광양만 해역 표층수온 변동특성

Abstract

Annual temporal and spatial fluctuation characteristics of sea surface temperature(SST) in Gwangyang Bay were studied by using the SST monitoring data for the period from November 2010 to October 2011. The monthly mean SST contour shows that warm sea surface areas developed near the Hadong thermal power plant through the year. The highest temperature (31.68°C) was measured at the outlet of Hadong thermal power plant(St.31) in Aug. 2011, and the lowest temperature(1.01°C) was measured at St.17 in Jan. 2011. The SST distribution shows that the temperature of the outlet(St.31) and near the outlet(St.19∼24) were high, while that of the south sea areas(St.1∼7) of Gwangyang Bay was low. The time series of SST at main stations shows that the patterns mostly expressed by regression-pattern all the year round and the yearly mean SST of near the Hadong thermal power plant(St.23) was approximately 3.5∼4.0°C higher than that of other stations. Also, SST of Seomjin River estuary(St.17) temporarily changed down and up due to heavy rain. The annual variation of SST was similar to that of air temperature. The difference of SST between air temperature became small when both SST and air temperature rise, while the difference of SST and air temperature became large when both SST and air temperature go down. The result of Maximum Entropy Method(MEM) analysis, there are commonly 6 peaks. The periods of these peak frequency are expressed as follows; (a) 24-hour’s cycle (b) 12-hour’s cycle (c) 8-hour’s cycle (d) 6-hour’s cycle (e) 5-hour’s cycle (f) 4-hour’s cycle. It seems that a diurnal-cycle variation of water temperature caused by solar radiation and a semidiurnal-cycle variation by tides are predominant. The temporal and spatial fluctuation characteristic of sea surface temperature was analysed by Empirical Orthogonal Function(EOF) method in Gwangyang Bay. The EOF analysis shows that the 1st mode which is almost close to 99% was extremely dominant, while 2nd and 3rd mode which are less than 1% were quite small.