Rainfall short-term forecast in the surveillance area of São Paulo weather radar.

Author(s)

José Felipe da Silva Farias

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Astronômico e Geofísico (IAG/SBD)
• Defense date: 2009-09-17

Examining board members

Augusto Jose Pereira Filho; Mario Thadeu Leme de Barros; Oswaldo Massambani

• Advisor: Augusto Jose Pereira Filho

Abstract

The evaluation of the rainfall short-term forecast up to 3 hours in advance within the surveillance area of São Paulo weather radar (RSP) for different types of precipitating systems, mainly the are associated to floods and landslides in Metropolitan Area of São Paulo (RMSP), was carried out with an 2D wind advective scheme and rainfall rates estimated with the RSP. The third-order upstream numerical scheme (ENTOCA) was used with a uniform wind vector. The rainfall forecast skill for a given time interval was evaluated by the Critical Success Index (CSI), Probability of Detention (POD) and False Alarm Rate (FAR). Quantitatively, the accuracy of the forecast was evaluated with the mean-square error (mse). The correlation coefficient showed that the quality of the forecast decrease with time, with better skill for the stratiform systems than for convective ones, given that the ENTOCA do not take into account spatial-temporal evolution of the rainfall systems. In general, the precipitation accumulation was underestimated. The forecasts had better skill up to 90 minutes. The average skill based on CSI for the thresholds of 0.2 mm at 60 minutes the precipitation accumulation are: FFs (77%), Lis (67,5%), BDs (58%), CIs (56,4%) and BMs (47%). In general, from 90 minutes of advection (convective systems) and 120 minutes (stratiform systems), the skill of the forecast decreases. (AU)