bluuebunny/crossref_metadata_2025 huggingface dataset:
Emerging threats: Cryosphere-related hazards in the Trans-Himalaya of Ladakh
Authors: Schmidt Susanne , Soheb Mohd , Nüsser Marcus
Published: February 2023

Cryosphere-related hazards are a growing but largely neglected threat for rural settlements, agrarian land use and local livelihoods in the cold-arid Trans-Himalayan region of Ladakh. Despite the growing number of studies on cryosphere-related hazards across High Mountain Asia and other glacierized mountain regions, the occurrence, frequency and magnitude of glacial lake outburst floods (GLOFs) are almost entirely overlooked for the region of Ladakh. Due to the small size and high elevational location of glaciers above 5200 m a.s.l. also the glacial lakes are of small size and some of them are almost permanently ice-covered. In the recent past several GLOF events occurred which destroyed infrastructure and agricultural area. It becomes obvious that even these small glacial lakes might be a permanent threat for local livelihoods and socioeconomic development. This is even more problematic as the number and size of lakes has significantly increased over the past decades. Many of these lakes are dammed by ice-cored moraines which tend to become instable due to climate warming. A comprehensive inventory of glacial lakes for the entire Trans-Himalayan region of Ladakh was carried out. This includes several almost permanently ice-covered high altitude lakes, which have to be detected by visual image interpretation. Changes in the extent and number of glacial lakes have been quantified for the years 1969, 1993, 2000/02 and 2018 in order to assess the potential threat of future GLOFs in the region. A total of 192 glacial lakes cover an area of 5.93 ± 0.70 km2 with an estimated water volume of about 61.11 ± 8.5 million m3, including 127 proglacial (PG) and 56 lakes located on recent moraines (RM) were mapped in 2018. The change detection analyses also indicated the disappearance of 22 glacial lakes (decrease by more than 90%) between 1969 and 2018. The lake development of selected former reported GLOF events were analysed in detail to reconstruct lake level changes which possibly indicate earlier GLOF events. Based on high temporal resolution remote sensing data, a sophisticated monitoring concept needs to be realized to indicate the development of short-lived lakes on glaciers or on debris landforms with buried ice or fast glacial lake growth.
Transient effect on groundwater age distribution – age measurements disprove steady state assumption
Authors: Kolbe Tamara , Marçais Jean , Vergnaud Virginie , Yvard Barbara , Chamorro Alejandro , Bishop Kevin
Published: February 2023

Groundwater ages are key indicators for flow and transport processes as well anthropogenic and geogenic solutes that impact groundwater quality. Commonly, lumped parameter models (LPMs) are applied to interpret environmental tracers, like chlorofluorocarbons (CFCs) or tritium. LPMs require a steady state assumption and they are less complex, computational demanding and data intensive compared to transient numerical models. But when steady-state assumptions are valid for groundwater age simulations is questionable.An initial sampling campaign of CFCs measured in 9 wells at different depths on a 0.47 km2 subcatchment of the Krycklan catchment in 2017 revealed a groundwater age stratification with depth that was representative for the area1. Mean groundwater ages at the water table (2-6 meters depth) in the unconsolidated till overburden were already 30 years and increased with depth to the deepest sampling at 30 meters. These results indicate a lag of rejuvenation caused by a subsurface discharge zone that evolves between two soils types with different hydrogeological properties. The comparison of the steady-state numerical simulation and LPM has proven that the LPM yields an overall recharge rate and estimation of the extent of the subsurface discharge zone.  Seasonal changes of recharge were not expected to impact the age stratification. But repeated sampling in 2021 and 2022 has shown a clear shift of the groundwater age stratification. Numerical modeling is used to understand that transient effect. References:1Kolbe, T, Marçais, J, de Dreuzy, J-R, Labasque, T, Bishop, K. Lagged rejuvenation of groundwater indicates internal flow structures and hydrological connectivity. Hydrological Processes. 2020; 34: 2176– 2189. https://doi.org/10.1002/hyp.13753 
Design Flood estimation based on Equivalent Geomorphological Instantaneous Unit Hydrograph for a Himalayan catchment
Authors: Rana Saroj , Chavan Sagar Rohidas
Published: February 2023

Recurrent flood estimation studies in Himalayan catchments located in India are crucial and require abundant monitoring and supervision. Reliable estimation of design floods for mountainous catchments corresponding to various return periods is challenging. Recently, climate change has exacerbated this challenge which pose a serious threat to the water resources within Himalayan region. The Geomorphology based Unit hydrograph theory can provide reliable estimates of design floods for Himalayan catchments. The theory involves determination of Geomorphological Instantaneous Unit Hydrograph (GIUH) corresponding to a catchment and utilizing the GIUH to predict design flood for a design rainfall input. In this study, it is envisaged to model the complex dynamics of floods in a Himalayan catchment by using a modified version of GIUH which is known as Equivalent Geomorphological Instantaneous Unit Hydrograph (E-GIUH). EGIUH overcomes many limitations associated with the conventional GIUH. The application of E-GIUH is performed for Seer catchment which is a sub-basin of Sutlej River basin. The design rainfall input to the E-GIUH is determined from Indian Meteorological Department (IMD) gridded rainfall data for the present (1951-2019) as well as the future time periods (2021-2060 and 2061-2100). Coupled Model Intercomparison Project phase 6 (CMIP6) experiments are considered to determine future projections of rainfall over Seer catchment which are subsequently used to estimate design rainfall input for future time periods. Design flood estimates are obtained for various Shared Socioeconomic Pathways (SSPs), particularly SSP126, SSP245 and SSP585 scenarios from CMIP6 experiments. The geomorphological descriptors used for development of E-GIUH model of the Seer catchment are evaluated using the GIS framework.Keywords: Climate Change, CMIP6, E-GIUH, IMD, SSP, Seer Catchment
Histogram-based edge detection as a tool for detecting river coastline
Authors: Walusiak Grzegorz , Witek Matylda , Niedzielski Tomasz
Published: February 2023

Flood management is very important task in the context of rapid climate changes. Increasing the frequency of extreme weather and fluvial phenomena, such as droughts, water shortages or floods determines that detecting water bodies and boundaries between them and surrounding surface is an important and challenging issue. We elaborated a new approach for delineating river coastline based only on close-range RGB nadir images acquired by means of UAV (unmanned aerial vehicle), converted to HSV (hue, saturation, value) color space. We used spectral characteristics of water surface which has uniform V component, while another land cover types have heterogeneous V. Areas, where character of V changes considerably, are suspected to be  river coastline. Every aerial image was divided into 250 x 250 px cells, within which we calculated some statistical values (kurtosis, concentration around mode) in order to characterize shape of empirical distribution. Among others, we focused on identifying multi-modal or leptokurtic histograms. Results show that the detection rate (also known as the producer accuracy) ranges from 22,22% to 92,00%, while the false hit rate (also known as error of commission) ranges from 5,00% to 82,76%. For 70% of all analyzed images, presenting both narrow (10 m) and wide (more than 100 m) rivers, the detection rate was above 50%. Considering the subset of photos presenting only wide rivers, detection rate above 50% occurred for 75% of these images. For these cases, 56% of images do not exceed the false hit rate above 40%. The research is supported by the National Science Centre, Poland, through the project no. 2020/38/E/ST10/00295.
Positive anomalies in Carbon Monoxide concentrations observed in the upper troposphere - lower stratosphere during the 2022 Asian summer monsoon season
Authors: Viciani Silvia , Barucci Marco , Bianchini Giovanni , Campos Teresa , D'Amato Francesco , Dang Caroline , Golstone Levi , Gurganus Colin , Iraci Laura , Montori Alessio , Okorn Kristen , Podolske James , Yates Emma
Published: February 2023

In the framework of the ACCLIP project (Asian summer monsoon Chemical and CLimate Impacts project), a measurement campaign was conducted during summer 2022 in the Western Pacific region, to investigate the impact of the Asian Summer Monsoon (ASM) on the composition of the upper troposphere and lower stratosphere (UTLS). Fifteen research flights were carried out by the NASA WB-57 stratospheric aircraft and 14 by the NCAR/NSF GV, with base in Osan (South Korea), covering a large region on the eastern edge of the ASM anticyclone.We report on the Carbon Monoxide (CO) measurements performed by three different mid-infrared absorption spectrometers (COLD2, COMA and ACOS) installed onboard the WB-57 and by two different infrared absorption spectrometers (Aerodyne-CO and Picarro G2401) installed on the GV. Positive CO anomalies, never measured before in the UTLS outside direct biomass burning plumes, were collected by all sensors, showing a very good agreement. During the flight of the 19th of August, CO mixing ratio values higher than 250 ppb were registered at altitude around 14-15 km.A comparison with the CO observations measured by the instrument COLD2 during the StratoClim (Stratospheric and upper tropospheric processes for better Climate predictions) campaign, conducted in summer 2017 from Kathmandu (Nepal), will be presented. Particular attention will be paid to the CO difference observed in the UTLS, by sampling the anticyclone directly from the Tibetan Plateau during StratoClim campaign or from the Western Pacific during ACCLIP.
Assessing flood situations and technical adaptation measures in the context of climate change in Ho Chi Minh City
Authors: Vu Thanh Noi Lam , Phu Quynh Nguyen , Dac Hai Do
Published: February 2023

There is typically limited knowledge on the key factors causing critical flood situations in the context of climate change in many regions, including in large cities like Ho Chi Minh City (HCMC), Vietnam. It is important to improve our understanding of the causes of flood and how to incorporate flood adaptation measures, especially the integration of technical measures into local climate change adaptation plans. This presentation describes the results and experiences of applying a hydraulic model (MIKE 11, 21 and Flood) for simulating flood situations under different climate change scenarios and integration into the master plan for flood prevention (2008) in HCMC. It was found that the water level in Sai Gon River will not increase under the current climate following completion of Phase 1 of constructing flood prevention infrastructure according to the master plan of 2008. However, under the same flood infrastructure prevention condition, the water level at Phu An station will increase from 1.74 m to 2.28 m under the most extreme scenario of Dau Tieng discharge and climate change without land subsidence. Flood prevention infrastructure was identified as a key factor reducing flooding in HCMC. Further studies are recommended to simulate alternative flood situations by applying the same hydraulic model under the new master plan for flood prevention (2021) in HCMC to support flood adaptation measures and strategies.Key words: Flooding, hydraulic model, flood prevention, climate change   
Inter-comparison of different sensors for in-situ airborne measurements of Carbon Monoxide during ACCLIP campaign
Authors: D'Amato Francesco , Barucci Marco , Bianchini Giovanni , Campos Teresa , Dang Caroline , Golston Levi , Gurganus Colin , Iraci Laura , Montori Alessio , Okorn Kristen , Podolske James , Viciani Silvia , Yates Emma
Published: February 2023

A series of in-situ Carbon Monoxide (CO) observations were recently performed in the Western Pacific region, during summer 2022, in the framework of the ACCLIP project (Asian summer monsoon Chemical and CLimate Impacts Project). During the ACCLIP measurements campaign, located in Osan (South Korea), two different research aircraft were employed with a set of sensors installed onboard. The NASA WB-57 aircraft carried out 15 research flights (reaching a maximum altitude of about 19 km), and the NSF/NCAR Gulfstream (GV) aircraft carried out 14 research flights (reaching a maximum altitude of about 15 km), covering a large region near Korea and Japan.We report on the inter-comparison between five different instruments for in-situ CO mixing ratio measurements: three installed onboard WB-57 (ACOS, COLD2 and COMA), and two installed onboard GV (Aerodyne-CO and Picarro G2401-m). COLD2 (Carbon Oxide Laser Detector 2) [1] and Aerodyne-CO [2] are mid-infrared Quantum Cascade Laser spectrometers, based on direct absorption in combination with a multipass cell. ACOS (Carbonyl Sulfide Analyzer) [3] and COMA (Carbon mOnoxide Measurement from Ames) [4] are mid-infrared absorption spectrometers based on Off-Axis ICOS (Integrated Cavity Output Spectroscopy) technology. The Picarro sensor is a cavity ring down absorption spectrometer [5].The in-flight CO mixing ratio values measured by the five spectrometers will be compared, with particular attention to both the accuracy of each instrument and the adopted or not-adopted calibration procedures, as, in principle, for many measurement environments the two sensors based on direct absorption do not need in-flight calibration. Laboratory measurements of common primary and secondary calibration standards made by the five CO measurement groups will be presented to increase confidence in method accuracy. [1] Viciani S., Montori A., Chiarugi A., and D’Amato F.: "A Portable Quantum Cascade Laser Spectrometer for Atmospheric Measurements of Carbon Monoxide", Sensors, 18, 2380 -1-18 (2018).[2] https://www.eol.ucar.edu/instruments/carbon-monoxide-co-and-nitrous-oxide-n%E2%82%82o-qcl-instrument[3] https://ams.confex.com/ams/103ANNUAL/meetingapp.cgi/Paper/421824[4] https://espo.nasa.gov/acclip/instrument/COMA[5] https://www.eol.ucar.edu/instruments/airborne-carbon-dioxide-co2-methane-ch4-carbon-monoxide-co-and-water-vapor-h2o
Urban atmosphere dynamics for air quality applications: Atmospheric boundary layer height and wind profiles from ground-based remote sensing networks
Authors: Kotthaus Simone , Haeffelin Martial , Céspedes Jonnathan , Van Hove Melania , Drouin Marc-Antoine , Dupont Jean-Charles , Foret Gilles
Published: February 2023

Atmospheric boundary layer (ABL) dynamics severely impact the horizontal transport of pollutants as well as their vertical dilution. Despite this, observations of vertical wind profiles and the ABL height are still rare, particularly in cities. Thanks to recent technological advances compact ground-based remote sensing instruments are now available to monitor the heterogeneous urban atmosphere across dense sensor networks. In urban settings, Doppler wind lidars (DWL) and automatic lidars and ceilometers (ALC) are particularly useful as they operate continuously and automatically with very low maintenance under all weather conditions. Thanks to those novel profiling instruments, high-resolution (time and vertical) wind information as well as aerosol backscatter profiles can be recorded.Based on the RI-URBANS (and ICOS-cities) pilot city of Paris, France, we demonstrate what advanced products can be derived using different detailed algorithms, including vertical profiles of horizontal wind and turbulence, boundary layer heights based on aerosol or turbulence indicators, as well as low-level jet characteristics. In Paris, RI-URBANS is embedded in the PANAME initiative that coordinates the synergy between numerous projects that are investigating the urban atmosphere. Clear measurement standards, careful quality control and advanced processing algorithms are required to ensure harmonised products are obtained from the diverse sensor networks that involve instruments of different models from various manufacturers with respective capabilities and limitations.Using the synergy of the different ABL products obtained in the Paris region, it is investigated how the urban boundary layer interacts with the synoptic scale flow, the underlying topography and the urban surface. A combination of wind direction, atmospheric stability and terrain clearly affect shallow boundary layer heights and the low-level jet characteristics. But also spatial variations across the region are registered during deep convective boundary layer development.
Including soil erosion and sediment delivery to surface waters in a high-resolution global hydrological model
Authors: Sorger-Domenigg Florian , Tang Ting , Fridman Dor
Published: February 2023

Soil erosion and sediment delivery to surface waters impact the human-water cycle in several ways. Eroded soil, along with nutrients, travels from intensive crop and grazing systems to waterbodies, reducing the fertility of agricultural land, degrading the integrity of freshwater ecosystems, and negatively impacting water quality on which the human population and other sectors depend. Furthermore, sedimentation reduces the functional capacity of vital energy and agricultural infrastructure, such as reservoirs and irrigation canals, resulting in reduced productivity and profitability of food and energy production systems. A few hydrologic models have accounted for the effects of soil erosion on water quality by implementing soil erosion models into their simulations. To our knowledge, soil erosion has not yet been included in large-scale hydrologic models. Our research adds an erosion-sediment transport module to the hydrological Community Water Model (CWatM). That is to assess soil erosion on a regional to a global scale and to simulate the concentration of suspended sediments in surface waters. CWatM is a fully-distributed, large-scale, open-source hydrological model. It runs on a daily time step and high resolution of up to 30 arc seconds (approximately 1 km at the equator). The model can account for human activity and management of water systems, including reservoir operations, water demand, and crop-specific irrigation requirements. A global dataset of 5 arc minutes is available for an easy simulation setup at a catchment, region, and global scale. The implementation of soil erosion and sediment delivery from terrestrial sources will rely on the Modified Universal Soil Loss Equation (MUSLE) and the stream network density within each grid cell. Further, simulating instream erosion uses a power law approach. Finally, the routing algorithm would move suspended soil particles downstream. For that purpose, we combine input datasets with CWatM variables, e.g., surface runoff. We apply this module to a case study in Uganda’s share of the Victoria Lake Basin at five arc minute resolution, where high soil erosion rates challenge the ecological integrity of the natural environment, as well as agricultural productivity and water quality. We further discuss the model sensitivity to input parameters’ variation (e.g., the fraction of daily rainfall in the half-hour of highest intensity).
The use and vulnerability of medieval masonries in Balaton region, Hungary
Authors: Török Ákos , Logó Bendek , Kis Annamária
Published: February 2023

The geology of the region strongly influences the construction materials of Medieval structures and, consequently, the available raw materials. The current study focuses on the use and vulnerability of various lithotypes and renders in a Medieval Ruined Chuch in West Central Hungary, close to Lake Balaton. The church was constructed in the 13th century and was rebuilt in several periods using various lithotypes and renders. The identification of primary lithologies followed the generation of point clouds by Terrestrial Laser Scanner and the drawing of walls. More than ten various stone types were found, including Jurassic cherty limestone, cemented Triassic limestone (Muschelkalk), basalt tuff, basalt, red Permian sandstone, grey Tertiary sandstone, highly porous Miocene limestone, and travertine. The properties of stones and condition assessment were made by using non-destructive on-site strength tests such Schmidt hammer and Duroskop. Micro-drilling technique was also applied to assess the strength parameters of renders: medieval lime-based mortars, 20th-century portland cement based mortars. Small samples were also taken for laboratory analyses. Our studies suggest that the application of portland cement bearing renders in the 20th century caused significant damage to the structure, accelerating weathering processes. Medieval lime mortars are relatively durable and show smaller-scale alterations. The use of various lithotypes leads to differential weathering of the structure. The long-term preservation of this building depends on the use of appropriate renders and the refurbishment of wall sections that are structurally unstable.
Temporal changes in velocity and scattering properties in the Sichuan region, China
Authors: Li Jinwu , Obermann Anne , Wu Sin-mei , Sánchez-Pastor Pilar , Song Xiaodong
Published: February 2023

The 2008 M7.9 Wenchuan Earthquake is the most devastating event in the last two decades in China. Here, we analyze 8 years (2007–2014) of seismic records to track the normal background level of the media properties, as well as the transient changes associated with tectonic activities (e.g., earthquakes). Understanding the long-term background pattern contributes to identifying transient changes. Temporal velocity variations of the surface waves show clear seasonal fluctuations and a co-seismic velocity drop after the Wenchuan mainshock in the 2-10 s period band. A comparison with meteoric data allows us to conclude that the main mechanism of the seasonal variation is the loading due to precipitation. The seasonal velocity changes exhibit spatial characteristics, where the amplitudes of the seasonal velocity changes are larger in the Tibet Plateau and smaller in the Sichuan basin. The spatial pattern is consistent with that of the tectonic deformation. The deformation is strong in the Tibet Plateau, while the Sichuan basin is relatively stable. Furthermore, there is a higher density of cracks in the Tibet Plateau than that in the basin.Moreover, we increased the time resolution of the noise cross-correlations to twenty days to investigate changes in media associated with the 2008 mainshock by analyzing 1.5 years of data from mid 2007 to 2008 for the surface wave at 2-10 s period band. Compared with the waveforms from seismically quiet time, we observe that the waveform similarity of surface waves decreased significantly about 10 days prior to the mainshock and persisted low until the end of September 2008. To exclude that our observation is related to a changing source pattern, we analyzed the seismic activity in the Sichuan region and the frequency spectrum of the ambient noise field in the corresponding time. Our results suggest that the decorrelation may indeed indicate a regional change in the scattering properties starting 10 days prior to the Wenchuan earthquake.
Parameterising Eddy-Mediated Heat Transports Across the Weddell Sea Continental Slope
Authors: Dettling Nicolas , Losch Martin
Published: February 2023

The Weddell Sea is an Antarctic marginal sea featuring extensive continental shelf areas. Here, dense water is produced through interactions with ice shelves and sea ice and propagates down the continental slope where it forms the densest contribution to the Antarctic Bottom Water. The downflow of dense water creates an isopycnal connection between the continental shelf and slope allowing for the intrusion of warm Circumpolar Deep Water (CDW) onto the continental shelf. When reaching the ice shelf cavities, CDW has the potential to strongly increase the melt rate of the ice shelves with global implications such as sea level rise. Mesoscale eddies sourced from local baroclinic instability play a central role in the shoreward transport of CDW since they supply the momentum to overcome the vorticity gradient imposed by the continental slope. Capturing these eddies in ocean models is particularly challenging because the small Rossby radius of deformation at high latitudes requires a much higher horizontal resolution than currently available in state-of-the-art climate models. This invites the question as to how the shoreward heat flux can be parameterised at coarse resolution and motivates a process oriented modelling study. For this purpose we use the MIT general circulation model (MITgcm) in a configuration featuring idealised sloping topography and surface forcing and typical hydrographic fields representing the Weddell Sea continental shelf and slope. In this setup, a strong heat transport from the open ocean onto the continental shelf only emerges at a resolution of O(1km). At coarser resolution, shoreward heat transport is almost absent resulting in a cold bias on the continental shelf and the exported deep water. We then apply the classical schemes of Gent-McWilliams and Redi (GM/Redi) which parameterise the effect of eddies by introducing an advective tracer flux as a function of the isopycnal slopes and by aligning the diffusion operator with the local isopycnals. We show that using the GM/Redi parameterization shoreward heat transports can be represented so that the difference between the high and coarse resolution hydrographic fields strongly reduces. Advective heat transport dominates over the centre of the continental slope and is captured by the GM part of the parameterisation. The diffusive heat flux dominating over the continental shelf break on the other hand is reproduced by the Redi scheme. In light of potential future changes to the Weddell Sea system we further discuss different approaches to obtain the transfer coefficients needed for the GM/Redi parameterisation based on the resolved flow and sub-grid eddy kinetic energy.
Advanced processing strategies for a future GFZ GRACE/GRACE-FO Level-2 data release
Authors: Murböck Michael , Dahle Christoph , Panafidina Natalia , Hauk Markus , Wilms Josefine , Neumayer Karl-Hans , Flechtner Frank
Published: February 2023

The central hypothesis of the Research Unit (RU) New Refined Observations of Climate Change from Spaceborne Gravity Missions (NEROGRAV), funded for the second three years phase by the German Research Foundation DFG, reads: only by concurrently improving and better understanding of sensor data, background models, and processing strategies of satellite gravimetry, the resolution, accuracy, and long-term consistency of mass transport series from satellite gravimetry can be significantly increased; and only in that case the potential of future technological sensor developments can be fully exploited.In continuation of the first RU phase, the individual project Improved Stochastic Modeling in GRACE/GRACE-FO Real Data Processing (ISTORE) 2 works towards the completion of the optimized stochastic modeling for GRACE and GRACE-FO gravity field determination. This includes three main tasks: (1) the extension of the stochastic instrument error models of the first phase including Global Navigation Satellite System (GNSS) observations; (2) the optimization of the combination of the different observations; (3) the inclusion of tidal and temporally changing non-tidal background model error variance-covariance matrices in the adjustment process. Based on recent developments within NEROGRAV we also work on a future GFZ GRACE/GRACE-FO Level-2 data release.This presentation provides an overview of the main outcomes of the advanced processing strategies. We will discuss details on stochastic modeling of accelerometer, inter-satellite ranging, and GNSS observations, and of ocean tide and non-tidal atmospheric-oceanic background models. We present Level-2 results based on the monthly solutions within the three test years 2007, 2014 and 2019 in the spectral and spatial domain in comparison with the standard GFZ GRACE/GRACE-FO RL06 time series.
From Super-Resolution to Downscaling - An Image-Inpainting Deep Neural Network for High Resolution Weather and Climate Models
Authors: Witte Maximilian , Filippou Danai , Plésiat Étienne , Meuer Johannes , Thiemann Hannes , Hall David , Ludwig Thomas , Kadow Christopher
Published: February 2023

High resolution in weather and climate was always a common and ongoing goal of the community. In this regards, machine learning techniques accompanied numerical and statistical methods in recent years. Here we demonstrate that artificial intelligence can skilfully downscale low resolution climate model data when combined with numerical climate model data. We show that recently developed image inpainting technique perform accurate super-resolution via transfer learning using the HighResMIP of CMIP6 (Coupled Model Intercomparison Project Phase 6) experiments. Its huge data base offers a unique training opportunity for machine learning approaches. The transfer learning purpose allows also to downscale other CMIP6 experiments and models, as well as observational data like HadCRUT5. Combined with the technology of Kadow et al. 2020 of infilling missing climate data, we gain a neural network which reconstructs and downscales the important observational data set (IPCC AR6) at the same time. We further investigate the application of our method to downscale quantities predicted from a numerical ocean model (ICON-O) to improve computation times. In this process we focus on the ability of the model to predict eddies from low-resolution data.An extension to:Kadow, C., Hall, D.M. & Ulbrich, U. Artificial intelligence reconstructs missing climate information. Nature Geoscience 13, 408–413 (2020). https://doi.org/10.1038/s41561-020-0582-5
The Role of Global Thunderstorm Activity in Modulating Global Cirrus Clouds
Authors: Saha Joydeb , Price Colin , Guha Anirban
Published: February 2023

Cirrus clouds provide a significant radiative forcing on the Earth's climate system. The net cloud radiative forcing for cirrus clouds results a warming of the climate.  More/less cirrus clouds result in more/less warming of the planet. The moisture for the formation of cirrus clouds in the upper atmosphere is transported there in large part via deep convective storms, many associated with lightning activity and hence defined as thunderstorms.  An increasing in cirrus clouds in a warmer atmosphere will amplify the initial warming. This paper looks at the connection in space and time between monthly mean lightning activity observed from the Lightning Imaging Sensor on board the International Space Station (LIS-ISS), and the global monthly mean cirrus cloud cover obtained from the MERRA-2 reanalysis product. The correlation coefficient between the global monthly mean cloud optical thickness (COT) of the cirrus clouds (clouds at altitudes above the 400hPa pressure levels) with the monthly mean lightning flash counts is 0.84, implying that monthly mean  lightning can explain 70% of monthly variability of the global high cloud optical thickness. In addition, lightning amount explains nearly 60% of the monthly mean global area coverage of cirrus clouds.  Given these statistically significant connections between lightning and cirrus clouds, we propose using global lightning data as an additional tool for monitoring monthly variability of cirrus clouds.
 
Ocean acidity extremes in the northeast Pacific, from multi-decadal trends to mesoscale drivers
Authors: Desmet Flora , Gruber Nicolas , Münnich Matthias , Vogt Meike , Köhn Eike E.
Published: February 2023

Superimposed on long-term ocean acidification are ocean acidity extremes (OAXs), i.e., periods of unusual acidity in the marine environment. Such extremes form through the interplay of the various spatio-temporal scales of variability associated with the ocean’s carbonate system, ranging from multi-decadal trends to subseasonal dynamics. Using a high-resolution regional ocean model coupled to a biogeochemical-ecosystem model (ROMS-BEC) we assess the role of five mechanisms associated with different scales of variability – namely atmospheric CO2 rise, the decadal North Pacific Gyre Oscillation (NPGO), the interannual El-Niño-Southern Oscillation (ENSO), seasonal upwelling, and mesoscale eddies – in the occurrence of OAXs in a 300 km nearshore band along the U.S. West Coast and the Alaskan coast over the period 1984 to 2019. We find that the annual fraction of the upper 250 m depth that is hit by OAXs increases at a rate of 0.16 % units.μatm-1 driven by the increase in atmospheric CO2 concentration. In addition, our analysis reveals that Pacific climate variability substantially modulates OAXs occurrence on interannual timescales. The fraction of the upper 250 m depth that is hit by OAXs increases by 0.53 % units per unit decrease in the ENSO index, and 0.39 % units per unit increase in the NPGO index. Last but not least, we find that seasonal upwelling and mesoscale cyclonic eddies are key regional drivers of OAXs along the U.S. West Coast. Our results show that coastal upwelling forms intense and shallow OAXs near the coast, while mesoscale cyclonic eddies drive large and long-lasting OAXs that propagate over hundreds of kilometers from the coast to the offshore. Altogether, our results quantify the respective imprint of five mechanisms associated with different scales of variability on the occurrence of OAXs in coastal regions. This knowledge opens new perspectives for improving the predictability of OAXs in the highly productive coastal regions of the northeast Pacific.  
Risk modelling for human displacement: what we’ve learnt and what’s next?
Authors: Kam Pui Man , Ponserre Sylvain , Kropf Chahan M. , Bresch David N.
Published: February 2023

Weather-related events were responsible for nearly 95 per cent of all disaster displacement recorded over the last decade. An average of 21.5 million internal displacements were triggered per year by weather related hazards. Although displacement can be a “short-term” pre-emptive evacuation measure that effectively prevent injuries or loss of lives, people whose home or livelihoods are destroyed or threatened might be forced into medium to long-term displacement.Risk assessment for displacement could help inform anticipatory action that protects people from the harmful impacts of being displaced. Past studies used CLIMADA (CLIMate ADAptation), an open-source probabilistic natural catastrophe risk assessment platform, to estimate the displacement risk in future for weather related hazards taking in account climate change variation in intensity and frequency and population growth. The platform also enables the implementation of impact forecasting for displacement for impending tropical cyclone events, with the possibility to transfer the implementation to other hazards and impact types.However, displacement is much more complex and context-dependent. The modelling assumptions may not be able to represent all the drivers and complex processes of displacement. From our modelling experience we will shed some light on the potential of probabilistic risk assessment for displacement, and the importance of uncertainty and sensitivity analysis that quantify the confidence of model outputs. We will identify and discuss the current scientific gaps of displacement risk modelling, and the way forward to support decision making process in mitigating displacement risk.
A discrete representation and the implementation for the finite-difference seismic waveform simulation with coarse grid
Authors: Jiang Luqian , Zhang Wei
Published: February 2023

The model discretization by the grid points has a great influence on the accuracy of the finite-difference seismic waveform simulation. Discretizing the discontinuous velocity model by the medium parameters of local points will lead to artefacts diffraction from stair-step representation and the inaccuracy of the calculated waveforms due to the interface error. To accurately represent layered models and reduce the interface error of finite-difference calculation, many equivalent medium parametrization methods have been developed in recent years. Most of these methods are developed for the fourth-order staggered-grid scheme and may not be accurate enough for coarse grids when applying higher-order and optimized schemes.In this work, we develop a tilted transversely isotropic equivalent medium parametrization method to suppress the interface error and the artefact diffraction caused by the staircase approximation under the application of coarse grids. We also present an efficient algorithm for implementing equivalent medium parameterization methods for complex layered models.
Near-Earth asteroids orbit determination by DRO space-based optical observations
Authors: Yezhi Song
Published: February 2023

In response to the problem that ground-based optical monitoring systems cannot monitor near-Earth asteroids which are too close to the Sun on the celestial sphere, we raise a method that tracks and determines the orbit of asteroids by Distant Retrograde Orbit (DRO) platforms with optical monitoring. Through data filtering by visibility analysis and the initial orbit information of the asteroids provided by Jet Propulsion Laboratory (JPL), the asteroids' orbits are determined and compared with the reference orbit. Simulation results show that with a measurement accuracy of two arcseconds and an arc length of three years, the orbit determination accuracy of the DRO platform for near-Earth asteroids can reach tens of kilometers, especially the asteroids with Atira orbits to an accuracy of fewer than ten kilometers. In conclusion, the near-Earth asteroids monitoring systems based on DRO platforms are capable to provide sufficient monitoring effectiveness which enables precise tracking of the target asteroids and forecast of their positions.
Leachability of elements in municipal, sewage sludge and industrial incineration ashes using a sequential extraction method
Authors: Kasina Monika , Jarosz Kinga , He Yingzun , Phan Nhung
Published: February 2023

A stable supply of raw materials required for industrial development and production of everyday goods is one of the major challenges for economies nowadays. EU countries are highly dependent on supplies which currently are extracted in only a few countries worldwide. It is also expected that the prices of industrially important raw materials will fluctuate, depending on the supplier policies. Growing concerns of mineral resources supplies on one hand, and the sustainable economy, where protection of natural resources is one of the key goals on the other hand, force us to search for alternative sources of economically important elements. For this reason, waste stream materials: municipal waste incineration ashes, sewage sludge incineration ashes and industrial incineration ashes were studied. The rational use of incineration wastes as a source of economically important materials requires detailed mineralogical and chemical characterization and evaluation of their recovery and leaching potential since they might contain both, important and potentially toxic for the environment elements. To maximize the extraction rates of valuable elements such as phosphorus and/or to minimize the leachability of potentially hazardous elements (e.g. As, Cr, Cd, Cu, Pb, Zn) a three-step sequential extraction procedure in accordance with the Community Bureau of Reference (BCR; Standards, Measurements and Testing Program) was implemented to characterize the content of trace elements and heavy metals, bonds and potential bioavailability of studied ashes. Leachates were analyzed using ICP methods. Mineralogical methods (XRD and SEM-EDS) were applied to study the composition of starting materials and post extraction solid samples. Efficiency of the proposed extraction method was strongly dependent on incineration technology, types of incinerated waste, bulk chemical composition and mineralogy of ashes that influenced their solubility and thus leaching efficacy.Acknowledgment. This publication has been funded from the Anthropocene Priority Research Area budget under the program "Excellence Initiative – Research University" at the Jagiellonian University.
Repeating earthquakes induced during a decameter-scale hydraulic stimulation experiment at the Grimsel Test Site, Switzerland
Authors: Villiger Linus , Kraft Toni , Gischig Valentin , Krietsch Hannes , Wiemer Stefan
Published: February 2023

We performed a similarity based hierarchical cluster analysis and carried out a master event relative relocation of seismicity induced during the hydraulic stimulation of a brittle and highly fractured shear zone. The shear zone was stimulated in an extend of about 10 m and is located in crystalline rock at the Grimsel Test Site, Switzerland. The objective of the experiment was to improve our understanding of stimulation processes associated with high-pressure fluid injections used for reservoir creation in enhanced geothermal systems. In addition to the seismic network exhibiting high spherical coverage at close distances (i.e., eight acoustic emission sensors ~10 – 15 m away from the injection interval), fluid pressures, rock mass deformations and fault dislocations were monitored around the injection location. 1/3 of the located seismic events could be assigned to 44 repeater families exhibiting high waveform similarity (i.e., >95%) when comparing waveform similarities sequentially in time. When comparing similarities to the chosen master event, similarities decay continuously within a repeater family which also reflects in a spatial migration of hypocenters. However, source areas of seismic events within repeater families mostly overlap assuming an appropriate stress drop. But the spatial extent of the observed migration of hypocenters compared to the measured mechanical deformation in the volume is larger and thus suggests that multiple asperities are responsible for seismic events within a repeater family. The repeater families themselves are distributed in clusters which are attributed to the stimulation of distinct fractures in the damage zone of the targeted shear zone. No repeating events were found in the seismicity accompanying a tensile fracture splaying off the stimulated pre-existing fractures. Statistically, events of repeater families are rather Gaussian than power-law distributed. The extended analysis of this multisensor array data presented here reveals a highly complex fracturing process on the 10 m scale during hydraulic stimulation (see also an earlier study of the same experiment focusing on source mechanism Villiger et al. (2021)). ReferencesVilliger, L., Gischig, V. S., Kwiatek, G., Krietsch, H., Doetsch, J., Jalali, M., Amann, F., Giardini, D., & Wiemer, S. (2021). Meter-scale stress heterogeneities and stress redistribution drive complex fracture slip and fracture growth during a hydraulic stimulation experiment. Geophysical Journal International. https://doi.org/10.1093/gji/ggab057 (Geophysical Journal International)
From MODIS cloud properties to cloud types using semi-supervised learning
Authors: Lenhardt Julien , Quaas Johannes , Sejdinovic Dino
Published: February 2023

Clouds are classified into types, classes, or regimes. The World Meteorological Organization distinguishes stratus and cumulus clouds and three altitude layers. Cloud types exhibit very different radiative properties and interact in numerous ways with aerosol particles in the atmosphere. However, it has proven difficult to define cloud regimes objectively and from remote sensing data, hindering the understanding we have of the processes and adjustments involved.Building on the method we previously developed, we combine synoptic observations and passive satellite remote-sensing retrievals to constitute a database of cloud types and cloud properties to eventually train a cloud classification algorithm. The cloud type labels come from the global marine meteorological observations dataset (UK Met Office, 2006) which is comprised of near-global synoptic observations. This data record reports back information about cloud type and other meteorological quantities at the surface. The cloud classification model is built on different cloud-top and cloud optical properties (Level 2 products MOD06/MYD06 from the MODIS sensor) extracted temporally close to the observation time and on a 128km x 128km grid around the synoptic observation location. To make full use of the large quantity of remote sensing data available and to investigate the variety in cloud settings, a convolutional variational auto-encoder (VAE) is applied as a dimensionality reduction tool in a first step. Furthermore, such model architecture allows to account for spatial relationships while describing non-linear patterns in the input data. The cloud classification task is subsequently performed drawing on the constructed latent representation of the VAE. Associating information from underneath and above the cloud enables to build a robust model to classify cloud types. For the training we specify a study domain in the Atlantic ocean around the equator and evaluate the method globally. Further experiments and evaluation are done on simulation data produced by the ICON model.
Stoichiometry on the edge - Humans induce strong imbalances of reactive C:N:P ratios in streams
Authors: Wachholz Alexander , Dehaspe Joni , Ebeling Pia , Kumar Rohini , Musolff Andreas , Saavedra Felipe , Winter Carolin , Yang Soohyun , Graeber Daniel
Published: February 2023

Anthropogenic nutrient inputs lead to severe degradation of surface water resources, affecting aquatic ecosystem health and functioning. Ecosystem functions such as nutrient cycling and ecosystem metabolism are not only affected by the over-abundance of a single macronutrient but also by the stoichiometry of the reactive molecular forms of dissolved organic carbon (rOC), nitrogen (rN), and phosphorus (rP). So far, studies mainly considered only single macronutrients or used stoichiometric ratios such as N:P or C:N independent from each other. We argue that a mutual assessment of reactive nutrient ratios rOC:rN:rP relative to organismic demands enables us to refine the definition of nutrient depletion versus excess and to understand their linkages to catchment-internal biogeochemical and hydrological processes. Here we show that the majority (94%) of the studied 574 German catchments show a depletion or co-depletion in rOC and rP, illustrating the ubiquity of excess N in anthropogenically influenced landscapes. We found an emerging spatial pattern of depletion classes linked to the interplay of agricultural sources and subsurface denitrification for rN and topographic controls of rOC. We classified catchments into stoichio-static and stochio-dynamic catchments based on their degree of intra-annual variability of rOC:rN:rP ratios. Stoichio-static catchments (4036% of all catchments) tend to have higher rN median concentrations, lower temporal rN variability and generally low rOC medians. Our results demonstrate the severe extent of imbalances in rOC:rN:rP ratios in German rivers due to human activities. This likely affects the inland-water nutrient retention efficiency, their level of eutrophication, and their role in the global carbon cycle. Thus, it calls for a more holistic catchment and aquatic ecosystem management integrating rOC:rN:rP stoichiometry as a fundamental principle.