| WANG Hui,LIU Kexiu,GAO Zhigang,FAN Wenjing,LIU Shouhua,LI Jing. 2017. Characteristics and possible causes of the seasonal sea level anomaly along the South China Sea coast. Acta Oceanologica Sinica, 36(1):9－16 |
| Characteristics and possible causes of the seasonal sea level anomaly along the South China Sea coast |
| 南海沿海季节性海平面异常变化特征及成因分析 |
| Received:October 09, 2015 Revised:November 13, 2015 |
| DOI：10.1007/s13131-017-0988-0 |
| Key words:seasonal sea level anomalies ENSO wind air pressure oscillations |
| 中文关键词: 季节性海平面异常 ENSO 季风 气压 振荡 |
| 基金项目:The National Key Research and Development Program of China under contract No. 2016YFC1402610. |
| Author Name | Affiliation | E-mail | | WANG Hui | National Marine Data and Information Service, State Oceanic Administration, Tianjin 300171, China | | | LIU Kexiu | National Marine Data and Information Service, State Oceanic Administration, Tianjin 300171, China | | | GAO Zhigang | National Marine Data and Information Service, State Oceanic Administration, Tianjin 300171, China | | | FAN Wenjing | National Marine Data and Information Service, State Oceanic Administration, Tianjin 300171, China | | | LIU Shouhua | National Marine Data and Information Service, State Oceanic Administration, Tianjin 300171, China | huazai950@hotmail.com | | LI Jing | College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China | |
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| Abstract: |
| Based on sea level, air temperature, sea surface temperature (SST), air pressure and wind data during 1980-2014, this paper uses Morlet wavelet transform, Estuarine Coastal Ocean Model (ECOM) and so on to investigate the characteristics and possible causes of seasonal sea level anomalies along the South China Sea (SCS) coast. The research results show that:(1) Seasonal sea level anomalies often occur from January to February and from June to October. The frequency of sea level anomalies is the most in August, showing a growing trend in recent years. In addition, the occurring frequency of negative sea level anomaly accounts for 50% of the total abnormal number. (2) The seasonal sea level anomalies are closely related to ENSO events. The negative anomalies always occurred during the El Niño events, while the positive anomalies occurred during the La Ni.a (late El Niño) events. In addition, the seasonal sea level oscillation periods of 4-7 a associated with ENSO are the strongest in winter, with the amplitude over 2 cm. (3) Abnormal wind is an important factor to affect the seasonal sea level anomalies in the coastal region of the SCS. Wind-driven sea level height (SSH) is basically consistent with the seasonal sea level anomalies. Moreover, the influence of the tropical cyclone in the coastal region of the SCS is concentrated in summer and autumn, contributing to the seasonal sea level anomalies. (4) Seasonal variations of sea level, SST and air temperature are basically consistent along the coast of the SCS, but the seasonal sea level anomalies have no much correlation with the SST and air temperature. |
| 中文摘要: |
| 本文通过对中国南海沿海1980年以来的潮位、风、气压、气温和海温等水文气象资料的分析，初步探讨了南海沿海季节性海平面异常变化的特征以及可能的成因。分析结果表明：(1)南海沿海海平面的季节变化区域特征明显，年变幅北边大南边小，约为15~30厘米。自北至南，海平面的迟角变化为135°~166°，相差1个月。(2)与渤海和黄海不同，南海沿海海平面出现异常的时间基本集中在1月至2月和6月至10月。其中，8月海平面出现异常的频次最高，且近年有增多的趋势。另外，这几个月海平面出现负异常的次数占全年总异常次数的50%。（3）从南海沿海海平面异常的时间分布特征来看，海平面出现正负异常的时间分布与ENSO事件密切相关，负异常出现的时间大多是在厄尔尼诺期间，而海平面出现正异常的时间基本是在拉尼娜期间（厄尔尼诺后期）。小波分析发现，南海沿海海平面在不同季节震荡周期存在明显差异，冬季与厄尔尼诺相关的3-7a的周期最为明显，其振幅约2cm；夏、秋季次之，春季较弱。(4)风场的异常变化是影响南海沿海海平面异常变化的重要因素，由风引起的风生流与海平面的高度场变化基本一致。另外，与渤海和黄海不同，中国南部沿海在夏秋季受热带气旋的影响时间集中，对海平面短期的影响更为明显。(5)中国沿海海平面的季节变化以年周期为主，在南海沿海海平面、海温、气温和气压等水文气象要素的季节性变化基本一致，但季节海平面的异常偏高或者偏低与海温、气温和气压的相关性较小。 |
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