bluuebunny/crossref_metadata_2025 huggingface dataset:
Ice sheet unzipping in the mountain-piedmont region of west-central Sweden: complex late-deglaciation of the Scandinavian ice sheet
Authors: Blomdin Robin , Peterson Becher Gustaf , Smith Colby , Regnéll Carl , Öhrling Christian , Goodfellow Bradley
Published: March 2021

Regional-scale glacial geomorphological maps provide important empirical data for reconstructions of former ice sheets, which may serve as analogues for the behaviour of modern ice sheets under climate warming. In particular, the extensive LiDAR-derived record of former ice sheet beds, provides an outstanding archive from which to infer former ice sheet behaviour. The stacking together and analysis of, tens of thousands of individual landforms, based on their spatial coherency, provides a powerful tool to reconstruct ice flow dynamics, temporally evolving ice divide positions and the “unzipping” of ice sheets into separate masses during deglaciation. In this study, we develop a glacial geomorphological dataset focussing on the mountain-piedmont region of Jämtland in west-central Sweden. We focus on this region because it is where the last (Weichselian) ice sheet is believed to have unzipped into separate domes and was inundated by vast ice dammed lakes. Jämtland also records a complex temporal evolution of subglacial processes and was formerly mapped without the benefit of a LiDAR-based elevation model. The dataset was created by mapping in GIS and covers an area of 50 000 km2 and almost 88 000 landforms, including glacial lineations, crag-and-tails, ice marginal moraines, lateral meltwater channels, eskers, and glacial lake shorelines. We use this unique dataset–in terms of spatial density and resolution–and quantitatively analyse cross-cutting relationships to establish a relative ice flow chronology. Our key findings include 1) a previously unmapped landform system, formed by the Early-to-Middle Weichselian westward expansion of a mountain centred ice sheet, and 2) a complex early Holocene deglaciation sequence with ice sheet unzipping occurring in southern and east-central Jämtland. The ice sheet split into a larger sheet retreating northward and a smaller ice sheet remaining southeast of the mountain piedmont. Our results provide new insights into the late deglaciation of the Scandinavian Ice Sheet.
Towards automatic microseismic cluster localization with DAS
Authors: Tuinstra Katinka , Lanza Federica , Grigoli Francesco , Rinaldi Antonio Pio , Fichtner Andreas , Wiemer Stefan
Published: March 2021

Currently the capability of detecting earthquakes with decreasing magnitudes demands efficient source localization, especially in seismic monitoring. This work is a step towards automatic high-resolution earthquake localization in a seismic monitoring setup that makes use of Distributed Acoustic Sensing (DAS) as its primary measuring technique. With DAS, the dense spatial sampling of the seismic wavefield leads to an improvement of both event detection and localization of earthquakes. The advantage of DAS is easy and cost-effective deployment compared to traditional seismic instruments (especially in boreholes). However, the single-component nature and the large storage requirements of DAS data demand novel methods for efficient analysis of the recorded events.

We apply a new seismic event location method to DAS data, based on a distance geometry problem in biochemistry for protein structure determination (HADES1). From the distances between individual earthquakes and a seismic station, the relative distance between the events can be computed. This approach allows us to first determine the relative location of earthquakes within a seismic cluster, and subsequently position the cluster in its correct absolute location. The technique has already been successfully applied for a single traditional seismometer. The densely spaced channels in DAS measurements accommodate accurate relative distance computation, without the ability to constrain the azimuth of the seismic cluster. Therefore, after finding the relative locations within the cluster, the position and orientation of the cluster with respect to the fiber-optic cable is calculated by minimizing the difference between observed and calculated P- and S-wave first arrival times, using a grid search approach (multi-event location). In this way, the absolute locations of all earthquakes present in the cluster are found efficiently. We first test this DAS-adapted method on synthetics, then we will move towards a real data application.

1 HADES: https://github.com/wulwife/HADES
Geochronology of Himalayan shear zones: unravelling the timing of thrusting from structurally complex fault rocks
Authors: Villa Igor M , Montemagni Chiara
Published: March 2021

Dating structurally complex fault rocks often results in internally inconsistent ages, as several mineral generations are intergrown at scales << 10 µm and almost always altered to various degrees. We describe here 39Ar-40Ar stepheating using the combination of two independent indicators that allow the discrimination of coexisting mica generations from each other and from the ubiquitous retrogression/alteration phases. A necessary first step is electron probe microanalysis to assess both inventory and spatial distribution of the mineral phases that need to be distinguished a posteriori by 39Ar-40Ar systematics. One indicator is based on mica stoichiometry, which can be proxied by the 39Ar concentration in combination with the 37Ar/39Ar and 38Ar/39Ar (i.e. Ca/K and Cl/K) ratios. The other indicator is the furnace temperature, at which a degassing peak accompanying dehydration and structural collapse is observed. As dehydration rates depend on the average bond strength in the crystal structure, it is predicted (and indeed observed) that the temperature of the differential Ar release peak is variable among different minerals. As the Ca/Cl/K signatures of pure micas coincide with the Ar release peak, their combination identifies the isochemical steps that correspond to the degassing of pristine micas. Only these should be used to date the activity of shear zones.

This procedure should become routine in analysing polydeformed metamorphic rocks.
Green and golden obsidian of ‘Cerro de Las Navajas’, Hidalgo (Mexico): geoarchaeological heritage that deserves international recognition
Authors: Cruz-Pérez Miguel A. , Canet Carles , Pastrana Alejandro , Carcavilla Luis , Salgado-Martínez Erika , García-Alonso Eduardo J.
Published: March 2021

The «Cerro de Las Navajas Obsidian» is a rock within the Comarca Minera, Hidalgo UNESCO Global Geopark, Mexico, that possesses outstanding archaeological, cultural and geological value. It exhibits a unique green-golden macroscopic hue and was exploited and traded since ca. 250 BC, by successive Mesoamerican cultures and until early Colonial times —ultimately recording the transition to a steel-based society. It is the largest deposit of its kind and the longest historical exploited site in the continent. We argue here the potential of this particular obsidian for a heritage designation that highlights its global significance; synergies derived from an international recognition may offer the chance (a) to put in value the multi-dimensional geoheritage of this obsidian, (b) to strengthen the sense of belonging among local community, (c) to require authorities to regulate obsidian mining and commercialization, under fair trade terms and compatible with conservation, research and responsible tourism, (d) to support further research on archaeology and cultural heritage linking geosciences with other disciplines, and (e) to contribute to UNESCO Global Geoparks program’s aims seeking local development and sustainability. The two last expected achievements would be relevant given the lack of legal advisory role of geoparks in geoheritage management in Mexico and its geoconservation community.
Holocene environmental reconstructions based on organic and mineral deposits of Mt Śnieżnica landslide, Outer Western Carpathians, Poland
Authors: Pawlik Lukasz , Okupny Daniel , Kroh Pawel , Cybul Piotr , Stachowicz-Rybka Renata
Published: March 2021

The Outer Western Carpathians is a region in Poland with an exceptionally high number of landslides. Besides geohazard issues, these landslides are frequently an archive of the past environmental changes thanks to organic and mineral material accumulated in numerous landlocked pits where small peat bogs formed. We investigated a large landslide body developed on the northside part of Mt Śnieżnica. No historical information exists related to the instability of this region. After finding and examining 20 pits, we selected three for detailed analyses. We extracted three cores with the use of a peat sampler. The cores were 10 cm in diameter and up to 4,2 m deep. Compared to other landslides in this region, the depth of peat bogs is substantial and suggests that the landslide is a minimum of several thousand years old. Laboratory analyses included: bulk density measurement, geochemical analyses (organic matter, SiO2ter, SiO2biog, CaCO3, TOC, TIC, C, N, S, Na, K, Mg, Ca, Fe, Mn, Cu, Zn, and Pb contents) of biogenic deposits (405 samples), AMC radiocarbon dating of plant tissue (20 pieces), macroscopic charcoal (420 samples each representing 1 cm slice of the core). The aim of the present study is 1) to reconstruct environmental conditions in the area, 2) dating of the landslide formation in relation to climate change during the Holocene, and the main events after its triggering: changes in vegetation cover, hillslope instability, e.g., soil erosion, hydroclimate fluctuations, and human impact. Our results fill the gap in environmental reconstruction encountered by other authors investigating this part of the Outer Western Carpathians and push forward the ongoing discussion on the environmental conditions during the Holocene in this region.
A three-dimensional groundwater flow simulation of Granger Basin, Yukon, Canada
Authors: Woo Audrey , McKenzie Jeffrey , Carey Sean
Published: March 2021

Groundwater flow and exfiltration (discharge) in Arctic and Subarctic mountain regimes is poorly understood yet plays an important role in areas underlain by continuous and discontinuous permafrost. Permafrost, ground with a perennial temperature below 0°C, acts as an impermeable barrier to groundwater flow and influences hydrogeologic connectivity and storage. The Arctic is warming at twice the global average rate, leading to rapid permafrost thaw with unclear consequences for groundwater systems. In this study, we develop a numerical groundwater model of the Granger Basin, Yukon, to further our understanding of the influence of permafrost and thaw on groundwater flow in basins impacted by climate change.

Granger Basin is a 7.6 km2  headwater catchment located within the Wolf Creek Research Basin, Yukon, Canada. It is representative of a subarctic-continental mountain environment with already observable climate change impacts. To date, there has been limited hydrogeology monitoring or numerical modeling at this site. To investigate cryohydrogeologic processes within the basin, we integrate existing field data, including 30 years of hydrometeorological records and geophysical data into a three-dimensional numerical model with saturated-unsaturated groundwater flow. We use the SUTRA-ice numerical model that couples groundwater flow and energy transport with dynamic freeze-thaw processes. The model incorporates both time-dependent thermal and hydrological surface boundary conditions and is used parametrically to understand the generation of groundwater baseflow in this setting. We will present initial results that will evaluate the impact of different hydrogeologic properties on the generation of groundwater streamflow in Wolf Creek, how permafrost in transition affects the groundwater system, and provide the framework for future research directions.
Exploring the complex uncertainties in coupled climate-ice simulations of the Last Glacial Maximum
Authors: Gregoire Lauren , Gandy Niall , Astfalck Lachlan , Smith Robin , Ivanovic Ruza , Williamson Daniel , Gregory Jonathan
Published: March 2021

Simulating the co-evolution of climate and ice-sheets during the Quaternary is key to understanding some of the major abrupt changes in climate, ice and sea level. Indeed, events such as the Meltwater pulse 1a rapid sea level rise and Heinrich, Dansgaard–Oeschger and the 8.2 kyr climatic events all involve the interplay between ice sheets, the atmosphere and the ocean. Unfortunately, it is challenging to simulate the coupled Climate-Ice sheet system because small biases, errors or uncertainties in parts of the models are strongly amplified by the powerful interactions between the atmosphere and ice (e.g. ice-albedo and height-mass balance feedbacks). This leads to inaccurate or even unrealistic simulations of ice sheet extent and surface climate. To overcome this issue we need some methods to effectively explore the uncertainty in the complex Climate-Ice sheet system and reduce model biases. Here we present our approach to produce ensemble of coupled Climate-Ice sheet simulations of the Last Glacial maximum that explore the uncertainties in climate and ice sheet processes.

We use the FAMOUS-ICE earth system model, which comprises a coarse-resolution and fast general circulation model coupled to the Glimmer-CISM ice sheet model. We prescribe sea surface temperature and sea ice concentrations in order to control and reduce biases in polar climate, which strongly affect the surface mass balance and simulated extent of the northern hemisphere ice sheets. We develop and apply a method to reconstruct and sample a range of realistic sea surface temperature and sea-ice concentration spatio-temporal field. These are created by merging information from PMIP3/4 climate simulations and proxy-data for sea surface temperatures at the Last Glacial Maximum with Bayes linear analysis. We then use these to generate ensembles of FAMOUS-ice simulations of the Last Glacial maximum following the PMIP4 protocol, with the Greenland and North American ice sheets interactively simulated. In addition to exploring a range of sea surface conditions, we also vary key parameters that control the surface mass balance and flow of ice sheets. We thus produce ensembles of simulations that will later be used to emulate ice sheet surface mass balance.  
Provenance Determination of Paleochannel Infillings in the Alsatian Upper Rhine Floodplain Using Mid-Infrared Spectroscopy-Discriminant Analysis
Authors: Abdulkarim Mubarak , Chapkanski Stoil , Ertlen Damien , Rambeau Claire , Schmitt Laurent , Le Bouteiller Louis , Preusser Frank
Published: March 2021

The Alsatian Upper Rhine floodplain (northeastern France) is characterized by a complex anastomosing network of paleochannels inherited from Late Glacial braided fluvial pattern of the Rhine system. These paleochannels are filled by mixed or stratified clastic and organic sediments originating from different sediment sources. Identifying these sediments' provenance is critically important for understanding past surface processes and reconstructing the Upper Rhine Valley evolution in the course of the Holocene. This study employed mid-infrared spectroscopy to determine the source of sediments and, therefore, understand which rivers may have contributed to the paleochannel infilling and establish the main patterns of filling through time. Sediment samples with unknown sedimentary provenance were collected in 16 sites consisting of paleochannels and the Ill River's levees. Mid-Infrared spectroscopic analyses were carried out on powdered (< 2 mm) samples using a Frontier Spectrometer (PerkinElmer) equipped with Diffuse Reflectance Infrared Fourier Transform accessory. Statistical analysis (Discriminant Analysis - DA) was performed to compare the spectral signatures obtained from the samples and a previously established reference spectral dataset (Chapkanski et al. 2020) covering potential sediment sources in the Upper Rhine area (the Rhine, Ill, and Vosges tributaries). The results showed well-contrasted sediment sources, with multiple rivers contributing to the paleochannel infilling history. The sediments were found to originate from the Rhine and Ill River systems and, to a lesser extent, Vosges tributaries. Some channels have an exclusively Alpine Rhine catchment origin while others showed purely Ill signatures. However, for most of the channels, infilling sources changed over time, presenting a relatively complex mixture of multiple sediment sources, indicating the lateral shifting of the two rivers within the alluvial plain. The results confirm that Mid-infrared spectroscopy (MIRS), combined with discriminant analysis, can give highly-specific determinations to sediments' sources. Thus MIRS-DA technique shows the potential of its being applicable as a rapid, low-cost, and efficient alternative method for provenance analysis of fluvial deposits in large, complex floodplains.
Surface and deep ocean connectivity inferred from robust extraction of coherent sets in ocean flow using models and sparse, scattered, and incomplete float data with transfer operator and dynamic Laplacian methods.
Authors: Froyland Gary , Abernathey Ryan , Denes Michael , Keating Shane
Published: March 2021

Transport and mixing properties of the ocean's circulation is crucial to dynamical analyses, and often have to be carried out with limited observed information. Finite-time coherent sets are regions of the ocean that minimally mix (in the presence of small diffusion) with the rest of the ocean domain over the finite period of time considered. In the purely advective setting (in the zero diffusion limit) this is equivalent to identifying regions whose boundary interfaces remain small throughout their finite-time evolution. Finite-time coherent sets thus provide a skeleton of distinct regions around which more turbulent flow occurs. Well known manifestations of finite-time coherent sets in geophysical systems include rotational objects like ocean eddies, ocean gyres, and atmospheric vortices. In real-world settings, often observational data is scattered and sparse, which makes the difficult problem of coherent set identification and tracking challenging. I will describe mesh-based numerical methods [3] to efficiently approximate the recently defined dynamic Laplace operator [1,2], and rapidly and reliably extract finite-time coherent sets from models or scattered, possibly sparse, and possibly incomplete observed data. From these results we can infer new chemical and physical ocean connectivities at global and intra-basin scales (at the surface and at depth), track series of eddies, and determine new oceanic barriers.

[1] G. Froyland. Dynamic isoperimetry and the geometry of Lagrangian coherent structures. Nonlinearity, 28:3587-3622, 2015

[2] G. Froyland and E. Kwok. A dynamic Laplacian for identifying Lagrangian coherent structures on weighted Riemannian manifolds. Journal of Nonlinear Science, 30:1889–1971, 2020.

[3] Gary Froyland and Oliver Junge. Robust FEM-based extraction of finite-time coherent sets using scattered, sparse, and incomplete trajectories. SIAM J. Applied Dynamical Systems, 17:1891–1924, 2018.
Improved multi-spectral polarimetric observations of UTLS aerosol and cloud from stratospheric balloon with the Aerosol Limb Imager
Authors: Letros Daniel , Bourassa Adam , Loewen Paul , Graham Liam , Lloyd Nick , Rieger Landon , Degenstein Doug
Published: March 2021

The Aerosol Limb Imager (ALI) is a multi-spectral imager capable designed to observe aerosol extinction and particle size profiles in the upper-troposphere lower-stratosphere. ALI uses a system of linear polarizers, a liquid crystal rotator, and an acoustic-optic tunable filter to select the linear polarization state and wavelength of limb scattered sunlight radiance between 600 nm and 1500 nm. From stratospheric balloon, spectral images have spatial resolution of <100 meters at the tangent point, and can produce useful aerosol observations between 5 km and 30 km in altitude. Of novelty is the polarimetric capability of ALI, which uses the orthogonal polarization states to detect cloud in the spectral data and facilitate its distinction from aerosol. Two previous iterations of the ALI instrument concept have already been successfully demonstrated, once in 2014 and again in 2018. Currently, a third iteration is being developed which improves upon the thermal, structural, and optical performance of the previous iterations. This improved iteration is scheduled for demonstration as part of the HEMERA program out of Kiruna, Sweden in the summer of 2021. This demonstration serves the larger objective of further proving the engineering and scientific readiness of the ALI instrument concept for eventual high-altitude aircraft and satellite platform deployments.  ALI is a proposed Canadian contribution to the NASA A-CCP satellite mission study.
Statistical Characterization of Temperature and Pressure Vertical Profiles for the Analysis of Laser Heterodyne Data
Authors: Miller J. Houston , Flores Monica , Bomse David
Published: March 2021

We present an analysis of historic pressure and temperature profiles from radiosonde

launches that will be used in retrieval of mixing fractions for greenhouse gases (GHGs, including

carbon dioxide, methane, and water vapor) in Laser Heterodyne Radiometry (LHR) data. With

over 2,700 stations worldwide, the global coverage for weather balloon observations is

extensive. Radiosonde stations included in the Integrated Global Radiosonde Archive (IGRA),

are launched simultaneously twice daily at 00:00 and 12:00 UTC. Global stations span all time

zones in both the Northern and Southern Hemisphere.

 

Mesa Photonics and George Washington University are developing a variant of LHR

known as Precision Heterodyne, Oxygen-Corrected Spectroscopy (PHOCS) that simultaneously

collects high-resolution, oxygen spectral line shape data. Because oxygen concentrations in the

troposphere and lower stratosphere are constant, these line shapes are uniquely sensitive to both

temperature and pressure profiles and constrained fitting of these line shapes enables more

precise GHG concentration retrievals.

 

Our approach is to collect historic data over several years (typically the prior decade) for

a particular date window surrounding a PHOCS measurement date for stations across the globe,

and mine this data for observation probability distributions as a function of level altitude, local

time of day of launch, latitude, etc. These distributions will then be used as Bayesian priors to

constrain temperature and pressure fits during the oxygen spectral fitting routine. Subsequently,

these priors will be used to estimate uncertainties in vertically-resolved GHG mixing ratios.
On the Generation and Evolution of Internal Solitary Waves in the Andaman Sea
Authors: Yu Yujun , Wang Shuya , Chen Xu
Published: March 2021

Internal Solitary Waves (ISW) are ubiquitous in the Andaman Sea as revealed by Synthetic Aperture Radar (SAR) images, but their generation mechanism and corresponding influence factors remain unknown. Based on a non-hydrostatic two-dimensional model, the generation of ISW across the channel between the Batti Malv Island and the Car Nicobar Island is investigated. Influences of the topography characteristics, seasonal stratification and tidal forcing are analyzed with a series of sensitivity runs. The simulated results indicate that no apparent ISW appear near the ridge because of small tidal excursion and low Froude number. Instead, they are evolved from the disintegrated internal tides which gradually steepen due to nonlinearity during propagation. East-west asymmetry of ISWs is revealed, which can be attributed to different topographic features on the two sides of the ridge. Two sills on the east side of the ridge further complicate the generation of eastward-propagating internal tides, resulting in the enhancement of ISWs in the Andaman Sea. Seasonally varying stratification has minor effect on the generation and evolution of ISWs. In addition, generation of ISW is mainly contributed by semidiurnal tidal forcing, while diurnal forcing only generates linear internal tides.
A minimal model of stratospheric vacillations
Authors: Hitchcock Peter
Published: March 2021

A new, low-order model of the variability of the Arctic polar vortex has been derived in the context of a shallow-water contour dynamics representation of quasigeostrophic shallow water flow on a polar f-plane. The model consists of a single linear wave mode propagating on a near-circular patch of constant potential vorticity (PV). The PV jump at the vortex edge serves as an additional degree of freedom.  The wave is forced by surface topography, and interacts with the vortex through a simplified parameterization of diabatic wave/mean flow interaction.

The resulting system of three coupled ODEs depends on four non-dimensional parameters, and the structure of the steady state solutions can be determined analytically in some detail. The system exhibits a range of dynamical behaviour closely related to that of the Holton-Mass model, including multiple steady states corresponding to weak and strong vortex states, and dynamically active limit cycles.

One key insight from the model is that, in dynamically active parameter regimes, the time-mean state of the vortex is predominantly controlled by the properties of the Rossby wave mode, while the strength of the topographic forcing plays a far weaker role.
Structure and Seasonal Variation of the Indian Ocean Tropical Gyre Based on Surface Drifters
Authors: Wu Wei , Du Yan , Qian Yu-Kun , Cheng Xuhua , Wang Tianyu , Zhang Lianyi , Peng Shiqiu
Published: March 2021

Using the Gauss–Markov decomposition method, this study investigates the mean structure and seasonal variation of the tropical gyre in the Indian Ocean based on the observations of surface drifters. In the climatological mean, the clockwise tropical gyre consists of the equatorial Wyrtki Jets (WJs), the South Equatorial Current (SEC), and the eastern and western boundary currents. This gyre system redistributes the water mass over the entire tropical Indian Ocean basin. Its variations are associated with the monsoon transitions, featuring a typical clockwise pattern in the boreal spring and fall seasons. The relative importance of the geostrophic and Ekman components of the surface currents as well as the role of eddy activity were further examined. It was found that the geostrophic component dominates the overall features of the tropical gyre, including the SEC meandering, the broad eastern boundary current, and the axes of the WJs in boreal spring and fall, whereas the Ekman component strengthens the intensity of the WJs and SEC. Eddies are active over the southeastern tropical Indian Ocean and transport a warm and fresh water mass westward, with direct impact on the southern branch of the tropical gyre. In particular, the trajectories of drifters reveal that during strong Indian Ocean Dipole or El Niño-Southern Oscillation events, long-lived eddies were able to reach the southwestern Indian Ocean with a moving speed close to that of the first baroclinic Rossby waves.
Are extreme precipitation events becoming stronger and warmer in the Andes?
Authors: Lagos-Zúñiga Miguel , Mendoza Pablo A. , Rondanelli Roberto
Published: March 2021

The Andes Cordillera serves as a physical barrier that modulates the atmospheric fluid dynamics, affecting the occurrence and intensity of precipitation events through orographic enhancement and the blocking and deviation of humidity transported by jets. The quantification of extreme precipitation events (EPEs) and their associated temperature is critical to address hydrological impacts and water availability for the Andes that also feeds the majority of the river and population in the region. 

As the atmosphere is getting warmer, the increasing amount of water vapor available in the troposphere is expected to enhance warm precipitation events during the 21st century. In this study, we examine observational trends in extreme precipitation events by season and analyze possible connections with air temperature. To this end, we perform Sen's Tests and compute Mann-Kendall values Maximum Precipitation daily precipitation and its associated temperature at ~80 meteorological stations. Then, we cluster the results geographically finding positive trends in high elevation areas for extreme precipitation events (EPEs) and their temperature, especially in mid-latitudes. In low stations (<800 m a.s.l.), we obtain a decrease in the magnitude of EPEs but and a decrease in air temperature (up to -0.4 [°C/decade]). In general, the temperature increase in EPEs for high elevation stations < 0.12 °C/year and could rise the freezing level up to 1000 [m], during the fall season.  The presented here suggest positive feedback between warmer atmospheric conditions and the open further pathways regarding hydrological impacts such as debris flow, floods, and less snow availability in the Andes regions.
A Statistical Approach to generate ensembles of observation data of precipitation using hindcast data over the Northwest Himalayas
Authors: Singhal Akshay , Jha Sanjeev
Published: March 2021

Availability of precipitation data at fine spatial resolution is highly desirable for hydroclimatic studies. Rain gauges are often considered as the primary source of precipitation data due to its reliability. However, due to either physical, climatic or economic constraints, setting up networks of rain gauges becomes unfeasible in many isolated terrains such as the Himalayan region. In the absence of gauge data, other alternate sources of weather information such as Satellite based Precipitation Products (SPPs) and Reanalysis precipitation Datasets (RPDs) are generally used. In this study, we aim to utilise 18 years of precipitation data (2001-2018) derived from the Integrated Multi-Satellite Retrievals for GPM (IMERG) at 10km spatial resolution as input to a Multiple-Point Statistics (MPS) based statistical model to obtain corresponding data for the year 2019 at 10km over the North-west Himalayan region. MPS is capable of generating fine scale data using the available coarse scale hindcast data by reproducing spatially connected spatial patterns. It requires data to be split into two parts. First part is called the training image and it requires both coarse and fine scale data. Second part is called the conditioning data which requires data only at coarse scale for the year 2019. In the attempt of using MPS as the tool for this study, the spatial field of Original IMERG data at 10 km (O_IMERG) is smoothen (S_IMERG) in order to transform the data features to a coarse scale reference data. The reference data used for this purpose is the High Asia Refined analysis (HAR) available at 30km spatial resolution over the South-Central Asia and Tibetan Plateau region. The variograms of both O_IMERG and S_IMERG are used to evaluate error frequency between the two data at specific distances followed by bias correction of S_IMERG. The bias corrected S_IMERG (BCS_IMERG) acts as the conditioning data for the MPS model. Training Image is composed of both BCS_IMERG and O_IMERG. Both the training image (year 2001-2018) and the conditioning data (2019) are provided to the MPS model. In addition to the variable of precipitation, the model also employs static parameters such as locational and topographical variables to help in identification of true patterns between training image and conditioning data. The study is significant in its ability to generate future precipitation information by utilising the available hindcast data observation data (10 km spatial resolution) by overcoming the spatial heterogeneity involved with observation data.
Deep Learning-based Damage Mapping with InSAR Coherence Time Series
Authors: Stephenson Oliver , Köhne Tobias , Zhan Eric , Cahill Brent , Yun Sang-Ho , Ross Zachary , Simons Mark
Published: March 2021

Satellite remote sensing is playing an increasing role in rapid mapping of damage after natural disasters. In particular, synthetic aperture radar (SAR) can image the Earth’s surface and map damage in all weather conditions, day and night. However, current SAR damage mapping methods struggle to separate damage from other changes in the Earth’s surface. In this study, we propose to map damage using the full time history of SAR observations of an impacted region from a single satellite constellation in order to detect anomalous variations in the Earth’s surface properties due to a natural disaster. We quantify Earth surface change using time series of sequential interferometric SAR coherence, then use a recurrent neural network (RNN) as a probabilistic anomaly detector on these coherence time series. The RNN is first trained on pre-event coherence time series, and then forecasts a probability distribution of the coherence between pre- and post-event SAR images. The difference between the forecast and observed co-event coherence provides a measure of the confidence in the identification of damage. The method allows the user to choose a damage detection threshold that is customized for each location, based on the local temporal behavior before the event. We apply this method to calculate estimates of damage for three earthquakes using multi-year time series of Sentinel-1 SAR acquisitions. Our approach shows good agreement with measured damage and quantitative improvement compared to using pre- to co-event coherence loss as a damage proxy.
Towards improved estimation of the atmosphere - terrestrial biosphere CO2 exchange over India using a diagnostic satellite based model
Authors: Ravi P Aparnna , K Pillai Dhanyalekshmi , Gerbig Christoph , Marshall Julia , Jha Chandra Shekhar
Published: March 2021

Several countries across the world have initiated considerable efforts to curb Greenhouse Gas emissions to limit the increase in global temperature to 2°C. However, planning of proper emission reduction policies and their successful implementation require accurate carbon budgeting. The objective of this study is to accurately quantify various sources and sinks of carbon dioxide over Indian domain using inverse modelling techniques. 

In order to better represent and quantify the atmosphere-biosphere CO2 exchange fluxes and ecosystem behaviour in the inverse modeling framework, the Vegetation Photosynthesis and Respiration Model (VPRM) is employed over Indian region. VPRM is a satellite based assimilation scheme with very simple model structure, so as to facilitate successive optimization of parameters in the inverse modelling framework. As an initial step, we evaluated the VPRM model with eddy covariance observations over India from two different vegetation types (Betul; Deciduous forest and Sundarbans; Evergreen forest) for the year 2017. The comparison reveals that the model needs further refinement in parametrization even though the VPRM showed better performance than other existing terrestrial biosphere models (e.g ., TRENDY and Carbon Tracker (CT)) over Indian domain. Among the VPRM products (Net ecosystem exchange (NEE), Gross Primary Productivity (GPP), and Ecosystem Respiration (Re)), the ecosystem respiration shows large deviations from observation. The analysis, based on the soil moisture (SM) data from IITM monsoon mission project shows that the SM plays a significant role, which is currently missing in the VPRM respiration calculations. Further, the study attempts to utilize Solar induced Fluorescence (SIF) as a proxy to estimate GPP and to be included in VPRM for the better representation of biospheric fluxes over India. Preliminary results will be presented and discussed.
Turbulence permitting air pollution simulation for the Stuttgart metropolitan area - A winter case study
Authors: Schwitalla Thomas , Warrach-Sagi Kirsten , Bauer Hans-Stefan , Wulfmeyer Volker
Published: March 2021

Currently a strong discussion is ongoing in Germany and Europe whether to ban vehicles from downtown areas in order to lower particle concentrations of e.g. PM10 and NO2. As often only few measurements exist inside city centers, little to nothing is known about the horizontal and vertical distributions of air pollutants. Within the EU demonstration project Open Forecast (https://open-forecast.eu/), we applied the WRF-Chem model system version 4.0.3 in order to close this knowledge gap. We zoom in the urban area of Stuttgart, a hot spot of air pollution in Germany. The outermost domain with convection-permitting resolution of 1.25 km encompasses parts of Central Europe in order to provide boundary conditions for the inner two domains.

The model system was improved in many ways, e.g., with respect to the representation of land cover, urban canopy, and soil properties, which turned out to be key for an acceptable performance. Furthermore, we developed a sophisticated infrastructure to ingest the required high-resolution emission data, which turned out to be very challenging.

We show that this model approach is likely the best means to understand and to predict air pollution, as the distribution of their constituents depends strongly and simultaneously on the vertical mixing by turbulence, the mesoscale circulation in the complex urban environment, and orographic environment.

The model system was operated and investigated for a case study of January 21, 2019 during which an alert with respect to the exceedance of PM10 was issued. We present the simulations of meteorological variables as well as PM10 and NO2 and show the complexity of their distribution in the nighttime stable and daytime shallow boundary layer in dependence of the temporal variability of the traffic in the Stuttgart metropolitan area.

To the best of our knowledge, the results reveal for the first time the complex dynamics of air pollution in complex urban space of Stuttgart at a very high spatial and temporal resolution that cannot currently be achieved with measurements.
Combining TRIGRS and Massflow Models for the Assessment of Flash Flood Disasters Related to Sediment Supply in Mountainous Watersheds
Authors: Sun Tong , Wang Xiekang , Yan Xufeng
Published: March 2021

Abstract: Evaluation of a large number of rainstorm disasters shows that the coupling effect of sediment supply and floodwaters is one predominant cause for the occurrence of flash flood disasters. Rainfall-induced shallow landslides often provide an adequate source of solid materials to recharge moving sediment during flash floods. In this study, we used the TRIGRS model to analyze the rainfall-related landslide stability in a mountainous basin and gain potential landslide volumes as potential sources for sediment loads. Then, with the calculated results of landslides as input, the Massflow model was used to evaluate how the landslides as sediment loads evolved with flows. The results showed that there was a large amount of sediment deposited in the channel, which can be initiated and transported by heavy rainfalls, leading to the destruction of villages at the mouth of gullies. In general, this study offers a strategy of evaluating sediment-coupled flash flood disasters that the TRIGRS can provides the estimate of landslide distribution and volume first and the Massflow provides the estimate of subsequent movement of the solids caused by flash floods.
 Quasi-3D mapping of soil moisture for agriculture using electric conductivity sensing  
Authors: Shaukat Hira , Flower Ken , Leopold Matthias
Published: March 2021

Knowledge of real time spatial distribution of soil moisture has great potential to improve yield and profit in agricultural systems. Rapid and precise quantification of water in crop fields is challenging due to the influence of highly variable soil properties such as texture and porosity.  Recent advances in non-invasive electromagnetic induction (EMI) techniques have created an opportunity to determine soil moisture content with high-resolution and minimal soil intrusion. So far, EMI has mainly been validated for homogenous soils, which are not common in agriculture. This study from a field site in Western Australia converts time series apparent electrical conductivity data recorded with a Dualem 1Hs EM-meter into spatiotemporal domains. A least square inversion algorithm was used to determine electric conductivities for individual soil layers (0-50cm, 50-80 cm and 80-160 cm) for two EMI surveys at a trial site, with different crop rotations and varying moisture conditions. A laboratory experiment under controlled conditions developed electric conductivity vs volumetric water content relations with power law functions for each layer with R2 values between 0.98 and 0.99. Subsequently, EMI data were converted to volumetric water contents for each layer and predictions were spatially displayed. These EMI soil moisture predictions were compared with neutron moisture meter measurements, with R2 values between 0.95 and 0.74 for the two surveys. The method is robust and offers a comparatively fast method to estimate the soil moisture status in fields and to subsequently make informed management decisions. 
The Changing-Atmosphere Infra-Red Tomography Explorer CAIRT – a proposal for an innovative whole-atmosphere infra-red limb imaging satellite instrument
Authors: Sinnhuber Bjoern-Martin , Höpfner Michael , Friedl-Vallon Felix , Sinnhuber Miriam , Stiller Gabi , von Clarmann Thomas , Preusse Peter , Plöger Felix , Riese Martin , Ungermann Jörn , Chipperfield Martyn , Errera Quentin , Funke Bernd , López Puertas Manuel , Godin-Beekmann Sophie , Peuch Vincent-Henri , Polichtchouk Inna , Raspollini Piera , Riel Stefanie , Walker Kaley
Published: March 2021

To improve our knowledge of the coupling of atmospheric circulation, composition and regional climate change, and to provide the urgently needed observations of the on-going changes and processes involved, we have recently proposed the Changing-Atmosphere Infra-Red Tomography Explorer (CAIRT) to ESA as Earth Explorer 11 candidate. CAIRT will be the first limb-sounder with imaging Fourier-transform infrared technology in space. By observing simultaneously the atmosphere from the troposphere to the lower thermosphere (about 5 to 115 km altitude), CAIRT will provide global observations of temperature, ozone, water vapour, as well as key halogen and nitrogen compounds. The latter will help to better constrain coupling with the upper atmosphere, solar variability and space weather. Observation of long-lived tracers (such as N2O, CH4, SF6, CF4) will provide information on transport, mixing and circulation changes. CAIRT will deliver essentially a complete budget of stratospheric sulfur (by observations of OCS, SO2, and H2SO4-aerosols), as well as observations of ammonia and ammonium nitrate aerosols. Biomass burning and other pollution plumes, and their impact on ozone chemistry in the UTLS region, will be detected from observations of HCN, CO and a further wealth of volatile organic compounds. The potential to measure water vapour isotopologues will help to constrain water vapour and cloud processes and interactions at the Earth’s surface. The high-resolution measurements of temperature will provide the momentum flux, phase speed and direction of atmospheric gravity waves. CAIRT thus will provide comprehensive information on the driving of the large-scale circulation by different types of waves. Tomographic retrievals will provide temperature and trace gas profiles at a much higher horizontal resolution and coverage than achieved from space so far. Flying in formation with the Second Generation Meteorological Operational Satellite (MetOp-SG) will enable combined retrievals with observations by the New Generation Infrared Atmospheric Sounding Interferometer (IASI-NG) and Sentinel-5, resulting in consistent atmospheric profile information from the surface up to the lower thermosphere. Our presentation will give an overview of the proposed CAIRT mission, its objectives and synergies with other sensors.
Mapping of Quaternary river terrace landforms with Unmanned Aerial Vehicle (UAV): A case study in the Sakarya River, NW Turkey
Authors: Karakoca Ebubekir , Uncu Levent
Published: March 2021

River systems are areas that respond most rapidly to regional and / or local tectonic movements, with global climate changes and general basement fluctuations that occurred during the Quaternary period. The most important geomorphological units where these events can be observed are terrace systems, which are the result of deposition and erosion processes. In fluvial geomorphology research on terrace systems, modern technological innovations are used as well as conventional field methods. Especially low-cost Unmanned Aerial Vehicles (UAV) and modern photogrammetry methods are preferred because they both provide detailed and precise identification of terraces and high resolution topography outputs in spatial and temporal terms.
This study aims to put a comprehensive mapping of the terrace systems observed in an area of 1.27 km² around Gemiciköy (Bilecik Province), which is located in the middle part of the Sakarya River valley, the largest river in Northwest Anatolia. Accordingly, we used the Structure from Motion (SfM) method which is based on photogrammetric principles and UAV. During the study, 582 images taken from a height of 100 m and having 80% overlap in line with the flight plans by using the DJI Mavic Mini UAV model were evaluated in Agisoft Metashape Professional software. With the use of image processing algorithms, the dense point cloud was first obtained, and then the orthomosaic and digital surface model with 3.29 cm resolution was produced. Two terrace levels (+10 m and +19 m) detected with digital surface modeling, and these were verified by stratigraphic and sedimentological observations made in the field.
As a result, low-cost UAV technologies are quite useful in terms of providing more detailed monitoring, mapping and analysis of river environments, together with the production of sensitive and high resolution topography data required in modern fluvial geomorphology research.
SEM-based mineralogical mapping at the submicrometer-scale of modern Sardinian stromatolites
Authors: Debrie Juliette , Prêt Dimitri , Benzerara Karim , Saint Martin Jean Paul
Published: March 2021

Stromatolites, i.e. macroscopically laminated carbonate rocks formed by diverse microbial communities, are particularly emblematic geobiological materials since they are the oldest evidence of life-mineral interactions, dated up to 3.5 Gyrs ago.  They are found throughout the history of the Earth and have received strong attention because they provide precious information about microbial paleobiodiversity and paleoenvironments. However, while this information is interpreted based on our knowledge about modern analogs, the latter remains very incomplete. Here, we studied recently discovered modern stromatolites from Mari Ermi1, a coastal pond in Western Sardinia, that seasonally experience severe evaporation and broad salinity variations. For this purpose, we explored the mineralogical composition of these unique sedimentary archives and its spatial variations in order to gain better insight into how mineral phases record the conditions and processes of their formation. We investigated the heterogeneous distribution of minerals using quantitative X-ray chemical maps provided by energy dispersive x-ray spectrometry analyses coupled with scanning electron microscopy (SEM-EDXS). Hyperspectral maps were analyzed using an innovative data treatment method 2 allowing phase recognition within the complex mineral mixtures and solid solutions encountered. This method provided quantitative data on spatial distribution, modal content and associated calculated unit formulas for each identified mineral and phase with a hundred nanometer resolution. Based on these results, we will discuss the origin of the laminations in the stromatolites.

Reference:

1. Saint Martin, J.-P. & Saint Martin, S. Geo-Eco-Marina 21, 35–53 (2015a).

2. Prêt, D. et al. American Mineralogist 95, 1379–1388 (2010).