An Extreme Drought Event in the 2002 Summer Monsoon Rainfall and its Mechanism Proved with a Moisture Flux Analysis

Abstract

Following the previous finding that drought occurred in summer monsoon over India synchronizing with the Equatorial Indian Ocean Oscillation (EQUINOO) negative phase and El Niño, a full analysis of moisture transport is carried out to explore the mechanism of the drought. It is suggested that the key component of relating the drought with the EQUINOO negative phase and El Niño tends to be a suppressed moisture convergence over the Arabian Sea, which may yield a low moisture transport across the western coast of India and the consequent drought. Among the recent drought years, the drought in 2002 is considered to be special with respect to its month-long duration in July. The moisture transport to India was comparable with those in the other drought years, while the Hadley cell completely reversed and expanded a downward belt over India. Both EQUINOO negative phase and El Niño were at the extreme states in this period and are considered to be responsible for the anomalous Hadley cell and the 2002 drought.