台风“巴蓬”对南海上层海洋水文特征与生态环境的影响

    The impact of typhoon "Phanfone" on hydrological characteristics and ecological environment of the upper ocean in the South China Sea

    • 摘要: 研究台风过境影响下海洋生态环境的变化是系统认识强天气过程下海洋响应问题的重要内容,对于防灾减灾、远洋运输等具有积极的意义。基于混合坐标海洋环流模式(Hybrid Coordinate Ocean Model, HYCOM)数据,结合Aqua卫星搭载的中分辨率成像光谱仪(MODIS)传感器数据,研究了慢速移动的台风“巴蓬”(1929号)过境对南海海表温度、叶绿素浓度以及水体垂向温盐结构和流场特征的影响。结果显示,台风“巴蓬”过境期间,波高由3 m增加至9 m,海表流速由0.3 m/s增加至0.7 m/s,台风周围最大流速甚至超过1.8 m/s;台风过境后,海表温度由原25.8 ℃下降至24.9 ℃。在台风影响下,水体垂向混合增加,混合层深度增加近15 m,从23 m到38 m。混合层内上部温度降低、盐度略微增加,下部温度升高、盐度降低;上层水体流速增加,方向偏转近90°,流速变化幅度由表及底逐渐减小。台风过境后3天内,由于温度降低、光照减弱,并且垂向混合增强补充的营养盐仍未被浮游植物充分利用,因此,叶绿素浓度并未快速升高,而是呈现短期内浓度微增的现象。

       

      Abstract: Based on Hybrid Coordinate Ocean Model (HYCOM) data and Moderate Resolution Imaging Spectroradiometer (MODIS) sensor data, we studied the impact of typhoon Phanfone on local surface temperature, chlorophyll-a concentration, vertical thermohaline structure, and ocean current in the South China Sea. Results show that in the typhoon event, wave height increased to 9 m and the velocity of surface current increased from 0.3 to 0.7 m/s, and reached the maximum of 1.8 m/s. After the typhoon passage, the sea surface temperature (SST) decreased from 25.8 ℃ to 24.9 ℃. The mixed layer depth increased by 15 m from 23 m to 38 m. In the upper part of the mixed layer, temperature decreased and the salinity slightly increased, while in the lower part, the opposite. The flow velocity of vertical layer increased with the direction deflection of nearly 90°, and the variation range of the flow velocity decreased gradually from the surface to the bottom. The chlorophyll-a concentration did not increase timely after the typhoon passage. As temperature and light were decreased during the typhoon, nutrients added by enhanced vertical mixing were not fully utilized by phytoplankton, resulting in a slightly increase in chlorophyll-a concentration three days after the passage of the typhoon Phanfone.

       

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