Work

Drought classification and parameter identification based on actual precipitation index

Year: 2025

Type: article

Abstract: Drought index studies are intensively in the literature, particularly based on various alternetive procedures for the standard precipitation index (SPI). This index requires transforming the original probability distribution function (PDF) into a standard normal (Gaussian) PDF with eight linguistical classifications. It is unfortunate that the SPI-based standard normal PDF cannot reveal statistical parameters regarding the actual durations, means, standard devistions and possible serial correlation coefficients of rainy and dry periods. The main objective of this paper is to explain the concept of the actual precipitation index (API) currently available in the literature and to determine the actual statistical parameters of rainy and dry periods within each categorization. Confusion has been expressed in the open literature that the SPI is based on statistical standardization operation, which is In fact, SPI is dependent on a completely invalid.statistical standardization procedure. In fact, the SPI relies on a probalistic standardization procedure that preserves the original unity of the hydro-meteorological variable after the probabilistic transformation to a normal (Gaussian) PDF with zero mean and unit standard deviation. After describing the APIs according to the classical SPI approach, its advanteges and disadvantages are presented comparatively. Long term application of the methodology is presented for hydro-meteorological time series from Romania, United States and Türkiye.

Source: Physics and Chemistry of the Earth Parts A/B/C

DOI: 10.1016/j.pce.2025.104149

Author: Zekâi Şen

Institution: Istanbul Medipol University

Language: English

Topic: Hydrology and Drought Analysis

Subfield: Global and Planetary Change

Field: Environmental Science

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $2,900

Funder: İstanbul Medipol Üniversitesi