Challenges in Early Warning of the Persistent and Widespread Winter Fog over the Indo- Gangetic Plains: A Satellite Perspective - Reducing Disaster: Early Warning Systems for Climate Change - page 49

Chapter 3
Challenges in Early Warning
of the Persistent and Widespread
Winter Fog over the Indo-Gangetic Plains:
A Satellite Perspective
Ritesh Gautam
Abstract Each year during the season (December-January), dense fog engulfs the
Indo-Gangetic Plains (IGP) in Southern Asia, extending over a stretch of 1,500 km,
for more than a month disrupting day-to-day life of millions of people inhabiting in
the IGP. Increasing atmospheric pollution combined with suffi cient moisture avail-
able due to the passage of frequent north-westerlies favor fog formation in this
region. Trends in poor visibility suggest a signifi cant increase in worsening air qual-
ity and foggy days over the IGP. The persistent and widespread nature of the winter
fog is strongly infl uenced by the regional meteorology during winter-time, i.e., a
stable boundary layer, cold temperatures, high relative humidity, and light winds.
The valley-type topography of the IGP, adjacent to the towering Himalaya, and high
concentrations of pollution aerosols/particulates, further favors the persistence of
hazy/fog conditions. A satellite- and surface-based observational portrayal is pre-
sented here, using various cloud, aerosol, and meteorological datasets, to character-
ize the widespread nature of winter fog. While the understanding of fog formation
is known in the literature, detailed surface observations are needed to help build
sophisticated fog forecast and early warning systems to minimize its impact on
public safety. Additionally, linkages between the seasonal fog cover, regional mete-
orology, and increasing air pollution should be further investigated against the back-
drop of a changing climate scenario.
Keywords Fog ￿ Haze ￿ Remote sensing ￿ Fog forecasting ￿ Aerosols ￿ Air quality
￿ Indo-Gangetic Plains ￿ South Asia