Monsoon rainfall over India in June and link with northwest tropical pacific: June ISMR and link with northwest tropical pacific

Surendran, Sajani and Gadgil, Sulochana and Rajendran, Kavirajan and Varghese, Stella Jes and Kitoh, Akio (2018) Monsoon rainfall over India in June and link with northwest tropical pacific: June ISMR and link with northwest tropical pacific. In: THEORETICAL AND APPLIED CLIMATOLOGY, 135 (3-4). pp. 1195-1213.

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Abstract

Recent years have witnessed large interannual variation of all-India rainfall (AIR) in June, with intermittent large deficits and excesses. Variability of June AIR is found to have the strongest link with variation of rainfall over northwest tropical Pacific (NWTP), with AIR deficit (excess) associated with enhancement (suppression) of NWTP rainfall. This association is investigated using high-resolution Meteorological Research Institute model which shows high skill in simulating important features of Asian summer monsoon, its variability and the inverse relationship between NWTP rainfall and AIR. Analysis of the variation of NWTP rainfall shows that it is associated with a change in the latitudinal position of subtropical westerly jet over the region stretching from West of Tibetan Plateau (WTP) to NWTP and the phase of Rossby wave steered in it with centres over NWTP and WTP. In years with large rainfall excess/deficit, the strong link between AIR and NWTP rainfall exists through differences in Rossby wave phase steered in the jet. The positive phase of the WTP-NWTP pattern, with troughs over WTP and west of NWTP, tends to be associated with increased rainfall over NWTP and decreased AIR. This scenario is reversed in the opposite phase. Thus, the teleconnection between NWTP rainfall and AIR is a manifestation of the difference in the phase of Rossby wave between excess and deficit years, with centres over WTP and NWTP. This brings out the importance of prediction of phase of Rossby waves over WTP and NWTP in advance, for prediction of June rainfall over India.

Item Type:	Journal Article
Publication:	THEORETICAL AND APPLIED CLIMATOLOGY
Publisher:	SPRINGER WIEN
Additional Information:	The copyright for this article belongs to Springer-Verlag Wien
Keywords:	June all India rainfall; Northwest tropical Pacific rainfall; Teleconnection; Subtropical westerly jet; Rossby wave phase
Department/Centre:	Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	15 May 2019 10:52
Last Modified:	15 May 2019 10:52
URI:	http://eprints.iisc.ac.in/id/eprint/62678

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