The Validation of the Thermal Regions in Iran with an Emphasis on the Identification of the Climatic Cycles

Background: The present study aimed to validate the thermal regions in Iran with an emphasis on the identification of the climatic cycles during the recent half-century. Methods: Data on daily temperature were extracted for 383 synoptic stations of Iran Meteorological Organization. For the zoning of the temperatures of Iran, multivariate statistical techniques (cluster analysis and discriminant analysis) were applied. In addition, the verification of the areas that were identified by cluster analysis and discriminant analysis was performed using the silhouette analysis. Results: Discriminant analysis and silhouette analysis could properly identify the thermal regions in Iran, and this claim was confirmed with 2% error. Moreover, the spectral analysis of the thermal regions indicated that the temperature of Iran in the first and second regions had a medium-term cycle or an occasional short-term cycle, while fluctuations were observed in the third and fourth regions, as well as 2-5-year short-term cycles. Conclusion: According to the results, the temperature of Iran was affected by several factors in some regions with variable patterns, so that diverse short-term, long-term, and medium-term cycles were dominant in the thermal regions in Iran.