Technical Note: Mapping and forecasting of North Indian winter fog: an application of spatial technologies

In India, the Indo-Gangetic plain (part of Northern India) is invariably affected by dense fog in the winter months every year due to typical meteorological, environmental and prevailing terrain conditions. Pollution also plays an important role in the formation of fog (smoke+fog = smog) in India. Using National Oceanic and Space Administration-advanced very high resolution radiometer data the fog-affected regions in Northern India were delineated and the spatial extent of fog for the winter months of the years 2002-03, 2003-04 and 2004-05 (December-February) were studied and mapped. Forecast for future fog based on the analysis of satellite and meteorological (air temperature, relative humidity and wind speed) data was also done. The fog-affected areas were classified into maximum-fog-affected area, moderately fog-affected area and least fog-affected area. It has been found that in the winter months of the years 2002-03, 2003-04 and 2004-05, the fog-affected area in Northern India was about 867 000 km2, 625 000 km2 and 706 800 km2 respectively. The maximum fog-affected area was found to be 606 400 km2, the moderately fog-affected area was found to be 230 400 km2 and the least fog-affected area was found to be 404 500 km2. Further, based on meteorological parameters, such as temperature, humidity and wind speed along with elevation data was used to derive an approach for future fog prediction in this region.