Author(s)

Dazhi Xu¹, Chunhua Qiu², Youfang Yan^3*

¹South China Sea Marine Prediction Center, State Oceanic Administration, Guangzhou, China.
²The Center for Coastal Ocean Science and Technology, School of Marine Sciences, Sun Yat-sen University, Guangzhou, China.
³State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.

Tropical cyclones (TCs) can affect the thermal structure in the upper ocean by mixing. In turn, upper-ocean thermal structure also affects the evolution of TCs. Here based on satellite data, in situ temperature and salinity observations and the best-track data of the U.S. Joint Typhoon Warning Center, combined with an ocean mixed layer model, the role of the pre-existing summer upwelling of the northern South China Sea (NSCS) in TCs self-induced sea surface cooling was explored. The modeling results showed that for a given atmospheric thermodynamic condition, TCs self-induced sea surface cooling is quite different when they pass over the regions with pre-existing upwelling and without upwelling. The amplitude of TCs self-induced cooling is larger by more than 50% in the region with pre-existing upwelling than that without. For example, for a slow-moving typhoon with translation speed of 4 m/s and wind speed of 45 m/s, TC self-induced surface cooling is 2.5°C when they pass over the upwelling region, but only 1.5°C when they pass over the region without upwelling. The results suggest that upwelling of the NSCS could amplify TCs self-induced cooling and play a negative role in TCs intensification before they made landfall in Southern China.

South China Sea, Summer Upwelling, Tropical Cyclone Intensity

Xu, D. , Qiu, C. and Yan, Y. (2019) Role of the South China Sea Summer Upwelling in Tropical Cyclone Intensity. American Journal of Climate Change, 8, 1-13. doi: 10.4236/ajcc.2019.81001.