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:: Volume 19, Issue 68 (4-2019) ::
جغرافیایی 2019, 19(68): 133-147 Back to browse issues page
The probability of continuity and frequency of frost in the Karaj township on the basis of possible rules
Mehrdad Ramazanipour *
islamic azad university of chalous
Abstract:   (1990 Views)
Spiring late and autumn early frosts is considered farming concerns. A sudden decrease in ambient temperature not only impede the process of blooming, plant pollination and fruit production, but it makes pathogens and freezing the water in the plant cells. In addition, the threat to economic infrastructure, including transport and dams, as well as an increase in energy consumption. In this regard, the frequency and persistence of early and late frosts in Karaj city were analyzed based on probabilistic laws as stochastic processes by using the Markov chains technique. For this purpose, mean daily minimum temperatures was used for a period of 24 years (1985_ 2008), derived from Karaj station. Since most harmful frosts are related to the start of transitional season and higher possibility, at first the probability matrix for frost and non-frost temperature was calculated based on the maximum likelihood method and then the possibility of stability and daily return period each of the two modes of frost and free-frost calculated for all months. The highest probability for freezing days was in January and equal to 0.87. Then 2 and 5-day return period continuation of frost days was calculated for the all months. April has shortest return period of 0.03 days for 2 days frost and 0.03 days for 3 days frost and December and February had the longest frost continuity that is 0.24 days for 2 days frost and 0.02 and 0.01 days for 3 days frost relatively. Also the probability of frost days of month With repetitions of  to  showed that December, January, February and March had the maximum probability of frost at . In other words, three occurrences of Frost in these months is more probable than any other probability.
 
Keywords: : Duration and Frequency of Frost, Early and Late Frost, Markov Chain, Return Period.
Full-Text [PDF 933 kb]   (322 Downloads)    
Type of Study: Research | Subject: Special
Received: 2018/02/18 | Accepted: 2018/04/30 | Published: 2020/05/18
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ramazanipour M. The probability of continuity and frequency of frost in the Karaj township on the basis of possible rules. جغرافیایی. 2019; 19 (68) :133-147
URL: http://geographical-space.iau-ahar.ac.ir/article-1-3177-en.html


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Volume 19, Issue 68 (4-2019) Back to browse issues page
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