Journal of Tropical Oceanography >
Impacts of Northwest Pacific anomalous anticyclone on sea surface height and circulation
Received date: 2016-12-31
Request revised date: 2017-04-06
Online published: 2017-07-26
Supported by
National Natural Science Foundation of China (41525019, 41521005)
“Global Changes and air-sea interaction” of State Oceanic Administration (GASI-IPOVAI-02)
Strategic Priority Research Program of the Chinese Academy of Sciences (XDA11010103)
International Partnership Program for Creative Research Teams (CAS/SAFEA)
Copyright
In this study, we investigate the Northwest Pacific anomalous anticyclone (NWPAC) associated with Indian Ocean warming and its impacts on ocean circulation and sea surface height in the northwest pacific by using the reanalysis wind, current and sea surface height data of National Centers for Environmental Prediction (NCEP) and SODA v2.2.4 during the period of 1971 to 2010. Composite results reveal that the NWPAC associated with Indian Ocean warming is the strongest during the boreal summer and it has significant impacts on the upper-ocean circulation and sea surface height in the NW Pacific. The anticyclonic wind anomaly produces a negative wind stress curl, inducing convergence of sea surface water and the resultant positive sea level anomalies. The effect of NWPAC on the upper-ocean circulation in the South China Sea is synchronous, while its impact on the upper ocean east of the Philippines delays by about one season and peaks in the boreal autumn. This may be attributed to the modulation of westward oceanic Rossby wave.
SHI Yanping , DU Yan , CHEN Zesheng . Impacts of Northwest Pacific anomalous anticyclone on sea surface height and circulation[J]. Journal of Tropical Oceanography, 2017 , 36(4) : 10 -17 . DOI: 10.11978/2016136
Fig. 1 Time series of Northwest Pacific anomalous anticyclone (NWPAC) index (a) and histogram of the 12 months’ standard deviation of NWPAC index (b)图1 标准化的1971—2010年西北太平洋反气旋指数(a)和1—12月西北太平洋反气旋指数的标准差(b) (a)中横线分别是正负一倍标准差所处的位置 |
Fig. 2 Averaged profile of zonal velocity in 112°45′E- 114°45′E, 10°15′N-11°15′N (a) and 135°45′E-137°45′E, 12°15′N-13°15′N(b)图2 112°45′E—114°45′E、10°15′N—11°15′N(a)和135°45′E—137°45′E、12°15′N—13°15′N(b)海域0~600m平均纬向流速随深度的变化 |
Fig. 3 Composites of 1000 hPa wind anomalies in the Northwest Pacific (125°E, 0-50°N) in NWPAC-IOBM years图3 NWPAC-IOBM年西北太平洋(125°E、0—50°N) 1000hPa的合成异常风场随时间变化 |
Fig. 4 Zonally-averaged sea surface height anomalies in the South China Sea (10°N-22°N, 112°45′E-118°45′E) (a, b) and the Northwest Pacific (129.75°E-139.75°E, 5°N-30°N) (c, d) during NWPAC-IOBM years (a, c) and La Niña events (b, d)图4 南海海域(10°N—22°N, 112°45′E—118°45′E) NWPAC-IOBM年(a)和单纯La Niña年(b)纬向平均的海平面高度异常(sea surface height anomalies, SSHA)随时间的变化; 西北太平洋海域(5°N—30°N, 129°45′E—139°45′E) NWPAC-IOBM年(c)和单纯La Niña年(d)纬向平均的海平面高度异常随时间的变化 |
Fig. 5 1000hPa wind anomalies and vorticity in spring (a), summer (b) and autumn (c) during NWPAC-IOBM years.图5 NWPAC-IOBM年春季(a)、夏季(b)、秋季(c)的异常风场(1000hPa)及其对应的涡度场 |
Fig. 6 Seasonal mean current anomalies (vector) in the upper (0~112m) layer and sea surface height anomalies (shading) in spring (a), summer (b) and autumn (c) during NWPAC-IOBM years图6 NWPAC-IOBM年春季(a)、夏季(b)、秋季(c)的异常流场(0~112m平均, 矢量)和海平面高度异常场(填色) |
Fig. 7 Seasonal mean current anomalies in the upper (0~112 m) South China Sea and sea surface height anomalies in spring (a) and summer (b) during NWPAC-IOBM years图7 NWPAC-IOBM年春季(a)、夏季(b)南海海域异常流场(0~112m平均, 矢量)和海平面高度异常场(填色) |
The authors have declared that no competing interests exist.
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