| WANG Hui,HAN Shuzong,FAN Wenjing,WANG Guosong,LIU Kexiu,ZHANG Zengjian. 2016. Characteristics and possible causes of sea level anomalies in the Xisha sea area. Acta Oceanologica Sinica, 35(9):34－41 |
| Characteristics and possible causes of sea level anomalies in the Xisha sea area |
| 西沙周边海域海平面异常变化特征及成因分析 |
| Received:October 16, 2015 Revised:November 13, 2015 |
| DOI：10.1007/s13131-016-0938-2 |
| Key words:Xisha sea area sea level anomalies ENSO wind current SST |
| 中文关键词: 西沙海域 海平面异常 ENSO 风 海流 海温 |
| 基金项目: |
| Author Name | Affiliation | E-mail | | WANG Hui | National Marine Data & Information Service, State Oceanic Administration, Tianjin 300171, China | | | HAN Shuzong | College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266003, China | hansz@ouc.edu.cn | | FAN Wenjing | National Marine Data & Information Service, State Oceanic Administration, Tianjin 300171, China | | | WANG Guosong | National Marine Data & Information Service, State Oceanic Administration, Tianjin 300171, China | | | LIU Kexiu | National Marine Data & Information Service, State Oceanic Administration, Tianjin 300171, China | | | ZHANG Zengjian | National Marine Data & Information Service, State Oceanic Administration, Tianjin 300171, China | |
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| Abstract: |
| Based on the analysis of wind, ocean currents, sea surface temperature (SST) and remote sensing satellite altimeter data, the characteristics and possible causes of sea level anomalies in the Xisha sea area are investigated. The main results are shown as follows:(1) Since 1993, the sea level in the Xisha sea area was obviously higher than normal in 1998, 2001, 2008, 2010 and 2013. Especially, the sea level in 1998 and 2010 was abnormally high, and the sea level in 2010 was 13.2 cm higher than the muti-year mean, which was the highest in the history. In 2010, the sea level in the Xisha sea area had risen 43 cm from June to August, with the strength twice the annual variation range. (2) The sea level in the Xisha sea area was not only affected by the tidal force of the celestial bodies, but also closely related to the quasi 2 a periodic oscillation of tropical western Pacific monsoon and ENSO events. (3) There was a significant negative correlation between sea level in the Xisha sea area and ENSO events. The high sea level anomaly all happened during the developing phase of La Ni.a. They also show significant negative correlations with Niño 4 and Niño 3.4 indices, and the lag correlation coefficients for 2 months and 3 months are -0.46 and -0.45, respectively. (4) During the early La Ni.a event form June to November in 2010, the anomalous wind field was cyclonic. A strong clockwise vortex was formed for the current in 25 m layer in the Xisha sea area, and the velocity of the current is close to the speed of the Kuroshio near the Luzon Strait. In normal years, there is a "cool eddy". While in 2010, from July to August, the SST in the area was 2-3℃ higher than that of the same period in the history. |
| 中文摘要: |
| 本文使用风、海流、海温以及卫星高度计资料详细分析了西沙周边海域海平面异常变化的特征及成因。分析结果表明：（1）自1993年以来，西沙周边海域海平面在1998年、2001年、2008年、2010年和2013年海平面较常年偏高明显，其中，1998年和2010年存在显著的年际异常升高，2010海平面较常年高13.2cm，达到历史最高。2010年6-8月，该海域海平面升幅达43cm，超过该海域海平面年变幅的2倍。（2）该海域海平面在明显上升的同时，还存在较显著的9a、2-3a和4-7a的周期性波动，说明该海域海平面的变化除了受到天体引潮力的影响外，还与热带西太平洋季风在该海域准2a的周期性震荡以及ENSO事件密切相关。（3）进一步分析发现，西沙周边海域海平面变化与ENSO事件存在显著的负相关关系，该海域海平面异常升高均发生在拉尼娜事件的前期；该海域海平面与Nino4和Nino3.4滞后2个月和3个月的相关系数分别为-0.46和-0.45，均超过95%的显著性检验。（4）2010年海平面异常升高期间，正处于2010/2011年拉尼娜事件的前期，西沙周边海域风场异常；同期，25米层海流在该海域形成一较强的顺时针涡旋，流速接近黑潮在吕宋海峡附近速度，在该区域涡旋的存在对海面高度变化的贡献高达80%；西沙周边海域在常年为一冷涡，2010年7-8月，该海域海温较2009年同期偏高2-3℃，温度变化引起的比容海平面的变化对海平面高度变化起了一定的作用。 |
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