bluuebunny/crossref_metadata_2025 huggingface dataset:
Headwall erosion rates from cosmogenic 10Be in medial moraine debris of five adjacent Swiss valley glaciers
Authors: Wetterauer Katharina , Scherler Dirk , Anderson Leif S.
Published: March 2022

Rock walls in high-alpine glacial environments are becoming increasingly unstable due to climate warming. This instability increases the erosion of headwalls above glaciers modifying glacial surface debris cover and mass balance and, thus, affecting the response of glaciers to climate change. As debris is deposited on glaciers, it is passively transported downglacier forming medial moraines where two glaciers join.

We assess headwall erosion by systematic downglacier-debris sampling of medial moraines and by computing headwall erosion rates from their 10Be-cosmogenic nuclide concentrations. Around Pigne d’Arolla in Switzerland, we collected a total of 39 downglacier medial moraine debris samples from five adjacent glaciers. We explicitly chose medial moraines with source headwalls that vary in size, orientation and morphology, to investigate how different debris source area characteristics may express themselves in medial moraine cosmogenic nuclide concentrations. At the same time, the downglacier-debris sampling enables us to derive headwall erosion rate estimates through time, as medial moraine deposits tend to be older downglacier.

Preliminary results reveal systematic differences in 10Be concentrations for the studied glaciers. At Glacier d’Otemma, Glacier du Brenay, and Glacier de Cheilon 10Be concentrations average at 17x103, 31x103, and 4x103 atoms g-1, respectively. Downglacier 10Be concentrations at Glacier d’Otemma vary systematically and headwall erosion rates tend to increase towards the present. At both Glacier du Brenay and Glacier de Cheilon downglacier 10Be concentrations are more uniform, suggesting that headwall erosion rates did not evolve significantly through time. Results for Glacier de Tsijiore Nouve and Glacier de Pièce will follow soon. In addition, samples at Glacier d’Otemma were collected along two parallel medial moraines sourced by different but adjacent headwalls. Yet, their downglacier 10Be concentrations deviate and our analyses suggest that at Glacier d’Otemma both differences in headwall orientation and headwall deglaciation history may account for the deviation of the two medial moraine records. For all five glaciers, we currently explore how lithology, slope angles, exposition, deglaciation, and elevation vary between the debris source areas and how differences therein could result in the observed differences in 10Be concentrations.
Eruption and Interplanetary Evolution of a Stealth Streamer-blowout CME Observed at ~0.5 AU 
Authors: Pal Sanchita , Kilpua Emilia , Good Simon , Lynch Benjamin , Palmerio Erika , Asvestari Eleanna , Pomoell Jens , Stevens Michael
Published: March 2022

The orbit of the Parker Solar Probe (PSP) during the 5th encounter with the Sun presented an opportunity for a multi-observation analysis including the observations of Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) coronagraphs and Large Angle and Spectrometric Coronagraph (LASCO) coronagraphs. Streamer-blowout coronal mass ejections (SBO-CMEs) are the dominant CME population during solar minimum. With the aid of extrapolated coronal fields and remote observations of the off-limb low corona, we study the initiation of an SBO-CME preceded by consecutive CME eruptions following a multi-stage sympathetic breakout scenario. The suprathermal electron pitch-angle distributions (PADs) and magnetic field observations by PSP suggest that draping of interplanetary magnetic field lines about the CME caused a curvature in the adjacent heliospheric current sheet, initiated magnetic reconnection with the CME flux rope about ~45 hours before it encountered PSP, and eroded ~38% of its initial poloidal magnetic flux at ~0.5 AU. This study covering inner heliospheric observation and analysis of SBO-CME magnetic content provides important implications for the origin of twisted magnetic field lines in SBO-CME flux ropes as the flux rope is not perturbed much by the interplanetary propagation. Also, the multi-spacecraft observations allowed us to estimate the distances where reconnection between the flux rope and its surroundings may be initiated. 
A simulation of flare-driven coronal rain
Authors: Ruan Wenzhi , Zhou Yuhao , Keppens Rony
Published: March 2022

Coronal rains are cool materials (~10,000 K) that appear at hot corona. They are frequently observed in non-flaring loops of active regions and recently observed in flaring loops at gradual phases. Hot coronal loops (~10 MK) are often produced in flare events due to magnetic reconnection. The hot flare loops gradually recover to typical coronal temperature due to thermal conduction and radiative loss, during which condensation can happen due to thermal instability. Here we demonstrate how the rains formed in a flare loop with a two-and-a-half dimensional magnetohydrodynamic simulation. We simulate a flare event from pre-flare phase all the way to gradual phase and successfully reproduce coronal rains. We find that thermal conduction and radiative losses alternately dominate the cooling of the flare loop. We find that runaway cooling and rain formation also induce the appearance of dark post-flare loop systems, as observed in extreme ultraviolet (EUV) channels.
Using the Virial Theorem to Analyze Effects of Energy Dynamics in the Magnetosphere
Authors: Brenner Austin , Pulkkinen Tuija , Toth Gabor , Al Shidi Qusai , Liemohn Mike
Published: March 2022

The solar wind couples with Earth’s magnetosphere driving plasma dynamics which can create magnetic perturbations at Earth’s surface impacting life on the ground. One classic way of understanding this process is via the Dungey cycle where magnetic flux is injected into the magnetosphere on the dayside via a dayside reconnection site. This flux is then transported downstream and is released from the magnetosphere via a tail reconnection site, bringing high hydrodynamic energy plasma earthward which becomes trapped in the ring current, leading to intense sustained magnetic perturbation.

In this work, we take a closer look at this process using 3D MHD results from the Space Weather Modeling Framework. Building off previous work by Brenner et al. 2021, the magnetopause surface is identified in the simulation domain to a fixed downstream tail distance. This 3D volume is then split into regions based on magnetic topology and L shell location. From here two methods are used to describe the magnetic perturbation resulting from each region. The first is using the Biot-Savart law that integrates current density vectors weighted by position and direction. The second uses the virial theorem which employs the scalar product of momentum with the position vector integrated over the magnetosphere. The latter formulation is advantageous since it directly relates the magnetic perturbation with stress terms at the magnetopause boundary and volume integrated energy density in the magnetosphere.

Results from the Biot Savart integration and virial theorem are compared with observations of ground based magnetic perturbations to study the effects of energy transport within the system during a simulated storm event.
Integration of BGC-Argo and the Mediterranean BGC forecast system: new developments of the oxygen data quality assessment and assimilation
Authors: Amadio Carolina , Teruzzi Anna , Cossarini Gianpiero
Published: March 2022

New insights on marine biogeochemical state and variability are yielded by recently available autonomous observation platforms such as the BGC-Argo floats. Additionally, the integration of BGC-Argo data and modelling systems can provide a further improvement on understanding marine biogeochemical dynamics. Indeed BGC-Argo variables can be profitably used for tuning and validation of biogeochemical models, and in data assimilation.

The Mediterranean Sea CMEMS marine forecasting system represents a convincing example of such integration: nitrate and chlorophyll BGC-Argo profiles are already assimilated providing corrections on nutrient and phytoplankton vertical dynamics, while  float oxygen data are used for validation and will be integrated in the data assimilation scheme in 2022. Despite their value, BGC float oxygen measurements are prone to uncertainties such as those related to sensor drifts and their real time and operational use requires caution and specific quality control.

Since the quality control procedures on the real-time oxygen data are limited and automatic and considering that the presence of trend in the deep ocean can be considered a proxy for oxygen sensor drift, a novel operational quality assessment procedure of BGC-Argo oxygen data for model validation and assimilation is here proposed. 

The QC procedure is based on (1) sensor drift computation with the RANSAC (RANdom SAmple Consensus) and Theil-Sen non parametric statistical estimators at two selected depths: 600 and 800m and (2) suspicious drift-oxygen-profiles correction.
Moreover, drift-corrected and uncorrected oxygen profiles are subjected to additional checks: (i) Comparison of surface value with oxygen at saturation (ii) Offset calculation between data and EMODnet2018_int climatological values at 550-650m (iii) Model-data misfit threshold.

The QC criteria have constrained more than one third of oxygen data to be corrected for a suspicious drift. In most cases, the removal of the drift acted as a relaxation factor towards the reference climatological fields.
To test the assimilation of quality-checked oxygen profiles into the CMEMS Mediterranean model system, a set of 2-year OGSTM-BFM-3DVarBio simulations have been implemented. Results show the feasibility of the oxygen data assimilation and the potential much higher impact of oxygen BGC-Argo data with respect to the chlorophyll and nitrate sensors given the evolution of the numbers of BGC-Argo sensors in recent years.
Application of electrical and electromagnetic methods to delineate changes in salt content of soda lakes
Authors: Hettegger Anna , Aigner Lukas , Armas Marco Antonio , Moser Clemens , Cimadom Arno , Flores-Orozco Adrián
Published: March 2022

The main objective of this study is to understand salt dynamics in the soda lakes of the Austrian National Park Neusiedlersee Seewinkel and the influence of climate change in these dynamics. To achieve this, we investigated the application of electrical and electromagnetical methods to quantify spatial and temporal variations in the salt and water content. Built on the link between electrical conductivity and salt content, we mainly present results obtained with low induction number electromagnetic (EMI). EMI data were collected with the CMD Explorer and CMD Mini Explorer (from GF Instruments). Our investigations present, on the one hand, mapping of four lakes, each related to a different degree of degradation, with the aim of understanding the general patterns of electrical conductivity and their link to vegetation and surface cover. On the other hand, we conducted measurements at different time-lapses to monitor changes in the electrical conductivity along three profiles. The monitoring datasets combined EMI and time-domain induced polarization (TDIP) imaging and were repeated every two weeks between April and October 2021 near the Wörthenlacken. Monitoring measurements were conducted with both horizontal and vertical coplanar configurations with 3 separate receiver coils, for a total of 12 measurements for each point with a maximal nominal depth up to 6.7 m. Mapping measurements were collected only with horizontal configurations with both instruments, for six measurements with the same nominal depth of investigation. The initial analysis of the raw data demonstrates changes in the electrical conductivity related to changes in vegetation. In a second step, we inverted the EMI data using the open-source application EMagPy to resolve vertical variations of electrical conductivity along the monitoring profiles. Based on these results we evaluated the variation in electrical conductivity and potential salinity accompanying seasonal variations. Our interpretation incorporates non-geophysical data (temperature, water level, and precipitation) collected in observation wells near the study area. Moreover, we compared EMI monitoring results with those obtained from the inversion of TDIP datasets.
First flight of the mid-infrared limb-imaging interferometer GLORIA on a stratospheric balloon
Authors: Höpfner Michael , Wetzel Gerald , Friedl-Vallon Felix , Gulde Thomas , Kleinert Anne , Kretschmer Erik , Laube Johannes C. , Maucher Guido , Neubert Tom , Nordmeyer Hans , Piesch Christof , Preusse Peter , Ungermann Jörn
Published: March 2022

GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) is a limb-imaging Fourier-Transform spectrometer (iFTS) providing radiances of the thermal infrared emission of atmospheric species. The nominal wavelength range is from 780 to1400 cm-1 with a spectral sampling of 0.0625 cm-1. GLORIA-B is an adaption of the airborne GLORIA instrument to stratospheric balloon platforms. It has performed its first flight from ESRANGE/Northern Sweden in August 2021 during the KLIMAT 2021 campaign in the framework of the EU Research Infrastructure HEMERA.

The maiden flight of GLORIA-B has proven its technical qualification and has provided a first imaging hyperspectral limb-emission dataset from 5 to 36 km altitude. Scientific objectives are, amongst others, the observation of the evolution of the upper tropospheric and stratospheric chlorine and nitrogen budget/family partitioning in a changing climate in combination with the set of 20 MIPAS-B (Michelson Interferometer for Passive Atmospheric sounding-balloon) flights since the mid-1990ies, the observation of photochemically active trace gases during sunset and sunrise, as well as the quantification of pollution of the Arctic upper troposphere/lower stratosphere, e.g. through forest fires.

In this contribution we will demonstrate the performance of GLORIA-B with regard to level-1 (calibrated spectra) as well as level-2 data, consisting of retrieved altitude profiles of a variety of trace gases. These retrievals will be thoroughly characterized as well as compared to externally available datasets (e.g. from simultaneous AirCore observations).
On the rise of Indian summer monsoon precipitation extremes and its correlations with long-term changes of certain anthropogenic factors and climate variability
Authors: Falga Renaud , Wang Chien
Published: March 2022

The trends of extreme precipitation events during the Indian summer monsoon measured by two different indicators have been analyzed for the period 1901-2020, covering the entire India in 9 regions segregated by a clustering analysis based on rainfall characteristics using the Indian Meteorological Department high-resolution gridded data. The important climatological parameters correlating to such increasing trends have also been identified by performing for the first time a multivariate analysis using a nonlinear machine learning regression with 17 input variables. It is found that man-made long-term shifting of land-use and land-cover patterns, and most significantly the urbanization, play a crucial role in the prediction of the long-term trends of extreme precipitation events, particularly of the intensity of extremes. To further study this urbanization impact, a regional cloud-resolving model has been used to examine causal relation between drastic long-lasting change brought by urbanization and extreme precipitation events. The preliminary results will be presented.
Investigating the effects of plate-driving forces on observed surface deformation using global mantle flow models 
Authors: Saxena Arushi , Dannberg Juliane , Gassmoeller Rene
Published: March 2022

Geodynamic models based on seismic tomography have been utilized to understand a wide range of physical processes in the Earth's mantle ranging from lithospheric stress states to plate-mantle interactions. However, the influence of various model components and the associated physical properties of the mantle on the observed surface deformation is still an open question and requires further research. In this study, we develop global mantle flow models based on high-resolution seismic tomography to quantify the relative importance of the plate driving and resisting forces on the surface motions. Our models include temperature and density variations based on seismic tomography, lithospheric structure, and the observed locations of subducted slabs, using the geodynamics software ASPECT. We use a diffusion/dislocation creep rheology with different parameters for the major mantle phases. To facilitate plate-like deformation, we prescribe weak plate boundaries at the locations given by global fault databases. We resolve the resulting strong viscosity variations using adaptive mesh refinement such that our global models have a minimum resolution of <10 km in the lithosphere. We analyze the influence of slab viscosity, plate boundary friction, asthenospheric viscosity, and plate boundary geometry on reproducing the observed GPS surface velocities. Our parameter study identifies model configurations that have up to 85% directional correlation and a global velocity mean within 10% difference with the observed surface motions. Our results also suggest that the modeled velocities are very sensitive to the plate boundary friction, particularly to variations in viscosity, dip angles, and the plate boundary geometry, i.e., open vs closed boundaries, or localized vs. diffused deformation zones. These models show the relative influence of plate-driving forces on the surface motions in general, and in particular the importance of using accurate models of plate boundary friction for reproducing observed plate motions. In addition, they can be used as a starting point to separate the influences of lithospheric structure and mantle convection on surface observables like strain rate, stress field, and topography.
Potential of lacustrine alkenones as a novel proxy for spring temperatures in mid-latitude European lakes
Authors: Martin Céline , Richter Nora , Schubert Carsten , Pomati Francesco , Amaral-Zettler Linda , Dubois Nathalie
Published: March 2022

Past temperature records are key tools for inferring climate dynamics and provide empirical data for testing climate models to improve our mechanistic understanding of natural climate variability. Unfortunately, very few quantitative records of pre-historic continental temperatures exist in Europe. Moreover, existing paleothermometers mainly provide mean annual or warm season temperatures, limiting our understanding of climate variability during the transitional seasons and winter. Alkenones are temperature-sensitive lipids produced by Isochrysidales algae, which have been used for decades to reconstruct quantitative changes in sea-surface temperatures. In lakes, they are not ubiquitous, but they have been increasingly reported in both saline and freshwater lakes worldwide, suggesting that there is great potential for alkenone-based paleotemperature reconstructions in lacustrine settings. Lacustrine alkenones have already been successfuly used to reconstruct paleotemperatures in high-latitude lakes. Depending on the timing of ice-out, they record winter/spring or summer temperatures. In our study, we found that a significant number of Swiss lakes contain lacustrine alkenones. Other studies in mid-latitude European lakes suggest that the peak of alkenone production occurs in spring. The monitoring of Lake St Moritz, an alpine lake in the South East of Switzerland, will allow determining the seasonality of alkenone production in mid-latitute high altitude lakes. Combining genetic analyses and the monitoring of physico-chemical parameters will provide more information about the ecology of the alkenone producers. Our first results suggest that we will be able to improve the understanding of alkenone production in freshwater lakes and to develop the first spring lake temperature reconstruction in Switzerland that extends beyond existing historical records.
Wetlands and foreshores: The solution to all your challenges
Authors: dankers petra
Published: March 2022

Nature-based solutions have become tremendously popular over the past few years. They are popular among large financing institutions such as the WorldBank and the Asian Development Bank up to very local governmental bodies that have heard of the many benefits these Nature-based solutions deliver. However, the supposed benefits of Nature-based solutions depend strongly on how, where and with what purpose these solutions are designed. The massive introduction of Nature-based solutions has led to many interesting and innovative projects that created multiple benefits. On the other hand, it has also led to projects in which the Nature-based component was not so clear, and the benefits were uncertain. This leads us to the question: are Nature-based solutions a way to solve all your challenges in the coastal zone and if they don’t, can we still call them a Nature-based solution? And, what do we actually mean with a Nature-based solution. We would like to tap on these questions with some examples of real projects and conceptual designs.

The projects and designs are all based in coastal areas where Nature-based solutions often take the form of wetlands or extended foreshores. These wetlands consist of mangrove systems in the tropics and salt-marsh systems in more temperate regions. The projects had different goals and different scales, they provided different benefits, but they all have in common that they were called a Nature-based solution. Depending on the goals and specific demands we encountered various interesting challenges. The final designs show that Nature-based solutions come in many sizes, shapes and forms. Sometimes they have the possibility to change livelihoods of people at a landscape scale and sometimes they only added a little green fringe.
Understanding the effects of plastic pollution on the biogeochemical cycle of elements: introducing PLANET project
Authors: Binda Gilberto , Nizzetto Luca
Published: March 2022

The interaction of plastics with (trace) elements has recently attracted research interest. Plastic particles, in fact, are contaminating water environments and can possibly act as sinks or vector of (trace) elements affecting their environmental fate and bioavailability.

The details of the mechanisms driving the interaction of plastic particles and (trace) elements are unclear. It has been argued that the degradation processes of polymers and the colonization by micro-organisms can enhance adsorption of (trace) elements. Moreover, the chemistry of water solution is a determinant of the interaction equilibria.

The PLANET project (understanding PLAstic pollutioN effects on the biogeochemical cycle of ElemenTs) aims at elucidating the mechanisms behind plastic - (trace) element interactions and at investigating the implications for the biogeochemical cycle of (trace) elements in water bodies. This aim will be reached through 4 main pillars, consisting in: i) experiments with artificially aged plastics and biofouling experiments, including the characterization of surface physicochemical properties in aged plastics, ii) sorption and desorption tests with ions and metals in batch experiments under varying physicochemical conditions to measure the energy of the interaction; iii) construction of predictive mathematical frames describing this interaction and its impication for (trace) elements’ cycling; iv) assessment of model predictions through microcosms experiments.

The project was launched in November 2021 and currently the first pillar is under development. Tested materials included both polyolefins (PE and PP) and biodegradable materials (PLA and PBAT). Controlled artificial ageing is achieved through UV radiation in water at varying salinity and pH and through inoculation of bacteria and algae consortia into specially designed microcosms. Plastic materials are analyzed through Fourier transform-Infrared spectroscopy to measure changes in surface functional groups, and through scanning electron microscopy to analyze surface morphology. Preliminary results show that biofouling processes take place rapidly under these experimental conditions on different types of polymer (with attachment of first algae in few days). Biofouling has a strong influence on functional groups changes on the polymers: the presence of polysaccharides from bacteria is observable in most of the biofouled plastics. These evidences highlight that a main role in adsorption-desoprtion processes in plastic particles is mediated by the colonizing microorganisms, which can cover an abundant portion of the plastic surface in waters.
RESECAN: citizen-driven seismology on an active volcano (Cumbre Vieja, La Palma Island, Canaries)
Authors: García-Hernández Rubén , Barrancos José , D'Auria Luca , Domínguez Vidal , Montalvo Arturo , Pérez Nemesio
Published: March 2022

During the last decades, countless seismic sensors have been deployed throughout the planet by different countries and institutions. In recent years, it has been possible to manufacture low-cost MEMS accelerometers thanks to nanotechnology and large-scale development. These devices can be easily configured and accurately synchronized by GPS. Customizable microcontrollers like Arduino or RaspBerryPI can be used to develop low-cost seismic stations capable of local data storage and real-time data transfer. Such stations have a sufficient signal quality to be used for complementing conventional seismic networks.

In recent years Instituto Volcanológico de Canarias (INVOLCAN) has developed a proprietary low-cost seismic station to implement the Canary Islands School Seismic Network (Red Sísmica Escolar Canaria - RESECAN) with multiple objectives:

supporting the teaching of geosciences.

promoting the scientific vocation.

strengthening the resilience of the local communities by improving awareness toward volcanism and the associated hazards.

Densifying the existing seismic networks.

On Sept. 19th 2021, a volcanic eruption started on the Cumbre Vieja volcano in La Palma. The eruption was proceeded and accompanied by thousands of earthquakes, many of them felt with intensities up to V MCS. Exploiting the attention drawn by the eruption, INVOLCAN started the deployment of low-cost seismic stations in La Palma in educational centres. In this preliminary phase, we selected five educational centres on the island.

The project's objective is to create and distribute low-cost stations in various educational institutions in La Palma and later on the whole Canary Islands Archipelago, supplementing them with educational material on the topics of seismology and volcanology. Each school will be able to access the data of its station, as well as those collected by other centres, being able to locate some of the recorded earthquakes. The data recorded by RESECAN will also be integrated into the broadband seismic network operated by INVOLCAN (Red Sísmica Canaria, C7). RESECAN will be an instrument of scientific utility capable of contributing effectively to the volcano monitoring of the Canary Islands, reinforcing its resilience with respect to future volcanic emergencies.
Low-level radiative cooling peaks in regimes of shallow convective organization
Authors: Fildier Benjamin , Muller Caroline , Pincus Robert , Fueglistaler Stephan
Published: March 2022

In models, a local maximum of clear-sky radiative cooling in the lower troposphere often appears as a necessary condition for the development and persistence of convective organization. However, no robust understanding has been provided for the emergence and disappearance of lower-tropospheric cooling in the atmosphere. Here we propose a theoretical characterization of clear-sky radiative cooling peaks, recently calculated from over 2,000 soundings launched during the EUREC4A field campaign in various patterns of shallow organization. A suite of scaling approximations are developed from simplified spectral theory to connect the longwave cooling peak to the vertical humidity structure set by convection. Its height is controlled by local maxima in the vertical gradients of water vapor path, and its magnitude is mainly controlled by the ratio between column relative humidity above and below the peak. In contrast, the value of the Planck function and the spectral width of emission only weakly vary across soundings.  Water vapor spectroscopy implies that upper-level intrusions of moist air detrained from lower latitudes can substantially dim these peaks, possibly by reducing the range of the spectrum that effectively cools to space at the level of the peak. This work motivates future modeling work, formulating the hypothesis that "Fish" patterns, which embed the widest persisting dry areas, may be the most favorable conditions for radiative processes to organize convection. If at play, this radiative feedback would maintain these patterns that are efficient at cooling the tropics, a type of "dry radiator fins" which could mitigate the risk of runaway climate states.
Analysis of spatio-temporal correlations of IGS repro3 station position time series
Authors: Niu Yujiao , Rebischung Paul , Altamimi Zuheir , Wei Na , Li Min
Published: March 2022

Temporally and spatially correlated noise has long been reported in Global Navigation Satellite System (GNSS) station position time series. Accounting for the temporal correlations of the noise is crucial to obtain realistic uncertainties for deterministic parameters, e.g., station velocities, while accounting for its spatial correlations is beneficial to various applications such as offset detection, velocity estimation and detection of local geophysical signals. The origins of the spatio-temporally correlated noise in GNSS series are however still unclear, and a realistic spatio-temporal noise model also remains to be elaborated. In this study, we therefore analysed GNSS residual time series from the International GNSS Service (IGS) third reprocessing (repro3), corrected from loading deformation models, with the purpose of characterizing and modeling their spatio-temporal correlations in detail.

We first estimated spectral correlation coefficients as a function of both the distance between GNSS stations and the temporal frequency. Different spatial correlation regimes could thus be evidenced for different frequency bands. Spatial correlations are in particular higher, and range longer distances, at the frequencies of the periodic (e.g., draconitic, fortnightly) errors in GNSS time series. Broadband spatial correlations are consequently reduced when these periodic errors are filtered out from the series.

To investigate possible spatial non-stationarities of the noise, we then estimated its spatial covariance, as a function of the distance between stations, over different regions. While the estimated spatial covariance is similar to the global average in Europe, Eastern US and Australia, it is consistently higher in Eastern South America, New Zealand and Western US. This may point to a partially geophysical origin of the spatially correlated noise in the latter regions, possibly attributable to unmodeled hydrological loading and tectonic deformation, respectively.

We finally converted the globally averaged spatial covariance of the residual repro3 series into a spatial power spectrum, i.e., power as a function of the spherical harmonic degree. It thus turns out that the average spatial covariance is well described by a spatial power-law model attenuated at the lowest degrees.
Assessing the generalization power of three machine learning models and three evapotranspiration formulas using 143 FLUXNET towers data
Authors: Amani Alireza , Boucher Marie-Amélie , Cabral Alexandre R. , Nadeau Daniel F.
Published: March 2022

Direct measurement of evapotranspiration (ET) is costly and difficult to implement on a large scale. It is therefore a necessity to count on reliable approaches to estimate it. Among such approaches, Machine learning models (MLMs) are easily applicable and computationally inexpensive, especially for broadscale analyses. In this study, three different types of MLMs, namely Random Forest, Light Gradient Boosting Machine and Neural Networks are assessed for their estimation accuracy on unseen locations (i.e. generalization power). Estimates of ET from these MLMs are compared against direct observation from 143 eddy-covariance flux towers spanning across a broad range of climate and vegetation types. We initially hypothesized that the MLMs, provided that they are trained using data from a wide variety of climate and vegetation types, are able to accurately estimate ET on unseen locations (default experiment).  The MLMs are benchmarked against Penman, Priestley-Taylor, and Oudin ET formulas/models. The results show that the MLMs indeed perform satisfactorily on the majority of the test locations, but not in all of them, yielding on average a 15% lower normalized mean-absolute-error (NMAE) than the Priestley-Taylor formula. Moreover, we compared the performance of the MLMs trained and tested using different data splitting strategies. When training and testing data are not spatially separated, the results show that the Random Forest model has a 7% lower NMAE compared to when the spatial separation is done (the default experiment). This suggests that the MLMs are prone to overfit to site-specific patterns that might not be relevant for other locations. In conclusion, the results of this large scale study points toward reliability of the MLMs as far as their generalization power is concerned. At the same time, they also show that different data splitting strategies can lead to significantly different results. 
In situ 4D dendritic crystallization in basaltic magmas reveals how magma mobility occurs within the Earth's crust
Authors: Arzilli Fabio , Polacci Margherita , La Spina Giuseppe , Le Gall Nolwenn , Llewellin Edward W. , Brooker Richard A. , Torres-Orozco Rafael , Di Genova Danilo , Neave David A. , Hartley Margaret E. , Mader Heidy M. , Giordano Daniele , Atwood Robert , Lee Peter D. , Burton Mike R.
Published: March 2022

The mobility of basaltic magma within the Earth’s crust is controlled by magma viscosity. Crystallization and crystal morphology affect the viscosity, mobility and ultimately eruptibility of magma, by locking it at depth or enabling its ascent towards the surface. However, relationships between crystallinity, rheology and eruptibility remain uncertain because of the challenges associated with documenting magma crystallization in real time. Here we show, for the first time, the results of in situ 3D time-dependent, high temperature experiments performed under water-saturated conditions to investigate crystallization kinetics in a basaltic magma at crustal pressure. This new 4D approach provides unique quantitative information on the growth kinetics and textural evolution of pyroxene crystallization in basaltic magmas, quantifying dendritic growth on initially euhedral cores and revealing surprisingly rapid increases in crystal fraction and aspect ratio at undercoolings ≥30 °C. Such crystallization favours a rheological transition from Newtonian to non-Newtonian behaviour within minutes. We applied a numerical model to quantify the effect of dendritic crystallization on basaltic dike propagation towards the surface. Modelling results show that dendritic crystallization can strongly affect magma rheology during magma ascent with important implications for the mobility of basaltic magmas within the crust. 
Competing radiative impacts of low-level and high-level clouds on the strength of an idealized extratropical cyclone
Authors: Voigt Aiko , Butz Klara , Keshtgar Behrooz
Published: March 2022

Extratropical cyclones are the main driver of everyday weather in the midlatitudes. These cyclones are known to be affected by latent heating and are a popular subject of research regarding possible changes in a warming climate. In contrast, the role of radiation - and especially the radiative impact of clouds - in shaping extratropical cyclones has hardly been investigated. To study how cloud-radiative heating of the atmosphere might impact cyclones, we present idealized baroclinic life cycle simulations with the global atmosphere model ICON-NWP in aquaplanet setup with prescribed sea surface temperatures. Several simulation setups are used to isolate not only the overall cloud-radiative impact but also the impacts of low-level clouds and high-level clouds. Moreover, the cloud-radiative impact is compared between two model versions, ICON 2.1 and ICON 2.6. While the model versions simulate similar cyclones when radiation is not taken into account, enabling cloud-radiation interaction leads to contradicting effects.In ICON 2.1 clouds lead to a weakening of the cyclone magnitude by 15%, whereas in ICON 2.6 they strengthen the cyclone by 7%. The different cloud impact results from a robust competition between the radiative impact of low-level clouds, which in both model versions weaken the cyclone, and high-level clouds, which in both model versions strengthen the cyclone. The difference in the overall cloud-radiative impact between the two model versions results from the fact that ICON 2.1 simulates much more low-level clouds than ICON 2.6. This shows that the vertical distribution of clouds and their radiative heating can be an important factor for the dynamics of extratropical cyclones. 
Mid-Pliocene North American Monsoon in Weather Resolving Coupled Simulations
Authors: Albright Mary Grace , Feng Ran , Zhu Jiang , Otto-Bliesner Bette , Li Hui , Bhattacharya Tripti
Published: March 2022

The North American Southwest (SW NA) has recently experienced periods of extreme drought, largely due to an increased intensity in evaporation. Yet, there remains large uncertainty in the predicted future changes of precipitation over this region. As a result, the future of SW NA hydroclimate remains uncertain.  The North American Monsoon (NAM) is an atmospheric circulation feature of SW NA hydroclimate that is generated by interactions between topography and moisture surge from the Gulf of California and the Gulf of Mexico.  Previous research has shown a weakened NAM in response to elevated levels of atmospheric CO2.  However, when analyzing proxy paleoclimate reconstructions during the Pliocene, various records suggest wetter conditions during that time.  We use the mid-Pliocene (3.3 – 3.0 Millions of years ago) as an analog for ongoing climate change because this interval featured topography, geography, and biome assemblages similar to today, but a warmer global mean temperature by 2 - 4 °C compared to pre-industrial, and a sustained 400 ppm CO2.  Here we are testing whether a high resolution simulation (25 km) can better capture the NAM and provide different sensitivity to boundary conditions compared to low resolution (100 km) simulations, using the same Community Earth System Model.  Increased resolution has been shown to improve the representation of features within the NAM for simulations of the present.   Our pre-industrial simulations display a more extensive monsoon region with high spatial resolution, which indicates a dependency of simulated NAM on resolving topographic features such as the Rockies, Basin and Range, and Gulf of California, all of which can only be captured at high spatial resolutions.  Simulations of the mid-Pliocene displayed weakened NAM precipitation along the west coast of the southwestern North America at a low resolution when compared to the pre-industrial run.  Yet, this weakening signal is limited to the Pacific side of the orographic slopes in the high resolution simulation, with the rest of the monsoon region featuring increased precipitation.  Ongoing work will explore the sources for this resolution dependency, and will quantify contributions of mesoscale systems, such as tropical and extratropical cyclones, to precipitation in the monsoon region.
Case study of a mesospheric inversion over Maïdo observatory through a multi-instrumental observation.
Authors: Hauchecorne Alain , Bellisario Christophe , Chane-Ming Fabrice , Keckhut Philippe , Simoneau Pierre , Trémoulou Samuel , Litowski Constantino , Berthet Gwenaël , Jégou Fabrice , Khaykin Sergey
Published: March 2022

Mesospheric temperature inversions are subject to investigations due to the links with multiscale dynamics such as planetary wave and gravity waves. Knowing the impact on climatological inversions also requires understanding the phenomena occurring before, through, and after a mesospheric inversion. We use data obtained during a measurement campaign over Maïdo observatory in La Réunion Island and focus on a specific event occurring in the night between the 9th and the 10th of October 2017. Among the several observations available, LIDAR measurements provided vertical profiles of temperature and gravity waves potential energy completed by high vertical resolution radiosoundings. The airglow layer observed by an InGaAs camera shows the evolution of gravity wave structures at about 87 km between 0.9 and 1.7 µm. Gravity wave parameters such as horizontal wavelengths or intensity emission variations are extracted, along with potential energy compared with LIDAR data. We use atmospheric models (ERA5, WACCM, WRF) and specific tools (NEMO, GROGRAT) to add supplementary information about the night selected. We present here the first results related to the gravity waves and energy exchanges in the frame of the temperature inversion.
Contribution of tropical variability on Antarctic climate changes over the past centuries
Authors: Dalaiden Quentin , Abram Nerilie , Goosse Hugues
Published: March 2022

The future evolution of the Antarctic Ice Sheet (AIS), particularly the West Antarctic Ice Sheet (WAIS), will strongly influence global sea-level rise during the 21st century and beyond. However, because of the sparse observational network in concert with the strong internal variability, our understanding of the long-term climate and ice sheet changes in the Antarctic is limited. Among all the processes involved in Antarctic climate variability and change, an increasing number of studies have pointed out the strong relationship between the climate in the tropics and Antarctic (also called tropical-Antarctic teleconnections), especially between the Pacific Ocean and the West Antarctic region. Most of those studies focus only on the past decades, but to fully understand the long-term Antarctic climate changes associated with tropical variability longer time-series are needed. This is achieved here by using annually-resolved paleoclimate records (ice core and coral records) that cover at least the last two centuries to study both the year-to-year and multi-decadal variability of tropical-Antarctic teleconnections. These records are incorporated into a data assimilation framework that optimally combines the paleoclimate records with the physics of the climate model. As data assimilation provides a climate reconstruction that is dynamically constrained – through the spatial covariance in the climate model – the contribution of tropical variability on Antarctic climate changes can be directly assessed. Different sensitivity tests are performed to isolate the contribution of each tropical basin. Additionally, the roles of multi-decadal and year-to-year variability are compared by averaging the annual paleoclimate records at a lower temporal resolution. This new method of combining the two time-scales is proposed in order to preserve the multi-decadal variability in the annual climate reconstruction.
Australian smoke-charged vortex observations above New Zealand
Authors: Khaykin Sergey , Querel Richard , Liley Ben , Sakai Tetsu , Uchino Osamu , Morino Isamu , Godin-Beekmann Sophie , Hauchecorne Alain , Legras Bernard
Published: March 2022

The Australian bushfires of 2019/20 caused a massive injection of combustion products into the stratosphere that led to a persistent planetary-scale perturbation of all stratospheric climate-relevant variables. This extreme event enabled study of a striking atmospheric phenomenon, the smoke-charged vortex (SCV) – a persistent synoptic-scale anticyclone, which acts to confine the carbon-rich aerosol clouds during their solar-driven rise. This way, highly-concentrated absorbing aerosols are lofted above 30 km, which prolongs their stratospheric residence time and radiative effects.  Here, we use lidar observations at Lauder, New Zealand together with high-resolution radiosonde data and ozone soundings as well as satellite observations (CALIPSO, MLS, TROPOMI) and ERA5 reanalysis to characterize the optical, chemical and thermodynamical properties of a matured 7-km-tall SCV during its transfer over the South Island at 27 km altitude. The gaseous composition of the SCV was characterized by strongly enhanced water vapour and depleted ozone concentrations, leading to a synoptic-scale ozone hole with the total column reduced by up to 20%. The lidar measurements reveal a characteristic bottom-side elongation of the smoke bubble – a tail of aerosols extending over hundreds of kilometers and rotating together with the main body.

 Using long-term ground-based lidar and satellite measurement records, we show that monthly-mean stratospheric aerosol optical depth in early 2020 was highest since the major eruption of Mt. Pinatubo in 1991. With that, the removal of smoke aerosol from the stratosphere took longer than one year.  
Ice-giant missions as gravitational-wave detectors
Authors: Saha Prasenjit , Soyuer Deniz , Zwick Lorenz , D'Orazio Daniel
Published: March 2022

Proposed missions to Uranus and Neptune usually involve a ∼10 year cruise time to the ice giants. This cruise time can be utilized to search for low-frequency gravitational waves (GWs) by observing the Doppler shift caused by them in the Earth-spacecraft radio link. We calculate the sensitivity of prospective ice giant missions to GWs, as well as that of past planetary missions which also searched for GWs. Then, adopting a steady-state black hole binary population, we derive a conservative estimate for the detection rate of extreme mass ratio inspirals (EMRIs), supermassive- (SMBH) and stellar mass binary black hole (sBBH) mergers. For a total of ten 40-day observations during the cruise of a single spacecraft, approximately 0.5 detections of SMBH mergers are likely, if Allan deviation of Cassini-era noise is improved by ∼102 in the 10−5 − 10−3 Hz range. For EMRIs the number of detections lies between O(0.1) − O(100). Furthermore, ice giant missions combined with the Laser Interferometer Space Antenna (LISA) would improve the GW source localisation by an order of magnitude compared to LISA by itself. With a significant improvement in the total Allan deviation, a Doppler tracking experiment might become as capable as LISA at such low frequencies, and help bridge the gap between mHz detectors and Pulsar Timing Arrays. Thus, ice-giant missions could play a critical role in expanding the horizon of gravitational wave searches and maybe even be the first to detect the first SMBH merger.