bluuebunny/crossref_metadata_2025 huggingface dataset:
Seismic velocity changes in response to snow loading at Mount Ruapehu volcano, New Zealand, using passive seismic interferometry
Authors: Yates Alexander , Caudron Corentin , Lesage Philippe , Mordret Aurélien , Pinel Virginie
Published: February 2023

Passive seismic interferometry has become a popular technique for monitoring volcanoes over the past two decades. Despite this, volcanoes still represent challenging locations to apply the methodology due to the presence of volcano seismicity. Volcanic tremor, in particular, can significantly alter the character of cross-correlation functions. This leads to the possibility of mis-interpreting changes in phase or waveform shape as due to real subsurface processes.Mount Ruapehu is one such volcano where volcanic tremor is regularly recorded above 1 Hz. Thus, a previous study applying passive interferometry at the volcano during its most recent eruptive period (2006–07) focused on lower frequencies to reduce the risk of contamination. In this work, we target the higher frequencies that include volcanic tremor (1–4 Hz) during approximately the same period (2005–2009), thus providing an opportunity to monitor changes at shallower depths within the volcanic system. To assess the suitability of the tremor as a repeatable seismic source, we first apply an unsupervised machine learning technique in the form of agglomerative hierarchical clustering of cross-correlation functions. Doing so allows us to form groups of data that share similar characteristics and, unlike commonly used similarity measures, does not require a defined reference period. Through this, we find that cross-correlation functions at higher frequencies are both relatively consistent in time and dominated by seasonal processes (with alternating summer and winter clusters clearly identified).Applying the wavelet method to compute travel-time changes in the time-frequency domain reveals snow loading to be the most likely process influencing seismic velocities on the volcano. Amplitudes of +/- 0.5% are recorded at the seismic station closest to the summit, with peak velocites occurring at the same time as maximum snow thickness. In contrast, the seasonal trends recorded at seismic stations with minimal snow cover are of lower amplitude (+/- 0.1%), opposite in sign, and are best fit using a model based on fluid pressure changes in response to precipitation. No obvious short-term changes are detected prior to phreatic eruptions in 2006 and 2007. It is of interest, however, that both eruptions occur approximately one year apart following the initial decrease of velocities in response to snow unloading/melt, suggesting a causal relationship may exist.
Current and future evolution of drought risk in Ethiopia: A framework to inform disaster risk reduction and climate change adaptation policies
Authors: Bovienzo Domenico , Marzi Sepehr , Monteleone Letizia , Mysiak Jaroslav , Pal Jeremy
Published: February 2023

Climate change is projected to increase the frequency and intensity of future droughts particularly affecting the most low-income countries directly dependent on local rainfed food security and livelihoods. Drought risk and its related impacts depend on the drought hazard, the exposure and the vulnerability of the different socioeconomic sectors and/or ecosystems as well as the adaptive capacity of affected locations. The Horn of Africa, which includes Ethiopia, is currently experiencing one of the most severe droughts in the last 40 years. This study applies a storyline approach to investigate changes in drought risk for Ethiopia combining vulnerability, hazard and adaptive capacity information for current and future projected climatic and socio-economic conditions using a subnational level composite indicator. For our analysis, we define drought based on the Standardised Precipitation-Evapotranspiration Index (SPEI) which characterises the deficits in local water availability based on the precipitation and potential evapotranspiration. SPEI is computed using bias corrected Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) project based on the Coupled Model Intercomparison Project Phase 6 (CMIP6). The Drought vulnerability assessment is carried out combining exposure, adaptive capacity and sensitivity indicators, using INFORM index developed by the Joint Research Centre of the European Commission to support humanitarian crisis and disaster decision-making. The analysis shows that future drought will increase people in need of food assistance both under current population and future population projections. If humanitarian aid and assistance are maintained at recent historical levels, these findings show a substantial increase in the required amounts. These conditions are exasperated when humanitarian access is impeded by local conditions such as the current conflict in Ethiopia, when imports are reduced by crises such as those associated with the Russian invasion of the Ukraine, and by pandemics such as COVID-19. Climate change mitigation is shown to reduce the vulnerability of Ethiopia through a reduction in drought hazard frequency and intensity. The framework presented in this study can be used as a policymaking tool to provide information on how to better prioritize future loss and damage funds and adaptation and mitigation investments to reduce population vulnerability and exposure.
Diagnosing the Transition Zones and Regional Dependencies of the Inverse Energy Cascade in the Eastern South Atlantic using Satellite Data
Authors: Breunig Emelie , Griesel Dr. Alexa , Dräger-Dietel Dr. Julia , Eden Prof. Dr. Carsten
Published: February 2023

Energy cannot be created nor destroyed; it can merely be transferred to different scales. Scott, Robert B., and Faming Wang (2005) showed that in the South Pacific, energy is transferred from mesoscale eddies to large ocean currents (inverse energy cascade). The regional dependencies of the inverse cascade are still not well understood and thus limit the correct parameterisation of energy transfers in climate models. The eastern South Atlantic (0-10°E, 30-35°S) offers a large dataset (satellite as well as drifter data) containing several high energetic processes, such as strong mesoscale eddies. The presence of such energetic mesoscale processes makes the question if the energy is transferred to larger scales, an especially interesting one. To investigate the spectral transitions of the inverse energy cascade, we calculate the energy flux similarly to Scott, Robert B., and Faming Wang (2005) using Sea Surface Height (SSH) satellite data and analyse the results for regional changes. Secondly, we use the same SSH dataset to calculate second- and third-order velocity structure functions (S2,S3). As S2,S3 are usually calculated from surface drifter datasets, this provides a new Eulerian insight into transition zones, making structure functions more widely applicable. 
Detecting Hydrological Barriers and Fragmentation in Wetlands using Deep Learning and InSAR
Authors: Hübinger Clara , Fluet-Chouinard Etienne , Hugelius Gustaf , Peña Francisco J. , Jaramillo Fernando
Published: February 2023

The loss of hydrological connectivity and fragmentation of natural wetlands have driven widespread wetland degradation worldwide. Monitoring techniques are needed to assess the degree of fragmentation and to aid with the restoration of affected wetlands. Hydrogeodetic tools such as wetland Interferometric Synthetic Aperture Radar (InSAR) can be used to monitor wetland hydrology as it provides information on three-dimensional flow dynamics at a high spatial resolution. While this technique has been utilized previously for the manual assessment of hydrological connectivity in wetlands, this study proposes the first deep learning-based approach for the automated detection of barriers to the natural water flow that cannot otherwise be identified by conventional space imagery. To this end, a deep convolutional network is trained by segmenting edge features in ALOS PALSAR-1 L-Band InSAR images captured between 2006 and 2011. The training dataset consists of manually labelled and delineated barriers showing abrupt changes in water surface elevation and 22 wrapped interferograms with high coherence across several sample sites in the Everglades and the wetlands of southern Louisiana, United States. The scenes were processed in the Interferometric synthetic aperture radar Scientific Computing Environment (ISCE). The network is set up using a UNet structure with alternating convolutional and pooling or upsampling layers along a contracting and expanding part. The validation of the resulting pixel-wise segmentation shows that the network can successfully detect hydrological barriers in wetlands. Apart from identifying the location of barriers, the CNN can be applied to identify the type and persistence of the fragmentation over the entire wetland. Utilizing the multitemporal data additionally helps detect seasonal changes in the presence or absence of hydrological barriers in the sample sites. This study demonstrates the potential of deep learning techniques for the automated detection of hydrological parameters in InSAR imagery and sets the groundwork for the automated monitor of wetland fragmentation across the world.
Stepwise recovery of vegetation from Permian–Triassic mass extinction in North China and implications for changes of palaeoclimates
Authors: Shu Wenchao , Tong Jinnan , Chu Daoliang , Yu Jianxin , Hilton Jason , Diez José B.
Published: February 2023

The Permian–Triassic was a major transition in the evolution of life in the earth history, when happened the greatest mass extinction during the Phanerozoic and an unusually prolonged or delayed recovery. Most studies have been carried in the marine facies while very few in the continental facies. On land, plants play a great role in the interaction of climate and terrestrial ecosystems. Here we present a regional case of stepwise recovery of vegetation in North China. Prior to the Permian–Triassic mass extinction, the voltzialean conifer forest community dominated in the Changhsingian. Consequently, the extinction event wiped out of the voltzialean conifer forest community, probably conciding with the extension of the red beds. The first post-crisis flora was an Induan herbaceous lycopsid community, succeeded by the Pleuromeia–Neocalamites shrub marsh community. A pteridosperm shrub woodland community dominated for a short time in the late Early Triassic along with the reappearance of insect herbivory. In the early Middle Triassic, gymnosperm forest communities gradually rose to predominate in both uplands and lowlands along with other diverse plant communities, indicating the beginning of the establishment of the Mesophytic Flora. In the late Middle Triassic–Late Triassic, it was occupied by the Danaeopsis–Symopteris flora and the opportunism elements gradually were replaced by the advanced taxa, which represents the complete establishment of the Mesophytic Flora.
Temporal constraints on Fe mobility in Jack Hills zircon
Authors: Reddy Steven , Taylor Richard , Harrison Richard , Saxey David , Rickard William , Tang Fengzai , Borlina Cauê , Fu Roger , Weiss Benjamin , Bagot Paul , Williams Helen
Published: February 2023

Ancient detrital zircon grains containing magnetite inclusions have the potential to record the Earth’s magnetic field as far back as the Hadean. However, this requires magnetite to be either a primary inclusion or to be a secondary inclusion that forms shortly after zircon crystallization. Microstructural and TEM analysis of Jack Hills zircon show that magnetite, the magnetic recorder in these zircon crystals, is secondary in nature and is associated with the mobility of Fe. However, the timing of Fe mobility within Jack Hills zircon is poorly constrained. Here we undertake nanoscale characterization of highly magnetic zones of zircon, identified by quantum diamond microscopy (QDM), using atom probe tomography (APT). The APT data show the presence of Pb-bearing nanoclusters and these record isotopic compositions consistent with formation during two discrete thermal events at 3.4 Ga and < 2 Ga. The older population of clusters contain no detectable Fe. However, the younger population of clusters are Fe-bearing. This result shows that the Fe required to form secondary magnetite was not present in the zircon prior to 3.4 Ga and that remobilization of Pb and Fe, the latter associated with magnetite formation, took place after 2 Ga, during an annealing event that took place more than one billion years after deposition of the Jack Hills sediment at 3 Ga. This use of APT to date Fe mobility provides a novel approach to temporally constrain the formation of intragranular secondary magnetite inclusions in highly magnetic areas of zircon grains.
Sediment pulse propagation and identification using a low-cost sensor network: a hydropeaking study on the Spöl river, Switzerland
Authors: Droujko Jessica , Molnar Peter
Published: February 2023

Hydropeaking in rivers changes the flow regime, increases river clogging, mobilizes fine sediment, and causes major stress to fish, macroinvertebrates, and aquatic plants that suffer from the rapid water level fluctuations. One in four medium- to large-sized rivers in Switzerland is affected by hydropeaking. In this study, we investigated the effect of hydropeaking on fine sediment transport during an experimental flood on the Spöl river, a tributary of the Inn river, in the canton of Graubünden, Switzerland. The study was a proof-of-concept for new smart turbidity sensors, which were developed in our laboratory, calibrated, and tested in mixing tank experiments in 2021 and again in 2022 with a range of different sediment types. These sensors were deployed at two locations on the Spöl during an experimental flood release by the upstream Ova Spinne hydropower dam. The collected data reveal sudden sediment concentration increases and decreases (pulsing) as the discharge increases steadily throughout the day. The highest concentration of sediment is much larger (4-5 g/L) than would be expected and appeared with the onset of the flood and again with the peak discharge. Our findings also reveal clockwise and counter-clockwise hysteresis loops in the stage-concentration relation, which point to a switch in the sediment supply between supply limited and unlimited conditions during the experimental flood. This study shows that high spatial- and temporal-resolution monitoring of suspended sediment is possible with a low-cost sensor network. The applications of such a network are plentiful: from identifying sediment source activation and transport in small streams, glacier networks and deltas, to environmental monitoring of maximum sediment concentration levels for the survival of fry fish, for prevention of river bed clogging, and for pollutant monitoring (binding to sediments).
Exploring colluvial channel agency in mountain sediment routing and erosion
Authors: Orr Elizabeth , Fame Michelle
Published: February 2023

Mountain sediment routing systems have been shown to preserve a valuable record of how climate and tectonics can influence earth surface processes and the topographic form of landscapes. Catchment drainage density and the efficacy of hillslope-channel sediment transport (namely through landslides and rockfalls) is shown to regulate mountain erosion and the response time of landscapes to external perturbations. The role of colluvial channels/gullies in the mountain sediment routing system is largely overlooked, despite recent research in upland deglaciated landscapes highlighting the significance of these upland channels in storing and transporting sediment via debris flow processes. This preliminary work, at the proof-of-concept stage, looks to (1) include and then reflect upon the contribution of these ephemeral channels to catchment drainage densities, and then (2) reexplore the links between catchment drainage density and erosion. The Blue Ridge Mountains of Central Appalachia, USA is an ideal location for this initial investigation as the range is unglaciated, tectonically inactive, and has a relatively uniform lithology and climate. High resolution LiDAR data and satellite imagery was used to map the channel network of 24 catchments in the Blue Ridge Mountains. Cosmogenic nuclide erosion rates for these catchments were then evaluated against their drainage densities. Initial results suggest that while drainage density likely influences the erosion rates recorded in Central Appalachia, the role of colluvial channels within this is complex. These findings have raised some important questions about the controls of colluvial channel sediment flux, morphology and distribution in mountain areas.
Estimating the interannual variability of vertical velocity within the global ocean thermocline from observation-based geostrophic meridional velocities.
Authors: Cortés Morales Diego , Lazar Alban
Published: February 2023

Vertical velocities are several orders of magnitude smaller than the horizontal ones when looking at patterns larger than the sub-mesoscales in the open ocean. Hence, direct measurement attempts of open ocean w are scarce. Methods for estimating w in the real ocean combine theory and observation-based fields. In the present work, climatological circulation patterns in Linear Vorticity Balance (LVB: βv=f∂w/∂z) are first identified in an eddy-permitting OGCM. Then, for such regime of circulation, we show that it is possible to reconstruct a robust w field for the climatological mean.In the first part, we present a thorough baroclinic analysis of the climatological LVB. Below the Mixed Layer, the LVB holds to first order in the tropical and subtropical gyres interior and part of subpolar and austral circulation throughout the water column. Within western boundary currents, the equatorial band, areas of the subpolar gyres and the Circumpolar Circulation, significant departures occur due to the dominance of other terms in the vorticity budget, such as nonlinearities or friction. Although the ocean transport adjustment occurs on time scales constrained by basin-crossing times of Rossby waves, we show that the LVB often holds at much shorter time scales of a few years. When the climatology is reduced, the LVB's strength to describe the ocean circulation is relatively maintained. However, the time-dependent of the vorticity balance becomes significant and impacts the vorticity balance in western boundary currents and western tropical regions.These results allow us to reconstruct the interannual variability of w for flows in LVB using geostrophic meridional velocities and satellite wind fields within large fractions of the global ocean. In the last part, we explore the differences at regional scale between our observation-based reconstruction and two other available estimates of w: one produced by an ocean reanalysis and the other reconstructed with observations and the Omega equation theory.
A parametric study of sea level and grounding line projections in the Amundsen Sea sector for coupled solid Earth - ice sheet models.
Authors: Houriez Luc , Larour Eric , Caron Lambert , Schlegel Nicole-Jeanne , Pelle Tyler , Seroussi Helene
Published: February 2023

The evolution of the Antarctic Ice Sheet (AIS) represents one of the most important and uncertain contributions to sea level rise in the upcoming centuries. Thwaites Glacier and the Amundsen Sea sector of the West Antarctic Ice Sheet (WAIS) have been identified as the continent's most critical areas. The retreat of Thwaites Glacier's grounding line - the transition area where ice is no longer grounded and becomes afloat - is the subject of considerable study for modelers as it governs the collapse of the glacier.

 

Recent advances towards the coupling of dynamical ice models with Glacial Isostatic Adjustment (GIA) models have provided the means to improve grounding line projections by considering solid-Earth processes and their interactions with the cryosphere and hydrosphere. However, the spatial and temporal model resolutions necessary to fully capture these interactions, and the sensitivity to model parametrization, remain elusive.

 

We investigate the grounding line retreat of Thwaites Glacier through 2300 using the parallelized coupled physics capabilities of the Ice-sheet and Sea-level System Model (ISSM) which capture the complex interactions between solid-Earth, ice-sheets, and ocean. We incorporate realistic climatology, ocean melt rates, and GIA models and we discuss the impact of spatial and temporal model resolution, and solid-Earth parametrization, on the grounding line retreat and sea level change.
Investigating the Causes of Poleward Shift in Monsoon Low-level Jet
Authors: Sreepriya Sukumaran , Mirle AchutaRao Krishna , Sandeep Sukumaran
Published: February 2023

Recent studies using coupled model simulations and observation datasets suggest a poleward shift and overall weakening of Indian Summer Monsoon (ISM) circulation (Sandeep and Ajayamohan, 2015). Their investigation using experiments from the fifth phase of coupled model Inter-comparison project (CMIP5) indicate a poleward migration of the monsoon low-level jet (LLJ), with the magnitude of shift  linked to the degree of warming. Here we investigate the changes in monsoon LLJ in multiple reanalysis datasets as well as historical and future scenario simulations of the sixth phase of coupled model Inter-comparison project (CMIP6). The latitudinal location of LLJ is defined as the latitude of zero absolute vorticity over the Arabian Sea, following Tomas and Webster (1997). Although all reanalysis datasets show a poleward shift in LLJ since late 1970s, the magnitude of shift varies among them. The multi model ensemble of CMIP6 historical simulations show a northward shift of 0.4 degrees in LLJ. The ensemble mean of SSP585 simulations show a northward shift in LLJ by 0.8 degrees in the 2081 - 2100 period. The changes in the latitudinal position of LLJ and the land-sea temperature difference are significantly correlated, with a Pearson correlation coefficient of 0.81 and 0.67 for the ensemble means of historical and SSP585 runs, respectively. This suggests that the underlying dynamics of the monsoon circulation is changing in a warming climate.ReferencesSandeep, S., & Ajayamohan, R. S. (2015). Poleward shift in Indian summer monsoon low level jetstream under global warming. Climate Dynamics, 45(1), 337-351.Tomas, R. A., & Webster, P. J. (1997). The role of inertial instability in determining the location and strength of near‐equatorial convection. Quarterly Journal of the Royal Meteorological Society, 123(542), 1445-1482.
Sensitivity to soil moisture initialization in the simulation of Indian pre-monsoon season, using a regional climate numerical model
Authors: Vasukuttan Arjun , Sangelantoni Lorenzo , Shateesan Ka , Redaelli Gianluca
Published: February 2023

Soil moisture content is crucial for the representation and predictability of hydroclimatic extremes of different spatial/temporal scales such as heavy rainfall, droughts and heatwaves. In order to include these effects and the relevant feedback with the atmosphere in a regional climate model, the soil moisture initialization has to be adequate.This study explores the soil moisture precipitation (SM-P) feedback, the soil moisture temperature (SM-T) feedback and the heat fluxes over the entire domain and 3 smaller regions of interest. A hydrostatic version of the Regional Climate Model  4.7 (RegCM4.7) with Arakawa B grid is used to run the simulations. The simulations  are performed for the months February to May during the years 2008, 2009 and 2010 with a spatial resolution of 12 km and temporal resolution of 3 hours. The initial and boundary conditions(ICBC)  are derived from the ERA5 data.  We examine results from simulations initiated using three different soil moisture datasets, namely, the control, dry and wet datasets. The soil moisture data from the ERA5-Land reanalysis is used for the control simulation. A dry/wet simulation is run using dry/wet datasets derived from the ERA5-Land data. This is done by halving/doubling the soil moisture values from ERA5-Land data, giving rise to new soil moisture values with lower/higher soil moisture as compared to the control dataset (ERA5-Land). CMORPH (Climate Prediction Center (CPC) Morphing Technique (MORPH)) and CRU (Climate Research Unit) datasets are used as reference to evaluate the precipitation and temperature values resulting from the control simulation.The results display the mean changes in the dry/wet simulation results with respect to the control simulation. Plots showing the vertical profile changes in relative humidity and air temperature, and changes in lower tropospheric wind and specific humidity, indicates the build-up of the observed precipitation events and temperature patterns induced by the initial soil moisture perturbation. Interestingly the simulation results show negative SM-P feedback.  In other words, the average precipitation seemed to increase/decrease for the dry/wet cases with respect to the control simulation. This is contrary to the general expectation that dry/wet soil moisture decreases/increases precipitation. The possible reasons for the negative SM-P feedback and its distribution over the region include the proximity to the ocean, topography, and the pre-monsoon dryline. The SM-T and the heat fluxes on the other hand display expected behaviour with few exceptions in some regions in the dry simulation case.
Temporal evolution of the aerosol radiative forcing due to changing emissions of individual aerosol species and their precursors over the Indian region as estimated using a global climate model CAM6.
Authors: Sharma Amit Kumar , Ganguly Dilip
Published: February 2023

Aerosols are known to play an important role in regulating the Earth’s energy budget, by directly interacting with solar and terrestrial radiation and modifying the cloud properties. Radiative forcing is commonly used as an index for quantifying such imbalances in the Earth’s radiation budget by any factor. Quantifying aerosol radiative forcing is an initial step towards understanding the response of the Earth’s climate system to changes in emissions of aerosols from anthropogenic sources from pre-industrial (year 1850) to present day.Our present study is designed to understand implications of changing emissions of aerosols over the historical period (1985-2014) on the evolution of aerosol and cloud radiative forcing using a state of art global chemistry-climate model named CAM6. The estimates of evolution of aerosol radiative forcing and its decomposition into direct radiative forcing (DRF or ERFARI), cloud radiative forcing (CRF or ERFACI) and surface albedo radiative forcing (SARF) on a global scale with special emphasis over the Indian region is being investigated. For this purpose, simulations are performed by CAM6 model for the 30-year period from 1985 to 2014 with model meteorology nudged towards the ERA5 reanalysis data using CMIP6 global emission inventory. We are trying to understand the implications of changing emissions of aerosols on the estimates of ERFARI, ERFACI and SARF to understand the contribution of each pathway through which changes in emissions of aerosols from PI to PD perturb the radiation budget of the earth-atmosphere system. We follow the methodology of Ghan et al. (2012) and use various combinations of additional radiative diagnostics with neglected absorption and scattering of aerosols and clouds along with all sky fluxes of shortwave (SW) and longwave (LW) radiation at top of the atmosphere (TOA) to decompose the total aerosol radiative forcing into ERFARI, ERFACI, and SARF.Our results show that although the overall effect of changing emissions aerosols and their precursors from anthropogenic sources is to produce a negative radiative forcing at the top of atmosphere (TOA) thereby resulting in cooling over the south Asian region, we find that the aerosol-radiation interaction (ari) leads to warming while aerosol-cloud interaction (aci) results in cooling over the same region. The results from our CAM6 simulations show that the annual mean shortwave aerosol direct radiative forcing (DRF or ERFARI) averaged across the Indian land mass due to major aerosol species has increased from 0.46 W/m2 to 0.76 W/m2 during the 30-year period from 1985 to 2014. More results with greater details on the contribution of individual aerosol towards the temporal evolution of ERFARI and ERFACI will be presented. Keywords: aerosols, Radiative forcing, ARI, ACI, CAM6 
Microphysical Modeling of Water Isotopic Composition in the Asian Summer Monsoon
Authors: Clouser Benjamin , KleinStern Carly , Khaykin Sergey , Singer Clare , Sarkozy Laszlo , Viciani Silvia , Bianchini Giovanni , D'Amato Francesco , Lykov Alexey , Ulanovsky Alexey , WIenhold Frank , Legras Bernard , Homeyer Cameron , Thornberry Troy , Moyer Elisabeth
Published: February 2023

The summertime Asian Monsoon (AM) is the single most important contributor to water vapor in the UTLS and overworld stratosphere. Much of that water comes from sublimating ice, but the life cycle of the condensate lofted by overshooting convection is not well understood. We report here on insights into that life cycle derived from the first in-situ measurements of water vapor isotopic composition over the Asian Monsoon. The Chicago Water Isotope Spectrometer (ChiWIS) flew on high-altitude aircraft in the monsoon center during the StratoClim (2017) campaign out of Nepal, and in monsoon outflow during ACCLIP (2022) out of South Korea. Both campaigns sampled a broad range of convective and post-convective conditions, letting us trace how convective ice sublimates, reforms, and leaves behind characteristic isotopic signatures. We use the Bin Resolved Isotopic Microphysical Model (BRIMM), along with TRACZILLA backtrajectories and convective interactions derived from cloud-top products, to follow the evolving isotopic composition along flight paths in both campaigns. Results support the wide diversity of isotopic enhancements seen in both campaigns and show how temperature cycles downstream of convective events progressively modify environmental isotopic compositions.
The Structure of the warped Io Plasma Torus constrained by the Io Footprint
Authors: Schlegel Stephan , Saur Joachim
Published: February 2023

The location of the Io Plasma Torus is routinely assumed to be the centrifugal equator of Jupiter's magnetosphere, i.e. the position along the magnetic field lines farthest away from Jupiter's rotational axis. In many models, the centrifugal equator is assumed to lay on a plane, calculated from a (shifted) dipole magnetic field, rather than on a warped surface which incorporates Jupiter's higher magnetic field moments. In this work, we use Hubble Space Telescope observations of the Io Main Footprint to constrain density, scale height and lateral position of the Io Plasma Torus. We show that the leading angle of the footprints can be used to calculate expected travel times of Alfvén waves along the magnetic field lines. For the magnetic field we use the JRM33 magnetic field model. The inversion results show peak densities between 1830 / cm3 and 2032 / cm3 and scale heights between 0.92 RJ and 0.97 RJ consistent with current literature values. Using a warped multipole centrifugal equator instead of a planar dipole the quality of the fit increases by about 25 %. To evaluate these findings quantitatively, a Monte-Carlo-Test was conducted confirming that the multipole centrifugal equator explains the data much better. Furthermore, in a second set of inversion the latitudinal displacement of the torus due to quadropole moments has been fitted using a half synodic periodicity. The best fit locations are comparable to the predicted multipole centrifugal equator location, calculated from the JRM33 model. The additional half synodic periodicity of Io's orbital position inside the torus due to the incorporated quadropole moments alters Io's relative position to the torus center by about  0.15 RJ , which changes the plasma density in Io's vicinity by up to 20 %. 
The Rising Pulse of Land Carbon Uptake
Authors: Steller Clara , Humphrey Vincent , Fischer Erich , Knutti Reto
Published: February 2023

Because long-term observations are sparse and heavily affected by inter-annual variability, the detection of forced trends in land carbon uptake has been remarkably difficult. While changes in aggregated monthly or yearly carbon uptake have been heavily studied, changes in the diurnal cycle of carbon uptake remain uninvestigated. Here, we evaluate long-term changes in three-hourly Net Ecosystem Production (NEP) and the contribution of different times of the day to long-term changes in the terrestrial carbon sink. We first show that between 1950 and 2014, five CMIP6 models show a significant increasing trend in the diurnal NEP amplitude (DNA). Second, we show that DNA trends have a much higher signal-to-noise ratio compared to trends in NEP itself, and linearly scale with long-term annual NEP. Evaluating these model-based results against observations, we show that positive DNA trends are also found at a majority of observational eddy-covariance sites between 1990 and 2022. The positive correlation between DNA and long-term NEP is also confirmed by these observations. Our results reveal a widespread but previously undocumented emergent climate signal in terrestrial carbon exchange at the diurnal scale with the potential to serve as a new observational constraint for Earth system models.
Applied geophysics for regeneration of past metallurgical sites
Authors: Dumont Marc , Isunza Manrique Itzel , Michel Hadrien , Debouny Tom , Caterina David , Nguyen Frédéric
Published: February 2023

Ancient metallurgical sites, such as those found in post-industrial cities, present both challenges and opportunities for the development of resilient cities. The legacy of these industries, including mining, smelting, and blast furnace, has left behind vast quantities of residues in the form of unrecorded slag heaps. The challenge of those ancient metallurgical sites is to combine the remediation of the polluted soil while leveraging the valuable resources it contains to support sustainable economic development. This requires a detailed understanding of the structure and composition of the slag heaps in order to safely and effectively extract valuable materials while minimizing environmental impacts.For decades, the regeneration of past metallurgical sites has relied on extensive drilling surveys and geochemical analysis. However, this approach has proven to be costly, time-consuming, and potentially hazardous for the operators involved. In this context, we present an integrated methodology for characterizing slag heaps using non-invasive geophysics. Developed as part of the NWE-REGENERATIS Interreg project, our approach consists of four main steps: (i) historical studies of the site activities and deposits to identify areas of interest, (ii) electromagnetic induction mapping of the identified areas of interest; (iii) 2D electrical resistivity tomography (ERT) and induced polarization (IP) to image the structure of the slag heap; and (iv) conducting a limited sampling survey to validate the geophysical interpretation and define the bulk composition of the deposit. Our approach is not only less time-consuming and less costly than the traditional method but also safer for the operators.This study has been applied to a former zinc production site nearby Liège city in Wallonia, Belgium. The application of the NWE-REGENERATIS methodology has allowed the imaging of the 3D structure of the anthropogenic deposits. The combination of ERT and IP measurements has revealed the presence of two types of residues, with the main part of the deposit composed of inert waste, and metallic slag lenses are present on the surface. These insights provide valuable information for assessing the feasibility of urban mining and developing effective regeneration plans for the site. The application of the NWE-REGENERATIS methodology in this study has proven to be a valuable tool for understanding the complexities of ancient metallurgical sites. Our approach is not only less time-consuming and less costly than the traditional method but also safer for the operators.
New technologies and insights from a real-time monitoring system of sea ice and oceanographic conditions in Northeast Greenland
Authors: Boone Wieter , Ponsoni Leandro , Johnen Geoffrey , Rysgaard Søren
Published: February 2023

Due to climate change, the Arctic environment has rapidly evolved in the last decades. Glaciers are melting at unprecedented rates, sea ice is forming later and melting earlier in the season, multiyear sea ice is being replaced by yearly sea ice, and the freshwater content in the ocean has increased. All this has impacts other large-scale, ocean-climate-related phenomena such as the water mass (trans)formation, ocean currents, and salinity fronts. The natural variability of the Arctic system itself has been reported to be bound to change. Apart from that, Arctic ecosystems are also expected to respond to evolving environmental conditions. Besides the importance of these changes at a regional and global scale, long-term and continuous environmental observations are still scarce both in time and space. Hard accessibility of Arctic regions, makes observational initiatives logistically difficult, time-consuming, and costly. In addition to providing environmental information, near-real-time and long lasting observing systems are key for supporting data to local communities, mariners and also for model assimilation and verification in the context of operational forecast systems. With the advent of new technologies, low-cost solutions for continuous and long-term coastal observations are possible. In this work, we introduce two systems. Firstly, a near-real-time observing system for sea ice and oceanographic conditions deployed in Northeast Greenland in the framework of the Greenland Integrated Observing System (GIOS.org). These systems are composed of mobile observatories powered by sun and wind allowing the near-real-time measurements of atmospheric, terrestrial and oceanographic drivers of the coastal ocean. The system measures several sea ice (e.g., sea ice thickness, images) and oceanographic (e.g., salinity, temperature, and currents) parameters. In practical terms, oceanographic sensors deployed for 2 years on underwater moorings collect data and transmit it via an inductive link to in-land containerized unities and transmit near-real-time data over satellite. Secondly, we present low-cost IoT (Internet of Things) units that enable transmission of a limited set of parameters via satellite from sensors dispersed in the landscape. For both systems, the data, once transmitted, enters a customized data processing system which allows displaying the post-processed environmental conditions in near-real-time via an open online dashboard. To conclude, this work will introduces new analysis methods and preliminary results based on real time data from the field on sea ice formation and melting and how these are directly influenced by oceanographic and atmospheric conditions.
Using climate model projections to provide relevant climate information to Arctic reindeer herding communities
Authors: Matthes Heidrun , Habeck J. Otto , Laptander Roza , Komu Teresa , Istomin Kirill , Horstkotte Tim , Tømmervik Hans , Rasmus Sirpa , Eronen Jussi T. , Forbes Bruce C.
Published: February 2023

Reindeer herding is a culturally and economically significant livelihood of local communities in the circumpolar North, strongly depending on environmental conditions. Providing climate information for such a target group requires brining together local knowledge and climate model projections.In this study, information collected in interviews with reindeer herders on what makes a year good or bad for them (critical conditions) was used as a basis for defining indices that can be calculated from climate model projections. In this process, we associated the critical condition to meteorological variables, for example “temperatures above 20°C in June and July” were related to an index tasmax20, which counts the number of days in June and July with daily maximum temperatures above 20°C. In this way, we identified three types of critical conditions/indices (1) indices that can be calculated relatively easily, some of them conforming to climate extreme indices common in climate change analysis; (2) indices that need either more specific information from herders (eg to make a condition “July and August should not be cold”, a specific definition of “cold” is needed) or scientific background knowledge (e.g. “abundance of mosquitos” needs information on the necessary meteorological variables and their thresholds) so they can be calculated; and (3) indices that cannot be calculated from the output climate models commonly provide, because they require for example variables like daily soil temperature (rain on frozen ground) or river ice.We have focussed our analysis on Fennoscandia and northwestern Russia, using data from the CMIP6, EURO CORDEX and Polar CORDEX data bases to calculate in a first step indices from category (1) for different RCP futures. For example, exposure multiplication factors reveal that for tasmax20, increases by the end of the century are up to a factor of 10 for RCP4.5 and a factor of 20 for RCP8.5, with obvious latitudinal patterns.
Satellite-derived estimates of slush and ponded water extent across Antarctica's ice shelves, 2013-202
Authors: Dell Rebecca , Willis Ian , Arnold Neil , Banwell Alison
Published: February 2023

Surface meltwater on Antarctic ice shelves is comprised of slush (saturated firn), and ponded water (lakes and streams). Often, slush forms as a precursor to ponded water, and its formation leads subsequently to water collecting in basins or flowing across ice shelf surfaces. Where slush and/or ponded water refreeze at the end of a melt season, the firn air content of ice shelves may be lowered. This can increase ice shelves’ susceptibility to future meltwater ponding, making them more vulnerable to potential hydrofracture and break-up. Slush and ponded water also have a lower albedo than snow or dry firn, further increasing ice-shelf surface melt under warmer climates. To date, most satellite-derived estimates of surface water on ice shelves have identified only ponded water, potentially underestimating the extent of surface meltwater. Here, we use a previously developed random forest classifier to produce a novel, continent-wide dataset of slush and ponded water extent across all Antarctic ice shelves between 2013 and 2021. Our dataset is comprised of monthly meltwater products for the austral summers (November-March where data availability allows), from which continent-wide, regional, and individual ice-shelf trends are investigated.The continent-wide total meltwater coverage (assessed between November and February) was greatest during January 2017, reaching 6078 km2. Notably, we find that including the slush extent in total meltwater calculations increases surface water extent by a mean of 56% during the melt-season peak (January). However, we identify marked inter-regional variation, with slush accounting for 71% of January’s total surface meltwater extent in Dronning Maud Land, but only 46% in the Antarctic Peninsula. This indicates that until now, the extent of surface meltwater across Antarctica’s ice shelves has been largely under-estimated on ice shelf, regional, and continent-wide scales, which has significant repercussions for calculations of the surface and sub-surface energy and mass balance of ice shelves, the long-term storage of meltwater on ice shelves, and predictions of future ice shelf stability.
Validation of the Aeolus L2A products with the eVe lidar during ASKOS/JATAC campaign
Authors: Paschou Peristera , Siomos Nikolaos , Marinou Eleni , Gkikas Antonis , Moussa Idrissa Samira , Tetteh Quaye Daniel , Dêgbé Fiogbe Attannon Désiré , Meleti Charoula , von Bismarck Jonas , Fehr Thorsten , Amiridis Vassilis
Published: February 2023

Abstract. The Joint Aeolus Tropical Atlantic Campaign (JATAC) for the Calibration and Validation (Cal/Val) of the ESA’s Aeolus mission was held on summer and September 2021 and 2022 at the remote tropical islands of Cabo Verde. The JATAC campaign comprises airborne and ground-based instrumentation delivering reference measurements of wind profiles and aerosol/cloud optical properties for the validation of the Aeolus products, as well as supporting related research activities. The ground-based component of JATAC, ASKOS (https://askos.space.noa.gr/) was stationed at the Ocean Science Center in Mindelo (OSCM), São Vicente Island, where measurements from active and passive remote sensing sensors have been deployed for the validation of the Aeolus Level 2 aerosol and wind products.The eVe lidar, which is the ESA’s ground reference lidar system, was deployed in ASKOS for the validation of the Aeolus Level 2A aerosol products. eVe lidar is a scanning system that can perform combined linear/circular polarization and Raman measurements that operates at 355 nm and retrieves the particle backscatter coefficient, the particle extinction coefficient, the lidar ratio, and the linear and circular depolarization ratios. The lidar is implemented in a dual-laser/dual-telescope configuration that allows eVe to simultaneously reproduce the operation of the ALADIN lidar onboard Aeolus, i.e. circularly polarized emission, as well as the operation of a traditional lidar system, i.e. with linearly polarized emission. Targeted measurements of eVe lidar for the Aeolus validation were performed every Friday evening during the nearest Aeolus overpass from Mindelo resulting to a dataset of fourteen collocations for the intensive ASKOS operation periods in 2021 and 2022. In this study, we present the results from the comparison of the particle backscatter and extinction coefficients, and the lidar ratio between eVe and Aeolus profiles. Acknowledgements:This research was supported by the European Space Agency project ASKOS (Grant agreement 4000131861/20/NL/IA) and the PANGEA4CalVal project (Grant Agreement 101079201) funded by European Union’s Horizon Widera 2021 Access program.
Observation of Gravity Waves and Turbulence at the Polar Night Jet
Authors: Baumgarten Gerd , Franco-Diaz Eframir , Fiedler Jens , Gerding Michael , Latteck Ralph , Mossad Mohammed , Renkwitz Thoralf , Strelnikova Irina , Strelnikov Boris , Wing Robin
Published: February 2023

The polar night jet, i.e., the edge of the polar vortex, maximises in the altitude range of 30 km to 70 km. The polar vortex is known to affect even underlying layers and the weather. The polar night jet shows the highest mean wind speeds observed in the atmosphere and likely plays an important role in multi-step vertical coupling not only from the ground, but also from the upper atmosphere downward.Direct measurements of the polar night jet’s extreme atmospheric motion are rare and limited to a few rocket soundings or locations with dedicated remote sensing techniques. We operate lidar and radar instruments capable of measuring temperatures and winds above northern Norway (ALOMAR, 69°N) and northern Germany (Kühlungsborn, 54°N). The instruments have observed the atmosphere frequently inside and outside the Polar Vortex for more than 10 years.Using lidar measurements of temperatures and winds allows for studying up- and downward-propagating gravity waves in complicated dynamical situations that are often found at the polar vortex edge. Observing simultaneously up- and downward propagating waves may indicate gravity wave breakdown as well as the generation of secondary gravity waves and turbulence. Turbulence is frequently detected using the MAARSY VHF radar. So called Polar Mesosphere Winter Echoes (PMWE) are observed if sufficient ionisation and turbulence exist.We will discuss the relationship between waves, turbulence, and the polar vortex based on lidar and radar observations.