Probability of Frequency and Spell of Early and Late Freezing Days in Zanjan City



      Â  Abstract   In this paper, Zanjan Freezing days' frequency and spell length has been analyzed based on probability rule, stochastic process and Markov chain usage. Due to harmfulness of the first months of transform seasons, and based on this projects’s achievements, the last 44-year-data of first months of Spring and fall seasons Farvardin (March 21to April 20) and Mehr (September 23 to October 22) have been used. Probability matrix of freeze-free of freeze days was established based on maximum likelihood method after frequency matrix had been provided. Persistence probability was estimated based on probability matrix of freeze and free of freeze days. Accordingly the probability of freezing day in Farvardin and Mehr is 0.3519 and 0.0375 respectively. Finally, probability of 2-5 days freezing spell has been calculated. The probability of spell length most frequently occurs in early spring.