abstract consistent decreasing and increasing of temperature in the short-term period that is called freezing and thaw cycles is one of the important factors of damage to crop productions. in this research as to determine freezing and thaw cycles in the khorasan razavi province, the data of daily minimum and maximum temperatures of 9 synoptic stations was used over 20 statistic years (1989-2008...

climatological parameters are among the most important ecological capability evaluation criterias, on other hand, climate changes which has intensified in the past decades and has the consequences such as; increases in climatic threshold phenomena like occurrence of horrific floodings, destructive hurricanes, abnormal and sudden colds and heats, untimely rainfalls and heavy snows, widespread dr...

an increase, even moderate, in global temperature is expected to result in a change in frequency of extreme weather events like drought, heavy rainfall and storms. the study of extreme events is difficult due to the fact that it is difficult to find long-term homogeneous data series. also the delimitation of extreme events is not univocal since a parameter value that would be defined as an extr...

abstract long-term historical weather data are needed to conduct crop simulation analysis. simulated climatic data may be used when long series of historic data are not available or convenient or when future data are needed. the aim of this study was to generate daily weather values for maximum and minimum air temperatures. a number of weather generators are compared here. data from ten station...

introduction linking resolution global climate models to local scale as a micro climatic process is a significant issue. recently, attempts have been made by the climatology scientists to develop dynamics and statistical downscaling methods to express climate change at a local and regional scale. two general techniques are been used for downscaling of the output of general circulation models (g...