![]() We excluded the rainy days among fog days to remove fog accompanied by rain. A fog day was defined as a day where there was one or more observations of fog, as defined by Cereceda and Schemenauer (1991). The first observation and last observation were taken at 07 LST, respectively, in winter. ![]() During most of this period, observations were made every 3 h from 0600 to 1800 local standard time (LST). These stations report fog when the visibility is 1 km or less. The typical elevation of a lighthouse is less than 100 m, except in Sonmido, Chilbaldo, and Ullungdo, South Korea. The island stations are lighthouses that observe fog, air temperature, and sea surface temperature. Coastal stations on the mainland are standard meteorological stations that routinely observe meteorological data. Most stations are located along the coast of the mainland in the east sea, whereas many stations are located on islands in the west sea. In this study, we documented historical data on sea fog and investigated the relation between sea fog occurrence and its environmental factors around the Korean Peninsula.įigure 2 shows nine coastal stations and 15 island stations for sea fog observations from 1986 to 1995. Although there have been routine observations of sea fog at island and coastal stations, most of the observation data were not documented. However, there has been a lack of understanding of the structure of sea fog occurrence and its spatial and seasonal variations. (1997) and Kim (1997) investigated the characteristics and occurrence of sea fog in the east sea. Kim and Lee (1970) classified the Korea peninsula into several regions by fog occurrence characteristics. There have been some reports on sea fog around the Korean peninsula ( Byun et al. These factors create different sea surface temperatures that may be important in the formation of sea fog ( Lee 1992). ![]() 1) originating from the Kuroshio, supplies heat to the east sea and the south sea throughout the year, while it has little effect on the west sea. The tidal current is more than 1.5 m s −1 at maximum velocity in the west sea and less than 0.3 m s −1 in the east sea ( Lee 1992). The west sea and the south sea are shelf seas with maximum depths of less than 100 m, while the east sea has a mean depth of over 1000 m. The west sea (Yellow Sea), the south sea, and the east sea (Japan Sea) of Korea show different characteristics in many oceanographic aspects ( Fig. Luckily, there are many island stations that routinely observe sea fog around the Korean peninsula. Well-documented data have been rare, however, because it is hard to observe sea fog routinely. An analysis of historical data on sea fog occurrence and its meteorological and oceanographic environments could provide useful information in understanding the physical processes and character specific to the region. This is mainly due to the lack of understanding of sea fog under various synoptic conditions in this region. However, there has been no proper forecasting of sea fog occurrence. In particular, the dense sea fogs have frequently caused the collision of ships. The disasters usually occur during bad weather, such as storms and sea fog ( Lee 1992). A heavy frequency of sea fog of more than 50% appears frequently in cold water regions by strong tidal mixing when DPT is over 12☌ and DPT–SST is larger than 2☌ in summer.ĭisasters at sea around the Korean peninsula have greatly increased, because transports by sea have increased with recent industrial development. The frequency of sea fog increases greatly when the DPT is high and the value of DPT minus SST (DPT–SST) is large. It is clearly shown that the sea fog occurrence depends on dewpoint temperature (DPT) and sea surface temperature (SST). Strong tidal currents provide relatively cold surface water at the mixing region in summer. The heavy frequency of sea fog occurrence appears at the strong tidal mixing region in the west sea in summer, when the temperature difference between the air and the sea surface is large. ![]() The value of the air temperature minus the sea surface temperature is highest in all seas in July, when the frequency of sea fog occurrence is at its maximum. The frequency shows a maximum in the west sea and a minimum in the east sea in spite of their similar latitude. The frequency of sea fog occurrence is at its maximum in July in all seas around the Korean peninsula. Historical daytime sea fog data were used to investigate the relationships between sea fog occurrence and its associated environmental factors. There are many island stations that routinely observe sea fog around the Korean peninsula.
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