A spatiospectral localization method is discussed for processing the global geopotential coefficients from satellite mission
data to investigate time-variable gravity. The time-variable mass variation signal usually appears associated with a particular
geographical area yielding inherently regional structure, while the dependence of the satellite gravity errors on a geographical
region is not so evident. The proposed localization amplifies the signal-to-noise ratio of the (non-stationary) time-variable
signals in the geopotential coefficient estimates by localizing the global coefficients to the area where the signal is expected
to be largest. The results based on localization of the global satellite gravity coefficients such as Gravity Recovery And
Climate Experiment (GRACE) and Gravity and Ocean Circulation Explorer (GOCE) indicate that the coseismic deformation caused
by great earthquakes such as the 2004 Sumatra–Andaman earthquake can be detected by the low-low tracking and the gradiometer
data within the bandwidths of spherical degrees 15–30 and 25–100, respectively. However, the detection of terrestrial water
storage variation by GOCE gradiometer is equivocal even after localization. 相似文献
First-ever ice core drilling at Mt. Kazbek (Caucasus Mountains) took place in the summer of 2014. A shallow ice core (18 m) was extracted from a plateau at ~4500 m a.s.l. in the vicinity of the Mt. Kazbek summit (5033 m a.s.l.). A detailed radar survey showed that the maximum ice thickness at this location is ~250 m. Borehole temperature of ?7 °C was measured at 10 m depth. The ice core was analyzed for oxygen and deuterium isotopes and dust concentration. From the observed seasonal cycle, it was determined that the ice core covers the time interval of 2009–2014, with a mean annual snow accumulation rate of 1800 mm w. eq. Multiple melt layers have been detected. δ18O values vary from ?25 to ?5‰. The dust content was determined using a particle sizing and counting analyzer. The dust layers were investigated using scanning electron microscopy and X-ray diffraction analysis. Dust can be separated into two categories by its origin: local and distant. Samples reflecting predominantly local origin consisted mainly of magmatic rocks, while clay minerals were a characteristic of dust carried over large distances, from the deserts of the Middle East and Sahara. The calculated average dust flux over three years at Kazbek was of 1.3 mg/cm2 a?1. Neither δ18O nor dust records appear to have been affected by summer melting. Overall, the conditions on Kazbek plateau and the available data suggest that the area offers good prospects of future deep drilling in order to obtain a unique environmental record. 相似文献
The aim of this interdisciplinary study is to assess the heat risk for Bratislava. The following layers were created to compute the risk index: the hazard layer of air temperature, a mitigation layer of tree vegetation, an exposure layer of population and a vulnerability layer of individuals over 65 years of age. The MUKLIMO_3 model was used to evaluate the field of mean surface air temperature at 9 PM during selected days of the summer heat wave in August 2018. The tree vegetation layer, in the form of percentage per grid cell, was derived from Sentinel-2 satellite data. Population density data are based on mobile positioning data, and elderly population data are based on a gridded database from the statistical census. Input layers were unified into a resolution of 500 × 500 m, and the heat risk index was calculated by summation of the weighted input layers. The results reflect the variability of the population and the elderly population within the city, as well as the variability of the temperature field, which is caused by the joint effect of an urban heat island and topography. The highest values of risk index occur within the broader city centre, with specific hot spots at several places.
This case study from the renowned Demänová Cave System in the Carpathians of Slovakia demonstrates that the conventional methods of fluvial sedimentology, combined with an allostratigraphic mapping and speleothem U‐series isotopic dating, can give unprecedented insights into the hydrological history of underground karst conduit. The deposits studied are a relic compound sidebar ranging from gravel to mud and encapsulating the conduit’s hydrological history from the middle Pleistocene to the present time. A succession of 10 allostratigraphic units, time‐constrained by speleothems, are recognized in the sidebar deposits, and the corresponding morphodynamics of an evolving cave‐floor sedimentation are reconstructed in considerable detail. The subterranean river water stages recognized from the deposits, time‐constrained by flowstone layers and stalagmites, correlate with and add to the regional record of climate changes. Two distinct episodes of flow ponding (high‐stage slackwater conditions) are recognized and attributed to the independently documented downstream cave‐roof collapses, probably triggered by the Carpathian post‐orogenic earthquakes. This multidisciplinary study may serve as a useful methodological guide for the analysis of fluviokarstic deposits in speleological research and reconstruction of their hosting cave hydrological history. 相似文献