EGU22-3307, updated on 14 Jun 2023
EGU General Assembly 2022
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Drivers for seasonal variability in sea level around the China seas

Ying Qu1,2,3, Svetlana Jevrejeva2,4, Joanne Williams2, and John Moore1,5,6
Ying Qu et al.
  • 1Beijing Normal University, College of Global Change and Earth System Science, Beijing, China (
  • 2National Oceanography Centre, 6 Brownlow Street, Liverpool, L3 5DA, UK
  • 3State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
  • 4Centre for Climate Research Singapore, Meteorological Service Singapore, Singapore
  • 5Arctic Centre, University of Lapland, P.O. Box 122, 96101 Rovaniemi, Finland
  • 6CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China

Globally variable ocean and atmospheric dynamics lead to spatially complex seasonal cycles in sea level. The China Seas, that is the Bohai, Yellow, East China and the South China seas, is a region with strong seasonal amplitudes, and straddles the transition between tropical and temperature zones, monsoonal and westerlies, shelf and deep ocean zones. Here we investigate the drivers for seasonal variability in sea level from tide gauge records, satellite altimetry along with output from the NEMO (Nucleus for European Modeling of the Ocean) model including sea surface height and ocean bottom pressure along with meteorological data in the China Seas. The seasonal cycle accounts for 37% - 94% of sea level variability in 81 tide gauge records, ranging from 18 to 59 cm. We divided the seasonal cycles into four types: 1) an asymmetric sinusoid; 2) a clearly defined peak on a flat background; 3) a relatively flat signal; 4) a symmetric co-sinusoid. Type 1 is found in northern China and Taiwan, Korea, Japan and The Philippines where Inverse Barometer (IB) effects dominates seasonality along with a steric contribution. The seasonal monsoon associated with barotropic response and freshwater exchange play important roles in type 2, (eastern and southern Chinese coasts), type 3 (East Malaysia) and type 4 (Vietnam and Gulf of Thailand). IB corrected seasonal cycle amplitudes are larger in continental shelf areas than the deep ocean, with a maximum in the Gulf of Thailand, and NEMO underestimates the seasonal amplitude along the coast by nearly 50%.

How to cite: Qu, Y., Jevrejeva, S., Williams, J., and Moore, J.: Drivers for seasonal variability in sea level around the China seas, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3307,, 2022.