Climatology of cold fronts over the Metropolitan Region of São Paulo (MRSP) and their influence in the limnology of water supply reservoirs

This study presents an analysis of climatology of cold fronts and wind regimes induced by these phenomena over the Metropolitan Region of São Paulo (MRSP) within a time period of 21 years from 1987 to 2007. The wind data series were acquired from the IAG/USP meteorological station, located at Água Funda neighborhood of São Paulo City. The results showed that three fronts, on average, reached the MRSP monthly, and their frequency is higher from March to May and from August to December. Winds showed to be more intense few days before the cold front passage. During the cold front arriving day, wind velocity was at lowest value, increasing gradually in the following days, when the direction was predominantly from southeast quadrant (90 % around the mean velocity and 70 % of the gusts). The correlations between the cold fronts and the dynamics of the reservoirs showed that, in average, the time lag between these events was 2 to 3 days for Guarapiranga Reservoir and 3 to 4 days for Billings Reservoir. The physical-chemical parameters measured in the reservoirs were temperature (C), pH and Turbidity (NTU).

Cold fronts; climatology; wind; reservoir