NEW DELHI: The Indian Institute of Tropical Meteorology (IITM) has developed an early warning system for predicting fog cover and visibility, which will for the first time look at the role of pollution (aerosols) in fog and dropped visibility in the Delhi-NCR during winters, scientists said on Thursday.
This system will not only help agencies prepare for severe fog spells that Delhi sees in December and January, but will also help in gauging its impact on the region's air quality, said scientists. The fog prediction system, which has been launched by IITM in collaboration with the UK Met office on an experimental basis, will give out advance forecasts of fog, visibility across the Indo-Gangetic Plains (IGP) and will also show how aerosols present in the atmosphere are impacting these.
"Basically, it will be an air quality forecast system coupled with fog and visibility prediction. Based on the past data, it has been observed that many a times, swelled aerosols (having consumed water from moisture content in the atmosphere) become heavier and form a thick layer, while there are no droplets of fog as such present in it, which reduce the visibility below 300 metres," said Sachin Ghude, scientist at IITM Pune.
IITM scientists said that at present, on an experimental basis, the system is giving predictions for two days in advance, but the technology is being studied and will be verified of its accuracy before the portal is launched full-fledgedly.
The system can predict probability of dense fog cover, when air quality reduces to less than 200 metres and up to 50 metres. Besides, it also shows the size of dust particles and its impact on visibility. "Most aircrafts cannot operate below 75 metres visibility. They can land but not take off when visibility is that low. We had been getting requests from the Delhi airport to develop a system that can help gauge the fog scenario in advance and help them prepare ahead of it," said Ghude.
This November, Delhi saw a similar smog episode when a thick layer of pollutants reduced the visibility at the city airports — IGI and Safdarjung — to below 300 metres. Meanwhile, the city saw a relatively cold day on Thursday, with the maximum temperature falling to 19.8 degrees C — three notches below normal for this time of the year.