04 Aug 2023
 | 04 Aug 2023

The Different Dynamic Influences of Typhoon Kalmaegi on two Pre-existing Anticyclonic Ocean Eddy

Yihao He, Xiayan Lin, Guoqing Han, Yu Liu, and Han Zhang

Abstract. Using multi-source observational data and GLORYS12V1 reanalysis data, we conducted a comparative analysis of different responses of two warm eddies, AE1 and AE2 in the northern South China Sea to Typhoon Kalmaegi during September 2014. The findings of our research are as follows: (1) For horizontal distribution, the area and the sea surface temperature (SST) of AE1 and AE2 decreased by about 31 % (36 %) and 0.4 °C (0.6 °C).The amplitude, Rossby number (Ro) and eddy kinetic energy (EKE) of AE1 increased by 1.3 cm, 1.4×10-2 and 107.2 cm2 s-2 after the typhoon, respectively, while AE2 weakened and the amplitude, vorticity and EKE decreased by 3.1 cm, 1.6×10-2 and 38.5 cm2 s-2, respectively. (2) In vertical direction, AE1 demonstrated enhanced convergence, leading to an increase in temperature and a decrease in salinity above 150 m. The response below the mixing layer depth (MLD) was particularly prominent (1.3 °C). In contrast, AE2 experienced cooling and a decrease in salinity above the MLD. Below the MLD, it exhibited a subsurface temperature drop and salinity increase due to the upwelling of cold water induced by the suction effect of the typhoon. (3) The disparity in the responses of the two warm eddies can be attributed to their different positions relative to Typhoon Kalmaegi. Warm eddy AE1, with its center located on the left side of the typhoon's path, experienced a positive work effect as the typhoon passed by. This induced a strong negative wind stress curl and triggered a negative Ekman pumping velocity (EPV), further enhanced by the converging sinking of the upper warm water, thereby strengthening AE1. On the other hand, warm eddy AE2, situated closer to the center of the typhoon, weakened due to the cold suction caused by the strong positive wind stress curl in the typhoon's center. These findings underscore the importance of relative positions of eddies in their interactions with typhoons.

Yihao He et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1734', Anonymous Referee #1, 24 Aug 2023
  • RC2: 'Comment on egusphere-2023-1734', Anonymous Referee #2, 08 Sep 2023

Yihao He et al.

Yihao He et al.


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Short summary
By utilizing multi-source observational data and GLORYS12V1 reanalysis data, we investigate the different responses of two warm eddies to typhoon Kalmaegi. Both AE1 and AE2 decrease in area and surface temperature during the typhoon, but other parameter exhibit opposite behaviors in AE1 and AE2. They also have different vertical structures. These differences attributed to their different positions, resulting in downwelling pumping in AE1 and upwelling suction in AE2.