Climatology
Mojtaba Nassaji Zavareh; Hossein Hokmabadi; Alireza Asadolahi
Abstract
Late spring frost cause a lot of damage to the agricultural sector every year. Prediction of this phenomenon is needed to active protection of plants. In this research, using FAO experimental method, daily and hourly data of two meteorological stations were used to determine the coefficients of the experimental ...
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Late spring frost cause a lot of damage to the agricultural sector every year. Prediction of this phenomenon is needed to active protection of plants. In this research, using FAO experimental method, daily and hourly data of two meteorological stations were used to determine the coefficients of the experimental model for prediction radiation frost in Qazvin Plain. also, in order to investigate the climatic condition of spring frost, the daily minimum temperature data of Qazvin and Buinzahra stations were used. The analysis of sixty years data in Qazvin stations showed that the intensity of frost has decreased during these years, but frequency of frost in Ordibehesht month has increased. Air, dew-point at two hours after sunset and minimum temperature relate 25 events of radiation frost at Simorgh station were used for regional coefficient calculation based on two models. These models were evaluated using 14 events of radiation frost at Tat stations. The mean absolute error(MAE) for testing and evaluating of Model1 was 0.71℃ and 1.21℃ and for Model2 was 0.67℃ and 1.09℃. The findings also showed that both models have acceptable accuracy in estimating the minimum temperature of the next day. It is proposed that these two models can be used for prediction of radiation frost in other regions.
Climatology
Yaghoob Rezazadeh; Bohloul Alijani
Abstract
Cold and freezinginthe North West ofthe country(Iran), has arrived allyearirreparabledamages to thetransportsectors, roadaccidents, gardens andagriculturalproductsandcrippled thenormal lifeof people incityand villagesAt first, theverycolddays of 18 stationsin the statistical periodwere extracted then ...
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Cold and freezinginthe North West ofthe country(Iran), has arrived allyearirreparabledamages to thetransportsectors, roadaccidents, gardens andagriculturalproductsandcrippled thenormal lifeof people incityand villagesAt first, theverycolddays of 18 stationsin the statistical periodwere extracted then of thestatistics, the number of 43 Severe and pervasive wave was selected..Finally, for Synopticanalysis ofcoldwaves, tworepresentativewaves on February1991 and January 2007were determined. The maps of Earth and the500Hpa pressuressurfaceof thefreezing from theNCEPwebsitehas been prepared andanalyzed. The results showed that in most cases of severe frost in the top level, a deep descends in the Iran west established and polar regionsCold Weatherwill leadtoIran. The establishment of above thebarrier in the East of this descends was due relativestagnation of descends and the continuity of cold inthe region intensifies. At the surface of Earth, west migrant high-pressures and the spread of Siberian high-pressure tab add to intensityat 500Hpa levels. Accordingly, we can at least 5 days prior to the deployment of these systems in the vicinity of the study area, predicted cold conditions, the managers and farmers are prepared to deal with cold.
