Identifying and Classifying Precipitation Regimes in Kurdistan Province Using Cluster Analysis

In climatic studies، although the total amount of precipitation is an important factor for determining weather conditions and، finally، ecology، its seasonal distribution and، in other words، compliance with environmental needs، especially in agriculture، is significant، too. In this research، first، the aim was to recognize precipitation regimes at the province scale for each location in Kurdistan province; then the precipitation regimes were compared and، the basis type and classification of each were found on the map. Therefore، 83 synoptic، climatology and rain gauge stations data were used in this study for a period of 30 years (1978-2007). The statistical problem of stations was completed using the regression model relative to 30 years in the most homogenous station. To perform of this classification، first، monthly precipitation of each station was divided by the total precipitation for the same year in order to obtain relative precipitation in each month for the stations. After that، cluster analysis was used along with Ward technique and the classification of the precipitation regimes of the province was prepared. Based on this method، there were two different regimes of precipitation، namely winter and winter – spring precipitations، which were separately illustrated; the winter precipitation in west and the winter-spring precipitation in the center of Kurdistan province were dominate. The winter regimes contained 44% of annual total precipitation، which related to the winter season. After that، autumn and spring precipitations had 28% and، 27% annual total precipitation، respectively. In the winter-spring regime، more amount of precipitation occurs approximately equally or with a little difference of about 2% in winter and autumn، so that the winter and spring seasonal precipitation came up to about 36% and، 34% of annual total precipitation، respectively. After that، autumn season had 28% of annual total precipitation of this area.