Document Type : Research Paper

Authors

• Saeed Jahanbakhsh Asl ¹
• Shahnaz Rashedi ²
• Mehdi Eslahi ³

¹ Professor of Climatology Department, University of Tabriz.

² M.A. in Climatology, Climatology Department, University of Tabriz

³ M.A. in Statistics, Meteorological Organization, East Azerbaijan.

Abstract

Freezing is one of the weather phenomena that almost happen in parts of the east Azerbaijan province such as Maragheh causing significant losses in agriculture, industrial activities, and transportation. The end of this research is studying of distribution and freezing return periods in Maragheh synoptic station during 48 year period (1343-1391) based on the minimum daily temperature. The methods of this study is Gumbel distribution method, three parameter log-logistic method and log-logistic method to analyzing probability of freezing parameters occurrence (starting date, ending date, length of the freezing season, length of the growing season).The Results of the computation of the spring and fall freezing return periods show that the first freezing in the fall starts on 10 Aban and the last freezing end on 17 Farvardin. Also analyzing of the beginning and end freezing trend shows that fall's freezing have an ascending trend , in other words, the dates of the occurring fall freezing goes ahead and spring's  freezing have a descending trend. It means that, the dates of spring freezing go back. Therefore, length of the cold season according to the global warming becomes shorter.

Keywords

• : Freezing
• Gumbel distribution
• Log-logistic
• Trend Analysis
• Freezing parameters
• Maragheh

Main Subjects

• Climatology