A study of the mixed layer of the South China Sea based on the multiple linear regression

2012 ◽  
Vol 31 (6) ◽  
pp. 19-31 ◽  
Author(s):  
Rui Duan ◽  
Kunde Yang ◽  
Yuanliang Ma ◽  
Tao Hu
2013 ◽  
Vol 43 (3) ◽  
pp. 498-506 ◽  
Author(s):  
Jiayi Pan ◽  
Yujuan Sun

Abstract The ocean responses to Typhoon Cimaron, which influenced the South China Sea (SCS) from 1 to 8 November 2006, are analyzed. Based on satellite-observed sea surface temperature (SST) and climatological temperature profiles in the SCS, mixed layer deepening, an important parameter characterizing turbulent mixing and upwelling driven by strong typhoon winds, is derived. Corresponding to the SST drop of 4.4°C on 3 November 2006, the mixed layer deepened by 104.5 m relative to the undisturbed depth of 43.2 m, which is consistent with a simulation result from a mixed layer model. Furthermore, baroclinic geostrophic velocity and vorticity are calculated from the surface temperature gradient caused by the typhoon. The negative vorticity, associated with the typhoon cooling, indicated an anticyclonic baroclinic circulation strongest at the base of the mixed layer and at the depth of 50 m, the geostrophic speed reached as high as 0.2 m s−1. Typhoon Cimaron proceeded slowly (1.7 m s−1) when it was making a southwestward turn on 3 November 2006, resulting in a subcritical condition with a Froude number (the ratio of typhoon translation speed to first baroclinic mode speed) of 0.6 around the maximum SST drop location and facilitating high SST cooling and mixed layer deepening because of the absence of inertial-gravity waves in the wake of the typhoon. Comparison of Argo buoy data with the climatological temperature suggests that the average uncertainty in the mixed layer deepening estimation caused by the difference between Argo and climatological temperature profiles is less than 10 m.


2015 ◽  
Vol 28 (15) ◽  
pp. 5952-5968 ◽  
Author(s):  
Wei Mei ◽  
Chun-Chi Lien ◽  
I.-I. Lin ◽  
Shang-Ping Xie

Abstract The thermocline shoals in the South China Sea (SCS) relative to the tropical northwest Pacific Ocean (NWP), as required by geostrophic balance with the Kuroshio. The present study examines the effect of this difference in ocean state on the response of sea surface temperature (SST) and chlorophyll concentration to tropical cyclones (TCs), using both satellite-derived measurements and three-dimensional numerical simulations. In both regions, TC-produced SST cooling strongly depends on TC characteristics (including intensity as measured by the maximum surface wind speed, translation speed, and size). When subject to identical TC forcing, the SST cooling in the SCS is more than 1.5 times that in the NWP, which may partially explain weaker TC intensity on average observed in the SCS. Both a shallower mixed layer and stronger subsurface thermal stratification in the SCS contribute to this regional difference in SST cooling. The mixed layer effect dominates when TCs are weak, fast-moving, and/or small; and for strong and slow-moving TCs or strong and large TCs, both factors are equally important. In both regions, TCs tend to elevate surface chlorophyll concentration. For identical TC forcing, the surface chlorophyll increase in the SCS is around 10 times that in the NWP, a difference much stronger than that in SST cooling. This large regional difference in the surface chlorophyll response is at least partially due to a shallower nutricline and stronger vertical nutrient gradient in the SCS. The effect of regional difference in upper-ocean density stratification on the surface nutrient response is negligible. The total annual primary production increase associated with the TC passage estimated using the vertically generalized production model in the SCS is nearly 3 times that in the NWP (i.e., 6.4 ± 0.4 × 1012 versus 2.2 ± 0.2 × 1012 g C), despite the weaker TC activity in the SCS.


2021 ◽  
Author(s):  
Lili Zeng ◽  
Eric P. Chassignet ◽  
Xiaobiao Xu ◽  
Dongxiao Wang

2006 ◽  
Vol 59 (1-2) ◽  
pp. 97-110 ◽  
Author(s):  
Chung-Chi Chen ◽  
Fuh-Kwo Shiah ◽  
Shi-Wei Chung ◽  
Kon-Kee Liu

2017 ◽  
Vol 122 (6) ◽  
pp. 5088-5104 ◽  
Author(s):  
Xin Wang ◽  
Rongwang Zhang ◽  
Jian Huang ◽  
Lili Zeng ◽  
Fei Huang

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