In order to make ship’s crew understand the regular pattern of fog setting or lifting in the northern coastal area of the Yangtze River estuary and provide reference for its
prediction of fog, based on the ground meteorological observation data of three
meteorological stations in Nantong, Qidong and Haimen between 1981 and 2010, the climatic
characteristics of fog in the northern coastal area of the Yangtze River estuary and its
relationship with meteorological elements were analyzed statistically. The results show
that the fog in the northern coastal area of the Yangtze River estuary is featured by
obvious inter-annual variation. The average is 16-17 days annually. The probability of the
dense fog (visibility ≤0.5 km) is more than 60%. Seasonal changes of fog are obvious,
mostly in winter, followed in spring and autumn, and the least in summer. The fog mainly
occurs from midnight to morning and dissipates after sunrise. The relative humidity is over
90%, the wind direction is E-ESE-SE-SSE, the wind speed is below 4 m/s, the sea level
pressure is between 101.5 and 103.0 kPa, and the temperature is in the range of 2℃-20℃,
all of which are favorable conditions for fog formation. The smaller the wind speed is, the
greater the relative humidity is, and the thicker the fog is formed.