INVESTIGADORES
ROBLEDO Federico Ariel
congresos y reuniones científicas
Título:
STUDY OF THE FREQUENCY OF EXTREME DAILY PRECIPITATION ON THE SOUTH OF ANDES MOUNTAIN RANGE. TEMPORAL VARIABILITY IN THE PERIOD 1961-2003 AND RELATION WITH ANTARCTIC OSCILATION
Autor/es:
ROBLEDO, FEDERICO ARIEL; PENALBA, OLGA
Lugar:
New Orleans
Reunión:
Conferencia; 20th Conference on Climate Variability and Change. 88th American Meteorological Society Annual Meeting; 2008
Institución organizadora:
American Meteorological Society
Resumen:
For the period 1961-2003, the climatology of extreme daily precipitation intensity presents a maximum in winter (22mm/day), as well as the percentage of extreme events (9%). Winter explains 36% of the annual percentage of events greater than percentile 75th (PE>75th), however summer explains 15%. Autumn and spring explains 27% and 22%, respectively. Trends for percentage of events greater than 0,1mm (PE>0.1) and PE>75th are non significant for all seasons and also for annual terms. However, during winter season the coefficient is negative for both indices (PE>0.1 and PE>75th), indicating that the number of rainy days or extreme rainy days are only decreasing in this season. This hypothesis was confirmed through the change of PE index between two excluded periods 1961-1975 and 1980-1996. The highest percentage of changes was observed for PE>75th during winter (-36%). In spring, interdecadal variability of PE>01 and PE>75th are in opposite phase. For the period 1979-2003, the relationship between Antarctic Oscillation (AAO) index and extreme rainy days (PE>75th index) was analysed. Both monthly indices are out of phase. This negative relationship was also observed when the seasonal analysis was performed, observing the highest and significant cross-correlation during autumn and spring (-0.52 and –0.27; respectively). Finally, the phase of AAO in autumn explains significantly the occurrence of PE>75th two seasons in advance (spring, -0.24).