New Delhi: Next year, weather researchers in India will study cyclones over the Bay of Bengal by flying right into them.
The temperature, air pressure and windspeeds, and humidity levels at the eye of the cyclone are invaluable numbers which cannot be calculated by remote satellites, but when known and fed into models can substantially ramp up the accuracy of predicting cyclone trajectories and intensity. The project proposal is a collaboration of India’s National Center for Medium Range Weather Forecasting (NCMRWF), and the United States’ National Centre for Atmospheric Research
(NCAR), and involves the Indo-US Science and Technology Forum (IUSSTF).
Weather project: India is likely to charter planes such as the Hurricane Hunters (above) from the US to eject dropsondes—weather probes which relay data to satellites—over the Bay of Bengal to study cyclones.
“We facilitated a meeting between researchers from both countries earlier this year,” said Arabinda Mitra, executive director, IUSSTF. “And a science plan has been prepared by researchers at both institutes which has to be cleared by both governments.”
A science plan, explained A. K. Bohra, head, NCMRWF, is a proposal that details the manner, project costs, and what scientists of each country expect to gain out of the exercise. “A decision on this proposal will be taken by the earth sciences ministry later this year.”
Indian researchers are doing a lot of work on numerical models—an increasingly popular method of weather forecasting in which the atmosphere is treated as a system of fluids, and consequently governed by the equations of fluid flow.
These mathematical equations, which use wind speeds and air pressure as variables, use the values of these variables at any particular moment—called the initial time— and are churned by supercomputers. The success of the forecast, according to Bohra, lies in devising the right equations and accurately measuring these initial conditions.
The eye, which is the calmest portion of a cyclone, is where the atmospheric sea pressure, a vital initial condition, is the lowest, and the best way to measure it is to be there, according to Ravi Nanjundaiah, atmosphere scientist at Indian Institute of Science, Bangalore.
“Satellites often give very hazy pictures during storms, and initial conditions have to be deduced rather than being actually measured,” he said. “Indian weather science is really weak on assimilating data.”
In the proposed project, air planes will fly into the cyclone’s eye, which is usually 30-65km in diameter, and eject dropsondes. These are weather probes, which look like cylindrical logs that will measure atmospheric parameters and relay the data to satellites.
Dropsondes have been developed by NCAR and are used by Hurricane Hunters, manned aircraft, which have been used by the US to study hurricanes and cyclones. A scientist in the earth sciences ministry, who didn’t wish to be quoted, said that in next year’s project India will charter planes from the US and by 2009, would use its own planes for similar projects.
“The Americans have a lot of experience in these sorties, ” said Nanjundiah. “But it’s good that such detailed experiments are going to be carried out for studying pressure systems in the Bay of Bengal.”
The Bay of Bengal is typically not a cyclone hot spot, as say, the East coast of the US. However given the population concentration in that region, even low intensity cyclones can wreak considerable damage, said Nanjundaiah.
In 1999, a supercyclone with winds up to 170mph hit the coast of Orissa killing more than 10,000 people. The Bay of Bengal, according to figures from the Indian Meteorological Department, has been the hotbed of over 16 major cyclones, but little attention in terms of data measurement has been given to it.