Breakpoints in annual rainfall trends in Cordoba, Argentina

Long-term rainfall variability in the Province of Cordoba, Argentina is studied. The methodology used was developed by Tome and Miranda (2004), and the most notable breakpoints in the time series were determined in order to identify sudden transitions from one period to another with a different linear trend sign. All the rain gauges operated by the Servicio Meteorologico Nacional (SMN) of Argentina in Cordoba Province, in the period 1930-2006, were analyzed. One of the stations studied, Cordoba Observatorio, has reliable rainfall data since 1873. In this case, the 1925-2006 period and the 1873-2006 period were studied to analyze the influence of series length in terms of the piecewise linear trends produced. Analyzing only one breakpoint in all the series, a trend change is observed from negative to positive in the 1950s in the north area of the region, while in the other areas the opposite change occurs in the 1970s. The residual sum of squares obtained with the partial trend method is compared to that produced by the traditional method. This comparison shows how the multiple trend method enables regional changes to be determined for a given climatological variable. (C) 2009 Elsevier B.V. All rights reserved.