基于WA方法的2013年夏秋越南东南外海暖涡初步分析

Preliminary analysis of the anti-cyclonic eddy off southeast Vietnam by WA method during summer and autumn in 2013

使用WA涡旋自动识别方法对2013年夏秋两季越南东南外海暖涡进行识别和追踪,同时利用同期CTD资料对该暖涡的内部结构和性质进行分析。结果显示:该暖涡于2013年夏初初步形成、呈单核结构,主要体现在跃层之下、100 m以深处,受暖涡影响的水体呈高温、低盐、低密特性,温盐等值线明显下凹。经过整个夏季的发展壮大,该暖涡在8—9月达到强盛且演化为双核结构,其西侧涡核强于东侧涡核,东侧涡核发育更快。发育最充分时涡旋纬向直径可达427 km,中心海平面高度异常达28.75 cm,最大振幅达6.04 cm,最大涡动能为384 cm2/s2,而涡旋强度则在涡旋形成之初达到最大值1.59×10-2cm2/s2km2。与夏初相比,秋季该暖涡的垂向上界提升到40 m,且在90—100 m最为显著。在100 m以浅,双核结构中西侧涡核更加强大、发育更加充分;从110 m层开始,西侧涡核中心北移且强度开始减弱,东侧涡核有所加强;在140 m层以下海域,西侧涡核基本消失,但东侧涡核仍然继续存在,其对盐度的影响持续到190 m层,对温度和密度的影响在200 m层仍可见。

The anti-cyclonic eddy off southeast Vietnam during summer and autumn in 2013 with satellite altimeter data and WA automated method is identified and tracked. At the same time, the interior structure and properties of the eddy are analyzed with CTD data. The anti-cyclonic eddy had a single core below 100 m in the early summer, with high temperature, low salinity and density, and deepened the isotherm and isohaline. The anti-cyclonic eddy was developed through summer and evolved into dual-core structure during the strongest period in August and September. The west core of the eddy was stronger than the east, and the east core was developed faster than the west. The largest zonal diameter, central sea level anomaly, amplitude, eddy kinetic energy, and eddy intensity of the eddy were 427 km, 28.75 cm, 6.04 cm, 384 cm2/s2 and 1.59 × 10-2cm2/s2km2,respectively. The upper bound of the eddy was 100 m in summer while it rose to 40 m in autumn. It was strongest at 90-100 m depth in autumn, and the west core was more powerful compared with the east at the upper 100 m.However, the west core was weakened and its center moved northward while the east core strengthened below110 m. Below 140 m, the west core disappeared but the east core still existed. The impact of the east core on salinity remained to 190 m and more deep on temperature and density.