 cm sea-level equivalent at the end of the century under Representative Concentration Pathway 8.5 (Seroussi et al., 2020, Edwards et al., 2021). However, due to high inertia of the system, the ice sheet response to perturbations in its climatic boundary conditions are rather slow. Consequences of potentially triggered unstable ice loss due to positive feedback mechanisms may therefore play out over long timescales (on the order of millennia).  Projections of the committed sea-level change at a given point in time, that is the sea-level change which arises by fixing the climatic boundary conditions and letting the ice sheet evolve over several millennia, might differ substantially from the sea-level change expected at that point in time (Winkelmann et al., 2022).

Previous assessments of the long-term contribution to sea-level rise from the Antarctic Ice Sheet have been primarily restricted to a single model and have rarely explored the full range of intra- and inter-model parameter uncertainties. Here, we determine the long-term, multi-millennial sea level contribution from mass balance changes of the Antarctic Ice Sheet by means of two ice sheet models, the Parallel Ice Sheet Model (PISM) and the fast Elementary Thermomechanical Ice Sheet (f.ETISh) model. More specifically, we assess the response of the Antarctic Ice Sheet to atmospheric and oceanic forcing conditions derived from state-of-the-art climate model projections available from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) under the Shared Socioeconomic Pathways SSP5-8.5 and SSP1-2.6 available until the year 2300. The sea-level commitment from the Antarctic Ice Sheet is quantified by branching off at regular intervals in time and running the ice sheet models for several millennia under fixed climate conditions. Key uncertainties related to ice dynamics as well as to interactions with the bed, atmosphere and ocean are taken into account in an ensemble approach.
A model for continental-scale water erosion and sediment transport and its application to the Yellow River Basin
Authors: Jiang Cong , J. R. Parteli Eric , Shao Yaping
Published: March 2022

A large-scale water erosion and sediment transport model is introduced and applied to predict continental-scale hydrological transport processes at the Yellow River Basin in China. Our model couples the Atmospheric and Hydrological Modelling System (AHMS) with the CASCade 2 Dimensional SEDiment (CASC2D-SED), by considering a scale-adaptive water erosion parameterization and eight possible flow directions of the channel routing model. Here, the AHMS-SED is applied to simulate the water erosion processes in the Yellow River Basin over 10 years with a spatial resolution of 20 km. The simulated daily sediment fluxes from four major hydrological stations along the Yellow River (namely, Tangnaihe, Lanzhou, Toudaoguai and Huayuankou) are compared with corresponding observations. There is a quantitative agreement between these observations and modelling results at all stations. Our results demonstrate the good performance of the new scale-adaptive parameterization and the integrated AHMS-SED, paving the way for the studies of water erosion and sediment transport at large scales. We also show how of our numerical simulations can be used to predict the evolution of sediment transport in the Yellow River Basin under consideration of specific climate change scenarios.
Revisiting the Moisture Budget of the Mediterranean Region in the ERA5 Reanalysis
Authors: Tootoonchi Roshanak , Bordoni Simona
Published: March 2022

Recent studies based on both regional and global climate models identify the Mediterranean region as a climate change hotspot, characterized by a marked rise in temperature and precipitation reduction. The drying tendency cannot be simply ascribed to the thermodynamic “wet-get-wetter” scaling, indicating an important role for circulation changes. However, exact mechanisms remain debated.  

In this study, we revisit the moisture budget in the Mediterranean, following previous work, using the 5th generation ECMWF atmospheric reanalysis (ERA5) data from 1979 to 2021, to: (1) explore how the different terms in the budget contribute to the observed climatological net precipitation patterns in the annual and seasonal means both over land and over the ocean, (2) to assess their variability on different time scales, and (3) to expose any trend that might be present in this dataset.

Results will be compared to those reported in the existing literature and will guide future analyses of projected trends in global climate models.
Full three-dimensional simulations of snow-avalanche flow with two-phase, incompressible, granular μ(I) rheology using OpenFOAM / interFoam 
Authors: Jarosch Alexander H. , Jóhannesson Tómas , Hákonardóttir Kristín Martha , Pétursson Hafþór Örn
Published: March 2022

Protective measures against snow- and landslides are widely used to improve the safety of settlements in avalanche-prone areas. Modelling of granular flow against obstructions is important for the design of catching and deflecting dams and other protective measures in run-out zones and for hazard zoning both below protective measures and in general for avalanche paths with complex terrain geometry. We describe the implementation of a two-phase (granular material and air), incompressible granular-flow rheology for the OpenFOAM / interFoam computational fluid dynamics software system based on the recently developed μ(I) granular rheology. The model has been calibrated with observations from eight large Icelandic avalanches and shown to reproduce the observed shapes of the avalanche deposits in the run-out zones, and some available radar measurements of avalanche velocities, with observed and estimated values for avalanche volume and release depth in the starting areas. Several of the avalanches are from paths with complicated geometries, including deep gullies and ridges that split the avalanche in the run-out zone, which indirectly provides constraints on the simulated flow dynamics. The model represents an important improvement with respect to depth-averaged models for snow-avalanche flow in complicated terrain geometries as it is able to simulate the full three-dimensional flow at impact with obstacles such as catching and deflecting dams and braking mounds, including the formation and time-dependent development of hydraulic jumps. Thus, splashing and airborne jets formed at impact with obstacles and landing of granular material on the terrain below obstacles can be modelled, as well as the formation of wedges behind the upstream face of dams or mounds, variations of the flow direction with depth within the flow and thus shearing overflow of the upper part of avalanches at impact with deflecting dams that deflects the main avalanche flow, the effect of the steepness of the upper face of catching and deflecting dams, and the effect of the curvature of the axis of deflecting dams and many other aspects of the flow against obstructions. Some examples of simulations of the flow of design avalanches against protective dams in Iceland will be shown in the presentation.
Comparison of Impulse response function and Machine learning models for use in groundwater level short to medium term future projections in the Baltic states
Authors: Jemeļjanova Marta , Bikše Jānis , Kalvāns Andis
Published: March 2022

Recent years have seen several major groundwater drought instances in Europe, increasing the interest in their research and future predictions. Modeling methods can be used to explore groundwater drought risk in near and medium term future using climate projection data sets as an input. Therefore an optimal modeling approach has to be chosen according to the available data and modeling capacity of the historic series. 

We  explore two approaches for modeling groundwater level time series: Transfer function-noise models with Impulse response functions (TFN-IRF) and machine learning (ML). In both approaches, daily meteorological variables are used as an input and models are calibrated against historical groundwater level observations. 

TFN-IRF input parameters are daily precipitation and potential evapotranspiration. Other time series data, such as groundwater abstraction, can be added to potentially increase the fit. Machine learning models can, in addition to the aforementioned, benefit from a wider variety of site parameters, including derived parameters (e.g., meteorological indices), however at the expense of increased data collection effort. In addition, the obscure input data interpretation in ML methods can erode the trust in these models. In this study, only the most basic meteorological parameters - precipitation, temperature - and derived parameters such as potential evapotranspiration were used. 

We draw from an extensive groundwater level monitoring database of more than one thousand monitoring wells from three Baltic countries. The study provides an insight into differences between the two modelling approaches, keeping in mind the limitations of future projection data.

This research is funded by the Latvian Council of Science, project “Spatial and temporal prediction of groundwater drought with mixed models for multilayer sedimentary basin under climate change”, project No. lzp-2019/1-0165.
Interactions between compound extreme events and technological change over rice yield in China as an opportunity to adapt. 
Authors: Quiroga Sonia , Suárez Cristina , Wang Haoran , Hernanz Virginia
Published: March 2022

Global climate change and more frequent and severe compound events poses a threat to agricultural productivity in China with important impacts on human development, and social stability. China has 18% about 25% of the world's grain production--accounting rice up to 34% of it.  Much of the existing research has focused on the important average effects of climate warming on rice yields showing. However, there is evidence about nonlinear interactions when compound events being present (ie. frost and heavy rainfall). As some of the major natural disasters in China at present, the overall spatial extent of drought and floods in China are expected to change significantly in the future, with more extreme events resulting. This paper analyzes total factor productivity growth in China's rice production to compute technological progress as an adaptative factor for total factor productivity growth response to compound extreme events. Labor inputs, education, fertilizer application and energy use are considered as control factors, jointly with socio-economic factors the the adoption of agricultural technology by growers. The Levinsohn-Petrin consistent semi-parametric estimation method was used to empirically analyze input-output panel data on rice yields in 30 Chinese provinces from 1990 to 2019 and to simulate the level of rice yield at the end of the 21st century under different RCPs scenarios. The model has stronger prediction ability for the central-eastern and southern production areas of China and reveals that rice yields may show opportunities of increase under average conditions for some climate scenarios, but it shows a bigger risk and vulnerability to compound extreme events.

 
Multistatic meteor radar observations and tomographic retrievals to assess the spatial and temporal variability of 3D winds on regional scales at the mesosphere and lower thermosphere
Authors: Stober Gunter , Liu Alan , Kozlovsky Alexander , Qiao Zishun , Tsutsumi Masaki , Gulbrandsen Njål , Nozawa Satonori , Lester Mark , Kero Johan , Belova Evgenia , Mitchell Nicholas
Published: March 2022

Multistatic meteor radar observations offer the possibility to investigate the short-term variability at the mesosphere and lower thermosphere on regional scales. Here we present preliminary results of spatially resolved 3D winds and their corresponding horizontal wavelength spectra using the Nordic Meteor Radar Cluster and CONDOR in Chile with a recently developed 3DVAR+div retrieval. The new retrieval provides for the first time a physically consistent solution for the vertical winds that conform the continuity equation. Based on these spectra we can separate the spatial scales that are driven by rotational modes from those dominated by divergent gravity waves. Furthermore, we present the first results of momentum flux spectra derived from these observations on a daily basis.
High-alpine Glacier Record Influenced by Melting
Authors: Huber Carla , Eichler Anja , Mattea Enrico , Brütsch Sabina , Jenk Theo , Gabrieli Jacopo , Barbante Carlo , Schwikowski Margit
Published: March 2022

High-alpine glacier ice cores are useful natural archives and allow access to continuous pollution records back to the pre-industrial era. This is especially true for glacier ice cores drilled in the European Alps, which are located close to the anthropogenic emission sources. However, due to global warming glaciers are increasingly affected by melting, subsequently altering the information stored in the natural archive.
Here we show the comparison between major ion records from shallow ice cores drilled on Grand Combin (4123 m a.s.l., Swiss Alps) in 2018 and 2020. Both shallow ice cores were dated applying annual layer counting using stable isotopes and concentrations of major ions (e.g., ammonium). Excellent agreement between both records was observed for the stable isotopes in the overlapping time period 2011-2018. However, in the core collected in 2020, effects of melting were detected for the major ion concentrations before 2016. As an extreme example: sulfate is significantly depleted in the years 2011-2016 in that core, losing 61% of the ion content in comparison with the core collected in 2018. Even for ammonium, which is the most preserved with only 16 % reduction, the seasonal cycle disappeared. The elution sequence matches the results of Avak et al. (2019).

Meteorological data indicate that mean annual air temperatures of 2019 and 2020 were not significantly higher than in the previous years. Instead, we attribute the melt damage in the 2020 core to a two-week period in summer 2019 with temperatures continuously above 0°C. Our finding that such a disturbance through melting can occur in only two years emphasises the critical state of these glacier archives. Thus, preserving these archives is important and a time sensitive matter.

 

REFERENCES

Avak, S. E., Trachsel, J. C., Edebeli, J., Brütsch, S., Bartels‐Rausch, T., Schneebeli, M., Schwikowski, M. and Eichler, A.: Melt‐induced fractionation of major ions and trace elements in an Alpine snowpack, Journal of Geophysical Research F: Earth Surface, 124(7), 1647-1657, https://doi.org/10.1029/2019JF005026.
Climate change detection and attribution in extreme precipitation using compact representations
Authors: Szemkus Svenja , Friederichs Petra
Published: March 2022

In the subproject CoDEx of the BMBF climXtreme project , we are investigating different data compression techniques to detect and attribute changes in the frequency and severity of extreme weather events in a changing climate. Especially for local processes on the atmospheric mesoscale, climate change signals are often masked by additional variability, resulting in poor signal-to-noise ratios. Therefore, these only become visible when the data are analyzed in compressed form. Our focus is on unsupervised learning approaches such as principal component analysis developed specifically for extremes. We focus on extreme precipitation over Germany and analyze how different data compression techniques can be used in a detection and attribution (D&A)study. Besides others, we use the approach proposed by Cooley and Thibaud (2019) on the decomposition of the tail pairwise dependence matrix, as an analogue to the covariance matrix for extremal dependence. Furthermore, we use a dualtree wavelet transform to study changes in extreme precipitation at different scales and different orientations. A D&A study will provide deeper insight into the effects of climate change on extreme precipitation events. 
Using temperature and precipitation combined to detect and attribute aerosol effects on large-scale climate
Authors: Roesch Carla , Ballinger Andrew , Schurer Andrew , Hegerl Gabriele
Published: March 2022

Anthropogenic aerosols (AER) have been found to impact both Earth’s energy and water cycle. Like greenhouse gases (GHG) they are an anthropogenic climate forcing, which will play an important role in shaping Earth’s future climate. To improve future predictions, it is, therefore, fundamental to understand and quantify the individual impacts these two forcings have on the climate system. This can be achieved by using detection and attribution methods facilitating the differentiation of the response of the climate system to different forcings.

Separating the signal of individual anthropogenic effects related to greenhouse gas and aerosol emissions is hindered by large uncertainties in the response to aerosol forcing in different climate models. Thus, in this study we investigate a joint change in temperature and precipitation to reduce the signal-to-noise ratio and better constrain the impact of anthropogenic aerosols since 1979. Building on previous findings on how aerosols affect climate, we focus on shifts in tropical precipitation by tracking wet/dry regions as well as changes in the interhemispheric temperature asymmetry (ITA) and the diurnal temperature range (DTR), due to its unique response to different radiative forcings. Individual fingerprints are derived from large-ensembles of historical single-forcing simulations from three models that are part of phase 6 of the Coupled Model Intercomparison Project (CMIP6).

We find inter-model agreement in the trends for wet regions, ITA, and DTR in single-forcing and historical (all-forcing) runs. Contrasting trends in these time series derived for AER-only and GHG-only simulations suggest that aerosols have offset some of the greenhouse gas induced precipitation and temperature changes in the past.  While a drying in the dry regions can be observed for GHG-only simulations, inter-model agreement is not found for aerosols. Early results show an improved constraint on the detection of a greenhouse gas signal when investigating a joint change in wet and dry regions, which is refined by including the other variables and indicators.
Insight into the mechanics of seismic swarms triggered by water-reservoir impoundment
Authors: Orlecka-Sikora Beata , Lizurek Grzegorz , Rudziński Łukasz , Olszewska Dorota , Shirzad Taghi
Published: March 2022

Water Reservoir Impoundment (WRI) can trigger swarms and strong earthquakes under favorable geological conditions. Although many studies have investigated the relationship between the pore pressure changes due to WRI and the observed seismicity, hydromechanical models that explain the observed processes are rare. We investigated the role of hydromechanical interactions in producing earthquake swarm bursts under pore pressure changes, using the Song Tranh 2 Water Reservoir Impoundment (WRI) in Vietnam as an example. Our work contributes to the investigation of the physical mechanisms responsible for earthquake swarms. We find that the seismic swarms accompanying WRI represent the shearing of a damage fault zone composed of multiple interfering surfaces. The source parameters of seismic swarms image the quasi-dynamic weakening of the fault damage zone. Fault weakening during the propagation of seismic rupture is a key process governing the earthquake rupture dynamics and energy partitioning. Quasi-dynamic weakening evolution means here that it captures histories of fault zone slip, including the seismic slip phases within this zone, and slip weakening shows a memory effect that fades with time. Based on the calculated traction evolution within the damage zones in ST2 we estimate the effective slip-weakening distance , which is a significant parameter for characterizing a fault-weakening process. The observed quasi-dynamic weakening process is fluid driven at slower migration velocity of the order of meters/day but over short duration the migration of seismicity accelerates to velocities of kms/day. We therefore conclude that the seismic swarms are driven by a combination of fluid pressurization and stress perturbation through aseismic slip induced by pore pressure changes.

This work was partially financed by National Statutory Activity of the Ministry of Education and Science of Poland No 3841/E-41/S/2021 (BOS, ŁR, TS, GL), and Polish National Science Centre grant No UMO-2017/27/B/ST10/01267 (GL), and co-financed by the European Union and the Polish European Regional Development Fund grant No POIR.04.02.00-14-A003/16 (DO)