Distribution functions
; Function evaluation
; Precipitation (meteorology)
; Stream flow
; Time series
; Akaike information criterion
; Calculation algorithms
; Exponentiated Weibull distribution
; Global precipitation climatology projects
; Max Planck Institute
; Occurrence probability
; Seasonal precipitations
; Standardized precipitation index
; Weibull distribution
; Akaike information criterion
; climate modeling
; drought
; ensemble forecasting
; index method
; observational method
; seasonal variation
; simulation
英文摘要:
The Standardized Precipitation Index (SPI) is a widely accepted drought index. Its calculation algorithm normalizes the index via a distribution function. Which distribution function to use is still disputed within the literature. This study illuminates that long-standing dispute and proposes a solution that ensures the normality of the index for all common accumulation periods in observations and simulations.
We compare the normality of SPI time series derived with the gamma, Weibull, generalized gamma, and the exponentiated Weibull distribution. Our normality comparison is based on a complementary evaluation. Actual compared to theoretical occurrence probabilities of SPI categories evaluate the absolute performance of candidate distribution functions. Complementary, the Akaike information criterion evaluates candidate distribution functions relative to each other while analytically punishing complexity. SPI time series, spanning 1983-2013, are calculated from the Global Precipitation Climatology Project's monthly precipitation dataset, and seasonal precipitation hindcasts are from the Max Planck Institute Earth System Model. We evaluate these SPI time series over the global land area and for each continent individually during winter and summer. While focusing on regional performance disparities between observations and simulations that manifest in an accumulation period of 3 months, we additionally test the drawn conclusions for other common accumulation periods (1, 6, 9, and 12 months).
Pieper, P., Institute of Oceanography, Center for Earth System Research and Sustainability, Universität Hamburg, Hamburg, Germany; Düsterhus, A., Irish Climate Analysis and Research UnitS (ICARUS), Department of Geography, Maynooth University, Maynooth, Ireland; Baehr, J., Institute of Oceanography, Center for Earth System Research and Sustainability, Universität Hamburg, Hamburg, Germany
Recommended Citation:
Pieper P.,Düsterhus A.,Baehr J.. A universal Standardized Precipitation Index candidate distribution function for observations and simulations[J]. Hydrology and Earth System Sciences,2020-01-01,24(9)