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The seasonal cycle and variability of sea level in the South China Sea

The seasonal cycle and variability of sea level in the South China Sea
The seasonal cycle and variability of sea level in the South China Sea
The spatial and temporal characteristics of the seasonal sea level cycle in the South China Sea (SCS) and its forcing mechanisms are investigated using tide gauge records and satellite altimetry observations along with steric and meteorological data. The coastal mean annual amplitude of the seasonal cycle varies between zero and 24 cm, reaching a maximum between July and January. The maximum mean semiannual amplitude is 7 cm, peaking between March and June. Along the coast, the seasonal cycle accounts for up to 92% of the mean monthly sea level variability. Atmospheric pressure explains a significant portion of the seasonal cycle with dominant annual signals in the northern SCS, the Gulf of Thailand and the north-western Philippines Sea. The wind forcing is dominant on the shelf areas of the SCS and the Gulf of Thailand where a simple barotropic model forced by the local wind shows annual amplitudes of up to 27 cm. In the deep basin of the SCS, the Philippines Sea and the shallow Malacca Strait, the steric component is the major contributor with the maximum annual amplitudes reaching 15 cm. Significant variability in the seasonal cycle is found on a year-to-year basis. The annual and semiannual amplitudes vary by up to 63% and 45% of the maximum values, 15 cm and 11 cm, respectively. On average, stepwise regression analysis of contribution of different forcing factors accounts for 66% of the temporal variability of the annual cycle. The zonal wind was found to exert considerable influence in the Malacca Strait.
seasonal sea level, steric, wind, South China Sea, Gulf of Thailand, Malacca Strait, Philippines Sea
2169-9275
5490-5513
Amiruddin, A.M.
3ea6660f-1d69-4ae4-bd71-a8f8373cdc9e
Haigh, I.D.
945ff20a-589c-47b7-b06f-61804367eb2d
Tsimplis, M.N.
df6dd749-cda4-46ec-983c-bf022d737031
Calafat, F.M.
7c43d62a-c376-446c-93b4-87d4c1bd9d05
Dangendorf, S.
113c456d-61d9-476f-9a5f-86e558ebc442
Amiruddin, A.M.
3ea6660f-1d69-4ae4-bd71-a8f8373cdc9e
Haigh, I.D.
945ff20a-589c-47b7-b06f-61804367eb2d
Tsimplis, M.N.
df6dd749-cda4-46ec-983c-bf022d737031
Calafat, F.M.
7c43d62a-c376-446c-93b4-87d4c1bd9d05
Dangendorf, S.
113c456d-61d9-476f-9a5f-86e558ebc442

Amiruddin, A.M., Haigh, I.D., Tsimplis, M.N., Calafat, F.M. and Dangendorf, S. (2015) The seasonal cycle and variability of sea level in the South China Sea. Journal of Geophysical Research: Oceans, 120 (8), 5490-5513. (doi:10.1002/2015JC010923).

Record type: Article

Abstract

The spatial and temporal characteristics of the seasonal sea level cycle in the South China Sea (SCS) and its forcing mechanisms are investigated using tide gauge records and satellite altimetry observations along with steric and meteorological data. The coastal mean annual amplitude of the seasonal cycle varies between zero and 24 cm, reaching a maximum between July and January. The maximum mean semiannual amplitude is 7 cm, peaking between March and June. Along the coast, the seasonal cycle accounts for up to 92% of the mean monthly sea level variability. Atmospheric pressure explains a significant portion of the seasonal cycle with dominant annual signals in the northern SCS, the Gulf of Thailand and the north-western Philippines Sea. The wind forcing is dominant on the shelf areas of the SCS and the Gulf of Thailand where a simple barotropic model forced by the local wind shows annual amplitudes of up to 27 cm. In the deep basin of the SCS, the Philippines Sea and the shallow Malacca Strait, the steric component is the major contributor with the maximum annual amplitudes reaching 15 cm. Significant variability in the seasonal cycle is found on a year-to-year basis. The annual and semiannual amplitudes vary by up to 63% and 45% of the maximum values, 15 cm and 11 cm, respectively. On average, stepwise regression analysis of contribution of different forcing factors accounts for 66% of the temporal variability of the annual cycle. The zonal wind was found to exert considerable influence in the Malacca Strait.

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More information

Accepted/In Press date: 7 August 2015
e-pub ahead of print date: 7 August 2015
Published date: August 2015
Keywords: seasonal sea level, steric, wind, South China Sea, Gulf of Thailand, Malacca Strait, Philippines Sea
Organisations: Physical Oceanography, Marine Physics and Ocean Climate

Identifiers

Local EPrints ID: 380305
URI: https://eprints.soton.ac.uk/id/eprint/380305
ISSN: 2169-9275
PURE UUID: 1eae6d4b-3371-43e0-a55e-6c77114e3a4b

Catalogue record

Date deposited: 12 Aug 2015 09:31
Last modified: 06 Jul 2018 16:31

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