Comparative analysis of mesoscale convective complexes using models simulations and satellite observations / Análise comparativa de complexos convectivos de mesoescala através de simulações de modelo e observações de satélite

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

26/09/2011

RESUMO

In this study was analyzed the behavior of the Mesoscale Convective Complexes (MCC) that occurred in the South Central region of South America (40°S-15°S and 80°W e 30°W). The period chosen for the study of these systems was between September to March for the years 2007 and 2010. The FORTRAC tool was used to identify MCCs and found 43 systems. The period in which we observed the largest number of MCCs was 2009/2010 (MCC 17), while the largest number occurred during the month of November. The preferential region of formation of MCCs was on the North of Argentine, Paraguay, Bolivia, and southern of Brazil. The average life cycle was between 12 an 24 hours. ETA and ETA/RPSAS model state variables were used to analyze how these models simulations assess the observed MCCs, which shows that in the average for the both models the environment simulated is favorable for convection, with positive moisture and temperature advection at 850 hPa in the MCCs formation region. In the model state, strong winds at low levels, that bring warmer and moist air to the region, are also noted. During the mature stage of MCCS, the environment still favorable for convection, there is an positive advection of temperature, but the moisture advection changes the signal, the average position of the winds at 850hPa unchanged. The average characteristics of the MCCs identified in the dissipation stage are: there isnt change in the advection signal when compared to the previous stage, the maximum winds at 850hPa weakens, the same occurs whit the ômega intensity at 500hPa level, notice divergence at height (250hPa) and surface, that represents the end of the system. In order to analyze how the \textit{Community Radiative Transfer Model} (CRTM) simulate the brightness temperature (BT) of the 4 channel of GOES 10 and 12, were realized simulations of 4 MCCs events using state variables extract of analysis and forecasts of the ETA and ETA/RPSAS models and also of the CFSR reanalysis how input data of the CRTM. These simulations were realized for all domain of the ETA model. Generally the data from ETA simulated the 4 systems, but the intensity and position didnt be very satisfactory, when the ETA/RPSAS data were used just 50\% of the cases could simulate the cloudiness associated with the systems. The CFSR data were the best represented the regions associated to the systems, although simulated more cloud that was observed. The analysis of simulations with observed atmospheric profiles for two points for the day 09/11/2008 MCC proves that adequate conditions of stability and cloudiness of the first guess profiles are essential to properly simulate the measure of the GOES channel 4 and so use such observation in the assimilation.

ASSUNTO(S)

complexo convectivo de mesoescala modelo de transferência radiativa assimilação de dados mesoscale convective complexes radiative transfer model data assimilation

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