%0 Conference Proceedings
%@holdercode {isadg {BR SPINPE} ibi 8JMKD3MGPCW/3DT298S}
%@nexthigherunit 8JMKD3MGPCW/3ESGTTP 8JMKD3MGPCW/3ETL868 8JMKD3MGPCW/3EUFCFP
%@resumeid
%@resumeid 8JMKD3MGP5W/3C9JHC3
%@resumeid 8JMKD3MGP5W/3C9JHFE
%B Conferência Latino-Americana de Geofísica Espacial, 9 (COLAGE).
%X The development and preliminary results of operational ionosphere dynamics prediction system for the Brazilian Space Program are presented. The system is based on the Sheffield University Plasmasphere-Ionosphere Model (SUPIM), a physics-based model computer code describing the distribution of ionization within the Earth mid to equatorial latitude ionosphere and plasmasphere. This model solves coupled time-dependent equations of continuity, momentum and energy balance along magnetic field lines for six different ions (O+, H+, He+, N2+, O2+ and NO+) and the electrons. Several physical and chemical processes are considered, and the code inputs include the solar flux, the neutral atmosphere model, and the model of meridional and zonal wind velocities. Depending upon the inputs, the model can describe different solar cycle, seasonal, daily, and magnetic activity variations. SUPIM outputs are the ion and electron densities, temperatures, and field-aligned fluxes. These outputs are given discreetly in a 2 dimensional plane aligned with Earth magnetic field lines, with fixed magnetic longitude coordinate. The fieldlines cove red are defined by the ground station coordinates and a pre-defined range of altitude. The geographic location of simulated points is aligned with magnetic coordinates, instead of the geographic coordinates. The first adaptation applied to the code was the output mapping from magnetic coordinates to geographical coordinates. It was made referring to the Earth´s magnetic field as an eccentric dipole, using the approximation based on International Geomagnetic Reference Field. During the system operation, several ionospheric simulation runs are performed at different geographic longitudes. The original code would not be able to run all simulations serially in reasonable time. So, a parallel version for the code (P-SUPIM) was developed for enhancing the performance using a hybrid parallel approach, employing the Message Passing Interface (MPI) version 2 and Open Multi-Processing (OpenMP) standards. Actually, a better performance was obtained using simultaneously both strategies for the P-SUPIM instead of considering each approach alone. After preliminary tests, it was frequently observed code instability, when negative ion temperatures or concentrations prevented the code from continuing its processing. After a detailed analysis, it was verified that most of these problems occurred due to concentration estimation of simulation points located at high altitudes, typically over 4000 Km of altitude. To achieve convergence, an artificial exponential decay for ion concentration was used above mentioned altitudes. This approach shown no significant difference from original code output, but improved substantially the code stability, since the ion diffusion is inversely proportional to the collisions, then at high altitudes the density of the atmosphere is very low, therefore the collisions of some atoms or molecules reaches values very close to zero. In order to make operational system even more stable, the initial altitude and initial ion concentration values used on exponential decay equation are changed within pre-defined values, in a search for convergence. When all P-SUPIM runs end, a set of simulation points are available, but its geographic location (following magnetic coordinates) does not allow geographic map visualization. A data interpolation technique was developed to obtain the ion concentration values for neighborhood of simulated points, in homogeneous grid. The neighborhood range can be increased, so all points in homogeneous grid are achieved. For every point in that grid, a weighted mean based on simulated point distance is applied. The resulting interpolated data is recorded in a file format that can be used on a software tool for visualization of Earth science data. The final system operates automatically using a cluster composed of 20 nodes, with 2 dual core processors on each. Every day, P-SUPIM is executed for ground station longitudes of -85, -80, -75, -70, -65, -60, - 55, -50, -45, -40, -35 e -30 degrees, covering South America region. A tri-dimensional homogeneous grid containing ion concentrations is generated for every hour of simulated day, in a total of 24 files. Its spatial resolution is 2 degrees of latitude for 2 degrees of longitude for 10 Km of altitude. The vertical total electron content (VTEC) is calculated for the grids points, and plotted in a geographic map. The whole process runs every day and predicts the VTEC values for South America with almost 24 hours ahead.
%@mirrorrepository sid.inpe.br/mtc-m19@80/2009/08.21.17.02.53
%T Adaptation of SUPIM code to operational ionospheric dynamics prediction in Brazilian Space Program
%@secondarytype PRE CI
%8 5 A 10 april
%@usergroup administrator
%@usergroup ana.silveira
%@group CRS-CCR-INPE-MCT-BR
%@group LAC-CTE-INPE-MCT-BR
%@group DAE-CEA-INPE-MCT-BR
%2 sid.inpe.br/mtc-m19/2012/01.19.13.10.03
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@versiontype publisher
%4 sid.inpe.br/mtc-m19/2012/01.19.13.10
%@documentstage not transferred
%D 2011
%A Petry, Adriano,
%A Velho, Haroldo Fraga de Campos,
%A Souza, Jonas Rodrigues de,
%A Pereira, André Grahal,
%A Bailey, Graham John,
%C Puntarenas, Costa rica
%@area GEST