Winter Fog Experiment Over the Indo-Gangetic Plains of India

Abstract

The objectives of the Winter Fog Experiment (WIFEX) over the Indo-Gangetic Plains of India are to develop better now-casting and forecasting of winter fog on various time-and spatial scales. Maximum fog occurrence over northwest India is about 48 days (visibility <1000 m) per year, and it occurs mostly during the December-February time-period. The physical and chemical characteristics of fog, meteorological factors responsible for its genesis, sustenance, intensity and dissipation are poorly understood. Improved understanding on the above aspects is required to develop reliable forecasting models and observational techniques for accurate prediction of the fog events. Extensive sets of comprehensive groundbased instrumentation were deployed at the Indira Gandhi International Airport, New Delhi. Major in situ sensors were deployed to measure surface micrometeorological conditions, radiation balance, turbulence, thermodynamical structure of the surface layer, fog droplet and aerosol microphysics, aerosol optical properties, and aerosol and fog water chemistry to describe the complete environmental conditions under which fog develops. In addition, Weather Forecasting Model coupled with chemistry is planned for fog prediction at a spatial resolution of 2 km. The present study provides an introductory overview of the winter fog field campaign with its unique instrumentation.

An operational fog prediction system for Delhi using the 330 m Unified Model

“…(NH 4 ) 2 SO 4 is the dominant aerosol type in the fog water sampled in Delhi as part of winter fog experiment (Ghude et al, 2017).…”

“…Although a large number of observational studies regarding fog in Delhi based on ground-based instrumentation exist (e.g., Ghude et al, 2017;Mohan & Payra, 2009), modelling attempts in simulating fog formation processes are limited. Payra and Mohan (2014) present some three-dimensional (3D) simulations using the Weather Research and Forecasting (WRF) model, demonstrating that the model can produce reasonable forecasts at the mesoscale, but postprocessing techniques can significantly improve the microscale skill.…”

“…In general, skill of numerical models in predicting fog is relatively poor, since fog is a small-scale phenomenon and depends not only on the meteorological conditions (wind speed, humidity, temperature) but also on the surface and aerosol characteristics (Gultepe, Muller, & Boybeyi, 2006).…”

Urban Heat Island Over Delhi Punches Holes in Widespread Fog in the Indo‐Gangetic Plains

“…Some of the major fertile regions subjected to dense fog cover include the central valley of California, Po valley in Europe, North China Plains (NCP), and Indo-Gangetic Plains (IGP) in south Asia (Baldocchi & Waller, 2014;Gautam et al, 2007;Ghude et al, 2017;Giulianelli et al, 2014;Hameed et al, 2000;Herckes et al, 2015;Quan et al, 2011). Low-lying plain, in the vicinity of continuous mountain ranges, is a common topographic feature among these fog-prevalent regions.…”

Modeling of the Effects of Wintertime Aerosols on Boundary Layer Properties Over the Indo Gangetic Plain

“…The lack of wet scavenging and weak ventilation (calm winds and low boundary layer height) during this season exacerbates the poor air quality conditions over North India. Long‐term observations show that majority of fog events occur over Northwest India during winter (December–February) with 60 % (74 days) of days are being classified as foggy (Ghude et al, ). Other parts of the Indian subcontinent (eastern and southern India) do not experience similar kinds of high aerosol/fog events.…”