2013年吕宋暖涡的生消过程及特征研究

Propagation and characteristics of Luzon Warm Eddy in 2013

基于HYCOM(HYbrid Coordinate Ocean Model)海洋模式,采用全球到西北太平洋,西北太平洋到南海两层嵌套的数值模拟方法,以2013年为例,获得了高精度(1/25°×1/25°×cosθ)的南海海洋动力数据资料。详细刻画了吕宋暖涡的演变过程及三维结构,并对吕宋暖涡演化过程中伴随的能量变化进行了分析。研究发现,2013年6月中旬吕宋暖涡生成于吕宋岛西北侧,该涡先向西移动,8月底滞留约一个月,随后沿200 m等深线向西南移动,最终于12月中旬消亡。以2013年8月4日为例,吕宋暖涡的影响深度可从海表面到达海底,涡的形状类似于圆柱状,涡中心存在倾斜,从海表面至海底涡的中心可倾斜约110 km;吕宋暖涡最大流速可达0.5 m/s。吕宋暖涡所在区域的温度高于周围区域2~6℃,盐度低于周围区域约0.1~0.3‰,最大温度异常值为6.5℃,盐度异常值可达-1‰,都出现在深度150 m左右的海域。吕宋暖涡的总能量可达左右,涡势能约是涡动能的6倍;正压能量转化与斜压能量转化之和占涡总能量变化的76%,对涡能量变化起决定性作用。

HYCOM （（HYbrid Coordinate Ocean Model） is used to obtain the high-resolution （1/25°×1/25°× cosθ） data of the South China Sea （SCS） , with the two-nesting method. This paper describes the generation, propagation, tree- dimensional structure and energy analysis of Luzon Warm Eddy （LWE） based on the data of 2013. According to the model results, the LWE was generated at southwest of Taiwan Island in the mid-June of 2013, and it initially moved westward, then moved southwestward along the 200 m isobath after staying in one place for approximately one month and ultimately disappeared in mid-December. On August 4 th, the impact depth of LWE was from surface to seabed in the shape of tilting cylinder and eddy center tilted for 110 km. For that day, the maximum velocity can be as high as 0.5 m/s while the maximum temperature anomaly at 150 meters could achieve 6.5 ℃. The EPE of LWE could be six times as its EKE; BTI and BCI accounted for 76 % of the total eddy energy transform, which were the most important sources of eddy energy.