SPI-3 Analysis of Medjerda River Basin and Gamma Model Limits in Semi-Arid and Arid Contexts
نویسندگان
چکیده
The Standardized Precipitation Index SPI-3, associated with three months of rainfall accumulation, is a drought index for detecting immediate impacts. two-parameter gamma distribution, recommended by the World Meteorological Organization as underlying distribution estimating SPI, has shown limits in semi-arid and arid conditions respect to normality test resulting SPI series. Our purpose was evaluate its relevance Medjerda River Basin (Tunisia), transboundary basin where climate classes are temperate, dry, hot summer, well desert steppe. When analyzing time series 144 stations from 1950 2018, we found that Shapiro–Wilk rejected 17% cases, which agreed literature review results. transition season (August, September, October) had highest rejection percentage. Three factors were identified explain deviation normality. We first rate occurrence completely dry (zero rain) three-month periods. higher was, probability rejecting test. High sample skewness second influencing factor. Finally, Grubbs’ identifying outliers more likely show SPI-3 deviating
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ژورنال
عنوان ژورنال: Atmosphere
سال: 2022
ISSN: ['2073-4433']
DOI: https://doi.org/10.3390/atmos13122021