Fluctuations of precipitable water over the Indian Ocean during the 1979 summer monsoon

D. L. Cadet

doi:10.3402/tellusa.v38i2.11710

Fluctuations of precipitable water over the Indian Ocean during the 1979 summer monsoon

Tellus

Volume 38 (1986): Issue 2

By: D. L. Cadet

Open Access

|Jan 1986

Abstract

Fluctuations of precipitable water (PW) over the Indian Ocean during the 1979 summer season are studied. Time series of space average PW over the Arabian Sea show the existence of a well-marked oscillation of humidity related to the active/break cycle of the monsoon. This cycle around 30–50 days was the major feature of the 1979 monsoon. It also appeared on the pressure and zonal wind fields. This oscillation resulted from perturbations originating over the equatorial eastern Indian Ocean and propagating northward toward India. The arrival over India of a trough-ridge characterized by humid/dry conditions gave rise to an active/break monsoon. It is also suggested that this type of oscillation might be related to the date of the onset of the monsoon. Another periodicity around 10–12 days is also found in the PW and meridional wind fields. This fluctuation appears to be associated with a westward propagating mode north of the equator.

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