Utilização de canais multiespectrais do sensor Seviri na detecção de sistemas convectivos severos no sudeste brasileiro : estudos de casos

Abstract

This study had as objective to show the importance of the spectral characteristics obtained by the physical properties of clouds measured by the METEOSAT geostationary satellite that helps on the understanding and prediction of severe storms. The study area was Brazil s southeastern because this region is located in a transition range between the mid-latitude temperate climate and the low latitudes warm climate and, therefore, becomes an area that has influence of various meteorological phenomena. With the strong topography and the proximity to the Atlantic Ocean, is a severe storms, strong winds and continuous rainfall favorable zone. It were used MSg datanot only by the images been captured from 15 in 15 minutes, but also because the SEVIRI radiometer on board of the European satellite has 12 multispectral channels that generate twenty times more information than the previous generation radiometers of the same. Were generated qualitative information of the atmospheric events in RGB color compositions, spectral response analysis and differences in the water vapor multispectral channels. The obtained results indicated that the RGB color composition (WV6.2μm - WV7.3μm; IR3.9μm - IR10.8μm; NIR1.6μm - VIS0.6μm) characterizes in a satisfactory way the convection in thunderstorms, showing when the system is in dissipation, stabilization or increasing, but is indicated only for storms occurring during the day and when analyzed the 3 RGB compositions (standard for air mass and convection) generate more information than analyzing only 1 of them. For the first case study, the values of the channel difference of the water vapor that were indicated as critical values with a trend to storm formation were of 4 to 13 ºC and for the second study case were of 8 to 13 °C.