Mine seismic prediction of tectonic faults by reflected waves using the method of location

The article presents the case-study of geological anomaly delineation by reflected waves in seismic logs of the common excitation point and the common receipt point using a dedicated software. The proposed data processing flow consists in consistent fulfillment of a sequence of stages. Sorting of seismic logs is followed by band and band-elimination filtering, selection of optimal filter passband and identification of interfering axes of phase synchronization of different-nature waves. The axes of phase synchronization of information-bearing waves are identified by the points of the first arrivals. By these points, ellipses are automatically drawn so that their focuses are at the excitation and receipt points while the value of doubled semi-axes is equal to the product of velocity and first arrival time of a wave. The criterion of reflecting boundaries is the distinctive approach or intersection of the ellipses in a local zone of a supposed reflecting boundary. The data processing algorithm allows revealing tectonic faults within a radius to 200 m around a roadhead. Reflecting boundaries at greater distances from roadheads are located on an estimation basis. The developed algorithm and software can be used by geophysical services and specialized geological exploration agencies for processing and analysis of seismic survey data when predicting structure of coal-and-rock masses.

Evaluation of TROPOMI cloud products for NO2 retrievals

<p>The first European Sentinel satellite for monitoring the composition of the Earth’s atmosphere, the Sentinel 5 Precursor (S5p), carries the TROPOspheric Monitoring Instrument (TROPOMI) on board to map trace species of the global atmosphere at high spatial resolution. Retrievals of tropospheric trace gas columns from satellite measurements are strongly influenced by clouds. Thus, cloud retrieval algorithms were developed and implemented in the trace gas processing chain to consider this impact.</p><p>In this study, different cloud products available for NO<sub>2</sub> retrievals from TROPOMI data are analyzed. The TROPOMI level 2 OCRA/ROCINN (Optical Cloud Recognition Algorithm/Retrieval of Cloud Information using Neural Networks) cloud products CRB (cloud as reflecting boundaries) and CAL (clouds as layers) as well as the FRESCO (Fast Retrieval Scheme for Clouds from Oxygen absorption bands) cloud product are compared with regard to e. g. cloud fraction, cloud height, cloud albedo/optical thickness, flagging and quality indicators. In particular, difficult situations such as snow or ice, sun glint, and high aerosol load are investigated.</p><p>The eventual aim of this study is to better understand TROPOMI cloud products and their quantitative impacts on trace gas retrievals. Here, we present first results of a statistical analysis on a limited data set comparing currently existing cloud products and their approaches focusing on NO<sub>2</sub>.</p>

Mass-conserving tempered fractional diffusion in a bounded interval

Transient anomalous diffusion may be modeled by a tempered fractional diffusion equation. A reflecting boundary condition enforces mass conservation on a bounded interval. In this work, explicit and implicit Euler schemes for tempered fractional diffusion with discrete reflecting or absorbing boundary conditions are constructed. Discrete reflecting boundaries are formulated such that the Euler schemes conserve mass. Conditional stability of the explicit Euler methods and unconditional stability of the implicit Euler methods are established. Analytical steady-state solutions involving the Mittag-Leffler function are derived and shown to be consistent with late-time numerical solutions. Several numerical examples are presented to demonstrate the accuracy and usefulness of the proposed numerical schemes.