The IPCC Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation defines the compound event as follows (IPCC SREX, 2012 ):
“(1) two or more extreme events occurring simultaneously or successively, (2) combinations of extreme events with underlying conditions that amplify the impact of the events, or (3) combinations of events that are not themselves extremes but lead to an extreme event or impact when combined.”

In the current system, monthly precipitation and temperature are used for the monitoring and prediction of compound dry and hot events. Two indicators will be used for characterizing the compound event. The first indicator is the occurrence based on thresholds of precipitation and temperature. The other indicator is the Standardized Compound Event Index (SCEI) based on the joint distribution.

Occurrence: SCEI: X and Y are two drought and hot indicators; P is the joint probability; F is the distribution function; Ф is the standard normal distribution.