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10Multiscale and high.performance computing for multiphysical problems 33
The research was supported by RSF Project No. 20.71.00134 (coupled heat and mass transfer), Project No. 0266.2019.0007 (hydrodynamics and acoustics), Project No. 0331.2019.0015 (electromagnetism).
Analysisofionosphericirregularitiesbasedonmulti.instrumentaldata
D. Sidorov1,2, Yu. Yasukevuch1, E. Astafyeva3, A. Garashenko1, A. Yasyukevich1, A. Oinats1, A. Vesnin1
1Institute of Solar.Terrestrial Physics SB RAS 2Institute of Energy Systems SB RAS 3Universite de Paris, Institut de Physique du Globe de Paris, CNRS UMR 7154, France Email: [email protected]
DOI 10.24412/cl.35065.2021.1.03.06
The most complex ionospheric phenomena occur in the areas of auroral ovals. These areas are character�ised by intense small.scale ionospheric inhomogeneities that exist in both calm and disturbed geomagnetic conditions. Such irregularities could result in radio wave scattering, GNSS (global navigation satellite system) positioning quality deterioration, failures in radio communication, etc. GNSS ROTI (rate of total electron con�tentindex) datasets along with other datasets are available to study complex dynamics ofionospheric irregu�larities. This report analyses the auroral oval dynamics datasets, based on GNSS global network, coherent ra�dars data, and satellite data. The SIMuRG system (https://simurg.iszf.irk.ru/) is employed. The auroral oval re�gions corresponds to high values of ROTI, therefore it is possible to separate their location from mid.latitude data. Coherent scatter radars record signal scattering from the oval boundary. The SuperDARN.like radars lo�cated in Russia were employed. Satellite data shows sharp variations in field.aligned currents. During magnetic storms the oval expands equatorward, and small.scale irregularities shifts to mid.latitudes. All the data show close positions of the oval boundary. The latter makes it possible to use the datasets of different modalities to estimate the oval boundary. Some advance was achieved by computer vision techniques to find the auroral oval boundary in the Northern hemisphere. The techniques implemented mathematical morphology to ex�pand data and decrease data gaps, Otsu techniques and K.means to cluster image data.
This work was supported by the Russian Science Foundation (project RSF 17.77.20005).
Mixedgeneralizedmultiscalefiniteelementmethodforflowprobleminthindomains
D. A. Spiridonov1, M. V. Vasilyeva1,2, Ya. Efendiev3, E. Chung4, M. Wang5
1M. K. Ammosov North.Eastern FederalUniversity, Yakutsk 2Institute for Scientific Computation, Texas A&M University 3Department of Mathematics & Institute for Scientific Computation (ISC), Texas A&M University, College Station, Texas, USA 4Department of Mathematics, The Chinese University of Hong Kong (CUHK), Hong Kong SAR 5Duke University (Durham), USA Email: [email protected]
DOI 10.24412/cl.35065.2021.1.02.83
In this work, we consider the construction of the Mixed Generalized Multiscale Finite Element Method approximation on a coarse grid for an elliptic problem in thin two.dimensional domains. We consider the ellip�tic equation with homogeneous boundary conditions on the domain walls. For reference solution of the prob�lem, we use a Mixed Finite Element Method on a fine grid that resolves complex geometry on the grid level.To construct a lower dimensional model, we use the Mixed Generalized Multiscale Finite Element Method, where we present the construction of the multiscale basis functions for velocity fields. The construction is based on
