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Waxing and waning of observed extreme annual tropical rainfall

Sukhatme, Jai and Venugopal, V (2016) Waxing and waning of observed extreme annual tropical rainfall. In: QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, 142 (694, A). pp. 102-107.

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Official URL: http://dx.doi.org/10.1002/qj.2633


We begin by providing observational evidence that the probability of encountering very high and very low annual tropical rainfall has increased significantly in the most recent decade (1998-present) compared with the preceding warming era (1979-1997). These changes over land and ocean are spatially coherent and comprise a rearrangement of very wet regions and a systematic expansion of dry zones. While the increased likelihood of extremes is consistent with a higher average temperature during the pause (compared with 1979-1997), it is important to note that the periods considered are also characterized by a transition from a relatively warm to a cold phase of the El Nino Southern Oscillation (ENSO). To probe the relation between contrasting phases of ENSO and extremes in accumulation further, a similar comparison is performed between 1960 and 1978 (another extended cold phase of ENSO) and the aforementioned warming era. Though limited by land-only observations, in this cold-to-warm transition, remarkably, a near-exact reversal of extremes is noted both statistically and geographically. This is despite the average temperature being higher in 1979-1997 compared with 1960-1978. Taking this evidence together, we propose that there is a fundamental mode of natural variability, involving the waxing and waning of extremes in accumulation of global tropical rainfall with different phases of ENSO.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the WILEY-BLACKWELL, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Keywords: rainfall; extremes; ENSO
Department/Centre: Division of Mechanical Sciences > Divecha Centre for Climate Change
Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 02 Apr 2016 05:20
Last Modified: 02 Apr 2016 05:20
URI: http://eprints.iisc.ac.in/id/eprint/53417

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