EGU21-8619
https://doi.org/10.5194/egusphere-egu21-8619
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Characteristics and mechanism of annual sea level variability in the southern tropical  Indian Ocean

Ke Huang
Ke Huang
  • South China Sea institute of Oceanology, LTO, China (kehuang@scsio.ac.cn)

The first baroclinic mode Rossby wave is known to be of critical importance to the annual sea level variability in the southern tropical Indian Ocean (STIO; 0°–20°S, 50°–115°E). In this study, an analysis of continuously stratified linear ocean model reveals that the second baroclinic mode also has significant contribution to the annual sea level variability (as high as 81% of the first baroclinic mode). The contributions of residual high-order modes (3 # n # 25) are much less. The superposition of low-order (first and second) baroclinic Rossby waves (BRWs) primarily contribute to the high energy center of sea level variability at ;108S in the STIO and the vertical energy penetration below the seasonal thermocline. We have found that 1) the low-order BRWs, having longer zonal wavelengths and weaker damping, can couple more efficiently to the local large-scale wind forcing than the high-order modes and 2) the zonal coherency of the Ekman pumping results in the latitudinal energy maximum of low-order BRWs. Overall, this study extends the traditional analysis to suggest the characteristics of the second baroclinic mode need to be taken into account in interpreting the annual variability in the STIO.

How to cite: Huang, K.: Characteristics and mechanism of annual sea level variability in the southern tropical  Indian Ocean, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8619, https://doi.org/10.5194/egusphere-egu21-8619, 2021.

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