Different Climatic elements have movements and variation during time which must be recognized them . Some of this variations are regular or irregular patterns . The irregular variation are known as random changes . Thus it was used Random Changes models for measuring and Random changes seasonal and annual precipitation of Iran. According to measuring and forecast models all stations had random seasonal precipitation changes. Seasonal precipitation of Ahvas , Bandar Anzali, Tabriz and Yazd had change Models but other stations were change Models . Annual precipitation all stations except Tabriz were under random changes effective
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