SPATIAL AND TEMPORAL STUDY OF EXTREME PRECIPITATION OVER NORTH OF IRAN

Two main focus of this study is the spatial and temporal analysis of annual 24-hour extreme precipitation amounts for different return periods, and the intra-annual variability of the frequency of month to month maximum rainfall using harmonic analysis. Data for analysis gathered from 51 stations that well-scattered at north of Iran (Caspian Sea's southern region). These data are analyzed using extreme values theory and harmonic analysis techniques. The results indicate that the Gen. Extreme Value (Jenkinson solution) is more appropriate than the linear Gumbel solution for the extreme value law. The maximum expected values of 200<x<375 mm are observed along the northern coasts of this region. The harmonic analysis showed that the highest percentage of variance for rainfall extremes explained by the first harmonic (PVR(1)) appears over western and central coastal parts. For eastern and mountainous parts PVR(3,4) is require for explain the variance.