• PAGE ONE
• INDEX
• HOME

Scanning the oceans from floats

M. Somasekhar

`EL NINO' and its less well known cousin `La Nina', were two crucial phenomena that had a major impact on the variations in global climate and natural disasters during the last decade.

Meteorologists termed the warming of the upper layers of the eastern tropical Pacific Ocean `El Nino', a current that alters the pattern of global atmospheric circulation and, in effect, changes weather patterns. It can lead to droughts, floods, hurrican es in different regions.

La Nina, on the other hand, is the cooling of these same waters in the Pacific, that sometimes follow the El Nino episode and bring a different kind of impact on the global weather conditions. To develop the forming, duration and strength of these phenom enon the US National Oceanic and Atmospheric Administration (NOAA) set up the El Nino Southern Oscillation (ENSO) observing system in 1994.

The ENSO observation system was the first capability to carry out measurements from the ocean surface and its sub-surface layers. The data is supplied to forecast centres in the US on a real-time basis.

To help forecast storms, weather patterns, and monsoons, meteorologists are today dependent on observations made by a global network of land and ocean surface measurements. These recordings are done through meteorological satellites, balloons carrying se nsors, and so on, and the data thus collected is analysed by fast-crunching computers.

In short, these two or three decades of research have given us the capability to forecast how the weather will be, when the monsoons will arrive over which part of the world, and act as an early warning of cyclones and typhoons with reasonable accuracy. The room for improvement, however, is considerable.

Satellites have drastically improved the scientific capability of observing the oceans. The earlier methods of study were ship-borne, through moored buoys, low-flying aircraft, balloons, etc. Satellites, however, can skim the surface of the ocean and can not look much deeper.

Taking a major step forward in complementing the existing satellite capability to scan and understand the oceans better is a new global programme called `Argo', based on building a worldwide ocean network of floats which will continuously gather data -- and provide important inputs to scientists.

Argo is considered the fallout of efforts of research sponsored by the National Science Foundation (NSF) and the Office of Naval Research, US. It also represents a critical complement to NASA's (National Aeronautical Sciences Association), $1-billion inv estments in space-based ocean observations, according to a source document on the project.

The proposed Argo programme will have a string of 3,000 floats across the oceans of the globe. Each float is designed to be separated by a distance of 300 km. When in place, the float will sink to a depth of 2,000 metres. After drifting with the ocean cu rrent for ten days, it will rise to the surface, measuring with its sensors the temperature, pressure and salinity of the layers through which it rises.

At the sea surface level the float will radio the data thus collected and its position to an orbiting satellite before it returns to the depth and continues its job in another cycle. The floats will continue in such cycles throughout their designed life of four to five years.

The satellites which pick up the radio data transmit the data to land-based receiver stations. The data is then distributed to a number of scientific teams around the world, who will then carry out quality control checks and make them available for use b y operational forecast centres on a near real-time basis, through the Global Telecommunications System (GTS).

India has joined this global project with a strategy to deploy at least 150 profiling floats in the Indian Ocean before 2005. Along with India, 14 countries have committed to support through floats, about 120 of which are already networked and functionin g in the Atlantic and Pacific Oceans.

The Indian National Centre for Ocean Information Services (INCOIS), Hyderabad, an autonomous institute under the Department of Ocean Development (DoD), is the nodal agency coordinating the participation of 10 more institutes, according to Dr K. Radhakris hnan, Director.

For India, the Argo programme can be quite beneficial. At present, its coverage of oceans is very minimal and, as Dr S. R. Shetye of the National Institute of Oceanography (NIO), Goa, says: ``We do not have data or theory about sub-sea events below 500 m etres of the Indian Ocean.''

The oceans, especially the Bay of Bengal play a crucial role in the behaviour of the south-west monsoon. The understanding of the sub-surface features can be very important in our predicting of the monsoon, he said.

According to the plans of the DoD, the country would have an Argo Data Centre and also an Ocean Portal, which will provide easy access to the data for value addition and research. The ongoing projects, such as the fishing zone advisory, ocean state forec ast and management of marine wealth will all get a fillip with this new dimension in ocean studies.

Dr Stanley Wilson, a Director at the NOAA, said issues such as climate change, how monsoon travels, disasters such as cyclones, typhoons, and so on, are becoming dominant challenges not only among research groups, but for countries with long coasts and d ependent on agriculture. The Argo programme is being tailored to work in conjunction with the satellite-based forecast systems, to ensure that the present capability of early warning and prediction are further sharpened.

How will the data from the Argo programme be useful? Dr Myers from Australia's Council of Scientific and Industrial Research Organisation (CSIRO) explains that Australia is looking at utilising the data generated from the Argo programme for better marine resource management, fishing industry, offshore energy exploitation for oil and gas, shipping and safety aspects.

With the shrinking resources on planet earth's landmass, due mainly to exploitation, the focus is now turning to oceans -- the next frontier in which to seek out newer resources as well as to better understand their impact on events on earth.