bluuebunny/crossref_metadata_2025 huggingface dataset:
Paleoseismic Investigation along the straight section of the central Altyn Tagh fault and its constrain on the rupture history
Authors: Han Longfei , Liu-Zeng Jing , Hu Guiming , Klinger Yann , Wang Wenxin , Wang Heng , Xu Jing , Zhang Bo , Gao Yunpeng , Wang Zijun , Zeng Xianyang , Liu Xiaoli
Published: February 2023

Paleoseismic records are essential for constraining the earthquake recurrence behavior of active faults and evaluating the rupture history. However, paleoseismic studies on the central Altyn Tagh fault (ATF) are still scarce, and previous studies indicate that this fault section with simple geometry is not periodic. In addition, paleoseismic data from two sites along central ATF reveal different amounts of paleoearthquakes and present discordant in time. Therefore, we conducted paleoseismic studies and documented six reliable paleoseismic events at the LaPeiQuan site along the straight section of the central ATF. The results indicate that the most recent event is a small earthquake with a tiny vertical offset. The data A.D. (1752–1880) yr (event A) is significantly later than the last event along the Xorkoli section. The penultimate event at the LaPeiQuan site is a large earthquake for the ages of this event B is A.D. (667–764) yr (event B), which is consistent with the Xorkoli site and Aksay double bend site, producing at least 140 km rupture. In addition, the large vertical offset measurement from the deformed sediment of event B also supports its large one. The ages of Event D are discordant with the adjacent paleoseismic sites. The ages of Event C, Event E and Event F are still in process. The reason earthquake histories are inconsistent may be that small-scale geometrical complexities can prevent earthquake rupture propagation.
Supporting subsurface preferential flow in a small forested catchment from geophysical data and hydrological modelling
Authors: Mary Benjamin , Kaffas Konstantinos , Censini Matteo , Manca di Villahermosa Francesca Sofia , Dani Andrea , Verdone Matteo , Preti Federico , Trucchi Paolo , Penna Daniele , Cassiani Giorgio
Published: February 2023

Subsurface flow at the hillslope scale is a critical process responsible for water redistribution and transport of nutrients to the stream. Despite its hydrological importance, understanding the mechanisms governing subsurface flow generation is still challenging. 

We investigated the case of a small forested catchment located in the Apennine mountains, Tuscany, central Italy, which experiences shallow lateral downslope water redistribution resulting in substantial differences in vadose zone water supply along the hillslope. We developed an integrated experimental and modelling approach in order to shed some light on the role of the subsurface structure on the generation of hillslope-scale subsurface flow in the study catchment.  

We used a combination of methods sensitive to different soil properties. Ground Penetrating Radar (GPR) surveys show a complex response reflecting the interplay of different factors such as the presence of rocks, banks and counterslope in the near-surface and thus highlighting the very heterogeneous soil that may control water flow patterns. Several Electromagnetic (EM) mappings were conducted and show top-down hillslope variations of soil electrical conductivity revealing that trees located at the footslope and that experience longer vegetative periods might benefit from larger soil moisture content compared to the smaller trees located on the hillslope top. Similar observations are made from the two parallel top-bottom hillslope Electrical Resistivity Tomography (ERT) transects. 

The geophysical results will be integrated into hydrogeological simulations using the CATHY model for different scenarios (e.g., initial soil moisture, preferential flow paths, drainable porosity, soil properties, bedrock topography or stratification of soils) to explore the main drivers for subsurface preferential flow. 
Obtaining pore size distribution of porous stone using non-Newtonian fluids
Authors: Slavík Martin , Lanzendörfer Martin
Published: February 2023

The characteristics of the pore space are considered a key factor in susceptibility of the stone to various weathering processes. The pore size distribution can be determined by a number of methods such as mercury intrusion porosimetry or computed topography. None of them is without disadvantages, namely the mercury intrusion porosimetry – despite being very popular – is the object of some critics due to the harmful effects of the mercury. Within the last decade, there has been a growing interest in the use of non-Newtonian fluids for obtaining the pore size distribution of the porous materials (see, e.g., Abou Najm and Atallah, 2016; Rodríguez de Castro et al., 2016). The principle exploits the behaviour of non-Newtonian fluids whose viscosity changes with shear rate. This is manifested by the fact that saturated flow of different fluids under different hydraulic gradients is distributed differently in the pore space. Therefore, conducting a set of saturated flow experiments with different fluids and/or under different hydraulic gradients allows – using a numerical model – to determine an approximation of the pore size distribution.Our goal is to test feasibility of determining the pore size distribution using saturated flow experiments with low-concentration water-xanthan solutions (<1 g/l) under relatively small hydraulic gradients (<5). We have now completed a set of laboratory experiments for three types of sandstone and we are performing a sensitivity analyses of the parameters used in the numerical model. The presented approach is low-cost, easy-to-use and can serve as an alternative to mercury intrusion porosimetry in geoscience and various cultural heritage studies. The research is funded by the Czech Science Foundation [21-27291S]. References:Abou Najm, M.R., Atallah, N.M., 2016: Non-Newtonian Fluids in Action: Revisiting Hydraulic Conductivity and Pore Size Distribution of Porous Media. Vadose Zone Journal, 15(19), 1–15.Rodríguez de Castro A., Omari, A., Ahmadi-Sénichault, A., Savin, S., Madariaga, L-S., 2016: Characterizing Porous Media with the Yield Stress Fluids Porosimetry Method. Transport in Porous Media, 114, 213–233.
Global perturbation of stratospheric water and aerosol burden by the Hunga Tonga eruption: a 1-year aftermath
Authors: Khaykin Sergey , Podglajen Aurelien , Ploeger Felix , Grooß Jens-Uwe , Tence Florent , Khlopenkov Konstantin , Bedka Kristopher , Rieger Landon , Baron Alexandre , Duflot Valentin , Clouser Benjamin , Sakai Tetsu , Godin-Beekmann Sophie , Bekki Slimane , Querel Richard
Published: February 2023

The eruption of the submarine Hunga Tonga Hunga Hapaii volcano on 15 January 2022 was associated with a powerful blast that injected sulfur and water to altitudes up to 58 km. In this study, we combine the data from various satellite instruments (MLS, OMPS-LP, CALIOP, SAGE III, Aeolus, COSMIC-2, ACE-FTS, GOES, Himawari), ground-based lidars at various locations, meteorological radiosoundings as well as model simulation using CLaMS chemistry-transport model to investigate the evolution of the stratospheric moisture and sulfate aerosol plume at a wide range of scales—from minutes and kilometres to monthly and planetary scale. We show that due to extreme altitude reach of the eruption, the volcanic plume has circumnavigated the Earth in only one week and dispersed nearly pole-to-pole in three months. The observations provide evidence for an unprecedented increase in the global stratospheric water mass by 13% as compared to climatological levels. As there are no efficient sinks of water vapour in the stratosphere, this perturbation is expected to persist several years. The eruption has also led to a 5-fold increase in the stratospheric aerosol load, the highest in the last three decades yet factor of 6 smaller than the previous major eruption of Mt Pinatubo in 1991.The unique nature and magnitude of the global stratospheric perturbation by the Hunga eruption ranks it among the most remarkable climatic events in the modern observation era. Given the expected longevity of the stratospheric humidity perturbation, the Hunga eruption can be said to have initiated a new era in stratospheric gaseous chemistry and particle microphysics with a wide range of potential long-lasting repercussions for the global stratospheric composition and dynamics. The eruption has thus provided a unique natural testbed, lending itself to studies of climate sensitivity to strong change in both stratospheric gaseous and particulate composition.Spanning more than one year, the satellite and ground-based observations available to-date enable the first accurate assessment of the annual-scale stratospheric aftermath of the Hunga Tonga eruption, uncovering its climate-altering capacity.
Swarm, FORMOSAT-7/COSMIC-2, and ICON ionospheric observations during the annular solar eclipse on 21 June 202
Authors: Kao Tzu-Hsun , Liu Jann-Yenq
Published: February 2023

On 21 June 2020, an annular solar eclipse pass over Africa, Europe, and Asia.  When the moon’s shadow sweeps, the solar radiation is blocked out and leads to weak photochemical effects and other variations on the ionosphere.  The ion/electron temperature, density, and the ion vertical drift velocity measured by multi-satellites have been estimated and analyzed.  EFI (Electric Field Instrument) onboard Swarm with a circular orbit of 88° inclination and 530 km altitude provides the data of electron temperature and density.  IVM (ion velocity meter) onboard FORMOSAT-7/COSMIC-2 (F7/C2) with a circular orbit of 24° inclination and 550 km altitude supplies information on the ion temperature, density, and ion vertical drift velocity.  IVM onboard Ionospheric Connection Explorer (ICON) with a circular orbit of 27° inclination and 579 km altitude offers the same parameters as F7/C2.  On the event day, a total of 9 paths of those satellites passed through the greatest eclipse path, 6 from F7/C2, 2 from ICON, and 1 from Swarm.  Referencing one-month data of each satellite path, both ion and electron temperature decrease about 500K after the maximum contact.  Three of the four solar eclipse signatures in the ion density are observed, including pre-ascensions, major depressions, and sunset ascensions.  Moreover, the ion drift velocity tends to be downward around the maximum contact.  Detailed results will be presented and discussed.
Soil Hot Extremes are Increasing Faster than Air Hot Extremes Regionally
Authors: García-García Almudena , Cuesta-Valero Francisco José , Miralles Diego G. , Mahecha Miguel D. , Quaas Johannes , Reichstein Markus , Zscheischler Jakob , Peng Jian
Published: February 2023

Hot temperature extremes are changing in intensity and frequency. Quantifying these changes is key for developing adaptation and mitigation strategies. The conventional approach to study changes in hot extremes is based on air temperatures. However, many biogeochemical processes, i.e. decomposition of organic material and release of CO2, are triggered by soil temperature and it remains unclear whether it changes as does air temperature. Here, we demonstrate that soil hot extremes are intensifying and becoming even more frequent faster than air hot extremes over central eastern and western Europe. Based on existing model simulations, we also show that the increase in hot soil extremes could amplify or spread future heat waves by releasing sensible heat during hot days. We find an increase of 3 (7) % in the number of hot days with a contribution of heat from the soil under a warming level of 2.0 (3.0) °C than under a warming level of 1.5 °C. Furthermore, defining intensity and frequency extreme indices based on soil and air temperatures leads to a difference of more than 1 °C in intensity and 10% in frequency regionally during the last decades of the 21st century under the SPP5 8.5 emission scenario. In light of these results, maximum soil temperatures should be included in ecological risk studies as a complementary perspective to the conventional approach using extreme indices based on air temperatures. 
Tropical precipitation biases in nextGEMS storm-resolving Earth System Models
Authors: Bordoni Simona , D'Agostino Roberta , Tompkins Adrian M.
Published: February 2023

Global Earth System Models at storm-resolving resolutions (SR-ESM, with horizontal resolutions of ~4km) are being developed as part of the nextGEMS collaborative European EU’s Horizon 2020 programme. Through breakthroughs in simulation realism, these models will eventually allow us to understand and reliably quantify how the climate will change on a global and regional scale, and how the weather, including its extreme events, will look like in the future.As part of the Storms & Ocean theme, we are exploring how resolving convective storms, ocean mesoscale eddies, and air-sea interaction on these scales influences the development of tropical SST anomalies and their influence on the mean climate (ITCZ and circulation biases) and its variability. Existing biases in the SR-ESM simulations in the first two development cycles are interpreted using the vertically integrated atmospheric energy budget to disentangle local and remote influences on tropical precipitation. More specifically, these biases are decomposed in hemispherically symmetric and antisymmetric components, which are linked, respectively, to biases in the atmospheric net energy input near the equator (tropical SST biases, low level clouds, etc) and to the cross-equatorial atmospheric energy flux (driven by inter-hemispheric contrast in net energy input, for instance biases in clouds in the southern ocean). We also explore the role that transient eddies, both of extratropical and tropical origin that are usually neglected in this framework, play in the global energetics and tropical precipitation patterns.
Winter North Atlantic jet variability under global warming: Past trends and future projections
Authors: Hermoso Alejandro , Schemm Sebastian
Published: February 2023

Regional weather variability and the occurrence of extreme weather events are highly connected to the position of jet streams. Climate models generally project a poleward shift of the jets under the influence of anthropogenic warming. However, ERA5 reanalysis data show that the North Atlantic jet stream in winter has roughly remained in place. We investigate the mechanisms that lead to this behavior.  The analysis reveals that upper-level temperature trends produce a reduction in stability that leads to an increase in baroclinicity. Furthermore, momentum convergence is also intensified across the jet core, producing an acceleration of the jet and not a weakening as suggested by arguments based solely on the Artic amplification.  Numerical simulations from an ensemble of fully coupled climate simulations run with the Community Earth System Model under the SSP3.7 scenario are also analyzed along with idealized warming experiments in an aquaplanet setup with a zonal asymmetry in sea surface temperature. The climate simulations exhibit a large spread during the historical period and only a few ensemble members reproduce the observed trends, suggesting that trends only based on ensemble means could lead to misleading projections. Additionally, the aquaplanet runs display high sensitivity to the location of the asymmetry. This provides a supplementary argument in support of inspecting all individual climate projections as small variations in the original jet position can lead to large disparities in the projected trends. 
Hemispheric Asymmetries in the Ionospheric Total Electron Content during 1999-2019
Authors: Chang Yu-Chi , Liu Jann-Yenq
Published: February 2023

This paper studies the hemispheric asymmetry of the total electron content (TEC) by means of the Global Ionosphere Map (GIM), which has been routinely publishing every 2 hours by the Center for Orbit Determination in Europe (CODE) during 1999-2019.  The study period including the solar cycles 23 and 24 allows us globally uniformly examine the ionospheric asymmetry phenomenon of the GIM TEC in the different solar activities.  At each time point, summations of the GIM TEC at low-, mid-, and high-latitude in the northern and southern hemispheres are computed.  Results reveal the maximum summations of the GIM TEC occurring in April or November and the minimum summations of the GIM TEC occurring in July, which indicates the extreme TEC values in each year are not at the equinox or solstice.  We compare the sums of the two hemispheres in various local times, months, and solar activities.  By computing the annual magnitude of the asymmetry phenomenon, it is found that the asymmetric phenomenon is more prominent during the low solar activity, although its fluctuation is proportional to the F10.7 index.  We further study the asymmetry phenomenon in various latitudes and find the latitudes with prominent signatures.
Strengthening tropical Pacific zonal temperature gradient linked with increasing West Indian Monsoon rainfall
Authors: Ghosh Rohit , Shepherd Theodore G.
Published: February 2023

The changes in the Indian summer monsoon rainfall under anthropogenic climate change would have a large socio-economic impact. The thermodynamic effect of the climate change on future monsoon rainfall is well understood with an overall increase in precipitation as the atmosphere moistens. Understanding the dynamical effect of climate change especially from the changes in the drivers of the monsoon remains challenging. Here we show that the observed western Indian monsoon rainfall has an increasing trend over the last 120 years. We find this observed trend is connected with the trend in the tropical Pacific zonal sea surface temperature (SST) gradient, where the western tropical Pacific or the warm pool region of the Pacific Ocean is warming faster than the eastern side. Applying a storyline approach to the future evolution of the zonal tropical Pacific SST gradient in 38 global climate models from the latest Coupled Model Intercomparison Project phase 6, we find a consistent connection in the models between the western Indian monsoon rainfall change and the strength of the change in the zonal tropical Pacific SST gradient under global warming. The models which warm more in the western compared to the eastern side of the tropical Pacific have higher rainfall increases over western India during the monsoon season. This link is associated with an anomalous easterly wind coming from the western tropical Pacific and converging over western India, leading to higher rainfall in both observations and models. This result suggests that future changes in the western Indian monsoon rainfall would depend on the changes in the strength of the zonal gradient of the tropical Pacific Ocean SST.
Meteo-hydrological precursors of water crisis in the Turin area: a first forecasting and management chain
Authors: Brussolo Elisa , Ronchi Christian , Salandin Alessio , Cremonini Roberto , Barbero Secondo
Published: February 2023

The Piedmont region (north-western Italy) is located between the Alps and the Mediterranean area, two territories that are recognized as climate hotspot regions, showing amplified climate change signals and associated with environmental, social and economic impacts.A number of water crisis that affected the Italian territory in the last twenty years exacerbated conflicts in different territories with regard to the priority use of water resource. The recent drought events (2017, 2021, and 2022) have seen areas not normally characterized by this type of phenomenon, such as the Piedmont region, go into crisis, involving all water users and human activities.In this framework, there is a renewed urgency for improved drought monitoring, forecasting and assessment methods, that will allow for better anticipation and preparation and will lead to better management practices, in order to reduce the vulnerability of society to drought and its subsequent impacts.As drought can be defined in a number of ways and the determination of drought magnitude and impacts can be quite complex, the top scientific priority and social challenge are the identification of meteo-hydrological precursors of water crises. This will lead from meteo-hydrological drought to socio-economic drought and drive water management and decision-making with a strong scientific basis.In this work we  focused on the Turin area and after identifying the events that have sent in crisis the drinking water supply sources, the meteorological data and appropriate drought indexes have been analyzed. Critical thresholds and parameters have been identified and a first combined index, for developing an operational chain that can alert water utilities, stakeholders and mayors reasonably in advance, is proposed.
A wind tunnel investigation on the ventilation coefficients of hailstones
Authors: Theis Alexander , Werner Laura , Mitra Subir , Borrmann Stephan , Szakáll Miklós
Published: February 2023

The rate of change of mass of a hailstone by diffusion is affected by its motions. In a stationary pure diffusive case the water vapor distribution around a spherical hailstone is spherically symmetric having rather weak water vapor gradients. However, when a hailstone falls in the air, the flow field and hence the water vapor distribution around the hailstone is asymmetric showing much stronger water vapor gradients which are high at the upstream side and lower at the rear side of the hailstone. When averaged over the whole surface area of the hailstone the mass transfer to or from the falling hailstone surface is always higher compared to a pure diffusive case. This convective enhancement is given by the ventilation coefficient. Thus, to reliably quantify growth or sublimation rates of falling hailstones with models, it is necessary to know their ventilation coefficients. The rate of change of mass is proportional to the rate of change of heat. Therefore, the growth or sublimation of hailstones has not only implications on the humidity of the ambient air but also the vertical temperature profile of the atmosphere and consequently cloud and storm dynamics.However, there is a lack of experimental studies on the ventilation coefficient of spherical hailstones in the literature. There are just three experimental studies available – all dating back to the 1960’s – which investigate the heat and mass transfer of spherical and oblate hailstones, but all were measured under accretional growth and melting conditions, respectively.Therefore, experiments in the Mainz vertical wind tunnel were carried out to determine ventilation coefficients of spherical hailstones during sublimation. We investigated stones with diameters between 1 and 3 cm or, equivalently, Reynolds numbers between 10.000 and 45.000. The spherical hailstones were produced by freezing water in moulds and introduced into the wind tunnel. While freely floating at their terminal velocities the hailstones lost mass due to sublimation. The temperature in the tunnel was set to -5°C and relative humidities were rather low, i.e. between 30 % and 50 % with respect to ice, to facilitate sublimation. The mass of the hailstones was measured before and after the wind tunnel measurements from which we calculated the rate of change of mass in the convective case. The recordings of temperature and dew point were used to calculate the rate of change of mass for the pure diffusive case. The ratio of these rates is, by definition, the ventilation coefficient, which was calculated and parameterized as a function of the Reynolds number.
Reworking processes during monogenetic eruptions. The case of the Parícutin volcano
Authors: Bolós Xavier , Macias José Luis , Ocampo-Díaz Yam Zul , Tinoco Claudio
Published: February 2023

One of the best-known examples worldwide of monogenetic volcanism is the Parícutin volcano. The eruption began its formation in the middle of a cornfield in February 1943 and lasted until March 1952. Parícutin is the youngest edifice of the Michoacán-Guanajuato Volcanic Field, which was witness initially by local inhabitants, and later by scientists and other observers. Observations of the eruption documented the remobilization of primary ashfall by rainfall and wind. Despite these observations, the resulting reworked deposits have not yet been described in the stratigraphic sequence. The distinction between primary pyroclastic and reworked deposits is critical for the geological understanding of eruptive processes and related hazards because of their different origins, frequencies, and environmental impacts. This categorization is not always obvious and needs a detailed study to characterize the complex interbedding of both types of deposits that coexist in the volcanic sequence. Referenced to these, we conducted new field reconnaissance, coupled with laboratory analyses of the ejecta ash fraction. The detailed composite stratigraphy obtained consists of six widely dispersed fallout deposits interbedded with seven reworked units. These reworked deposits display sedimentary structures produced by tephra remobilization due to lahars and stream flows. In addition, some layers show dunes and ripples generated by duststorms. By using GIS tools, we integrated the existing data with our new composite stratigraphic column and the distribution map of the syn-eruptive reworked deposits. This analysis reveals that more than 70% of the total thicknesses correspond to syn-eruptive reworked deposits. Therefore, previous studies had overestimated the distribution of primary tephra from the Parícutin explosive phases. The lowest and flattest areas with wide rill networks, which are located 4 to 6 km north of the volcano, are composed of up to 90% reworked deposits. In contrast, proximal locations with gentler slopes located at medium altitudes better preserve pyroclastic deposits. To that end, we constructed a new isopach map of the pyroclastic deposits based on the distribution of the reworked deposits. This study brings new light to understanding the sedimentary processes that occur during volcanic eruptions and highlights the importance of recognizing pyroclastic and reworked deposits during monogenetic eruptions.
Straw mulch effect on soil and water losses in different growth phases of Maize sown on Stagnosols in Croatia
Authors: Bogunovic Igor , Hrelja Iva , Kisic Ivica , Dugan Ivan , Krevh Vedran , Defterderovic Jasmina , Filipovic Vilim , Filipovic Lana , Pereira Paulo
Published: February 2023

Soil and water losses due to traditional intensive types of agricultural management are high and non-sustainable in Croatian croplands. In order to mitigate the accelerated land degradation, we study different cropland soil management to obtain possible sustainable agrotechnical practices. A rainfall simulation experiment was conducted at 60 mm h–1 over 30 min on 10 paired plots (0.785 m2), bare and straw covered (2 t ha-1). The experiment was carried out in maize cultivation (Blagorodovac, Croatia) established on Stagnosols on slopes. Measurements were conducted during April (bare soil, after seeding), May (five leaves stage), and June (intensive vegetative growth) making 60 rainfall simulations in total. Straw reduced soil and water losses importantly. The highest water, sediment loss, and sediment concentrations were identified in tillage plots during May. Straw addition resulted in delayed ponding (for 7%, 63 and 50% during April, May and June, respectively) and runoff generation (for 37%, 32 and 18% during April, May and June, respectively). Compared to the straw mulched plot, tillage and bare soil increase water losses by 349%. Maize development reduced the differences between bare and straw mulched plots. During May and June bare plots increase water losses by 92% and 95%, respectively. The straw mulch reduced raindrop kinetic energy and sediment detachment from 9, 6 and 5 magnitude orders at April, May and June. Overall, the straw mulch was revealed to be a highly efficient nature-based solution for soil conservation and maize cultivation protection.
Smart-SWS: Combining flood protection and drought prevention -- Concept and site selection criteria
Authors: Baumann Thomas , Augustin Lea , Dietmaier Annette
Published: February 2023

Climate changes in the anthropocene lead to an increase of rainfallintensity while the infiltration capacity of the soil is reducedduring extended dry periods. As a consequence surface runoff increasesand groundwater levels are reaching all-time lows: even close to thealps water becomes scarce. Keeping precipitation water local is a mustand one option is to direct flood water into local aquifers(Flood-MAR). This comes with a number of challenges, first of all, apronounced asymmetry of floods with very high volume flow in veryshort times, and droughts requiring long-term storage. From ahydrogeological perspective, infiltration of flood waves requiresextremely well-connected groundwater bodies with high hydraulicconductivity contrasting with slow groundwater flow required forlong-term storage. Geotechnical measures like sheet-pile walls or sandinjections can be used to control the release of groundwater back tothe river. The infiltrated water has to be conditioned to meethydrochemical and sanitary criteria. In contrast to conventionalmanaged aquifer recharge (MAR) the time frame for treatment isextremely limited. As floods are not occurring regularly, any treatmentsystem has to work autonomously and to be insensitive to longdowntimes between flooding events. The decision tree for theselection of suitable sites starts with the occurrence and extent offlooding events (regular flooding events with volumes less thanroughly 1 million m³), the morphology of the site (leveled withgroundwater levels below river water), and the hydrogeologicalproperties of the adjacent aquifers (ideally porous aquifers with highspecific yield and hydraulic conductivity). Further criteria are landuse (agriculture preferred), infrastructure (access to the site, nosubsurface installations), protection zones (groundwater, habitats,...) and ecosystem services, and risk factors in the catchment(hazardous substances, extended mobilization of soil during flooding,...).  Three sites have been selected as pilot sites and will bepresented.
Determining the correct river incision mechanism under different climatic and lithological conditions using disorder metrics
Authors: Ruiz Sánchez-Oro Marina , Mudd Simon M , Gailleton Boris
Published: February 2023

Fluvial incision patterns help us understand the role of precipitation in river formation and evolution. Incision is generally thought to be a function of channel gradient and either discharge or drainage area. Many studies use drainage area as a proxy for discharge, but incision could potentially be related to area rather than discharge because area determines sediment fluxes. Assumptions about discharge or drainage area control on incision impact the calculations of chi profiles and steepness indices, which are indicators of the erosional and tectonic history of the landscape. Here we use numerical modelling and topographic analysis to determine if spatially varied precipitation leads to distinctive patterns of channel profiles that can be used to differentiate if a discharge or drainage-area driven incision rule is appropriate for a given landscape.  We use the modelling framework Fastscape to set up two scenarios: one including an incision rule with drainage area and another with discharge (rainfall). We evolve them to steady state and extract from the resultant topography a disorder metric, which measures the relation between the tributaries and the main river in chi space. To simulate a blind test of the incision conditions, we calculate the disorder metric under the two incision case assumptions. We find that scenarios in which incision is discharge-driven cases are statistically distinguishable from those in which incision is driven by drainage area alone. We repeat these analyses with variable rainfall gradients, simulating those found in real landscapes. The results are in agreement: in a sandbox model with homogeneous lithology, it is possible to distinguish the incision case based on the disorder metric under all rainfall conditions. Real landscapes are not sandboxes, however, so we run further simulations to quantify the impact of heterogeneous lithology under different rainfall scenarios. This reveals that it is not possible to distinguish the incision case, as the distortions to channel profiles driven by lithology masks evidence of discharge dominance. We complete the analysis by testing the hypothesis in 10 real landscapes across the globe, with different lithological and climatic regimes. Some study areas, such as the Pyrénées or the Alburz Mounts, show a weak trend towards discharge dominance, although there is no conclusive statistical evidence of the preference of one incision rule, hinting at the dominance of lithology over rainfall as shown in the models.
What are the causes of repeated mass-transport deposits in perialpine Lake Brienz (Switzerland)?
Authors: Girardclos Stéphanie , Gastineau Renaldo , Kremer Katrina , Anselmetti Flavio S.
Published: February 2023

Mass transport deposits (MTDs) are common features in lakes that impose a significant natural hazard as they can be tsunamigenic (e.g., in Lake Geneva; Kremer et al., 2012). MTDs can be assigned to different categories, such as lateral-slope landslides, margin collapses, delta collapses and rockfalls (Sammartini et al., 2019). In 1996 AD, a MTD occurred in Lake Brienz, a 260 m deep Alpine lake at the frontal range of the Bernese Swiss Alps. The 1996 MTD extends over ∼8.5 km2 and has a total volume of 2.7 106 m3, which amounts to ∼8.7 years of the lake’s annual sediment input. The 1996 MTD had no specific trigger and occurred as a spontaneous failure due to sediment accumulation on the Aare Delta (Girardclos et al., 2007).However, the 1996 delta collapse was not a unique event: a dense grid of 240 km of seismic lines reveals at least four older massive MTDs in the lake basin with similar dimensions. Our study aims to identify the ages and the processes behind these large deposits. For this purpose, we focus on long sediment cores with a cumulative length of about 40 m from four coring locations. A combined analysis of seismic profiles and sediment cores, coupled with an age model combining radionuclides, radiocarbon, coal and steamboat slag, and historical flood events, allows us to explore the feedback between climate and anthropogenic impact acting upon these MTDs. The MTDs are analysed regarding their source areas, either the Aare or the Lütschine deltas, both occurring at the opposite ends of the elongated lake basin. Moreover, we investigate whether earthquakes, spontaneous failures or a shift of the Lütschine River could act as potential triggers, as well as the role of sediment loading in the deltas related to climate changes or anthropogenic impacts in the watershed. Altogether, these factors have likely affected the recurrence rates of these significant sedimentological events. References:Girardclos, S., Schmidt, O.T., Sturm, M., Ariztegui, D., Pugin, A., Anselmetti, F.S., 2007. The 1996 AD delta collapse and large turbidite in Lake Brienz. Mar. Geol. 241, 137–154. https://doi.org/10.1016/j.margeo.2007.03.011Kremer, K., Simpson, G., Girardclos, S., 2012. Giant Lake Geneva tsunami in AD 563. Nat. Geosci. 5, 756–757. https://doi.org/10.1038/ngeo1618Sammartini, M., Moernaut, J., Anselmetti, F.S., Hilbe, M., Lindhorst, K., Praet, N., Strasser, M., 2019. An atlas of mass-transport deposits in lakes. Submar. Landslides Subaqueous Mass Transp. Depos. Outcrops Seism. Profiles 201–226. https://doi.org/10.1002/9781119500513.ch13 
MAX-DOAS measurements characterise severe ozone pollution in Central London during summer 2022 heatwaves
Authors: Gershenson-Smith Eleanor , Ryan Robert G. , Marais Eloise A. , Ramsay Robbie , Muller Jan-Peter , Tirpitz Jan-Lukas , Friess Udo
Published: February 2023

In the UK, the public health threat of heatwaves is exacerbated by the co-occurrence of ozone pollution episodes. Here we present retrieved vertical profiles of nitrogen dioxide (NO2) and formaldehyde (HCHO) over Central London from a newly installed long-term Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument on a 60-m altitude rooftop site during two of three heatwaves in the hottest summer on record. We evaluate routine space-based sensor observations of air pollutant precursors over London and enhance the permanent air quality monitor network. Daily mean tropospheric column densities of NO2 and HCHO from the TROPOspheric Monitoring Instrument (TROPOMI) are consistent with those from the MAX-DOAS (both R = 0.71) after accounting for different vertical sensitivities. As expected, TROPOMI NO2 is 27-31% less than MAX-DOAS NO2, due to horizontal dilution of local sources of road-traffic NO2. TROPOMI HCHO is 20% more than MAX-DOAS HCHO; a larger difference than in past validation studies, but within the range of systematic retrieval errors. MAX-DOAS lowest layer (0-110 m) retrievals have analogous day-to-day variability to surface site NO2 (R ≥ 0.7). Surface site measurements of isoprene, which rapidly oxidises to HCHO with a high yield, also have similar diurnal variations to MAX-DOAS HCHO (R > 0.6). Generally, daytime ozone production, which is diagnosed with MAX-DOAS HCHO:NO2 tropospheric column ratios, is limited by the availability of volatile organic compounds. During heatwaves, ozone production shifts from NOx-saturated to NOx-limited as biogenic emissions of isoprene increase exponentially with temperature, leading to non-compliance with ozone regulatory standards. In ongoing work, we are assessing the ability to retrieve the NOx (NO + NO2) reservoir compound nitrous acid (HONO) to address uncertainties in HONO chemistry. This will aid understanding of the oxidation capacity of the atmosphere and ozone budget in centres of megacities such as London.
Check dam and its functions on the Loess Plateau of North Shaanxi Province, China
Authors: Wang Fei , Ge Wenyan , Chen Hao
Published: February 2023

The Loess Plateau is one of the most severe soil erosion area worldwide, and the north Shaanxi Loess Plateau is the main sediment source of the Yellow River. The functions of check dam are analyzed based on the data of land use and land cover change, hydrological process and filed survey on soil property and yield. The average annual soil erosion rate in this region varied from 8000-10000 ton per square kilometer before 1980s and reduce to 2000-4000 ton per square kilometer in recent years. The check dam is one of the most important practices of soil and water conservation in this region. It has a long-term history inspired by the natural dam caused by great landslide in 1969 of Ming Dynasty and developed very fast since 1960s. The functions of check dam cover the whole soil erosion process, sediment and flow of the branches and the Yellow River, agricultural production, soil carbon consequence, and local climate regulation. There were about 33.9 thousand check dams in this region, and the sedimentation in the check dams is around 5.9 billion tons that the average annual reduction of sediment load of the river accounted for 3000-5000 ton per square kilometer in their formation period of 20 to 30 years. The current check-dam land was about 57.3 thousand hectors with very good fertility condition and soil moisture because of the deposition induced by soil erosion of the topsoil and seasonal flashflood in the catchment. The average yield on the check-dam land could be 6000-15000 kg per hector in the semiarid cropland, about 3-10 time of that on the slope, that could reduce the cultivation on the slopes for more food demands and the relating soil erosion generation. The soil moisture retained in the check dam were estimated to about 2 billion ton annually and the SOM in the whole profile of check-dam land could be 3 times high than that in the top-soil layer (less than 1g/kg). The reduction of sediment load in the Yellow River could save a great amount of capacity of reservoirs, decrease the rising of the riverbed and flood risks of the lower stream of the Yellow River, and it also could save 1-3 billion cubic meters of runoff to flush the sediment away into the Bohai Sea. The functions of check dam could be sustainable if well-maintained.
Winter Atlantic Water intrusions in Kongsfjorden: atmospheric triggering and oceanic preconditioning
Authors: De Rovere Francesco , Chiggiato Jacopo , Langone Leonardo , Rubino Angelo , Zanchettin Davide
Published: February 2023

Kongsfjorden is an Arctic fjord in Svalbard facing the West Spitsbergen Current (WSC) transporting warm and salty Atlantic Water (AW) through the Fram Strait to the Arctic. In this work, winter AW intrusions in Kongsfjorden occurring in the 2010-2020 decade are assessed by means of oceanographic and atmospheric observations, provided by in-situ instrumentations and reanalysis products. Winter AW intrusions are relatively common events, bringing heat and salt from the open ocean to the fjord interior; they are characterized by water temperatures rising by 1-2 °C in just a few days. Several mechanisms have been proposed to explain winter AW intrusions in West Spitsbergen fjords, tracing back to the occurrence of energetic wind events along the shelf slope. Here we demonstrate that the ocean plays a fundamental role as well in regulating the inflow of AW toward Kongsfjorden in winter.Winter AW intrusions in 2011, 2012, 2016, 2018 and 2020 occurred by means of upwelling from the WSC, triggered by large southerly winds blowing on the West Spitsbergen Shelf (WSS) followed by a circulation reversal with northerly winds. Southerly winds are generated by the setup of a high pressure anomaly over the Barents Sea. In these winters, fjord waters are fresher and less dense than the AW current, resulting in the breakdown of the geostrophic control mechanism at the fjord mouth, allowing AW to enter Kongsfjorden. The low salinity signal is found also on the WSS and hence is related to the particular properties of the Spitsbergen Polar Current (SPC). The freshwater signal is hypothesized to be linked to the sea-ice production and melting in the Storfjorden and Barents Sea regions, as well as the accumulation of glaciers’ runoff. The freshwater transport toward West Spitsbergen is thus the key preconditioning factor allowing winter AW intrusions in Kongsfjorden by upwelling, whilst energetic atmospheric phenomena trigger the intrusions. Winter 2014 AW intrusion shows a different dynamic, i.e., an extensive downwelling of warm waters in the fjord lasting several weeks. Here, long-lasting southerly winds stack surface waters toward the coast. The fjord density is larger than the WSC density, forcing the AW intrusion to occur near the surface, then spreading vertically over the water column due to heat loss to the atmosphere. We hypothesize the combination of sustained Ekman transport and the shallower height of the WSC on the water column to be the key factor explaining the AW intrusion in this winter. After mixing with the initial AW inflow, fjord waters undergo heat loss to the atmosphere and densification. The water column becomes denser than the WSC, restoring the geostrophic control mechanism and blocking further intrusions of AW.
Comparison of a rotational sensor and an array on Piton de la Fournaise volcano, La Réunion
Authors: Vesely Nele I. K. , Eibl Eva P. S. , Ferrazzini Valérie , Wassermann Joachim
Published: February 2023

Piton de la Fournaise is a shield volcano located on La Réunion island in the Indian Ocean and most recently tends to erupt once - twice annually. Besides volcanic tremor during eruptions and rockfall, long-period (LP) and volcano-tectonic (VT) earthquakes are dominating signals on the island.In October 2022, a rotational sensor and an array of seven seismometers were installed within the Enclos Fouqué, the youngest caldera of volcano Piton de la Fournaise. We record volcano-seismic signals that were also detected by the seismic network of the Observatoire Volcanologique du Piton de la Fournaise (OVPF). Our aim is to test the performance of the rotational sensor and the conventional seismic array with respect to these events.Local VT and rockfall events have been detected on all instruments and could be compared by calculations of backazimuth (BAZ) and signal-to-noise ratio (SNR). We derive the rotational rate using three array stations for array derived rotation (ADR). First results indicate an agreement between the BAZ obtained from the rotational sensor, the array and the location using the OVPF network for strong rockfall events. Summit VT and weak local earthquakes could furthermore be located by the array BAZ. Preliminary SNR results from all considered events indicate higher values for the array stations. Since the instruments could not be buried on site and the rotational sensor is likely affected by wind noise, it is assumed that comparison between the instruments will work best for strong and/ or close events.
From rain-fed to irrigated agriculture? Projecting the future irrigation water demand in Germany using a hydro-economic multi-agent system model
Authors: Heilemann Jasmin , Nagpal Mansi , Klassert Christian , Peichl Michael , Klauer Bernd , Gawel Erik
Published: February 2023

Climate change increases the frequency and severity of droughts in Central Europe and thereby threatens food production in the German agricultural sector, which is mostly rain-fed and heavily dependent on precipitation. Farmers need to adapt to these changing conditions, for instance by shifting to irrigated production systems. This increases the future agricultural water demand and may result in competition for water use and higher groundwater depletion. Simultaneously, farmers adapt their land-use patterns towards an optimal crop mix, responding to changes in climatic and economic conditions. This land-use adaptation also affects the irrigation water demand.To project the future irrigation water demand in Germany considering land-use adaptation, we present the spatial multi-agent system (MAS) model DroughtMAS which simulates agricultural land-use adaptation of the 8 major field crops using a positive mathematical programming (PMP) approach. Each agent captures the behavior of farmers in one of Germany’s 401 NUTS-3 regions, is individually calibrated to the observed production conditions for a 20-year historic average, and is empirically validated for the same period. Therefore, the agent-based structure portrays the agroeconomic and biophysical heterogeneity of Germany. To consider uncertainties concerning future climate change levels and socioeconomic developments, we project the future land-use adaptation and irrigation water demand using integrated RCP-SSP scenarios. To this end, the MAS model is coupled to a statistical crop yield model driven by meteorological indicators and soil moisture, derived from the mesoscale Hydrologic Model (mHM). Projections of the agricultural crop prices are based on the SSP scenarios. The integrated hydro-economic model consequently reflects the adaptive behavior of agents responding to changing crop yields and prices.The results emphasize the importance of accounting for land-use adaptation to accurately project farmers’ irrigation water demand and to consider changes in biophysical and socioeconomic variables simultaneously. Such estimates are crucial in planning for future agricultural water demands to prevent user conflicts and water resource depletion.