drought is a climatic phenomenon that causes much detrimental influence on ecological environments. this research investigates the performance of meteorological drought indices in different time scales in thetajan basin in iran. indices undergone in this study include: percent normal precipitation index (pnpi), z-score index (zsi), standard precipitation index (spi), china z index (czi), modifi...

An archive of land-based, surface-observed cloud reports has been updated and now spans 39 years from 1971 through 2009. Cloud-type information at weather stations is available in individual reports or in long-term, seasonal, and monthly averages. A shift to a new data source and the automation of cloud reporting in some countries has reduced the number of available stations; however this datas...

nowadays, undoubted access to up to date with high spatial resolution and low temporal resolution of meteorological parameters is a one of the necessary needs for meteorological science researches. in order to doing this research have been used the different daily, monthly and yearly iran precipitation from global and regional data base of gpcpøŒ gpccøŒ aphrodit v101 0.25øŒ aphrodit v101 0.5 ùˆ...

A nonparametric wet/dry spell model is developed for resampling daily precipitation at a site. The model considers alternating sequences of wet and dry days in a given season of the year. All marginal, joint, and conditional probability densities of interest (e.g., dry spell length, wet spell length, precipitation amount, and wet spell length given prior to dry spell length) are estimated nonpa...

Climate change projections for California indicate reduction in the percentage of precipitation that falls as snow, and increase in the percentage that falls as rain, due to warmer temperatures in the future. Previous work has shown overall decreases in rainfall / snowfall ratios for the western US over the last 60 years. Of interest in this study is the quantification of snow/rain ratios for s...