- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
The Standardized Precipitation Index (SPI) is widely accepted and used throughout the world in both research and operational modes because it is normalized to a location and is normalized in time. This standardization allows the SPI to determine the rarity of a current drought event, as well as the probability of the precipitation necessary to end the current drought . It also allows the SPI to be computed at any location and at any number of time scales, depending upon the impacts of interest to the user. On the basis of an analysis of stations across Colorado, McKee et al. (1993) determined that the SPI is in mild drought 24% of the time, in moderate drought 9.2% of the time, in severe drought 4.4% of the time, and in extreme drought 2.3% of the time. These percentages are expected from a normal distribution of the SPI.