IMD partners with premier institutes to forecast fog more accurately

Every year, travelling in north India during December and January is fraught with uncertainty brought by thick fog. Delhi or the National Capital Region is by far the worst affected region in the stretch as visibility, especially in the hours of dawn, plummets during these months. The news of traffic accidents due to low visibility and of flights and trains getting delayed or cancelled is almost a routine during this time of the year.

In an effort to mitigate the losses and inconvenience caused due to fog, the India Meteorological Department (IMD) has been collaborating with other premier scientific institutions to better understand and forecast fog formation.

As a part of these collaborations, a two-day brainstorming meet, titled “Understanding processes of fog formation and its use in forecasting”, was conducted by the IMD on December 14 and 15 at Prithvi Bhavan, Ministry of Earth Sciences, in Delhi. Scientists from IMD, Indian Institute of Tropical Meteorology (IITM), Indian Space Research Organisation (ISRO), Indian Institute of Sciences (IISc), IITs and other institutions working on fog and atmospheric sciences participated to share latest research on fog.

At the meeting, IMD Director General L S Rathore said, “We started the fog programme and began issuing fog forecasts in 2008. We have looked to improve all three components of fog forecasting – onset, condensation and dissipation – under this programme.” He explained that between 2008 and 2014, their accuracy had increased from 66 per cent to 92 per cent and flight diversion had reduced by 58 per cent. But there is still a lot of scope especially in railways, the power sector and agriculture to study impacts of fog on these areas and the way this impact can be reduced. “Work in railways is ongoing and we expect that a system for fog prediction shall be in place by next winter,” he added.

While the progresses made in fog modelling and tracking fog cover in the country using satellite imagery remained the main agenda for discussion, the role and interactions of aerosols, water content and atmospheric parameters were discussed at length during the two day meeting. “Fog is an important and complicated weather phenomenon that envelops Delhi-NCR and the Indo-Gangetic plain during winter months that causes a lot inconvenience and losses. The issue is even more pertinent around the international airport where we even see pockets of fog with different intensities. While we can predict onset of fog to some satisfaction, the way it evolves, its intensity and duration are still being looked at,” said R K Jenamani, the head of the airport met office and one of the main organizers of the meeting.

The meeting also served as a location to take stock of the pilot project, IITM-IMD Joint Delhi Fog Campaign, planned over five years and starting this year. This time, IMD and IITM will jointly monitor and analyse fog. The campaign, planned on the lines of the Paris and Toronto fog experiments, will look to further understanding of fog triggers, evolution, intensity and dissipation in order to help in forecasting efforts.

It was decided over two meetings at IITM, Pune, in August and September, that monitoring would begin this year. Sites at the IGI airport and the Pusa institute campus were identified following field studies for the installment of monitoring instruments. “There are several factors that affect formation and evolution of fog. We plan to look intently at the microphysics involved along with constant monitoring of other factors such as aerosols, dust and environmental factors such as relative humidity and atmospheric temperature which have not been addressed in models adequately,” said G S Bhat, a professor at the Centre for Atmospheric and Oceanic Sciences at IISc, Bengaluru, and the chairman of the fog campaign.

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