شناخت مناطق همگن بارشي در غرب ايران

Delineation of homogeneous precipitation regions in Western Iran

The mountainous region of western Iran was regionalized applying R mode principal component analysis (PCA) and Cluster Analysis (CA) on 9 precipitation derived variables in 140 stations distributed across the study area. In this way, the used variables were reduced to 4 principal components and then rotated using Varimax rotation criterion. Applying a Hierarchical Cluster Analysis, Wardʹs algorithm, on principal component scores, the stations were grouped into 5 individual clusters. The results indicated that the study area comprises of 5 distinctive homogenous subdivisions. The topography and latitude play an important role in determining boundaries between identified subdivisions and existence of spatial differences between them as well. Investigation of time evolution of monthly precipitation across the identified sub-regions indicated that the month of maximum precipitation moves from winter in the south to spring in the north-western most of the study area. The existence differences between south and north of the study area considering the time of occurrence of monthly maximum precipitation implied that the precipitation laden mechanisms are different in south and north of the study area.