bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards RNA life on Early Earth: From atmospheric HCN to biomolecule production in warm little ponds
Authors: Pearce Ben K. D. , Molaverdikhani Karan , Pudritz Ralph , Henning Thomas , Cerrillo Kaitlin
Published: March 2022

The origin of life on Earth involves the early appearance of an information-containing molecule such as RNA. Warm little ponds are ideal sites for the emergence of RNA, as their periodic wet-dry cycles provide conditions favorable for polymerization (e.g. Da Silva et al. 2015, Ross & Deamer 2016).

 How did the building blocks of RNA come to be in warm little ponds on early Earth? Is it necessary that they were delivered by meteorites or interplanetary dust? Or was early Earth capable of producing them on its own? In the latter case, the process can begin with the production of HCN in the atmosphere, which reacts in aqueous solution to produce several key RNA precursors such as nucleobases, ribose, and 2-aminooxazole (e.g. Yi et al. 2020, Hill & Orgel 2002, Becker et al. 2018, Powner et al. 2009).

 Here, we construct a robust physical and non-equilibrium chemical model of the early Earth atmosphere in which lightning and external UV-driven chemistry produce HCN. The atmosphere is supplied with hydrogen from impact degassing of meteorites, sourced with water evaporated from the oceans, carbon dioxide from volcanoes, and methane from undersea hydrothermal vents. This model allows us to calculate the rain-out of HCN into warm little ponds (WLPs). We then use a comprehensive sources and sinks numerical model to compute the resulting abundances of nucleobases, ribose, and nucleotide precursors such as 2-aminooxazole resulting from aqueous and UV-driven chemistry within them. We find that at 4.4 bya (billion years ago) peak adenine concentrations in ponds can be maintained at ∼2.8μM for more than 100 Myr. Meteorite delivery of adenine to WLPs produce similar peaks in concentration, but are destroyed within months by UV photodissociation, seepage, and hydrolysis. The early evolution of the atmosphere is dominated by the decrease of hydrogen due to falling impact rates and atmospheric escape, and the rise of oxygenated species such as OH from H2O photolysis. Our work points to an early origin of RNA on Earth within ~200 Myr of the Moon-forming impact.
Wind-driven freshwater export at Cape Farewell
Authors: Duyck Elodie , Gelderloos Renske , De Jong Femke
Published: March 2022

The Atlantic Meridional Overturning Circulation redistributes heat across the Atlantic and is therefore a critical element of the climate system. Increased freshwater fluxes to the subpolar north Atlantic from the Greenland ice sheet and from the Arctic could lead to a strengthening of stratification in deep convection regions, and impact deep water formation and the overturning circulation. However, this additional freshwater first enters the boundary current on the Greenland shelf, and freshwater pathways from the shelf to deep convection regions are still unclear. In this study, we investigate the possible role of winds in driving short-lived freshwater export events from the south-east Greenland shelf to the deep convection region of the Irminger Sea.

Along the south-eastern shelf, strong and consistent north-easterly winds tend to restrain fresh surface waters over the shelf. This wind pattern changes at Cape Farewell, where strong westerly winds could lead to across-shelf export. Using a high-resolution model, we identify strong wind events and investigate their impact on freshwater export. The strongest westerly winds, westerly tip jets, are associated with the strongest and deepest freshwater export across the shelfbreak, with a mean of 40.7 mSv of freshwater in the first 100 m (with reference salinity 34.9). These wind events tilt isohalines and extend the front offshore, especially over Eirik Ridge. Moderate westerly events are associated with weaker export across the shelfbreak (mean of 17 mSv) but overall contribute to more freshwater export throughout the year, including in summer, when the shelf is particularly fresh. Particle tracking shows that half of the surface waters crossing the shelfbreak during tip jet events are exported away from the shelf, either entering the Irminger Gyre, or being driven over Eirik Ridge. During strong westerly wind events, sea-ice detaches from the coast and veers towards the Irminger Sea, but the contribution of sea-ice to freshwater export at the shelfbreak is minimal compared to liquid freshwater export.
On the Temporal Variability of Tidal Atmospheric Signals
Authors: Balidakis Kyriakos , Zus Florian , Dobslaw Henryk
Published: March 2022

The reduction of geophysically induced high-frequency harmonic variations inherent in space geodetic measurements is carried out on the basis of physically-driven empirical models that may vary spatially, under the implicit assumption that they do not vary in time. Motivated by the fact that the parameters driving processes such as the atmospheric tides (largely induced by the absorbtion of ultraviolet and infrared radiation by Ozone and water vapor) that in turn partly excite the oceanic tides are affected by climate change, in this contribution we put the time-invariance modelling assumption to the test with a focus on harmonic deformation and atmospheric delay. To study temporal variations in atmospheric tides, we have analyzed hourly series from ECMWF’s latest reanalysis, the ERA5, including its back-extension. To validate the harmonic estimates and the temporal evolution thereof, we have resorted to two largely independent reanalyses: the MERRA2 and the JRA55. Recovering the evolution of harmonic coefficients has been carried out employing a square-root information filter (SRIF) and a Dyer-McReynolds smoother. Subsequently, the pressure harmonic fields are convolved with load Green’s kernels to simulate crustal displacements and harmonic pressure, temperature, and humidity fields are used to evaluate the refractivity integrals via ray-tracing. We found that the most important high-frequency waves, that is, the solar diurnal and semi-diurnal exhibit marked secular and seasonal variations. We find that harmonic S2 estimates for sites in the tropics from an hourly five-year long time series segment vary by up to 25% depending on the temporal boundaries thereof and the annual amplitudes of the S2 amplitude series from the SRIF can exceed 10 Pa.
Links between intermediate ocean circulation and cryosphere dynamics during Heinrich Stadials in the NE Atlantic: a foraminiferal perspective
Authors: Depuydt Pauline , Mojtahid Meryem , Barras Christine , Bouhdayad Fatima , Toucanne Samuel
Published: March 2022

Understanding the interaction between ocean circulation and ice sheet dynamics is fundamental to study the rapid Quaternary climate changes that punctuate major glacial-interglacial periods. Compared to the surface and deep compartments of the Atlantic Meridional Overturning Circulation (AMOC), intermediate water depths during key time periods, such as Heinrich Stadials (HSs), remain poorly documented, especially in the Northeast Atlantic.

In this study, we use benthic foraminiferal assemblage data from an upper slope sediment core from the Northern Bay of Biscay to reconstruct paleoenvironmental and paleohydrological changes at ~1000m water depth, from ~35 to 14 kyr cal BP. Our results show a strong response of benthic communities to hydrodynamic changes (related to AMOC) and to instabilities of the European Ice Sheet during the last three HSs. Benthic foraminifera provide species-specific responses to the induced physico-chemical changes, in coherence with the various geochemical and sedimentological proxies documented in the area. The three HSs are characterized by the low abundance of species indicative of high-energy environments (Cibicides lobatulus and Trifarina angulosa) and the simultaneous presence of Cibicidoides pachyderma (meso-oligotrophic species) and Globobulimina spp. (anoxia-tolerant species).   This species composition suggests a slowing of the intermediate circulation during the three HSs. Nevertheless, HS1 is very distinct from HS2 and HS3 by the high presence of high-organic flux indicator species (Cassidulina carinata and Bolivina spp.) during its early phase (Early HS1). This result confirms that EIS meltwaters were much less charged in organic material derived from the continent during HS2 and HS3 than during HS1 due to the scarcer vegetation cover and partially frozen soils. Finally, benthic foraminifera depict clearly the rapid "re-ventilation" during Mid-HS2, corresponding to a response to regional glacial instabilities.
Evaluating empirical models of lake methane emissions and concentrations in hemiboreal and subarctic regions
Authors: Schenk Jonathan , Sieczko Anna Katarzyna , Rudberg David , Pajala Gustav , Sawakuchi Henrique Oliveira , Bastviken David
Published: March 2022

Lakes are responsible for substantial emissions of methane (CH4) to the atmosphere globally, but their contribution is poorly constrained and current estimates vary widely. One of the reasons for this large uncertainty lies in the practical challenges involved in collecting CH4 concentration and flux data at the suitable temporal and spatial scales to capture their natural variability. Here, we present the results of an attempt to account for the spatial and temporal variability of CH4 concentrations and fluxes when deriving whole-lake and yearly average values. We used these average values to investigate the main environmental drivers of CH4 concentrations in the surface water of lakes and CH4 emissions from lakes. We made surface water CH4 concentration and CH4 fluxes measurements using headspace equilibration and floating chambers, respectively, in a set of boreal lakes located in different parts of Sweden and with various morphological and biogeochemical properties. Measurements covered different periods of the open-water season at multiple locations covering various depths/distances to shore in each lake. Individual CH4 flux measurements (150-300 measurements per lake) were interpolated based on relationships with local spatial and temporal variables. Relationships between mean open water season CH4 concentrations and emissions, and one to three independent environmental variables were tested as different models. The results suggest that the frequency and spatial coverage of the measurements is critical for identifying reliable quantitative empirical models of CH4 concentrations and emissions from lakes.
A parameter for the solar cycle variation in geomagnetic activity as quantified by bursts in the AE and SMR indices
Authors: Bergin Aisling , Chapman Sandra , Moloney Nicholas , Watkins Nicholas
Published: March 2022

Geomagnetic storms have the potential for significant impact on a wide range of technologies, including aviation, communications and power transmission grids. The likelihood of occurrence of geomagnetic storms varies with the solar cycle of level of activity, and each solar cycle has a unique amplitude and duration. The space weather response at earth then varies within and between successive solar cycles and can be characterized by the statistics of bursts, that is, time-series excursions above a threshold, in geomagnetic indices derived from ground based magnetometer observations. We consider non-overlapping 1 year samples of the minute-resolution auroral electrojet index (AE) and the minute-resolution SuperMAG-based ring current index (SMR), across the last four solar cycles. These indices respectively characterize high latitude and equatorial geomagnetic disturbances. We propose that average burst duration T and burst return period R (that is, the time between successive upcrossings of the threshold) form an activity parameter, T/R [1] which characterizes the fraction of time the magnetosphere spends, on average, in an active state for a given burst threshold. If the burst threshold takes a fixed value, T/R for SMR tracks sunspot number, while T/R for AE peaks in the solar cycle declining phase. Level crossing theory directly relates T/R to the observed index value cumulative distribution function (cdf). For burst thresholds at fixed quantiles, we find that the probability density functions of T and R each collapse onto single empirical curves for AE at solar cycle minimum, maximum, and declining phase and for -SMR at solar maximum. Moreover, underlying empirical cdf tails of observed index values collapse onto common functional forms specific to each index and cycle phase when normalized to their first two moments. Together, these results offer operational support to quantifying space weather risk which requires understanding how return periods of events of a given size vary with solar cycle strength.

 

[1] A. Bergin, S. C. Chapman, N. Moloney, N. W. Watkins, Variation of geomagnetic index empirical distribution and burst statistics across successive solar cycles, J. Geophys. Res, in press (2022)
Quantifying subglacial soft bed sedimentary processes
Authors: Hart Jane , Martinez Kirk , Baurley Nathaniel , Robson Benjamin
Published: March 2022

An understanding of subglacial processes are a vital component of ice-sheet models for sea level rise prediction as the use of different sliding laws can result in very different outcomes. In particular, the West Antarctic ice streams, are potentially unstable, and are underlain by soft (unconsolidated) beds, which have rarely been studied. Innovative in situ wireless subglacial experiments and web connected RTK GPS data from Iceland have shown that stick-slick motion can occur at different time scales throughout the whole year, and this allowed the quantification of different sedimentary processes. We investigate the results from four soft bedded glaciers. We compare the similarities and differences; and in particular describe the relationship with subglacial hydrological processes and temperature rise. We discuss the implications for ice sheet models and reconstructions of Quaternary sedimentary processes.
Urban heat island estimation from crowdsensing thermometers embedded in personal cars
Authors: Marques Eva , Masson Valery , Naveau Philippe , Mestre Olivier , Dubreuil Vincent , Richard Yves
Published: March 2022

An ever-growing portion of population lives in urban areas. Cities are expanding quickly and consequently, the urban heat island effect has become a major health concern to maintain city dwellers’ thermal comfort. For this reason, city planners want to access urban meteorological databases in local areas where specific attention is needed. With the growth of connected devices, it is possible to collect unusual but massive temperature measurements from people’s activities. In this article, we study temperatures measured by thermometers embedded in everyday personal cars. To assess the quality of such opportunistic data, we first detect factors deteriorating the measurement. After pre-processing, the measurement error is then estimated thanks to two weather station networks providing a local-scale reference through Dijon and Rennes cities, France. The overall aggregation of private car temperature measurements allows to estimate very precisely the urban heat island at a 200m resolution. We detect the cooling effect of parks in Rennes and Paris urban areas. In Barcelona and Dijon, we observe the impact of regional environments and the orographic effect on the urban heat island. With our method, similar maps can be made accessible to every interested city in western Europe to target critical areas and support urban planning decisions.
Spatio-Temporal Rainfall Estimation from Communication Satellite Data using Graph Neural Networks
Authors: Krebs Julian , Mishra Kumar Vijay , Gharanjik Ahmad , Shankar M. R. Bhavani
Published: March 2022

Accurate precipitation estimation with high spatial and temporal resolution is key to many applications including weather forecast, flood monitoring and the prediction of natural hazards such as the recent extreme weather events around the world. While weather radars are able to monitor the spatio-temporal dynamics of precipitation, they are expensive and sparsely deployed around the world.

Alternatively, existing ground terminals used in satellite communication services (e.g. broadband internet) have shown the potential to function as accurate rain sensors. By analyzing the carrier-to-noise (C/N) data between the satellite and ground terminal, the rain-induced signal attenuation is estimated. The relationship between the attenuation and rain rate at millimeter-wave then allows computation of the latter. To tackle the difficulty of detecting rainy events and rain-induced attenuation, machine learning approaches are often used to learn from measurements of co-located rain gauges. These methods utilize dense or long short-term memory networks taking a temporal sequence of C/N values from one terminal as input to obtain the local rain rate. So far, most approaches have investigated each ground terminal as an independent sensor, fusing them only after rain rate estimation in order to create two-dimensional (2-D) rain maps. Since neighboring terminals are not considered, the rain estimates suffer from local inconsistencies and malfunctioning terminals are harder to detect which further impacts the accuracy.

In this work, to achieve spatio-temporal consistency, we propose to estimate rainfall from a dense grid of ground terminals using graph-neural networks (GNN). By including neighboring terminal information directly in the estimation, rain rates are more consistent and malfunctions are easier to detect. We model local terminal neighborhoods in a GNN combined with one-dimensional convolutional neural networks taking the temporal sequence of C/N values of each terminal as input. The neural networks directly map C/N values to rain rates that are supervised during training using external rain gauge and weather radar data. After estimating rain rates for all terminals, 2-D rain maps are created by using ordinary kriging interpolation.

Initial results for January 12, 2021 storm event across the entire French metropolitan regions using 8000 active ground terminals indicate an improved average rain rate accuracy in comparison to weather radars. Furthermore, the resulting rain maps are significantly more spatio-temporally consistent compared to independent terminal approaches. These promising results allow rainfall estimation from satellite communication data to strongly complement the weather radar data or become a viable alternative in areas not covered with radars.
SAGE III/ISS aerosol/cloud categorization and its impact on GloSSAC
Authors: Kovilakam Mahesh , Thomason Larry , Knepp Travis
Published: March 2022

The Stratospheric Aerosol and Gas Experiment (SAGE III/ISS) aboard ISS began its mission in June 2017. SAGEIII/ISS is an updated version of SAGEIII-Meteor instrument that makes observations of stratospheric aerosol extinction coefficient at wavelengths that range between 385 and 1550 nm with a near global coverage between 60S-60N. While SAGEIII/ISS makes reliable and robust solar occultation measurements in stratosphere—similar to its predecessors, interpreting aerosol extinction measurements in the vicinity of tropopause and in the troposphere have been a challenge for all SAGE measurements. Here, we study the challenges associated with the discrimination of aerosols and clouds from the extinction measurements. Additionally, recent volcanic/PyroCb events make it more challenging to separate aerosols from clouds. Here, we describe the methods implemented to categorize Clouds and aerosols using available SAGEIII/ISS aerosol measurements. Cloud categorization is developed based on a method proposed by Thomason and Vernier (2013) with some modifications that now incorporates the influence of recent volcanic/PyroCb events and a new method of locating aerosol centroid based on k-medoid clustering. We use version 5.2 of SAGE III/ISS extinction coefficients for the analysis. The current algorithm now classifies standard (background) and non-standard (enhanced) aerosols in the stratosphere and identify enhanced aerosols and aerosol/cloud mixture in the tropopause region. Extinction coefficient measurements from SAGE series of observations make an important contribution in the GloSSAC data base and therefore, the impact of cloud-filtered aerosol extinction coefficient measurements on the latest version of GloSSAC (version 2.1) is also discussed.
On the benefit and cost of artificial glacier melt reduction
Authors: Huss Matthias
Published: March 2022

The artificial reduction of glacier melt is gaining increased attention due to accelerated ice wastage with atmospheric warming. In Switzerland, active coverage of glaciers using geotextiles is performed at currently ten sites and since more than 15 years. The measures represent an efficient method to locally safeguard the operability of ski slopes or other touristic attractions. Furthermore, ideas for large-scale technical interventions to save glaciers using artificially produced snow were proposed, with considerable resonance in the international media.

Here, an assessment of the benefit and applicability, as well as the costs and the drawbacks of different techniques to artificially reduce glacier melt is presented. On the one hand, observational data (in situ and remote sensing) across the Swiss Alps are used to analyze the efficiency and the spatial extent of the applied technical measures in the past. On the other hand, an integrative model approach is presented for investigating the potential of large-scale artificial snow production to limit the retreat of an entire glacier over the 21st century, including an evaluation of the related costs and risks.

Presently, about 0.18 km2, or 0.02% of the total Swiss glacier area, are covered by geotextiles, with a doubling of the covered area since 2012. Up to 350,000 m3 of ice melt per year have been mitigated by this technique. It is estimated that 1 m3 of saved glacier ice comes at a cost of 0.6 to 7.9 CHF m-3 yr-1, depending on the type of installation and its location on the glacier. These relatively high costs are an indication for the considerable economic value attributed to glacier ice.

It is shown that artificial melt reduction is not scalable. Whilst local interventions can be efficient and profitable, climate scenario-based model results for large-scale interventions indicate that saving Alpine glaciers by technological solutions is neither achievable nor affordable. It is a challenge to adequately communicate this gap between feasible local-scale ice-melt reduction, and the impractical technological 'saving' of entire glaciers to a broader public.
A low-cost GNSS buoy for water vapour monitoring over the Oceans
Authors: Bosser Pierre , Bennini Victor , Bouasria Mohammed , Grit Yanis , Panetier Aurélie
Published: March 2022

In recent years, the significant growth of positioning applications has come with the development of low-cost dual frequency Global Navigation Satellite Systems (GNSS) receivers. The accuracy of these receivers in terms of positioning has been proved. Various studies have also highlighted the ability of these receivers to precisely monitor the atmospheric water vapour. The low cost of such receivers enables large deployment, thus presenting an advantage for many geoscience applications.

In this context, we have developed a hydrographic buoy prototype, equipped with low-cost GNSS receiver and antenna. This buoy was first aimed to be used for the monitoring in delayed time of offshore tides and currents, by a precise point positioning analysis of the GNSS raw data. In addition, the ability of this low-cost GNSS buoy for the water vapour monitoring was also investigated through the assessment of Zenith Tropospheric Delay (ZTD) estimates from the post-processing of the raw data. The comparisons with ZTD estimates from a nearby ground-based GNSS geodetic antenna and the ECMWF fifth ReAnalysis (ERA5), provide pretty good results with RMS differences lower than 10 mm. 

These conclusive results highlight the opportunities for the use of such low-cost systems for meteorology and climatology applications over the Oceans.
Periodicity in fields of elongating dunes
Authors: Gadal Cyril , Narteau Clément , Courrech du Pont Sylvain , Rozier Olivier , Claudin Philippe
Published: March 2022

Dune fields are commonly associated with periodic patterns that are among the most recognizable landscapes on Earth and other planetary bodies. In zones of loose sand, this periodicity is associated with the development of the flat bed instability, coupling wind, sediment transport and sand bed evolution. However, in zones of limited sediment supply, where periodic dunes elongate and align in the direction of the resultant sand flux, there has been no attempt to explain the emergence of such a regular pattern. Here, we show, by means of numerical simulations, that the elongation growth mechanism does not produce a pattern with a specific wavelength. Periodic elongating dunes appear to be a juxtaposition of individual structures, the arrangement of which is due to regular landforms at the border of the field acting as boundary conditions. This includes, among others, dune patterns resulting from bed instability, or the crestline reorganization induced by dune migration. The wavelength selection in fields of elongating dunes therefore reflects the interdependence of dune patterns over the course of their evolution.
Impact of an abrupt climate change on sediment distribution from source to sink, PETM, Southern Pyrenees (Spain)
Authors: Prieur Marine , Whittaker Alexander C. , Schlunegger Fritz , Sømme Tor O. , Braun Jean , Fillon Charlotte , Castelltort Sebastien
Published: March 2022

 

Allogenic factors such as climate and tectonics are regulating the mechanisms involved in sediment generation, transport and deposition. A key challenge for modern society is to predict and better understand how sedimentary systems adapt to an abrupt change in climate. The geological record allows an insight on past climate crises and their registration in sediments.

This study focuses on the changes in physical sedimentary processes during the Paleocene-Eocene Thermal Maximum (PETM, 56 Myrs ago) in the Southern Pyrenees (Spain). A lengthening of the siliciclastic system has been shown to occur coevally to the PETM. Yet, connections throughout the sedimentary system from source to sink and reconstructions of the processes involved in this short-term lengthening lack constraints. Although higher seasonality in pluviometry is usually invoked to explain the increase in sedimentary export, this hypothesis is based on very few continental outcrops only and do not include any system-scale quantification. Here we propose to test this hydrology-based hypothesis thanks to (i) a better understanding of the source-to-sink system’s paleogeography, (ii) paleohydraulic quantifications applied on supplementary outcrops and (iii) grain-size used as a down-system common thread.

First, the sources are better constrained thanks to provenance analyses combining petrography and double dating on detrital zircons (U/Pb and (U-Th)/He). Then, reconstructions of paleohydraulics in several continental outcrops allow to compare paleoslopes and water discharges between pre- and syn-PETM deposits. Finally, studying grain-size along the whole system allows a quantitative estimation of the climate-related evolution of the system’s diffusivity.

This system-scale study provides quantitative insights on the changes in sediment transport processes during an abrupt climate change. The deduced landscape evolution is then a valuable tool to be applied on today’s systems.

 

This research is carried out in the scope of the lead author’s PhD project and is part of the S2S-FUTURE European Marie Skłodowska-Curie ITN.
Identifying efficient ensemble perturbations for initializing subseasonal-to-seasonal prediction
Authors: Demaeyer Jonathan , Penny Stephen , Vannitsem Stéphane
Published: March 2022

The prediction of weather at subseasonal-to-seasonal (S2S) timescales is affected by both initial and boundary conditions, and as such is a complicated problem that the geophysical community is attempting to address in greater detail. One important question about this problem is how to initialize ensembles of numerical forecast models to produce reliable forecasts1, i.e. initialize each member of an ensemble forecast such that their statistical properties are consistent with the actual uncertainties of the future state of the physical system.

Here, we introduce a method to construct the initial conditions to generate reliable ensemble forecasts. This method is based on projections of the ensemble initial conditions onto the modes of the model's dynamic mode decomposition (DMD), which are related to the procedure used for forming Linear Inverse Models (LIMs). In the framework of a low-order ocean-atmosphere model exhibiting multiple different characteristic timescales, we compare the DMD-oriented method to other ensemble initialization methods based on Empirical Orthogonal Functions (EOFs) and the Lyapunov vectors of the model2, and we investigate the relations between these.

References:

1. Leutbecher, M., & Palmer, T.N. (2008). Ensemble forecasting. Journal of Computational Physics, 227, 3515–3539.

2. Vannitsem, S., & Duan, W. (2020). On the use of near-neutral Backward Lyapunov Vectors to get reliable ensemble forecasts in coupled ocean–atmosphere systems. Climate Dynamics, 55, 1125-1139.
First Sounds from Mars : Results of the Microphones on Perseverance
Authors: Lorenz Ralph ,   Mars 2020 Acoustics Working Group
Published: March 2022

While Mars Polar Lander and Phoenix carried microphones, InSight has recorded infrasound, and Huygens and Venera returned some acoustic measurements, Mars 2020/Perseverance is the first planetary mission to return significant amounts of human-audible acoustic data. In addition to the public appeal of planetary sound recordings, these data reveal important aspects of the Martian environment.

Positioned near the top of the rover’s mast, the SuperCam microphone records audible sounds from 20 Hz to 10 kHz. A separate body-fixed microphone is associated with the EDL cameras. Detected sounds originate from three main sources: the atmosphere (turbulence, wind), the crack of the SuperCam laser blasts on rocks, and other rover sounds, such as the high-speed scroll compressor pump on the MOXIE instrument, or the aeroacoustic signal generated by the high-speed rotating blades of the Ingenuity helicopter. These sounds spread over the entire frequency domain accessible by the microphone: (i) the turbulence/wind-induced acoustic signal starts from the lowest frequency, continuously up to few hundred Hz depending on the wind activity. Acoustic power versus frequency shows a decreasing slope consistent with the dissipative regime. (ii) The frequency content of the laser-induced spark lies at higher frequencies (2 - 10 kHz) where it shows destructive interference gaps due to echoes on the mast structure. (iii) Rover generated sounds (MOXIE compressor, rover thermal pump) are monotonic. (iv) Three of the Ingenuity helicopter flights are heard, at the blade’s passing frequency of ~84Hz (with a small Doppler shift due to flight speed) and its first harmonic at 168 Hz.

Passive microphone observations are now made routinely to characterize turbulence, where the observations can access timescales shorter than conventional wind sensors.  Similarly, the propagation times of the crack sounds from rapid series of laser shots can interrogate temperature fluctuations on length scales smaller than is possible with conventional temperature sensing.  The observations also constrain the acoustic propagation in the Martian atmosphere, where the abundant CO2 causes appreciable attenuation, especially at high frequencies.  This presentation will review results to date.

 
Communicating Arctic issues to the Italian public through a magazine
Authors: parigi riccardo
Published: March 2022

Communication and scientific dissemination can be very important if we want people to focus on specific items. This is also why we should question the ways in which we communicate an idea or a particular issue.

Osservatorio Artico is the first Italian online magazine focused on the Arctic region. In issues related to external affairs, economics, migration and climate change Italy usually looks more towards continental Europe, at the Mediterranean area and the Middle East.. However,  the Arctic region, even if it is far from Italian shores, is emerging dramatically into the Italian awareness, due to the relevance of global environmental issues. The Arctis is also important because the Italian Navy and the scientific and academic Italian world are increasingly conducting scientific research in the Arctic about climate change, the environment and hydrography.

Osservatorio Artico also aims to be the  main news channel  for this issue for a wide public. What happens so far away has direct implications for our climateand our economy. Changes in the Northern Sea Route will, in the next few years, change the Mediterranean commercial sea routes, modifying the pivotal role of Italy in the Mediterranean,  In addition, Italian cultural heritage, such as the Venetian Laguna, is under great threat, from sea level rise.

The Arctic is closer to Italy than it appears, and Osservatorio Artico aims to be a helpful tool for Italian speaks. Our collaborators live and work in several countries,  including the Arctic. We want also to reach a wider and different public, so we are navigating between newspaper and academic publishing. Our use of social media channels is very relevant to our aim of  building up a strong international network for information about the Arctic in Italy.

 
Prestorm root zone soil moisture conditions critical for flood forecasting in Europe
Authors: Massari Christian , Marra Francesco , Tramblay Yves , Crow Wade , Camici Stefania , Modanesi Sara , Brocca Luca , Gruendemann Gaby
Published: March 2022

Recent evidences suggest that in Europe, flood frequency and precipitation frequencies are often not aligned. Beside other factors pre-storm conditions exert a significant impact on flood generation thus their knowledge is paramount for a proper flood forecasting. A number of predictors have been used in the past to understand how much precipitation is transformed into runoff (i.e., runoff coefficient, RC). Notable examples are the antecedent precipitation index (API), the prestorm river discharge and soil moisture. On top of these new products potentially available from satellite observations like surface soil moisture and total water storage anomalies (TWSA), root zone soil moisture from reanalysis and hydrological models can be used along with precipitation to predict in advance the severity of the storm runoff.Our goal here is to provide an objective description of the role played by different predictors for hydrologic forecasting in Europe. In particular, we aim at answering the following research questions:

How variable is runoff coefficient across the European catchments?

How much are surface and root zone soil moisture, river discharge, antecedent precipitation and total water storage anomalies able to explain the RC variability across European floods?

Under which conditions (climate period, location and flood magnitude) are the different pre-storm indices able to predict this runoff coefficient variability?

We answered these questions using long term (1980-2016) precipitation and river discharge observations from more than 100 basins covering different European regions. Results demonstrated that root zone soil moisture and TWSA are the best predictors of prestorm conditions under a variety of climatic and geographic features and thus their correct representation in land surface and hydrological models is strategic for an effective flood forecasting.
Local drivers of marine heatwaves: A global analysis with an Earth system model
Authors: Vogt Linus , Burger Friedrich , Griffies Stephen , Frölicher Thomas
Published: March 2022

Marine heatwaves (MHWs) are periods of extreme warm ocean temperatures that can have devastating impacts on marine
organisms and socio-economic systems. Despite recent advances in understanding the underlying processes of individual events, a
global view of the local oceanic and atmospheric drivers of MHWs is currently missing. Here, we use daily-mean output of
temperature tendency terms from a comprehensive fully coupled Earth system model to quantify the main local processes leading
to the buildup and decay of MHWs in the surface ocean. Our analysis reveals that net ocean heat uptake associated with more
shortwave heat absorption and less latent heat loss is the primary driver of the buildup of MHWs in the subtropics and mid-to-high
latitudes. Reduced vertical mixing from the nonlocal portion of the KPP boundary layer scheme partially dampens the temperature
increase. In contrast, ocean heat uptake is reduced during the MHW build-up in the tropics, where reduced vertical local mixing
and diffusion cause the warming. In the subsequent decay phase, ocean heat loss to the atmosphere dominates the temperature
decrease globally. The processes leading to the buildup and decay of MHWs are similar for short and long MHWs. Different types of
MHWs with distinct driver combinations are identified within the large variability among events. Our analysis contributes to a
better understanding of MHW drivers and processes and may therefore help to improve the prediction of high-impact marine
heatwaves.
Arctic Warming: A Perspective from the Underground
Authors: Cuesta-Valero Francisco José , Beltrami Hugo , García-García Almudena , Jaume-Santero Fernando , Gruber Stephan
Published: March 2022

The thermal regime of the Arctic subsurface is important, for example, in the context of greenhouse-gas release from thawing permafrost soils. Measurements of Arctic subsurface temperatures, however, are scarce and limited in time, with virtually no observations over climatological time scales. We address this gap in knowledge by estimating the long-term evolution of subsurface temperatures in the Arctic (north of 60ºN) since 1600 Common Era (CE) to the present using 110 deep subsurface temperature profiles. The Arctic subsurface has warmed by 1.7±0.8 ºC during 1970-2000 CE. These estimates are conservative, as the effects of latent heat are not included in the analysis. Although there are significant spatial variations, the Arctic subsurface is warming faster than the global land surface and subsurface (1.2±0.2 ºC) during the same period. Uncertainties in this analysis arise mostly from deficient knowledge about the subsurface physical properties and limited data coverage.
Modeling the spatial distribution of soil organic carbon and carbon stocks for the Casanare flooded Savannas, Colombia
Authors: Martín-López Javier M. , Verchot Louis , Martius Christopher , da Silva Mayesse
Published: March 2022

Flooded savannas are extensive in South America and this study was conducted to assess two digital soil mapping (DSM) approaches to predict the spatial distribution of soil organic carbon (SOC) content and stocks in the Orinoco flooded savannas of Casanare department, located in the eastern plains of Colombia. SOC was estimated using a total of 80 sites sampled at two soil depth intervals (0-10 cm and 10-30 cm). SOC ranged from 0.41% at 0-10 cm and 0.23% at 10-30 cm in drier soils found in continental dunes with sandy textures and low vegetation cover (steppe) to over 14.50% and 7.51% in soils that experienced seasonal flooding located in depressions with loamy textures and flooded savanna vegetation. Predictions of the spatial distribution of SOC were done through Expert Knowledge (EK) and Random Forest (RF) approaches across the study area at 0-10 cm and 10-30 cm soil depth. Both DSM approaches were assessed through root mean square errors, mean absolute errors, and coefficients of determination. Although both DSM approaches performed very well, EK was considered slightly superior to predict SOC in the Casanare flooded savannas. Covariates derived from vegetation coverage, topography, and soil texture properties were identified as key drivers in controlling its distribution at the study area. We found total SOC stocks of 55.07 Mt with a mean density of 83.13 ± 24.32 t ha-1 stored in the first 30 cm soil depth, with 12.3% of this being located in the flooded parts of the savanna landscape, which represented only 7.9% of the study area (664,752 ha). This study provides the first effort to systematically quantify SOC stocks in the Casanare flooded savannas and shows the importance of conserving this ecosystem with the aim of avoiding SOC losses and consequent increased CO2 emissions to the atmosphere. We estimate that the department of Casanare would release an average of 2,42 Mton of CO2 emissions per year over 30 years if there were large scale conversion of the flooded savannas to intensive agriculture, which corresponds to 62% of the current emissions of the department. At regional level, the impact of a large-scale land use conversion of the flooded Llanos del Orinoco ecosystem area (15 Mha) would represent 1/3 of the current net Colombian CO2 emission (AFOLU), which makes this region a potentially important source of emissions if correct decisions are not taken regarding the land management.
Making the Schmidt Hammer Great Again!
Authors: Huxol Benjamin , Pruß Gunnar , Voigtländer Anne , Dietze Michael , Turowski Jens M
Published: March 2022

Have you ever applied the Schmidt hammer method and wondered what the R‑value represents? What SI unit it would have and which material properties it actually assesses? The Schmidt rebound hammer is a device initially intended to test the curing state and strength of concrete. Since then, the concept has been transferred to determine the strength, weathering, and sometime even surface exposure age of rocks in geomorphology. The advantage of the Schmidt hammer that it is non-destructive, easy to handle, light, and readily applicable in the field. However, the method is only based on correlation, without physical explanation of the measured value being provided, and using a seemingly arbitrary resolution of the scale without reference. Here we present our approach to put the Schmidt hammer and especially the physics behind the R‑value on solid ground. Using a dataset of material properties and R‑Values, we find that the Schmidt hammer best represents the elasticity of the material. The elasticity and, along with it, the elastic modulus, can be independently and complementarily assessed with other geophysical methods. Both metrics are known to vary with i) moisture level, ii) stress state, and iii) temperature. Consequently, we conducted controlled experiments to constrain the influence of these conditions on R‑values. A major disadvantage of the Schmidt hammer, the resolution of the scale, remains and needs further calibration.
The reactivation and monitoring of Steamboat geyser, the tallest geyser on Earth
Authors: Manga Michael , Reed Mara , Munoz-Saez Carolina , Hajimirza Sahand , Wu Sin-Mei , Barth Anna , Girona Tarsilo , Behesht Majid , White Erin , Karplus Marianne , Hurwitz Shaul
Published: March 2022

After 34 years of isolated and erratic activity, Steamboat Geyser in Norris Geyser Basin, Yellowstone, USA began a period of frequent major eruptions in March 2018. The geyser is positioned near a variety of monitoring equipment which allows for a multiparameter study of potential triggering mechanisms for its reactivation and to evaluate how well eruption attributes can be determined from monitoring data. Prior to 2018, Norris Geyser Basin experienced an increase in regional seismicity, a slight rise in radiant temperature, and a period of uplift. These signals might indicate magmatic processes promoted the reactivation. But because no other dormant geysers became active, previous earthquakes with greater seismic moment release did not noticeably change Steamboat’s behavior, and geothermometry indicates no significant change in geothermal reservoir temperature, we conclude that the reason for reactivation remains ambiguous. Eruption intervals are modulated seasonally, with shorter intervals in the summer, until May 2021 when the pace of eruptions slowed. We find that erupted volumes calculated from streamflow data is affected by wind speed, and after accounting for this, we identify no relation between eruption volume and interval. Based on data from geysers worldwide, we find a correlation between eruption height and shallow reservoir depth, implying that Steamboat has tall eruptions because water is stored deeper there than at other geysers. Finally, we observe that the amplitude of ground motion recorded by a seismometer ~330 m distant from the vent depends on the depth of snow cover, and that higher frequencies are diminished more than lower frequencies. This is consistent with the seismometer recording sound generated by the eruption that is attenuated by the snow.
Changes in the internal structure of polythermal glaciers over the last decade: the case study of Fridtjofbreen and Erdmanbreen from 2010 to 2021, Svalbard
Authors: Borisik Aleksandr , Novikov Aleksandr , Lavrentiev Ivan , Glazovsky Andrey
Published: March 2022

Glaciers on Svalbard have been shrinking in recent decades in response to current climate change. Most of them have decreased in size, area and surface elevation with stable negative or even accelerated changes in mass balance. Many of them are of the polythermal type, and as they shrink, their thermal regime might also change significantly depending on climate and local parameters, such as distribution of ice facies, firn thickness, and other factors affecting hydrology and glacier movement. In this study, we used data from repeated GPR surveys in 2010/12 and 2020/21 to identify likely changes in the thermal regime of the two polythermal glaciers Fridtjovbreen and Erdmanbreen in the western part of the Nordenskiöldland. These changes we have identified by comparison of changes in the depth of the internal reflection horizon (IRH) which corresponds to the cold-temperate transition surface (CTS) in polythermal glaciers.

Comparison of radio-echo sounding (RES) data obtained along the same transverse and longitudinal transects shows that in the last decade the most prominent CTS changes have occurred in the upper western basin of the Fridtjovbreen, where the mean total ice thickness decreased with rate −0.76 m a-1 (from 151 to 144 m in 9 years), meanwhile the thickness of the temperate ice core decreased with rate −2.52 m a-1 (from 115 to 92 m). As a result, with a general reduction in the thickness of the glacier, its upper cold layer increased from 36 to 52 m. These changes we attribute to the reduction of the firn area in this basin, which resulted in less thermal insulation and water retention and internal refreezing, and, therefore, in the fast cold front penetration into the glacier body with rates more than 3 times higher than the glacier thinning.
Substantial increases in riverine sediment loads in a warmer and wetter Third Pole
Authors: Li Dongfeng , Lu Xixi , Overeem Irina , Walling Desmond , Syvitski Jaia , Kettner Albert , Bookhagen Bodo , Zhou Yinjun , Zhang Ting
Published: March 2022

Rivers originating in the Third Pole (Tibetan Plateau and surrounding high-Asian mountains) are crucial lifelines for one-third of the world’s population. These fragile headwaters are now experiencing amplified climate change, glacier melt, and permafrost thaw. Observational data from 28 headwater basins demonstrate substantial increases in both annual runoff and annual sediment fluxes across the past six decades. The increases have accelerated since the mid-1990s, in response to a warmer and wetter climate. The total riverine sediment load from HMA is projected to more than double by the mid-21st century under an extreme climate change scenario. The substantially increasing riverine sediment loads could negatively impact the hydropower-food-environmental security in the Third Pole region. Such findings also have implications for other cold environments such as the Arctic, Antarctic, and other high mountain areas.