南海海表温度日变化特征及其影响因素研究

Diurnal variation of sea surface temperature in the South China Sea and its influencing factors

利用国家海洋环境预报中心的逐时海表温度(SST)数据和欧洲中期数值预报中心的ERA5数据集研究了南海海表温度日变化(DSST)的特征及其影响因素。研究结果表明:南海区域的DSST平均为0.56℃,总体呈纬向分布,近岸海域DSST幅度较大,但超过1.5℃的日增暖事件发生频次较少;南海DSST具有显著的季节变化特征,总体表现为春季最大(约0.7℃),冬季最小(约0.2~0.3℃);净辐射通量日变化和风速的季节变化是影响南海DSST季节变化的主要原因,南海月平均DSST与净辐射通量日变化的季节变化具有很好的一致性,DSST随着净辐射通量日变化的增加而增大,但DSST与风速的变化关系则相反;南海季风对南海DSST的季节变化也有着重要影响;南海SST具有明显的日循环特征,通常在每日16时到达峰值,08时到达谷值;影响南海SST日循环的主要因素为净辐射通量的日循环,风速日循环的影响相对较小。

Based on the hourly sea surface temperature(SST)data from National Marine Environment Forecasting Center and ERA5 datasets from European Center for Medium Weather Forecasting,the characteristics and influencing factors of diurnal variation of sea surface temperature(DSST)over the South China Sea are studied in this article.The results show that the climatology of DSST exhibits a zonal variation with a mean value of about 0.56℃.Also,the amplitude of DSST in offshore areas is larger while the frequency of warming events of DSST exceeding 1.5℃is rare.The DSST shows significant seasonal variation character istics with peak in spring(about 0.7℃)and valley in winter(about 0.2~0.3℃).This is mainly due to the seasonal variations of diurnal variation of net radiation flux and the wind speed over the South China Sea.Totally,the seasonal DSST increases along with the increase of diurnal variation of net radiation flux and the decrease of mean wind speed.Meanwhile,the South China Sea monsoon also plays an important role in the seasonal variation of DSST.The SST in the South China Sea also has an obvious diurnal cycle,which commonly reaches the peak at 16 p.m.and the valley at 8 a.m.The main factor affecting SST diurnal cycle in the South China Sea is the diurnal cycle of net radiation flux,while the influence of wind speed is relatively small.