CR 75:23-31 (2018)  -  DOI: https://doi.org/10.3354/cr01506

ABSTRACT: We studied the inter-annual variability of the vertically integrated zonal/meridional moisture transport in the lower troposphere over the northern Indian Ocean using observed data from 1971-2016 for the South Asian summer monsoon (SASM) season. The moisture transport variability was dominated by the zonal component associated with the Somali low level jet. For identification of the dominant modes of inter-annual variability, 3-dimensional empirical orthogonal function analysis was performed. The leading mode, associated with suppressed meridional moisture transport in both the Arabian Sea and Bay of Bengal and increased zonal moisture transport over the Bay of Bengal, was linked with the positive phase of the Indian Ocean dipole and El Niño conditions in the Pacific Ocean. The second leading mode was associated with the enhanced zonal moisture flow over the Arabian Sea extending up to the Bay of Bengal allied with the Somali low level jet, and enhanced northeastward moisture transport over the whole region. This enhanced moisture flow results in stronger monsoon circulation and increased rainfall over South Asia.

KEY WORDS: Inter-annual variability · Monsoon · Moisture transport · IOD · ENSO · South Asia