BEIHAI

natural conditions Wind conditions: The wind direction in the port varies significantly seasonally, with northerly winds prevailing in winter and mostly southeasterly winds in summer. The prevailing wind direction is north, followed by southeast, with frequencies of 22.1% and 10.8%, respectively. In summer and autumn, typhoons affect the port 2-4 times a year on average. When a typhoon enters the Beibu Gulf from the South China Sea, it is usually only 6-10 levels due to the obstruction of Hainan Island and Leizhou Peninsula. Strong winds with wind speeds greater than 8 levels occur an average of 11.1 days per year. Precipitation: The annual precipitation ranges from 849.1 millimeters to 2211.2 millimeters, with an average annual precipitation of 1664 millimeters. It is mainly concentrated from July to September, with thunderstorms being the most common, and is significantly affected by the passage of typhoons. Fog condition: The average annual number of foggy days is 13.2 days, mainly concentrated in spring. The appearance time usually starts from 02:00 and ends at 09:00, mostly advection fog, with a visibility of 100-800 meters. Temperature: Beihai Port has a subtropical maritime climate with an average annual temperature of 22.6 ℃. The highest temperature over the years is 37.1 ℃, and the lowest temperature over the years is 2 ℃. Ice condition: Hong Kong is located in the subtropical zone and there is no freezing throughout the year. Tide: Beihang Port belongs to a mixed tide type dominated by irregular diurnal tides. The flood season of high tide is full day tide, with an average of 22 days per month. The Xiaochao flood season is a semi diurnal period with an average of 8 days per month. The highest tide level is 5.55 meters, the lowest tide level is 0.03 meters, the maximum tidal range is 5.36 meters, the minimum tidal range is 0.17 meters, and the average tidal range is 2.55 meters. Tide: During the high tide flood season in Shibuling Port Area of Beihang Port, the average flow velocity of the rising tide is 0.13 meters per second. The average flow velocity during ebb tide is 0.31 meters per second; During the small tide flood season, the average flow velocity during high tide is 0.11 meters per second, and the average flow velocity during low tide is 0.15 meters per second. The maximum flow velocity during high tide is 0.79 meters per second, and the maximum flow velocity during low tide is 1.03 meters per second. During the long ebb tide process, local rotational currents are also formed. Apart from tidal currents, there are no residual currents generated by hydrological and meteorological factors. The measured residual current velocity is very small, ranging from 0.56 to 1.17 meters per second.