Variabilidad interanual a interdecádica de la precipitación en Patagonia norte

the objective is to analyze the interannual to interdecadal variability in summer and winter precipitation on the northern argentine patagonia region, called pampa amarilla (rpa), during 1969-2006. the annual 28 regime shows a strong change on annual cycle along the northeast-southwest transect in the rpa. towards the northeast the annual cycle of precipitation has the maximum records with winter minima and summer equinoccial maxima (march). towards the southwest the records are smaller, with uniform distribution throughout the anual cycle, presenting slight winter minimum. the observed frequency distribution of the precipitation anomalies tends to show greater occurrence of negative frequencies in the interval (- 100; 0)mm with a slight major probability of occurrence of positive anomalies interval (right tail). the interannual variations for the warm period show, over the north sub-region, a positive and significative trend. an exception is the central region which trend is negative and significative. in the cold season, positive and significative trends are observed, especially in the north and in the southeast areas of the rpa. the rpa can be chracterized by devicing two precipitation indices, one for summer and the other for winter. the indices do not show significant trends. for the summer it is possible to split the región into two: one the northern rpa and the other the southern rpa, with diverse inter-annual behavior. in the northern the dominant cycles are 5 years and to 8 years, and in the southern, around 2-4 years, 11 years and 15 years. during the winter the whole rpa behaves as a uniform region with significant cuasi-cycles around 4-5 years and 11 years. for both summer and winter the regional precipitation indices do not show significant trends. the low-frequency processes between 2 and 6 years could be related to the southern annular mode (sam). the solar cuasi-cycle could be also involved. for the summer, the tropospheric circulation of lower level