The Eaux-Chaudes massif provides keys to unravel the deep-seated deformation of the Iberian rifted margin during the Alpine orogeny in the Pyrenees. The massif conforms to an inlier of upper Cretaceous carbonate rocks within the Paleozoic basement of the western Axial Zone, originally deposited in the upper margin shelf before the Cenozoic collision. New geological mapping and cross-section construction lead to the description of the lateral structural variation from a km-scale fold nappe in the west to a ductile, imbricate fold-thrust fan in the east. The transition from a Variscan pluton to Devonian metasediments underlying the autochthonous Cretaceous induced this structural change. Recumbent folding, which involved upper Paleozoic rocks, was facilitated by a lower detachment in Silurian slates and an upper detachment in an overlying Keuper shale and evaporite thrust sheet. Remains of this allochthonous sheet form shale and ophite bodies pinched within the upper Cretaceous carbonates, conforming unusual tertiary welds. Ductile shear in the overturned limb of the Eaux-Chaudes fold nappe imparted strong mylonitic foliation in carbonate rocks, often accompanied by N-S stretching lineation and top-to-the-south kinematic indicators. The burial of the massif by basement-involved thrust sheets and the Keuper sheet, along with their Mesozoic-Cenozoic cover, account for ductile deformation conditions and a structural style not reported hitherto for the Alpine Pyrenees. Two hypotheses for the tectonic restoration of this part of the Pyrenean hinterland are proposed in this work.

The Mediterranean Hellenic Arc subduction zone (HASZ) has generated several Mw>=8 earthquakes and tsunamis. Seismic-probabilistic tsunami hazard assessment typically utilizes uniform or stochastic earthquake models, which may not represent dynamic rupture and tsunami generation complexity. We present an ensemble of ten 3D dynamic rupture earthquake scenarios for the HASZ, utilizing a realistic slab geometry. Our simplest models use uniform along-arc pre-stresses or a single circular initial stress asperity. We then introduce progressively more complex models varying initial shear stress along-arc, multiple asperities based on scale-dependent critical slip weakening distance, and a most complex model blending all aforementioned heterogeneities. Thereby, regional initial conditions are constrained without relying on detailed geodetic locking models. Varying hypocenter locations in the simplest, homogeneous model leads to different rupture speeds and moment magnitudes. We observe dynamic fault slip penetrating the shallow slip-strengthening region and affecting seafloor uplift. Off-fault plastic deformation can double vertical seafloor uplift. A single-asperity model generates a Mw~8 scenario resembling the 1303 Crete earthquake. Using along-strike varying initial stresses results in Mw~8.0-8.5 dynamic rupture scenarios with diverse slip rates and uplift patterns. The model with the most heterogeneous initial conditions yields a Mw~7.5 scenario. Dynamic rupture complexity in prestress and fracture energy tends to lower earthquake magnitude but enhances tsunamigenic displacements. Our results offer insights into the dynamics of potential large Hellenic Arc megathrust earthquakes and may inform future physics-based joint seismic and tsunami hazard assessments.

Aging flood infrastructure systems will need to be closely monitored as metropolitan areas globally face increasing inundation risk from sea level rise. To augment traditional ground survey, synthetic aperture radar (SAR) is shown to efficiently quantify elevation change along earthen levees with continuous spatial coverage. The study area, California’s Sacramento-San Joaquin Delta, has an exemplar earthen levee system that protects the region from flooding. We investigate evidence of settling from historic levee breaks and small-scale subsidence features with a vertical velocity map and time-series of cumulative displacement derived from data acquired by the UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar) L-band SAR, during 2009-2015. Comparison between radar and lidar maps (2007 and 2017) show that typical laser elevation surveys can miss subsidence features in the presence of normal maintenance activities. Historic levee break sites show more stable conditions due to the nature of repairs, and can be monitored using the SAR time series product. SAR information helps monitor the efficacy of repairs and targeted improvements to decrease the risk of levee breaks. In light of the upcoming NASA-ISRO SAR satellite mission, for which UAVSAR is the prototype, detailed monitoring will be attainable for levees worldwide.

The Neoproterozoic Era represents extreme environmental conditions with three major glaciation events. Associated with these glaciation and deglaciation periods are high amplitude positive and negative δ13C excursions which have been observed in the rock records, suggesting perturbations in oceanic biogeochemical cycles. However, whether these isotopic records reflect primary depositional signature and open ocean condition are debated. The Marwar Basin of the Indian Shield preserves one such record of the Ediacaran time period. The magnitude of negative δ13C excursion from the Marwar Basin is comparable with the Shuram excursion.1 We report elemental compositions of sixty-eight carbonate samples collected from five spatially distributed sections from the Bilara carbonates of the Marwar Basin. Selected samples from two of these sections were analyzed for their radiogenic Sr (87Sr/86Sr) and stable Ca (δ44/40Ca) isotopic compositions. Elemental compositions were measured using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS, X series II) while 87Sr/86Sr and δ44/40Ca (reported relative to NIST SRM 915a) values were measured using a Thermal Ionization Mass Spectrometer (TIMS, Triton Plus), both at the CEaS, IISc Bangalore, India. The Bilara Group carbonates are sub-divided into two populations based on non-redox REY anomalies and the Y/Ho ratio. Super-Chondritic Y/Ho (40-52) and positive La anomaly (1.01-2.65) of some samples suggest deposition under open ocean conditions and connectivity to the global ocean. While heterogeneity in δ13C values is evident in samples with low Y/Ho (<40), samples with high Y/Ho (> 40) preserve low δ13C values. No significant correlation has been observed between δ13C and Ce anomaly (Ce/Ce*) suggesting absence of any paleo-redox gradient. The lowest 87Sr/86Sr (~0.7079) observed in the carbonates is comparable with Ediacaran seawater confirming retention of primary depositional signatures in these samples. These carbonates show heavy δ44/40CaSRM915a compositions (1.44‰-2.21‰) typical of Neoproterozoic post-glacial successions2. Our study confirms primary origin and open ocean nature of the late Neoproterozoic δ13C excursions in the Marwar Basin. [1] Ansari et al., (2018) Precambrian Research, [2] Silva-Tamayo et al., (2010) Precambrian Research

The electrical transport behavior of lizardite was investigated by in-situ impedance measurements up to 22.6 GPa in a diamond anvil cell with comparation to its dehydrated counterpart. The conductivity of lizardite is found to increase one order of magnitude with increasing pressures from 0.2 to 1.9 GPa, due to pressure-activated ionic and electronic transportation. The proton hopping and hopping-created vacancy accounts for the conduction mechanisms. Compression initially promotes proton hopping at lower pressures and then impedes it at elevates pressure to make conduction purely electronic. Compared to the dehydrated specimen, the hydroxyl in lizardite enhances conductivity 4-7 times. The electronic resistivity at higher pressures gradually increases at a constant rate, except in the pressure range where pressure minimized the misfit structural disordering. The pressure-activated proton hopping in the lizardite and other phyllosilicates may ascribe the high conductive layer in the craton lithosphere and geoelectric anomalies related to earthquakes.

We report the radiocarbon age, chemistry, and mineralogy of sinter deposits from Castle and Giant Geyser in the Upper Geyser Basin of Yellowstone National Park. At each geyser, we sampled following the stratigraphy of the older terrace and younger cone. We analyzed 15 samples with x-ray diffraction, x-ray tomography, x-ray fluorescence, scanning electron microscopy, thin section microscopy, 3D imaging, and loss on ignition. Castle Geyser's terrace and Giant Geyser's cone are composed of more increasingly more mature sinter. The concentrations of Na, K, Cs, and Ga decrease in the sinter with decreasing H2O and increasing SiO2, therefore water and trace element concentrations correlate with stratigraphic position, and sinters exhibit progressive dehydration with increasing age. However, radiocarbon dates resulted in stratigraphically out-of-sequence ages. This suggests both physical mixing and the influence of magmatically dead carbon. By isolating and dating individual pieces of externally sourced organic material, we report ages as upper bounds---increasing the known age of Castle Geyser cone to 2,000 yr BP. Additionally, we demonstrate that Castle Geyser's shield is mineralogically distinct from and at least 1,000 years older than it's cone.

We report the results of position ties for short baselines at eight geodetic sites based on phase delays that are extracted from global geodetic very-long-baseline interferometry (VLBI) observations rather than dedicated short-baseline experiments. An analysis of phase delay observables from two antennas at the Geodetic Observatory Wettzell, Germany, extracted from 107 global 24-hour VLBI sessions since 2019 yields weighted root-mean-square scatters about the mean baseline vector of 0.3, 0.3, and 0.8 mm in the east, north, and up directions, respectively. Position ties are also obtained for other short baselines between legacy antennas and nearby, newly built antennas. They are critical for maintaining a consistent continuation of the realization of the terrestrial reference frame, especially when including the new VGOS network. The phase delays of the baseline WETTZ13N–WETTZELL enable an investigation of sources of error at the sub-millimeter level. We found that a systematic variation of larger than 1 mm can be introduced to the up estimates of this baseline vector when atmospheric delays were estimated. Although the sub-millimeter repeatability has been achieved for the baseline vector WETTZ13N–WETTZELL, we conclude that long term monitoring should be conducted for more short baselines to assess the instrumental effects, in particular the systematic differences between phase delays and group delays, and to find common solutions for reducing them. This will be an important step towards the goal of global geodesy at the 1 mm level.

Anaerobic microbial activity in the ocean causes losses of bioavailable nitrogen and emission of nitrous oxide to the atmosphere, but its predictability at global scales remains limited. Resource ratio theory suggests that anaerobic activity becomes sustainable when the ratio of oxygen to organic matter supply is below the ratio required by aerobic metabolisms. Here, we demonstrate the relevance of this framework at the global scale using three-dimensional ocean datasets, providing a new interpretation of existing observations. Evaluations of the location and extent of anoxic zones and a diagnostic rate of pelagic nitrogen loss are consistent with previous estimates. However, we demonstrate that the flux-based threshold is qualitatively different from a threshold based solely on the ambient oxygen concentration. Since the framework is feasible for application in global biogeochemical models, it represents a way forward for more dynamic, mechanistic predictions of anaerobic activity and nitrogen loss.

Hydraulic roughness is a fundamental property in river research, as it directly affects water levels, flow strength and the associated sediment transport rates. However quantification of roughness is challenging, as it is not directly measurable in the field. In lowland rivers, bedforms are a major source of hydraulic roughness. Decades of research has focused on dunes to allow parameterisation of roughness. This study aims to establish the predictive capacity of current roughness predictors, and to identify reasons for the unexplained part of the variance in roughness. We quantify hydraulic roughness based on the Darcy-Weisbach friction factor calculated from hydraulic field data of a 78 km long trajectory of the Lower Rhine and River Waal in the Netherlands. This is compared to predicted roughness values based on dune geometry, and to the spatial distribution of the local topographic leeside angle, both inferred from bathymetric field data. Results from both approaches show the same general trend and magnitude of roughness values (friction factor f=0.019-0.069, mean 0.035). Roughness inferred from dune geometry explains 42% of the variance, for the best performing predictor. Efforts to explain the remaining variance from statistics of the local topographic leeside angles, which supposedly control flow separation, were unsuccessful. Unexpectedly, multi-kilometer depth oscillations explain 34% of the total roughness variations. We suggest that flow divergence associated with depth increase causes energy loss, which is reflected in an elevated hydraulic roughness. Depth variations occur in many rivers worldwide, which may imply a cause of flow resistance that needs further study.

Climate change adaptation under resource constraints and future climate uncertainties would benefit from fully probabilistic climate risks assessments. Conducting such risk analyses requires assigning probabilities to the future greenhouse gases (GHG) and land-use scenarios used by global climate models. This paper proposes an approach to estimate the relative likelihood of carbon dioxide (CO2) concentration scenarios used in key climate change modeling experiments. The approach relies on the comparison of CO2 emissions from probabilistic simulations of Integrated Assessment Models (IAM) with compatible CO2 emissions diagnosed by global climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and 6 (CMIP6). The approach is demonstrated with five emission simulations from four IAMs, leading to independent estimates of the relative likelihood of CMIP5 Representation Concentration Pathways and CMIP6’ Shared Socioeconomic Pathways (SSP) up to 2100. Results suggest that SSP5-8.5 is an unlikely scenario for the second half of the century, but there is no clear consensus on the most likely scenario. Scenario likelihood is affected by a number of potential errors, including sampling errors, differences in emission sources simulated by the IAMs, and the lack of a common experimental framework for IAM simulations. These errors, along with the small IAM ensemble size, limit the applicability of the results. The delivery of fully probabilistic climate risk assessments would benefit from a coordinated probabilistic IAM experiment jointly designed with a coordinated climate modeling experiment where Earth System Model are driven by representative emission pathways.

Understanding of the spatial distribution of near-surface oceanic chlorophyll a (Chl-a) in relation to eddy activity is important because Chl-a is critical to biological production and carbon absorption, and its distribution is closely related to meso-scale eddies and Rossby waves. Chl-a distributions based on satellite observations from 2001 to 2018 were analyzed in association with eddy activity in mid-latitude regions of the five ocean basins (North/South Pacific, North/South Atlantic, and South Indian oceans) and related to physical eddy scales including the internal Rossby deformation radius (LD) and Rhines scale (LR). In the open ocean, the horizontal scale of Chl-a (D) decreased with increasing eddy kinetic energy (EKE), converging to πLD in the high-eddy-activity region. The ratio of zonal (Dz) to meridional (Dm) scales, RD (= Dz/Dm), converged to 1 with increasing EKE, implying isotropic uniformization with meso-scale eddies. In regions of low EKE (especially the central subtropical and eastern parts of each basin), Dm was larger than LD, with a scale similar to πLR. In these regions, Dz values greater than Dm were found (with scales of 500–1000 km), indicating the effects of planetary phenomena on Chl-a. In such regions the sensitivity of D to EKE tended to be higher than in western boundary regions, indicating the influence of meso-scale eddy activity on the Chl-a distribution, even with low EKE.

With the launch of the new Geostationary Operational Environmental Satellite-R (GOES-R) satellite series with the Advanced Baseline Imager (ABI) onboard both GOES-16, and -17 satellites, new capabilities are available at unprecedented temporal and spatial resolution from a geostationary-orbiting platform viewing North and South America. Measurements from three water vapor bands available from ABI presents a unique opportunity to assess the delineation in the vertical distribution of atmospheric moisture through multispectral (Red, Green, Blue, i.e., RGB) composites. Analysis of multispectral composites may provide improved capabilities to quickly identify specific features through qualitative analysis. The utilization of water vapor bands in the derivation of RGB imagery can be used to enhance thermodynamic and/or dynamical features associated with the development of significant weather events and hazards (e.g., cyclones, hurricanes, convection, turbulence) that are commonly found in single band water vapor analysis. The Air Mass RGB was developed with the launch of Meteosat Second Generation Spinning Enhanced Visible and Infrared Imager (SEVIRI) and is used to enhance regions of warm, dry, ozone rich stratospheric air associated with jet stream dynamics and tropopause folding that impact cyclone and hurricane intensity. With the launch of Himawari-8 Advanced Himawari Imager, the Japan Meteorological Agency developed a complimentary water vapor RGB, the Differential Water Vapor RGB, as a tool to assess the vertical distribution of water vapor in the atmosphere. This presentation will discuss the applications and advantages of the Air Mass and Differential Water Vapor RGB as complimentary tools for assessing thermodynamic and dynamical features associated with significant weather events.

Digital Elevation Model (DEM) is the 3D-representation of terrain surface in the discrete form and a standard tool to examine the hydrological and research application related to terrain characterization, landscape and water resources management. It helps in identifying physical features of an area, watershed delineation and stream network generation. However, several issues related to DEM’s accuracy is the utmost concern for researchers. The present study is based on the comparative studies of DEMs viz., Cartosat-1, SRTM, ALOS and ASTER having the same spatial resolution of 30m each, under two different categories of elevation data and topographic attributes. The vertical accuracy of DEMs is examined by using ground control points as a reference level of elevation generated from topographic map. Analysing different sources of error in the DEMs, the RMSE and MAE based validation of elevation suggests that Cartosat-1 shows relatively high vertical accuracy (RMSE=45.2 & MAE=7.7) and ASTER shows the least (RMSE=60.5 & MAE=34.6). The grid size, spatial variation and vertical accuracy of DEM are among the prime attribute of data sources to determine the variation in basin morphometry. The study area shows a gradually undulating topography with 5 th order drainage network. An inference can be made out of research study that the mean elevation values of ALOS, SRTM, Cartosat-1 are relatively lower than ASTER whereas differences in stream parameters are also observed.

Since 2008, the rate of seismic events within the Central United States has dramatically increased, which is likely associated with wastewater injection from nearby oil and gas operations. Surface deformation measurements derived from spaceborne interferometric synthetic aperture radar (InSAR) data can be used to quantify the magnitude and spatial extent of the injection-related stress perturbation, which are critical for understanding the complex interaction between the injected fluid and the earth’s subsurface. In this study, we processed Sentinel-1 InSAR data over Central and West Texas using a recently developed processing framework that performs topography/geometry phase corrections prior to the interferogram formation (Zebker 2017). We streamlined the creation of upsampled digital elevation maps (DEMs) from NASA Shuttle Radar Topographic Mission (SRTM) data, as well as the collection of Sentinel-1 precise orbit data. We developed a tool for InSAR time-series analysis and data visualization. To detect unknown deformation signatures from large volumes of InSAR data, we employed computer vision ideas for feature detection independent of scale, well known through their success in the Scale Invariant Feature Transform (SIFT). We used multi-scale Laplacian-of-Gaussian (LoG) filters to find local maxima and minima in a coarse deformation solution, corresponding to “bowls” of uplift and subsidence, respectively. This allowed us to drastically cut down processing time of high-resolution InSAR products. As a validation, our method successfully detected all sinkhole locations, injection-related uplift signals and production-related subsidence signals as reported in Kim and Lu (2017) over a 100 km x 100km search area without the need for manual inspection. We then examined the Dallas Fort Worth Basin area for evidence of deformation near wastewater injection and oil/gas production sites. We begin to quantify the uncertainty from common noise sources to produce more confident time-series results.

The Madden-Julian oscillation (MJO) significantly impacts North Atlantic hurricanes, with more hurricane activity occurring when the MJO favors enhanced convection over Africa and the tropical Indian Ocean and suppressed hurricane activity occurring when the MJO favors enhanced convection over the tropical Pacific. Using data from 1905-2015, we find more hurricanes make landfall in the continental US when the MJO enhances convection over the tropical Indian Ocean. In addition, when the MJO enhances convection over the Western Hemisphere, tropical cyclones tend to form in the Gulf of Mexico or the Caribbean, leading to more Gulf Coast landfalls. As the MJO moves to the Indian Ocean, more storms form in the tropical Atlantic, increasing the number of Florida and East Coast landfalls. The MJO’s modulation of tropical cyclone steering winds appears to be secondary to its effects on genesis locations.

Although the Brown mathematical model is the standard model for waveform retracking over open oceans, coastal waveforms usually deviate from open ocean waveform shapes due to inhomogeneous surface reflections within altimeter footprints, and thus cannot be directly interpreted by the Brown model. Generally, the two primary sources of heterogeneous surface reflections are land surfaces and bright targets such as calm surface water. The former reduces echo power, while the latter often produces particularly strong echoes. In previous studies, sub-waveform retrackers, which use waveform samples collected from around leading edges in order to avoid trailing edge noise, have been recommended for coastal waveform retracking. In the present study, the peaky-type noise caused by fixed-point bright targets is explicitly detected and masked using the parabolic signature in the sequential along-track waveforms (or, azimuth-range echograms). Moreover, the power deficit of waveform trailing edges caused by weak land reflections is compensated for by estimating the ratio of sea surface area within each annular footprint in order to produce pseudo-homogeneous reflected waveforms suitable for the Brown model. Using this method, Jason-2 altimeter waveforms are retracked in several coastal areas. Our results show that both the correlation coefficient and root mean square difference between the derived sea surface height anomalies and tide gauge records retain similar values at the open ocean (0.9 and 20 cm) level, even in areas approaching 3 km from coastlines, which is considerably improved from the 10 km correlation coefficient limit of the conventional MLE4 retracker and the 7 km sub-waveform ALES retracker limit. These values, however, depend on the coastal topography of the study areas because the approach distance limit increases (decreases) in areas with complicated (straight) coastlines.

The term “weather whiplash” was recently coined to describe abrupt swings in weather conditions from one extreme to another, such as from a frigid cold spell to anomalous warmth or from drought to prolonged precipitation. These events are often highly disruptive to agriculture, ecosystems, and daily activities. In this study we propose and demonstrate a novel metric to identify weather whiplash events (WWEs) and track their frequency over time. We define a WWE as a transition from one persistent large-scale circulation regime to another distinctly different one, as determined using an objective pattern cluster analysis called self-organizing maps (SOMs). We focus on the domain spanning North America and the eastern N. Pacific Ocean. A matrix of representative atmospheric patterns in 500-hPa geopotential height anomalies is created. We analyze the occurrence of WWEs originating with long-duration events (defined as lasting 4 or more days) in each pattern, as well as the associated extremes in temperature and precipitation. A WWE is detected when the pattern two days following a long-duration event is substantially different, measured using internal matrix distances and thresholds. Changes in WWE frequency are assessed objectively based on reanalysis and climate model output, and in the future with climate model projections. Temporal changes in the future under RCP 8.5 forcing are more robust than those during recent decades, with consistent increases (decreases) in WWEs originating in patterns with an anomalously warm (cold) Arctic.

We examine the midlatitude jet stream responses to projected Antarctic and Arctic sea-ice loss and global ocean warming in coordinated multi-model experiments from the Polar Amplification Model Intercomparison Project. Antarctic and Arctic sea-ice loss cause an equatorward shift of the winter jet stream in the southern and northern hemisphere, respectively, on average across the models. Models with stronger eddy feedback simulate farther equatorward jet shifts in response to both Antarctic and Arctic sea-ice loss. The models simulate too weak eddy feedback compared to the real world, particularly in the northern hemisphere, resulting in an underestimation of the boreal jet response to Arctic sea-ice loss. More precise estimates of the jet shifts are obtained by using the observed eddy feedback as a constraint and suggest that the equatorward jet shifts in response to Antarctic and Arctic sea-ice loss exceed in magnitude the opposing poleward shifts due to ocean warming.