To get a better grip on forecasting fog, a series of organisations has partnered with the airport authorities here to develop a system that can warn of fog at least 6-24 hours in advance, calculate its severity, and estimate when it is likely to lift enough for flights to take off and land safely.
Predicting a fog is a daunting challenge the world over, primarily because a range of meteorological conditions contribute to it, and it can play out differently even within a city. While the immediate utility would be for aviation, officials associated with the exercise said if the underlying science of the fog-prediction system was perfected, it would be able to warn of extreme pollution events such as the severe smog that enveloped Delhi this year after Diwali.
About 30 instruments have been installed abutting one of the runways in Delhi’s Indira Gandhi International Airport, said Madhavan Rajeevan, Secretary, Ministry of Earth Sciences, and the first forecasts would be available in January.
“Various measurements of the atmosphere need to be made and this will be used to improve a fog weather model that’s being developed by the Indian Institute of Tropical Meteorology (IITM),” he added. He clarified that the forecasts would continue to be issued by the Indian Meteorological Department (IMD).
These instruments will measure the surface meteorological conditions, radiation balance, turbulence, thermo-dynamical structure of the surface layer, droplet and aerosols microphysics, aerosol, fog water chemistry, vertical profile of winds, temperature, and humidity, to describe the conditions that cause fog.
Last year, the Indian Institute of Tropical Meteorology (IITM) Pune and the IMD, Ministry of Earth Sciences, conducted a pilot-study at the Indira Gandhi International Airport (IGIA) and at the Indian Council of Agrigultural Research at Pusa as preparation for the project.
Currently, the IMD issues fog advisories to airports. But they are, at best, delivered a few hours in advance and don’t give information on when the fog is expected to lift. “If information like that were to be available, then airlines could arrange to cancel flights…that saves money and avoids inconvenience to people,” Mr. Rajeevan added.
Many variables
Meteorologists with private organisations said that predicting the intensity of fog was extremely challenging and made forecasts useless. “There are too many variables involved… pollutants, moisture — and they interfere with models,” said Mahesh Palawat, Chief Meteorologist, Skymet Weather.
