Non-stationary and non-linear influence of ENSO and Indian Ocean Dipole on the variability of Indian monsoon rainfall and extreme rain events

Arjun Shankar — Fri, 06 Feb 2015 12:00:21 +0000

Non-stationary and non-linear influence of ENSO and Indian Ocean Dipole on the variability of Indian monsoon rainfall and extreme rain events Arjun Shankar Fri, 02/06/2015 - 12:00

Year of Publication

2014

Authors

Krishnaswamy srini Rajagopalan Balaji Bonell Mike Mahesh Sankaran bhalla Badiger Shrinivas

Journal

Climate Dynamics

Pagination

1–10

Date Published

Fri, 08/01/2014 - 12:00

ISSN

0930-7575, 1432-0894

Abstract

The El Nino Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) are widely recognized as major drivers of inter-annual variability of the Indian monsoon (IM) and extreme rainfall events (EREs). We assess the time-varying strength and non-linearity of these linkages using dynamic linear regression and Generalized Additive Models. Our results suggest that IOD has evolved independently of ENSO, with its influence on IM and EREs strengthening in recent decades when compared to ENSO, whose relationship with IM seems to be weakening and more uncertain. A unit change in IOD currently has a proportionately greater impact on IM. ENSO positively influences EREs only below a threshold of 100 mm day-1. Furthermore, there is a non-linear and positive relationship between IOD and IM totals and the frequency of EREs (>100 mm day-1). Improvements in modeling this complex system can enhance the forecasting accuracy of the IM and EREs.

URL

http://link.springer.com/article/10.1007/s00382-014-2288-0

DOI

10.1007/s00382-014-2288-0

Programme

Natural Resource Management

Refereed Designation

None

Project

Hydrologic and carbon services in the Western Ghats: Response of forests and agro-ecosystems to extreme rainfall events

Keywords

Climatology, Dynamic linear models, Generalised additive models, Geophysics/Geodesy, Indo-Gangetic plain, La Nina, Oceanography, Western Ghats