Trends of rainfall classes in the metropolitan region of Sao Paulo

• Published in: Revista brasileira de meteorologia 2014-09, Vol.29 (3), p.397-408
• Main Authors: RAIMUNDO, Clebson do Carmo, SANSIGOLO, Clovis Angeli, MOLION, Luiz Carlos Baldicero
• Format: Article
• Language: English
• ISSN: 0102-7786
• DOI: 10.1590/0102-778620130655

Trends of the annual and summer rainfall totals of 21 rain gauges located in the Metropolitan Region of Sao Paulo (MRSP) are analyzed using three rainfall classes: drizzle, moderate and intense. The rainfall data series are variable in time length within the period 1888 to 2004. Mann-Kendall tests are used to highlight the possible trends that are fitted by simple linear regression when they are statistically significant. Positive trends are found in the annual totals of 9 stations in the MRSP central area, but only 3 of them occurred in the summer period. Significant increasing (decreasing) trends in the frequency of drizzle events in the annual (summer) period are evident in 9 (8) of the gauges analyzed and, in 4 (6) of them, the drizzle frequency decreases. Regarding the moderate annual rainfall class, 3 gauges show increasing trend whereas one presents decreasing trend. However, considering only the summer season, 5 gauges show significant decreasing trend and only in one of them the trend is increasing. With respect to the severe annual rainfall events, 4 stations present significant increasing trend and only in one of them trend appears to be declining. When summer season is considered, only 2 gauges present significant decreasing trend.