基于SODA资料的南海表层风能输入的空间分布与长期趋势研究

海面风不仅是驱动上层海洋运动的主要动力, 其能量也是维持海洋表层流动的主要机械能来源。为了分析南海表层流风能输入的变化, 用SODA(Simple Ocean Data Assimilation)(1901—2010)资料估算了风向南海表层流(表层地转流+表层非地转流)的能量输入。结果表明, 风向南海表层流、表层地转流和表层非地转流输入的能量总体均呈减少趋势, 110年间分别减小了约56%、65%和49%。导致风能输入减小的最主要因素是风应力的减弱(减小了35%)。由于南海受季风系统的控制, 风向表层流及其各成分输入的能量呈现出显著的季节性变化。冬季风能输入最强, 高值区位于南海西部及北部区域, 呈一个显著的“回力镖”状结构。这些结果对深入认识南海环流具有理论意义。

Spatial patterns and secular trends of wind energy input into the surface layer in the South China Sea based on SODA reanalysis

Sea surface wind is not merely a major driving force to the upper-ocean currents; the wind energy input is the main source of mechanical energy to keep these currents moving. To analyze the secular trend of wind energy input into the South China Sea (SCS), we calculate the wind energy input into the surface current, surface geostrophic current and surface ageostrophic current from 1901 and 2010 by using SODA (v 2.2.4) data. The results show that during the past 110 years, the trend of the wind energy input into surface current, surface geostrophic current and surface ageostrophic current decreased on the whole. The reducing amplitude is 56%, 65% and 49%, respectively. The dominant factor is the decline of wind stress (about 35%). Due to the monsoon systems, seasonal variation of wind energy input into the SCS is significant. In winter, the wind energy input is the strongest, mainly in the north and west parts of the basin, and the shape of energy input distribution is like a “boomerang.” Our results have some implication for further understanding SCS circulation in terms of energy.