台风对上层海洋初级生产力和营养盐输运的影响

Impacts of Typhoon on Ocean Primary Production and Nutrients Transport

利用垂直一维物理-生物耦合模型模拟了台风"派比安"和超强台风"珍珠"对南海北部水温、营养盐和叶绿素垂直分布的影响,并估算了2次台风对初级生产力和营养盐垂直输送的贡献。结果表明,"派比安"引发50m以浅海水温度降低,表层降温2.0℃,50~130m海水温度升高,混合层加深30m,海表叶绿素浓度增加0.18mg·m^(-3),营养盐垂向输运对初级生产力的贡献为2.3×103 mg C·m^(-2),约占全年的3%。"珍珠"引发55m以浅海水温度降低,表层降温超过5.0℃,55~150m海水温度升高,混合层加深85m,海表叶绿素浓度增加0.9mg·m^(-3),带来的营养盐垂向输运量约为全年的30%,对初级生产力的贡献为12.8×103 mg C·m^(-2),约占全年的18%。可见,台风过程,特别是强台风过程对上层海洋的初级生产和生物地球化学过程具有显著影响。台风的强度和移动速度等自身特征是决定海洋环境要素对台风响应程度的核心要素,同时台风过境前的水体层化状态和营养盐水平也是不可忽视的因素。

Typhoons are intense atmospheric events with strong effects on the physical and biological environment in oceans.In this study,a 1-D physical-biological coupled model was used to study the impacts of the typhoon Prapiroon and the supper typhoon Chanchu on the vertical structures of water temperature,nutrients and chlorophyll-a in the northern South China Sea.The model successfully reproduced the climatological seasonal variations of the physical and biological elements by comparing the model results and the observations at the SEATS station.Besides,the sea surface temperature（SST）and chlorophyll-a concentration（Chl-a）compared well with satellite data during the typhoon passages.The model results indicated that the typhoon Parpiroon resulted in cooling in the water above 50 m with the maximum decrease of SST by 2.0℃,and warming in the deep layer from 50 mto about 130 m.The mixed layer depth（MLD）deepened by 30 m.The maximum increase of sea surface Chl-a was 0.18 mg m-3.The integrated primary production（IPP）yielded by typhoon Prapiroon was 2.3×10^3 mg C·m-3,accounting for～3% of the annual IPP.Typhoon Chanchu resulted in cooling in the water above 55 m with the maximum decrease of SST by 5.0℃,and warming in the deep layer from 55 mto about 150 m.The MLD deepened by 85 m.The maximum increase of Chl-aat surface was 0.90mg·m-3.The upward amounts of nutrients pumped by typhoon Chanchu accounted for～30% of annual value.The IPP yielded by typhoon Chanchu reached up to 12.8×10^3 mg C·m^-3,accounting for 18% of the annual IPP.In addition,the effects of typhoons on ocean ecosystem mainly depend on the intensity and translation speed of typhoons,and the pre-conditions of the ocean before typhoon passage such as water stratification and nutrients level should also be considered.