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Significance Statement
International Collaborative Projects by the author’s Institute- Nansen Environmental Research Centre(India) (http://www.nerci.in)
Nansen Environmental Research Centre India(NERCI), anon-profit, Scientific and Industrial Research Organization (SIRO) established in 1999 as a joint venture between the Indian and Norwegian partners. It conducts basic and applied research in ocean and atmospheric sciences. Two major international projects currently being coordinated by NERCI are:
Indo-European research facilities for studies on marine ecosystem and climate in India (INDO-MARECLIM) is a project of the European Commission to facilitate and improve cooperation of European Union Member States and Associated Countries with India in the research on marine ecosystems and climate, including their impact on society. INDO-MARECLIM aims at analyzing and understanding some of the challenges (e.g. changes in the monsoon, sea level rise, coastal erosion, changes in primary production, fisheries and biodiversity) of the Indian Ocean and the Indian sub-continent under global climate change. The project and cooperation is expected to contribute to building strategic R&D partnerships between institutions in Europe and India. The details of this project can be viewed from http://www.indomareclim-nerci.in
Exploring Decadal to Multi-decadal Scale Variability and Changes in the Indian Summer Monsoon during the last millennium (India-Clim Project) – A study of observed and modelled variations in climate in India, in response to the Research Council of Norway’s call “Climate change – research collaboration with India”. The overall objective of this project is to explore decadal to multi-decadal variations in Indian climate during the last millennium and to do research on its association with the Atlantic Multidecadal Oscillation (AMO) in sea surface temperature (SST). A scientific paper under this project “Variability of Summer Monsoon Rainfall in India on Interannual and Decadal timescales” by Joseph et al.,(2013) was published in Atmospheric and Oceanic Science Letters Vol16 (2013) 398-403, doi:10.3878/j.issn.1674-2834.13.0044.
Surveys in Geophysics, May 2014, Volume 35, Issue 3, pp 723-738.
Porathur V. Joseph .
Nansen Environmental Research Centre India, 6A, Oxford Business Center, Sreekandath Road, Ravipuram, Cochin, 682016, India and
Cochin University of Science and Technology, Cochin, India.
Abstract
Asian summer monsoon sets in over India after the Intertropical Convergence Zone moves across the equator to the northern hemisphere over the Indian Ocean. Sea surface temperature (SST) anomalies on either side of the equator in Indian and Pacific oceans are found related to the date of monsoon onset over Kerala (India). Droughts in the June to September monsoon rainfall of India are followed by warm SST anomalies over tropical Indian Ocean and cold SST anomalies over west Pacific Ocean. These anomalies persist till the following monsoon which gives normal or excess rainfall (tropospheric biennial oscillation). Thus, we do not get in India many successive drought years as in sub-Saharan Africa, thanks to the ocean. Monsoon rainfall of India has a decadal variability in the form of 30-year epochs of frequent (infrequent) drought monsoons occurring alternately. Decadal oscillations of monsoon rainfall and the well-known decadal oscillation in SST of the Atlantic Ocean (also of the Pacific Ocean) are found to run parallel with about the same period close to 60 years and the same phase. In the active–break cycle of the Asian summer monsoon, the ocean and the atmosphere are found to interact on the time scale of 30–60 days. Net heat flux at the ocean surface, monsoon low-level jetstream (LLJ) and the seasonally persisting shallow mixed layer of the ocean north of the LLJ axis play important roles in this interaction. In an El Niño year, the LLJ extends eastwards up to the date line creating an area of shallow ocean mixed layer there, which is hypothesised to lengthen the active–break (AB) cycle typically from 1 month in a La Niña to 2 months in an El Niño year. Indian monsoon droughts are known to be associated with El Niños, and long break monsoon spells are found to be a major cause of monsoon droughts. In the global warming scenario, the observed rapid warming of the equatorial Indian ocean SST has caused the weakening of both the monsoon Hadley circulation and the monsoon LLJ which has been related to the observed rapid decreasing trend in the seasonal number of monsoon depressions.
