Seminário: Data assimilation experiment of a local heavy rainfall using a nested LETKF system

Data: 
06/06/2014 - 13:00
Local: 
Auditório 2 do IAG (Rua do Matão, 1226, Cidade Universitária)
 
O seminário "Data assimilation experiment of a local heavy rainfall using a nested LETKF system" será apresentado pelo Dr. Hiromu Seko (Meteorological Research Institute, Japan Meteorological Agency) como parte de visita de delegação japonesa ao Departamento de Ciências Atmosféricas, a convite do Prof. Dr. Augusto José Pereira Filho.
 
 
Resumo:
 
The nested Local Ensemble Transform Kalman Filter (LETKF) system has been developed to improve the accuracy of numerical forecast on local heavy rainfalls. To reproduce local heavy rainfalls, their positions and rainfall intensities need to be improved, simultaneously. Mesoscale convergence, in which local heavy rainfalls are generated, was reproduced in this study by the LETKF with the grid interval of 15 km (Outer LETKF). The convection cells that caused local heavy rainfall were reproduced by the LETKF with the grid interval of 1.875 km (Inner LETKF). The boundary conditions of the Inner LETKF were produced from the outputs of the Outer LETKF, and the results of the Inner LETKF influenced the Outer LETKF every 6 hours.
To show the performance of this system, this system was applied to a thunderstorm that caused the local heavy rainfall on the Osaka Plain on 5th September 2008. Convergence of low-level water vapor is indispensable in reproducing local heavy rainfalls. GPS-derived PWV or SWV (slant path water vapor) and horizontal wind or radial wind observed by Doppler radars provide information about low-level convergence of water vapor.
The impacts of Doppler radar data and GPS water vapor data were investigated by using the nested-LETKF system. The nested LETKF system and the impacts of Doppler radar data and GPS water vapor data will be shown in the presentation.