محاسبه و تجزيه و تحليل ساعت هاي تداوم يخبندان با استفاده از برنامه نويسي به زبان دلفي مطالعه موردي استان لرستان

Calculation and Analysis of Frost Duration, by Using Delphi Programming: A Case Study of Lorestan, Iran

One of the climatological events is the occurrence of frosts. Depending on its intensity, duration and extension, it can extremely affect human activities, including agriculture, transportation, energy, bioenvironmental matters, and biological activities of animals and plants. Frosts have different elements such as beginning, end, frost season, duration, etc. Duration refers to the length of time in which the temperature falls down to zero or less than zero and continues for a while in a region. This duration is of great importance in agriculture. Since every type of plant has got a particular temperature threshold, the degrees below or above this threshold may lead to plant extinction. Therefore, the study of the duration of frosts is necessary. In addition, this type of study is indispensible and useful for construction works such as darn building, to increase safety coefficient. The purpose of this study is to calculate the duration of frosts by Delphi programming. To do this, the data related to the daily minimum temperature of four meteorology stations of Lorestan Province, i.e. Khoram-Abad, Boroujerd, Naseredin and Aligoudarz having a ten-year statistics (from 1989 to 1999) were obtained from the information bank of the National Meteorology Organization. After drawing out the frost days in desired threshold (zero and less than zero) during the statistical period, frost duration of each station was calculated and extracted, using algorithm of the afore-mentioned program. Then, duration periods were selectively divided into eight (three-hour) classes. Their frequency percentile charts were drawn and all stations were compared to one another in three classes of 0 to 3 hours, 9 to 12 hours, and 21 to 24 hours. It was concluded that Boroujerd Station enjoys the most frost hours and, hence damages to crops were the highest in this station compared with other ones. It was further concluded that the land cover is the most influential factor in frost duration of the region, and that the height factor had no effect on the duration of frosts.