Application of satellite cloud image to monitoring and early warning of heavy fog along the coast

Based on FY-2E satellite image from 2005 to 2010, the weather data of 28 heavy fog events along the coast and meteorological data from island weather stations from 2008 to 2010, the satellite cloud image with aerological sounding data, the surface weather chart was overlaid and temperature of the inversion layer profile of temperature field and TBB values were compared with sea surface temperature, and the areas and depth of sea fog, the temperature in fog region in autumn and winter were evaluated with MICAPS 3.0 system by the atmospheric static equation and thermodynamic theory. The results indicate that the fog monitored with infrared image and visible cloud image changes from light fog to heavy fog along the coast of Dalian, Yantai and Tianjin under special circulation background around the Bohai sea regions, and it moves to the north along the coast. The vertical depth of fog reaches 400-600 m, the lapse rate of temperature is 0.02-0.04 ℃/100 m. The difference values of temperature are 1-2 ℃ and 3-5 ℃ between the east and the west directions and between the south and the north directions in the Bohai sea, respectively. Radiative fog and advection fog are associated with weakly high and low pressure fields, respectively. The heavy fog is strengthened for the fog area is covered by the low cloud, while the visibility of the light fog is weakened because of the overlaying of low cloud. The advection fog is mixed into water vapor conveyer belt of low level after it is lifted by the frontal surface, which is indicative to subsequent snowfall or rainfall. The effect of forecasting for these heavy fog events during 2009-2010 is good in terms of the above mentioned method, and it could provide guidelines for selecting the forecasting factors and improving the work flow of forecasting and monitoring operation of heavy fog events.