El Nino Southern Oscilation and the interannual variability of Pan evaporation and air relative humidity in Santa Maria, RS, Brazil

The objective of this study was to associate the interannual variability of Pan evaporation and air relative humidity with the El Nino Southern Oscilation (ENSO) phenomenon in Santa Maria, RS, Brazil. Daily data records of Pan evaporation (PAN, mm day(-1)) and mean daily relative humidity (RH, %) measured in Santa Maria, RS, were used. PAN was measured from 1973 to 2000 and RH was measured from 1969 to 2006. Years were grouped into El Nino (EN) years, La Nina (LN) years, and Neutral (N) years, from July 1(st) of the year to June 30(th) of the following year. Results showed that PAN is lower in EN years and greater in LN years. On the other hand. RH was greater in EN years and lower in LN years.