Meteorological Drought

Background

Meteorological drought is characterized by a significant and prolonged deficit in precipitation compared to the historical average for a specific region and time period. It is often the earliest indicator of drought conditions, potentially leading to other types such as agricultural or hydrological droughts if dry conditions persist. Unlike other drought types that affect specific systems or sectors, meteorological drought is solely concerned with atmospheric conditions, particularly the lack of rainfall. To quantify and monitor meteorological drought, standardized drought indices are commonly used. Two widely applied indices are: Standardized Precipitation Index (SPI): This index measures precipitation anomalies over various timescales (e.g., 1, 3, 6, or 12 months) by comparing current precipitation levels to long-term historical averages. SPI values help identify both short-term and long-term droughts. Standardized Precipitation Evapotranspiration Index (SPEI): Building on the SPI, the SPEI incorporates potential evapotranspiration (PET), making it sensitive to changes in both precipitation and temperature. This allows for a more comprehensive assessment of drought under changing climate conditions. Together, these indices provide valuable tools for assessing the onset, severity, and duration of meteorological droughts, supporting early warning systems and resource management decisions.