Standardized Precipitation Index (SPI) Recent Conditions

Droughts are natural occurring events in which dry conditions persist over time. Droughts are complex to characterize because they depend on water and energy balances at different temporal and spatial scales. The Standardized Precipitation Index (SPI) is used to analyze meteorological droughts. SPI estimates the deviation of precipitation from the long-term probability function at different time scales (e.g. 1, 3, 6, 9, or 12 months). SPI only uses monthly precipitation as an input, which can be helpful for characterizing meteorological droughts. Other variables should be included (e.g. temperature or evapotranspiration) in the characterization of other types of droughts (e.g. agricultural droughts). This layer shows the SPI index at different temporal periods calculated using the SPEI library in R and precipitation data from CHIRPS data set. Read more in our blogs: Water Conflicts in International Rivers Mapping Drought Trends in the U.S. Sources: Climate Hazards Center InfraRed Precipitation with Station data (CHIRPS) SPEI R library干旱是一类自然发生的气候事件，其特征为干燥条件持续存在。干旱的表征颇具复杂性，因其依赖于不同时空尺度下的水分与能量平衡状况。 标准化降水指数（Standardized Precipitation Index, SPI）被用于气象干旱的分析。SPI通过计算不同时间尺度（如1、3、6、9或12个月）下降水量相对于长期概率分布的偏差实现评估，且仅以月降水量作为输入变量，这一特性使其非常适用于气象干旱的表征工作。 而针对农业干旱等其他类型干旱的表征，则需要纳入温度、蒸散发等额外变量。 本图层展示了不同时间尺度下的SPI指数，其计算依托R语言的标准化降水蒸散发指数（Standardized Precipitation-Evapotranspiration Index, SPEI）库与CHIRPS数据集（Climate Hazards Center InfraRed Precipitation with Station data）的降水数据。 如需了解更多详情，可参阅我们的博客：《国际河流中的水冲突》《美国干旱趋势制图》 数据来源：气候灾害中心站点校正红外降水（Climate Hazards Center InfraRed Precipitation with Station data, CHIRPS）数据集、R语言SPEI库