Comparison of Spatio-Temporal Trends on Drought Characteristics Using Meteorological Drought Indices (SPI and EDI) in the United States

The U.S. Drought Monitor (USDM) is a weekly drought monitoring tool for tracking drought conditions and policy makers informing decisions about drought response and relief actions. Currently, the USDM involves analysis of multiple drought indicators using soil moisture, meteorological, hydrological, climatological, and remotely sensed inputs. Various drought indices have been proposed in past few decades, but make it hard to decide that which drought index and time step are the suitable to show the drought condition. This study focuses on two meteorological drought indices (the Standardized Precipitation Index, SPI, and the Effective Drought Index, EDI) and compares them over time to the USDM drought categories. Additionally, effective drought monitoring depends on the ability to detect quantitative drought conditions relies on drought indices, which consider the characteristics of drought severity, frequency, impacted area, and duration. This study investigates the spatial and temporal patterns of drought characteristics (frequency, duration, severity and magnitude) using the run theory method based on different timescales of the drought indices.