Interannaul variation of fog in Pintang island and the analysis of spring circulation in 1961-2010
With method of wavelet analysis,characteristics of fog-day change in Pingtan Island in the past 50 years has been studied according to the monthly data measured from 1961-2010.The results indicate that it is quasi-triennial period with 1961-1975 and 1985-1990 through significance test.The days of fog descend with undulation by nine-point moving average,and the rate of descend is-0.26 d/a.The fog-day and fog-duration only increase simultaneously in February,while fog-day decreases and fog-duration increases in April and May.Based on NCEP\NCAR reanalysis data,the variation characteristics of fog-day in spring is analyzed.The results shows that in spring with more fog,the sea surface temperature at the TAIWAN STRAIT is lower,while the temperature at the equatorial pacific is warmer obviously,and Western Pacific Subtropical High is enhanced and the East Asia trough moves more southerly,which benefits meridian circulation.Furthermore,the profiles of vertical circulation along 115°E,20°N to 125°E,30°N illustrate that there exists distinct sinking motion on the ground layer for more stratification stability during the spring of more fog.Finally,the vertically integrated moisture flux shows that water vapor comes from the South China Sea and the Bay of Bengal especially on the level of 850hPa during the spring of more fog.But the characters during the spring of less fog,such as sea surface temperature,the intensity and location of Western Pacific Subtropical High,vertical circulation,moisture flux,are opposite to during the spring of more fog.
国家科技期刊平台
NSTL
万方数据
