• Investment World
• eWorld
• Brand Line
• Mentor
• Life
• Canvas
• Praxis
• Urban Pulse
• Brand Quest
• The New Manager

Stocks

• Quotes
• SE Diary
• Scoreboard
• Open-End Mutual Fund

Cross Currency

• Rates
  
  

Shipping

• Ports
  
  

Archives

• Yesterday
• Datewise
• Resources
• In Focus
• In Depth

Group Sites

• The Hindu
• The Hindu ePaper
• Business Line
• Business Line ePaper
• Sportstar
• Frontline
• The Hindu eBooks
• The Hindu Images

Vinson Kurian

Thiruvananthapuram, June 27 Scientists at the Japan Agency for Marine-Earth Science and Technology Centre (Jamstec) say that the torrential rainfall marking the ongoing India monsoon is the best available indicator that a positive Indian Ocean Dipole (IOD) may already have started working.

A positive IOD is characterised by the anomalous cooling of surface temperatures in the southeast equatorial Indian Ocean (around Indonesia) and a corresponding warming in the west equatorial Indian Ocean (along east Africa). Warm seas drive convection and bring about better precipitation.

Dr Toshio Yamagata of the Department of Earth and Planetary Science at The University of Tokyo had informed Business Line in May that the seesawing of sea surface temperatures in the Indian Ocean would combine with an emerging La Ni na event in the equatorial Pacific to dish out a virtuoso performance with implications for the Indian monsoon.

“As suggested by Prof. Yamagata, recent sea-surface temperature (SST) and sea level anomalies indicate the onset of an IOD event. The torrential rain that killed several people in Mumbai and other parts of India also support this,” said Dr Swadhin K. Behera, Sub-leader, Climate Variations Research Programme of the Frontier Research Centre for Global Change (FRCGC) at Jamstec.

According to Dr Yamagata, who is a lead researcher with Dr Behera at the FRCGC, the expected combination of a La Nina and a positive IOD was a very rare occurrence. It was Dr Yamagata’s team that first identified the IOD phenomenon.

What seemed to buttress his case was the fact that the preceding year (2006) has also been IOD positive. IOD normally shows a biennial character, which makes this sequence very rare. The correlation between the IOD and a concurrent Indian monsoon has been showing an increasing trend.

When the IOD event occurs in the absence of an intense El Nino/La Nina, it can strongly influence the season’s rainfall, as was the case in 1961. The La Nina event evolving this year is yet to show signs of rapid intensification, which may have allowed the IOD to play out the dominant theme.

Both the International Research Institute (IRI) for Climate and Society at Columbia University and the European Centre for Medium Range Weather Forecasting (ECMWF) have predicted excess monsoon rainfall for the west coast as well as central India this year.

Meanwhile, India Meteorological Department (IMD) said on Wednesday that the previous day’s ‘low’ in the northwest Bay of Bengal has undergone one round of intensification to lie as a well marked low over north and adjoining central Bay of Bengal.

The system is likely to concentrate into a depression by Thursday. Under its influence, widespread rainfall with scattered heavy to very heavy falls and isolated extremely heavy falls (above 25 cm) are likely over Orissa, Chhattisgarh and north Andhra Pradesh during next three days. The enhanced rainfall activity is likely to extend into Vidarbha and Madhya Pradesh Friday.

Fairly widespread rainfall with isolated heavy to very heavy falls are likely over Konkan, Goa (including Mumbai), Madhya Maharashtra and Gujarat during the three days from Thursday, which may enhance further thereafter.

Scattered heavy to very heavy rainfall with isolated extremely heavy falls have been forecast over north Andhra Pradesh and Orissa during the next two days. Isolated heavy to very falls are likely over Chhattisgarh, Konkan, Goa and Madhya Maharashtra.

Outlook for two days from Saturday indicated enhanced rainfall activity with scattered heavy to very heavy falls and isolated extremely heavy falls over Chhattisgarh, Telangana, Vidarbha, Madhya Pradesh, Konkan, Goa, Madhya Maharashtra and Gujarat region.

More Stories on : Climate & Weather | Climate & Weather

Article E-Mail :: Comment :: Syndication :: Printer Friendly Page

Stories in this Section
‘Indian Ocean Dipole event driving rainfall’

Copyright © 2007, The Hindu Business Line. Republication or redissemination of the contents of this screen are expressly prohibited without the written consent of The Hindu Business Line