Interdecadal and Interannual variations of annual and extreme precipitation over central-northeastern Argentina. Changes in the extreme precipitation seasonal cycle

PENALBA O., VARGAS W.

INTERNATIONAL JOURNAL OF CLIMATOLOGY

JOHN WILEY & SONS LTD

Lugar: LOndres; Año: 2004 vol. 24 p. 1565 - 1580

0899-8418

Long annual precipitation time series from central-northeastern Argentina are analyzed with special attention to interdecadal and interannual variations. The results show a variability that is highly non-stationary. The most outstanding feature is the difference in annual precipitation before and after the 1950s. The interdecadal variability is particularly well defined in the west and there is a significant linear trend in the study area. Negative anomalies of the areal-averaged annual precipitation can be observed in all the areas around 1910 and 1930 or 1940. In the western zone there are two better-defined negative periods around 1950 and 1970 and a gradual increase can be observed in the eastern zones starting in the 1950s. The interdecadal and interannual variations affect the behavior of extreme precipitation in the annual scale and during the months with maximum precipitation in the region. In support of these conclusions different representation methods are used (running means, power spectrum analysis and wavelet transforms). The variations in the annual cycle of extreme precipitation under different conditions are analyzed applying harmonic analysis. The wettest years are represented by an annual and semi-annual cycle while dry years need the input of lower-frequency cycles.