According to SAFAR bulletin, the air quality failed to improve as expected even when the wind conditions were better because of the high stubble burning.
A considerable contribution to aggravated levels of pollution in the winters is due to inversion-triggered long periods of low ventilation and a consequent build-up of pollutants.
According to a bulletin from SAFAR, the air quality failed to improve as expected even when the wind conditions were better because of the high stubble burning
Delhi continues to experience ‘very poor’ quality air as farm fires increased to an estimated 40%, on Sunday, the highest recorded so far this year, reported IE. Stubble burning from neighbouring states like Haryana, Uttar Pradesh, Punjab and Uttarakhand contributed to the ‘very poor’ AQI, finds the Centre’s System of Air Quality and Weather Forecasting And Research (SAFAR).
According to a bulletin from SAFAR, the air quality failed to improve as expected even when the wind conditions were better because of the high stubble burning and night-time trapping of pollutants due to low boundary layer height during winters.
Boundary layer height is the maximum height in the atmosphere where the pollutants can travel. It is also referred to as mixing depth. During winter when the temperature is low and wind speed falls and with low sunlight, the boundary layer height falls, not letting pollutants to disperse and causing higher level pollution near the ground surface.
Sunday, November 1, was this season’s coldest day with the lowest minimum temperature recorded at IMD’s Safdarjung observatory at 11.4 degree Celsius. This winter is all set to break records as the Safdarjung Observatory normally records lowest minimum 14 -16 degree Celsius during the first week on November.
Night-time wind speed has fallen to 3 kmph or lower in the past one month until early morning. It is a normal phenomenon as monsoon season retrenches, making a dispersion of pollutants a hindrance. , said an IMD official. Although the wind speed that improves during the day over the last couple of days, the director is being favourable for the transport of pollutants from states practising stubble burning, further mentioned the official.
The AQI is set to marginally deteriorate on November 3 and any chances of its improving is dependant on stubble fire episodes from neighbouring states, concluded the SAFAR bulletin.