bluuebunny/crossref_metadata_2025 huggingface dataset:
Retrieval of Elevated Moist Layers using Hyperspectral Infrared Sounders
Authors: Prange Marc , Brath Manfred , Buehler Stefan A.
Published: March 2022

Satellite based hyperspectral infrared (IR) sounders like IASI, AIRS and CrIS offer a wealth of information about the atmospheric composition and vertical structure. A key quantity these instruments are able to capture is the vertical profile of water vapor in clear-sky and partly cloudy conditions. The work presented here revolves around mid tropospheric layers of increased humidity, so called Elevated Moist Layers (EMLs). EMLs frequently emerge in the vicinity of deep convection in the tropics as they are thought to originate from detrained moisture of convective plumes near the stable freezing level at around 5 km altitude. Previous retrieval case studies indicate limited retrievability of EMLs based on hyperspectral IR observations depending on the exact retrieval method, retrieval setup and the atmospheric conditions. Since EMLs severely influence the local radiation budget of the atmosphere, we need to understand what operational retrievals capture and what they may miss about EMLs.

As a starting point, we present an EML case study from the NARVAL-2 measurement campaign to directly compare IASI and AIRS retrieval products to in-situ soundings. We also introduce ERA5 as an additional reference to assess whether limitations in the retrieval product propagate to the reanalysis. As a next step, we conduct a first systematic statistical assessment of EML retrievability based on long term operational retrieval data. As reference, we use radiosonde data from the GRUAN database and ERA5. The EMLs in the different datasets are first identified by introducing smooth reference humidity profiles. The EMLs are then characterized by their layer averaged anomalous humidity, their thickness and altitude. These EML characteristics are compared statistically to assess what type of EMLs the retrievals capture well and where there might be systematic issues. We also calculate radiative heating profiles and assess the impact of EML retrievability on radiative heating.
Glacial Isostatic Adjustment in Antarctica : a rheological study
Authors: Boughanemi Alexandre , Mémin Anthony
Published: March 2022

 The Antarctic Ice Sheet (AIS) is the largest ice sheet on Earth that has known important mass 
 changes during the last 20 kyrs. These changes deform the Earth and modify its gravity field, 
 a process known as Glacial Isostatic Adjustment (GIA). GIA is directly influenced by the mechanical
 properties and internal structure of the Earth, and is monitored using Global Navigation Satellite 
 System positioning or gravity measurements. However, GIA in Antarctica remains poorly constrained  
 due to the cumulative effect of past and present ice-mass changes, the unknown history of the past
 ice-mass change, and the uncertainties of the mechanical properties of the Earth. The viscous 
 deformation due to GIA is usually modeled using a Maxwell rheology. However, other geophysical
 processes employ Andrade (tidal deformation) or Burgers (post-seismic deformation) laws that could 
 result in a more rapid response of the Earth. We investigate the effect of using these
 different rheology laws to model GIA-induced deformation in Antarctica.  

Employing the ALMA and TABOO softwares, we use the Love number and Green functions formalism to
compute the surface motion and the gravity changes induced by the past and present ice-mass redistributions.
We use the elastic properties and the radial structure of the preliminary reference Earth model (PREM) and the
viscosity profile given by Hanyk (1999). The deformation is computed for the three rheological laws mentioned
above using ICE-6G and elevation changes from ENVISAT (2002-2010) to represent the past and present changes
of the AIS, respectively. 

We obtain that the three rheological laws lead to significant Earth response within a 20 kyrs time interval since
the beginning of the ice-mass change. The differences are the largest between Maxwell and Burgers rheologies
during the 500 years following the beginning of the surface-mass change. Regarding the response to present
changes in Antarctica, the largest discrepancies are obtained in regions with the greatest current melting rates,
namely Thwaites and Pine Island Glacier in West Antarctica. Uplift rates computed twelve years after the end of
the present melting using Burgers and Andrade rheologies are five and two times larger than those obtained
using Maxwell, respectively. 
The cold and warm contributions to the eastern South Atlantic subtropical gyre
Authors: Olivé Abelló Anna , Pelegrí Josep L. , Artana Camila , Poli Lea , Provost Christine
Published: March 2022

The returning limb of the Atlantic Meridional Overturning Circulation is sustained partly by the Southern waters entering from the Pacific Ocean through the Drake Passage, what is commonly referred to as the cold-fresh water route, and by the Indian waters entering through the Agulhas Current system (ACS), what is known as the warm-salty route. Here we carry out numerical simulations of Lagrangian trajectories to identify the multiple direct and indirect cold and warm intermediate-water pathways reaching the eastern South Atlantic subtropical gyre: predominant trajectories, transit times, water transformations, changes in thermohaline properties and spatiotemporal variability. These different inflows have been characterized with thousands of particles released backward in the eastern subtropical gyre along 34°S (from 10°W to 18°E, hereafter the reference section) in 2019 and tracked during 50 years, using daily velocity fields from the GLORYS12v1 reanalysis product with a 5-day resolution.

The total cold-route contribution of intermediate waters to the reference section represents 7.1 ± 0.6 %, slightly less than the 9.0 ± 1.2 % fraction reaching this section via the warm-route ACS; both contributions decrease substantially in summer: 5.9 ± 0.7 % for the cold route and 6.2 ± 3.0 % for the warm route. The cold route consists of three main pathways: direct incorporation with over 90% of particles and water particles that recirculate either in the western subtropical Atlantic or enter the Indian Ocean before flowing back to the reference section, respectively, with about 7% and 2%. Different routes can also be identified for the warm route into the reference section, largely dominated by the direct route through the ACS but also with alternative pathways characterized by recirculations within the Atlantic and Indian Oceans. We also discuss some of the water transformations, in particular the largest changes in thermohaline properties that occur in the confluence zones of Malvinas-Brazil Current and the Agulhas-South Atlantic Current. For instance, during austral summer and along their direct path from the Drake Passage, the cold-water parcels gain a mean of 0.86 ± 0.11 ºC, 0.26 ± 0.01 in salt, increasing their mean density in 0.08 kg/m3.
Australian Wildfires cause the largest stratospheric warming since Pinatubo.
Authors: Damany-Pearce Lilly , Johnson Ben , Wells Alice , Osborne Martin , Allan James , Belcher Claire , Haywood Jim
Published: March 2022

Global mean lower stratosphere temperatures rose abruptly in January 2020 reaching values not experienced since the early 1990s. Anomalous lower stratospheric temperatures were recorded for 4 months at highly statistically significant levels (p-values of 0.0004 to 0.02). While the warming event of 1991-1993 has been definitively attributed to absorption of sunlight by stratospheric sulfate from the eruption of Pinatubo, no candidate volcanic eruption for explaining the 2020 stratospheric heating exists. Here, we use a combination of satellite and surface-based remote sensing observations to derive a time-series of stratospheric biomass burning aerosol optical depths originating from the intense 2019/20 S.E. Australian wildfires and apply these to a state-of-the-art climate model. We show beyond doubt that the biomass burning aerosols emitted by the S.E. Australian wildfires are the cause of this lower stratospheric warming, with implications for stratospheric dynamics and stratospheric ozone should this type of event become more frequent in the future.
Estimation of Fine Sediment Stocks in Embanked Alpine Rivers
Authors: Deng Junjian , Piednoir Téa , Pénard Lionel , Camenen Benoît
Published: March 2022

Fine sediment is a fundamental component of the river system. Fine sediment conditions support good ecological status in different environments since they can affect river habitat and also transport pollutants and nutrients. Moreover, fine sediments can lead to security issues for hydroelectric buildings in the river channel, i.e. sedimentation in reservoirs, turbine erosion, etc. In alpine rivers, a large amount of fine sediments travels over the gravel-bed system as suspension and interacts with the gravel matrix (deposition, infiltration, resuspension). Recent studies highlight that fine sediment stocks in the river bed can be a significant source of suspended load at the event scale, and can have a non-negligible effect on sediment budget estimation. However, there exists no proper estimation of fine sediment stocks in gravel-bed rivers, especially for the sand fraction. One can also question the spatial and temporal variability of these stocks, which makes the estimation of such source of fine sediments challenging.

In this study, we intend to quantify fine sediment stocks in an Alpine river system (Arc-Isère in the French Alps) characterized by the presence of alternate bars. We estimate the potentially resuspended fine stocks from the gravel bar matrix for different discharges by coupling field measurements, GIS spatial analysis, and 1D modelling. Fine sediment stocks in the gravel bars are firstly measured using a field protocol optimized from the one proposed by Misset et al. (2021). The evaluation of the total stocks of fine sediments is made by combining these local measurements to GIS spatial analysis based on LiDAR data. Then, in order to predict the resuspended fine stocks, a 1D numerical hydraulic model is used to calculate bed shear stresses on the bar surface and evaluate the thickness of the potential remobilized coarse sediments. Having the volume of sediments remobilized, one can evaluate the potentially re-suspended fine stocks for different discharges. The measured fine stocks show a significant amount of sand present in the river bed, which was rarely if not measured in most studies. The silt-clay part of the calculated re-suspended stocks is found equivalent to around 30% of annual Suspended Sediment Matter (SSM) flux for a 15-year return period flood event, which appears consistent since such a large event may yield up to 50% of the annual SSM flux. However, the silt-clay stocks represent around 20% of the total fine stocks only, 80% corresponding to sand. Therefore, a large amount of sand could be re-suspended from the gravel bar matrix and should not be neglected when estimating the downstream sediment budget.
Seismic properties profiles of the alpine slab predicted by petrophysics versus ambient noise tomography lithospheric model
Authors: Sonnet Manon , Labrousse Loïc , Bascou Jérôme , Plunder Alexis , Nouibat Ahmed , Stehly Laurent , Paul Anne
Published: March 2022

The objective of the present study is to use potential lithologic analogues sampled in the European crust units exhumed in the Alps to predict the seismic properties of the buried continental crust panel. To this end, from the chemical compositions of representative rock samples, we calculate seismic velocities (Vp, Vs or Vp/Vs) at any P and T, under the assumption that the rocks have completely re-equilibrated during burial.

The sample catalog comprehend (1) the mafic intercalations, present in the Variscan basement series of the External Crystalline Massif; (2) the rocks involved in the Grand Paradis - Schistes Lustrés contact (metabasites and garnet bearing micaschists of the upper unit, mylonite and gneiss of the lower unit); (3) those along the Lanzo-Canavese contact (serpentinites, blue schist facies mylonites and biotite bearing gneiss); (4) lithologies of the Ivrea domain (peridotites, garnet bearing gabbros, textured mafic rocks, amphibolitic and mylonitic paragneiss), (5) those from the Gruf massif (biotite bearing orthogneiss, deformed leucogranites and charnockites from the Gruf complex and amphibolites and serpentinites from the Chiavenna unit); (6) lithologies from Alpine Corsica (pelitic gneisses of the granulite facies and more or less foliated metagabbros, from the San Petrone and Farinole unit).

In these diagrams, the main seismic contrasts appear to correspond to the early stages of jadeite crystallization (mainly in the Vp/Vs diagram), as well as to the boundaries of the garnet and clinopyroxene stability fields. Considering the selected rocks as relevant analogues, we then compare the evolution of seismic properties along the top of the Alpine dipping panel with profiles inferred from recent Vp and Vs tomography models (CIFALPS 1 and AlpARRAY), varying the effective thermal profile of the Alpine panel, its reaction degree and overall chemistry. Preliminary results suggest that the lower crust of the plunging panel has a seismic velocity too low to be eclogitized. Its velocity rates are closer to those of an underreacted quartzo-felspathic gneiss. At first sight, observed velocities are too low compared to values predicted for any lithology fully reacted during subduction. The best-fitting scenario turns out to be that of a lower crust thermally relaxed in the variscan without significant mineralogical footprint of subduction. If detected, the velocity rise due to eclogitization might offset of several tenth along the slab, implying a sensible impact of reaction kinetics.
A risk analysis framework: Key risks from permafrost thaw in Arctic coastal areas
Authors: Gartler Susanna , Larsen Joan Nymand , Ingimundarson Jon Haukur , Schweitzer Peter , Povoroznyuk Olga , Meyer Alexandra
Published: March 2022

This paper presents the results from fieldwork conducted in three focal areas of the “Nunataryuk” EU H2020 permafrost project: the Nordic Area (Greenland and Svalbard), the Beaufort Sea Area in Canada (Northwest Territories/ Inuvialuit Settlement Region and Gwich’in First Nation Traditional Territory) and Northeastern Siberia in Russia. The paper analyzes the entanglement between social and environmental change and presents a risk analysis framework, including the interconnected geo-physical & socio-cultural risks, with the aim to improve adaptation and mitigation strategies of local communities. Guided by a mixed-methods approach, the research outcomes are the result of field-based research, including focus groups, qualitative interviews, participant observation, community workshops – as well as a quantitative survey in three settlements (Qeqertarsuaq in Greenland, Aklavik in Canada and Longyearbyen on Svalbard).
Adapting an Earth Global Climate Model for a Modern-day Martian climate.
Authors: McCulloch Danny , Mayne Nathan , Bate Matthew , Sergeev Denis
Published: March 2022

Mars climate modelling is essential for understanding the atmosphere of a planet with limited in-situ observations. Such research is crucial if humanity will ever hope to explore the red planet in the coming decades. There are already Global Climate Models (hereafter; GCMs) for Mars that are tackling this challenge, but there are still processes that are poorly understood or difficult to simulate, such as inter-annual dust storms or a dynamically-calculated CO2 ice cycle which affects global pressure changes. In order to address these issues in current Mars modelling, we propose a GCM capable of reproducing similar results by using different parameterisation. This multi-faceted approach would be pivotal in tackling the aforementioned issues, in addition to providing validation of modelling techniques in extreme conditions. 

We adapt a highly-sophisticated and modular GCM, the Met Office Unified Model, currently routinely employed for weather and climate prediction on Earth, to the present climate of Mars. We detail the key climate processes driving Mars' atmosphere and how we characterise them, namely:

Dust

Orography

Orbital parameters

Atmospheric composition and pressure

Atmospheric H2O

CO2 ice

By incrementally adapting schemes already established and used extensively for Earth simulations, we can reproduce a comprehensive and complex climate model of Mars, whilst simultaneously assessing the significance of each process. To verify our model, we compare our GCM against in-situ data from the Viking landers and outputs from the LMD Mars GCM. Through this, we demonstrate how we are able to reproduce key processes in the Martian atmosphere across its seasons, between which conditions can vary greatly. We then speculate what processes still need implementation or refinement and the impact they may have on our current outputs. 

We will finish by detailing the remaining schemes to be implemented and how they might impact the output of our GCM, namely; a CO2 ice scheme and atmospheric moisture. The implementation of these processes will further increase the validity and accuracy of our results. Potential future work would include investigating diurnal fluctuations or inter-annual phenomena. Our GCM and modelling methods would eventually aim to expand the capabilities of the wider Mars-modelling community, the benefits of which, will bring us closer to unlocking and understanding the intricacies of Mars' unique environment.
Nested crater morphology, ring-structures and temperature anomalies detected by close-range photogrammetry and thermal remote sensing at Láscar volcano, Chile
Authors: Ai Lun , Walter Thomas , Massimetti Francesco , Aguilera Felipe , Mania Rene , Zimmer Martin , Kujawa Christian , Pizarro Manuel
Published: March 2022

Volcanic craters often develop in clusters and enclose smaller, subsidiary vents and ring structures. Details on the ongoing geomorphology and structural evolution, however, are commonly lacking for active volcanic craters due to difficult and hazardous access. Therefore, remote sensing based investigation at active volcanoes is providing unique data allowing entrance to inaccessible summit craters. Here we describe novel drone and satellite data collected at Láscar, the most active volcano in the central Andes. Láscar hosts five partially nested craters, the deepest crater of the eastern three persist active and was the site of numerous violent explosions in the past decades. Using a Pleiades tri-stereo satellite dataset, we constructed a 1-m resolution digital terrain model (DTM) and orthomap that we used to identify subtle structures and morphologies of the eastern three nested craters. However, due to the shadow effect caused by the deep concave shape of the active crater, its geometry remains unclear. We complement this analysis by unoccupied aerial vehicle (UAV) surveys in 2017 and 2020 by employing both an optical and a thermal imaging camera. We systematically mapped the entire crater field and could also fly into the deep active crater to acquire close range images. We applied the Structure-from-Motion (SfM) method that enables us to create centimeter-scale DTMs, optical and thermal orthomosaics. Using this data-set we create an inventory of fumaroles and thermal anomalies. By calculating the difference of the 2017 and 2020 data, we quantify the spatial and volumetric changes that occurred during the observation period. We find changes mostly concentrated at the crater floor, material accumulation, thermal anomalies changing, as well as localized rock falls into the crater. We note that highest temperature anomalies are restricted by the central circular structure at the crater floor, consistent with the location of a thermal anomaly episode that peaked in late 2018, possibly representing the surface expression of the underlying conduit. Thus, by linking the satellite and drone data we derive important morphological, thermal and structural information and discuss the crater morphology and characteristics of episodic unrest phases at Láscar.
The International Data Centre infrasound processing system, a 25 years travel
Authors: Mialle Pierrick ,   PTS colleagues
Published: March 2022

In 2001, when the first data from an International Monitoring System infrasound station started to arrive in near real-time at the International Data Centre (IDC), its infrasound processing system was in a premature state. The IDC embarked for a multi-year design and development of its dedicated processing system, which led to operational IDC automatic processing and interactive analysis systems in 2010. In the next twelve years the IDC produced over 40,000 infrasound events reviewed by expert analysts.
In an effort to continue advancing its methods, improving its automatic system and providing software packages to Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) users, the IDC focused on several projects. First, the automatic system for the identification of valid signals was redesigned with the development of DTK-(G)PMCC (Progressive Multi-Channel Correlation), which is in IDC Operations and made available to CTBTO users within NDC-in-a-Box. And second, an infrasound model was developed for automatic waveform network processing software NET-VISA with an emphasis on the optimization of the network detection threshold by identifying ways to refine signal characterization methodology and association criteria.
Ongoing and future improvements of the IDC processing system are planned to further reduce analyst workload and improve the quality of IDC products.
Redox properties of particulate electron acceptors affect anaerobic microbial respiration under oxygen-limited conditions in floodplain soils
Authors: Aeppli Meret , Thompson Aaron , Dewey Christian , Fendorf Scott
Published: March 2022

Mountain floodplains are characterized by spatiotemporal variations in soil redox conditions that arise due to dynamic hydrological and resulting biogeochemical states. Under oxygen-depleted conditions, solid phase Fe(III) can serve as terminal electron acceptor (TEA) in anaerobic microbial respiration. It remains unclear, however, to what degree the redox properties of Fe(III) phases limit rates of anaerobic respiration and hence organic matter degradation. Here, we assess such limitations in iron-rich soils collected across a gradient in native redox states from the Slate River floodplain (Colorado, U.S.A.). We incubated soils under anoxic conditions and quantified electron transfer to TEAs, TEA reactivity toward electrochemical reduction, and CO2 production. Fe(III) reduction occurred together with CO2 production in native oxic soils; no Fe(II) nor CO2 production was observed in native anoxic soils. Initial CO2 production rates increased as the reactivity of TEAs toward electrochemical reduction increased across all soil depths and, thus, native soil redox states. The low redox reactivity of TEAs was likely caused by higher acid-extractable Fe(II) concentrations rather than higher crystallinity of Fe(IIII) mineral phases based on analysis of Fe(III) mineral identity and crystallinity using Mössbauer spectroscopy. Our findings indicate that the low redox reactivity of TEAs limited microbial respiration rates in our incubation experiments. This work advances our understanding of controls on anaerobic microbial respiration and can help anticipate organic matter degradation under future hydrological conditions.
Sensitivity of stratospheric pathways of Arctic-midlatitude linkages to the modification of the gravity wave drag parameterization in ICON model using deep learning
Authors: Mehrdad Sina , Karami Khalil , Handorf Dörthe , Quaas Johannes , Höschel Ines , Jacobi Christoph
Published: March 2022

The global warming has been observed to be more severe in the Arctic compared to the rest of the world. This enhanced warming i.e. Arctic Amplification is not just the result of local feedback processes in the Arctic. The stratospheric pathways of Arctic-midlatitude linkages and large-scale dynamical processes can contribute to the Arctic Amplification. The polar stratospheric dynamics crucially depends on the atmospheric waves at all scales. The winter polar vortex can be disturbed by gravity waves in the middle atmosphere. To investigate the sensitivity of the polar vortex dynamics, large-scale dynamical processes, and the stratospheric pathways of the Arctic-midlatitude linkages to the modification of gravity wave drag, we conduct sensitivity experiments using the global atmospheric model ICON-NWP (ICOsahedral Nonhydrostatic Model for Numerical Weather Prediction). These sensitivity experiments are performed by imposing a repeated annual cycle of the year 1985 for sea surface temperatures and sea ice as lower boundary conditions and for greenhouse gas concentrations as external forcing. This year is selected as both El-Nino Southern Oscillation and Pacific decadal oscillation were in their neutral phase and no explosive volcanic eruption has occurred. Hence, lower boundary and external forcing conditions in this year can serve as a useful proxy for the multi-year mean condition and an estimate of its internal variability. We performed simulations where in the control simulation the sub-grid parameterization scheme for both orographic and non-orographic gravity wave drags are switched on. The other two experiments are identical to the control simulation except that either orographic or non-orographic gravity wave drags are switched off.

    Recently, deep learning has extraordinarily progressed our ability to recognize complex patterns in big datasets. Deep neural networks have shown great capabilities to capture the dynamical process of the atmosphere. Applying deep learning algorithms on experiments’ results, the impact of gravity wave drag modifications on large-scale mechanisms of the Arctic Amplification will be analyzed. Special emphasis will be put on the effects of gravity wave drag modifications on the polar vortex dynamics.
Organic aerosols and dust as contributors to ice nucleating particles formation in the marine atmosphere
Authors: Kanakidou Maria , Chatziparaschos Marios , Daskalakis Nikos , Myriokefalitakis Stelios , Kalivitis Nikos
Published: March 2022

Atmospheric Ice nuclei particles regulate in cloud properties such as, cloud lifetime, precipitation rates and cloud’s radiative properties due to their ability to trigger ice heterogenous formation. Particles ejected into the atmosphere during bubble bursting through the sea surface microlayer, which is enriched in organic matter, are considered as the major precursors of INPs over the ocean. In addition, mineral dust particles that are considered as the most important precursor of INP in the mixed-phase cloud regime globally and terrestrial bioaerosols that have been also shown to have INP activity are transported over the ocean and contribute to the INP in the marine environment.

In the present study we present results from the global 3-D chemistry transport model TM4-ECPL that accounts for INPs concentrations from marine organic aerosols, terrestrial bioaerosol and K-rich feldspar and quartz mineral dust particles. The simulated distribution of INP concentrations over the global ocean agrees with currently available ambient measurements. The relative contribution of the various INP precursors in the different compartments of the marine atmosphere is discussed on the basis of simulated 3-dimensional number concentrations of INP, providing insight to the cloud glaciation processes in the marine environment.

Support from PANACEA (MIS 5021516) funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund), and the Excellence grant, the U Bremen Excellence Chair and the European Union Horizon 2020 project FORCeS under grant agreement No 821205.
Evaluation of Submesoscale Variability Captured by a Glider Mission and high-resolution numerical experiments in the Gulf of Finland, Baltic Sea 
Authors: Salm Kai , Väli Germo , Liblik Taavi , Lips Urmas
Published: March 2022

The development of submesoscale phenomena in seas is recognized with the refinement of observational and model grids. While in situ measurements are discrete and limited in time and/or space, numerical models could fill the entire sea with simulation data. Three high-resolution glider missions were conducted in the Gulf of Finland, Baltic Sea, in 2018–2019 with an aim to detect submesoscale processes. We captured frontal submesoscale features affecting water column structure in spring 2018. In this study, a three-dimensional hydrodynamic model GETM (General Estuarine Transport Model) with eddy-resolving grid spacing of 0.5 nautical miles and submesoscale permitting grid spacing of 0.125 nautical miles is used to simulate the dynamics in the study area.  We compare the model results with the measurements, present differences, and propose probable explanations.  

The submesoscale processes are related to the energetic mesoscale flow field and they contribute to the energy transfer at smaller scales. We investigate the statistical features to characterize the submesoscale structures in the simulated area during the glider missions. The regions of order one Rossby and Richardson numbers characterize the spots with active submesoscale dynamics. Further, horizontal buoyancy gradients are one of the primary sources of submesoscale processes. We propose that the smaller-scale tracer patterns at a lateral scale up to a km demonstrated an ageostrophic secondary circulation. The phenomenon illustrates the relation between horizontal and vertical structures. The high-resolution simulation allows us to have a three-dimensional view of the submesoscale features and describe the events that permitted the smaller-scale structures to arise along with some estimate for the re-occurrence of the event.  
The relationship between atmospheric heat transport and monsoonal precipitation variability
Authors: Awal MD Rabiul , Turner Andrew , Ferreira David
Published: March 2022

During the boreal summer monsoon, the temperature gradient between land and ocean in the Northern Hemisphere (NH) facilitates large transports of moist air masses towards the land regions, where their convergence causes precipitation. This is associated with an export of net energy (internal, potential, and latent energy) away from the land. On a global scale, there is a tight relationship between the location of the intertropical convergence zone (ITCZ) and the cross-equatorial atmospheric heat transport (AHT) on seasonal, interannual and climate time scales: a more northward cross-equatorial AHT is associated with a displacement of the ITCZ (as defined by precipitation) toward the equator. We further analyse the relationships between cross-equatorial AHT and common streamfunction-based measures of the ITCZ position and width found in the literature. However, it remains unclear whether links between energy transport and the monsoonal precipitation exist at the scale of monsoon regions.

To address this question, we combine data from the European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis ERA5 and Global Precipitation Climatology Project (GPCP-version 2.3) rainfall data. In the annual cycle, the cross-equatorial northward AHT transport peaks in July and the annual net northward cross-equatorial AHT is -0.34 PW (negative sign denotes southward). A regression analysis confirms that the global ITCZ shifts southward when the cross-equatorial AHT is anomalously large, although we demonstrate this mainly happens over the Pacific Ocean. Outside of the Pacific sector, the relationship between cross-equatorial AHT and JJA precipitation is complex. For the West African monsoon region, greater northward cross-equatorial AHT is related to weaker rainfall along the Gulf of Guinea coast, while there is stronger rainfall in the Atlantic Ocean ITCZ. In the Indian sector, anomalous northward AHT is associated with a weak monsoon, marked by strong decreases in precipitation on the Western coast of India and the southern flank of the Himalayas.

In future work, the CMIP6 multi-model dataset will be analysed to examine future projection of AHT and its impact on monsoonal precipitation. The characteristics of the ITCZ will be explored using the same datasets.
Investigating a small-scale archaeological feature in the ancient city of Miletus using shear wave seismics
Authors: Fischer Simon Levin , Erkul Ercan , Zolchow Manuel , Kaplanvural Ismail , Brückner Helmut , Berns Christof , Rabbel Wolfgang
Published: March 2022

The ancient city Miletus is located at the Mediterranean coast of present Turkey. Its former geographical position on a land tongue in the Gulf of Miletus with four bays, which can be used as harbours, made the city a place of great economical interest. During the last decades, several archaeological and geophysical investigations were carried out to reconstruct the cityscape of Miletus.
In 2018, geoelectrical measurements revealed a high-resistive anomaly near the ancient western market place. The aim of the presented study is a more detailed imaging of this anomaly with help of shear wave seismic methods. 
For this purpose, a 35.5m long profile was build up across the geoelectric anomaly. An overall of 72 S-geophones was used with a spacing of 0.5m. Shots were struck every 1m by the use of a hammer and a shear wave source. 
A "simple" velocity evaluation by the Wiechert-Herglotz method shows shear-wave velocities between 270-380 m/s in the first three meters. This depth gradient of velocities is verified by a refraction tomography using the first breaks of each channel. The tomography also shows a high velocity zone of about 470 m/s in the deepest part of the model. 
A Full Waveform Inversion (FWI) was calculated using the refraction tomography as a start model. The inversion model shows three distinct high velocity zones in a, apart of these anomalies, quite homogeneous model. In these zones, velocity reaches values of more than 500 m/s. 
The results are in accordance to geoelectrical measurements conducted on the same profile. High velocity zones strongly correlate with areas of higher electrical resistivity. Corings near these velocity and resistivity anomalies show massive layers of limestone starting at a depth of about 1.5m and thus verify the findings of the geophysical investigations.
In conclusion, the shear wave seismic measurements are capable of resolving small-scale features even in shallow depths, especially with help of FWI. Together with the geoelectrics and corings, the results deliver an important contribution for the further interpretation of the buried archaeological feature.
Dynamics of fires, harvest and carbon stocks in U.S. forests 1926-2017
Authors: Magerl Andreas , Gingrich Simone , Matej Sarah , Lauk Christian , Cunfer Geoffrey , Yuskiw Cody , Forrest Matthew , Schlaffer Stefan , Erb Karlheinz
Published: March 2022

Human-fire interactions have always played an important role in the United States of America. Important processes include land clearing with fires in the course of agricultural expansion and development of the West during the 19th century, large-scale fire suppression in the first half of the 20th century and recent “mega-fire” events in California. Strong regional divergences occurred: Fire regimes in the Eastern U.S. were significantly altered due to settlement and land-use changes over the past 100 years, resulting in reduced severity of fire events. In the West the area extent and severity of wildfires has increased, especially in recent decades, arguably due to more frequent climatic extreme events. Although the historical fire narrative in the U.S. has been studied in numerous publications, the links between these developments and changes in the socio-metabolic system i.e., changes in resource use, and consumption, are to our knowledge less well understood.

In this study we investigate the influence of anthropogenic alteration of fire regimes on forest biomass Carbon stocks in comparison to forest uses, i.e., the extraction of woody biomass and forest grazing on multiple spatial scales. We develop a long-term reconstruction of biomass burned in forests on the national, regional, and state level based on statistical and remote-sensing data. We describe and examine historical differences between fire regimes in the Eastern and Western United States in connection with human use of forest for the period 1940-2017. Using panel data analysis, we investigate the diverse connection between forest change, socio-metabolic processes, natural disturbances (i.e., wildfires), and associated human fire control on various spatial and temporal scales. With this study we aim to contribute to a better understanding of the underlying socio-metabolic drivers and accompanying processes of altered forest fire regimes.
Dynamical forcing factors of severe windstorms: their seasonal forecast skill and influence on seasonal windstorm predictions
Authors: Degenhardt Lisa , Scaife Adam , Leckebusch Gregor
Published: March 2022

Seasonal forecasts of extratropical storms are of interest to the scientific community as well as insurers, government contingency planners and the general public.

In previous studies, seasonal forecasts of winter windstorm events over Europe from the Met Office GloSea5 model have shown significant skill especially over north-west Europe for windstorm frequency and were connected to large-scale patterns, i.e., the NAO. Recent investigations show links between windstorm intensities and the three dominant large-scale patterns over Europe (NAO, SCA and EA) which explain up to 80% of interannual windstorm variability.

This new investigation quantifies the role of additional, dynamical forcing factors that could influence windstorm predictions. The factor selection is based on known dynamical influences on cyclone development and is thus related to the existence to severe windstorms.  We analyse the Eady-Growth-Rate (EGR), 200hPa jet speed and location, a proxy for Rossby wave source (RWS), and one factor related to tropical precipitation. The seasonal forecast skill of the factors themselves shows positive and significant skill in regions they are expected to be most influential or dominant, like for the RWS around its dipole over the south-west of the North Atlantic or for the EGR east of North America.

The links between these dynamical forcing factors to windstorm impact-relevant regions in the model and reanalysis data will be presented and the explanatory power of these factors for the overall model skill is discussed.
Petrology and Geochemistry of intrusive igneous rock from the Inthanon zone, Northwestern Thailand
Authors: Santitharangkun Srett , Hauzenberger Christoph , Gallhofer Daniela , Skrzypek Etienne
Published: March 2022

Large plutons are common within the Inthanon Zone in Northwestern Thailand. These igneous rocks are also known as Central Granitoids Belt in mainland Southeast Asia. They are interpreted to be part of the suture zone between Sibumasu and Indochina and were emplaced mainly in the Upper Triassic.

Here, we present new petrological and geochemical data for the Central Granitoids Belt.  A geochronological study on selected samples will follow.  The sampled granitoids can be separated into three groups: (1) biotite granite, (2) hornblende granite, (3) syenite/monzonite. The samples consist of various light colored to dark grey granitoids due to the type and amount of mafic minerals (biotite or hornblende) present. The general mineral assemblage of all the intrusive igneous rocks is quartz + plagioclase + K-feldspar + biotite + apatite + zircon ± allanite ± titanite ± ilmenite. The biotite granites are mostly composed of biotite aggregates associated with accessory minerals: zircon, ilmenite, and apatite. The syenite/monzonite group usually contains additional clinopyroxene and hornblende. Plagioclase and hornblende of the syenite/monzonite group commonly exhibit a sieve texture.

The biotite granite group is typically peraluminous and belongs to the high-K calk-alkaline to shoshonitic series. The hornblende granite group is mostly peraluminous and of predominantly shoshonitic affinity. The syenite/monzonites are typically metaluminous but also belong to the shoshonitic series. The chondrite normalized rare earth element (REE) patterns are quite similar for all igneous rocks with elevated LREE, pronounced negative Eu anomaly and a flat HREE segment. The granite tectonic discrimination plots after Pearce et al. (1984) classify most samples as syn-collision granites (syn-COLG) and when using the Batchelor and Bowden (1985) discrimination diagram as syn-, late, and post-collisional.

The intrusive igneous rocks from Northwestern Thailand were presumably emplaced in a syn- to post-collisional setting when the Sibumasu block collided with the Sukhothai terrane and was eventually amalgamated to the Indochina block. This led to the closure of the Palaeotethys along the eastern area of the Sibumasu block.

Batchelor, R.A. and Bowden, P. (1985) Petrogenetic Interpretation of Granitoid Rock Series Using Multicationic Parameters. Chemical Geology, 48, 43-55.

Julian A Pearce, Nigel BW Harris, Andrew G Tindle (1984). Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25, 956-983.

 
The hierarchy of factors controlling long-term coastal erosion: a statistical approach from topographic reconstruction of volcanic islands.
Authors: Bossis Rémi , Regard Vincent , Carretier Sébastien
Published: March 2022

In global geochemical cycles, the solid flux from the continent to the ocean is usually reduced to the input of sediments from rivers [1]. However, regional studies have shown that the input of sediments from rocky coast erosion may be a significant part of this flux [2]. So, it is important to consider this input into global cycles and to quantify it over different timescales.

On short-term timescales, from the year to the century, coastal erosion is currently quantified with direct measurement of the coastline recession, between successive time intervals [3]. Extrapolating on timescales longer than a thousand years is difficult. This leads to a lack of data and therefore a gap in knowledge in longer term coastal erosion [4].

A solution to quantify long-term erosion of rocky coast is to reconstruct the initial geometry of the coastline and to know the age of its formation. Volcanic islands are suitable objects for this method. Indeed, their initial shape is simple and can be easily reconstructed, and their maximum extension can be dated [5,6,7], although this age can be difficult to estimate. Thus, the topographic reconstruction of a volcanic island allows, by comparison with its current topography, the quantification of volumes lost by erosion. In turn, it becomes possible to obtain values of the rocky coast total recession on timescales from thousands to hundreds of thousands of years [8]. Moreover, the wide geographic distribution of volcanic islands provides a diversity of climatic and geodynamic settings allowing to analyze the effects of various factors on long-term coastal erosion.

Here we propose an improvement of this erosion quantification by accounting for the submarine morphology. Applying this approach for different volcanic islands, we carried out a statistical analysis of the impact of several factors that control long-term coastal erosion. This analysis allows us hierarchize these factors. This is the first step towards the formulation of long-term coastal erosion universal laws and towards the quantification of rocky coast sediment influx in global cycles.

 

[1] Milliman and Farnsworth (2013). Cambridge University Press.

[2] Regard et al. (in press).

[3] Bird (2011). John Wiley & Sons.

[4] Prémaillon et al. (2018). Earth Surface Dynamics 6, 651-668.

[5] Lahitte et al. (2012). Geomorphology 136, 148-164.

[6] Ramalho et al. (2013). Earth-Science Reviews 127, 140-170.

[7] Karátson et al. (2016). Geomorphology 253, 123-134.

[8] Bossis et al. (in press).
Global Mean Surface Temperature Projection Constrained by Historical Observations
Authors: Lykke Jingying Zhou , Bennedsen Mikkel , Hillebrand Eric
Published: March 2022

In this paper, we propose a state space representation (EBM-SS model) of the two-component energy balance model (EBMs). The EBM-SS model incorporates three extensions to the two-component EBM. First, we include ocean heat content (OHC) as a measurement of the temperature in the deep ocean layer. Second, we decompose the latent state of radiative forcing into a natural component and an anthropogenic component. The anthropogenic component is modeled as a random walk process with a local linear trend to represent the deterministic and stochastic trends of anthropogenic forcing, while the natural component captures the variations in solar irradiance and transitory episodes in forcing following major volcanic eruptions. Lastly, we use multiple GMST anomaly data sources from separate research groups as measurements for the latent state -- the temperature in the mixed layer in the two-component EBM. 

We estimate the EBM-SS model using observations at the global level during the period 1955 -- 2020 by maximum likelihood. We show in empirical estimation and in simulations that using multiple data sources for the latent process reduces parameter estimation uncertainty. When fitting eight global mean surface temperature anomaly observational series, the physical parameter estimates are comparable to those obtained by using datasets from Coupled Model Intercomparison Project 5 (CMIP 5) in other literature.  We find that using this set of parameter estimates, the GMST projection results under Representative Concentration Pathway (RCP) 4.5, 6.0, and 8.5 scenarios considerably agree with the outputs from the climate emulator Model for the Assessment of Greenhouse Gas Induced Climate Change (MAGICC) 7.5 and CMIP 5 models. We show that utilizing a simple climate model and historical records alone can produce meaningful GMST projections.