Spatio-temporal Variation of Eddy Kinetic Energy in the Southwest Pacific Ocean

LI Hao-min;LI Cheng;College of Ocean and Meteorology/Laboratory for Coastal Ocean Variation and Disaster Prediction,Guangdong Ocean University;Key Laboratory of Climate, Resources and Environment in Continental Shelf Sea and Deep Sea of Department of Education of Guangdong Province;Key Laboratory of Space Ocean Remote Sensing and Application, Ministry of Natural Resources;

southwest Pacific Ocean;;mesoscale eddy;;energy equation;;eddy kinetic energy;;spatio-temporal variation

【Objective】 The Southwest Pacific Ocean is an area of active eddy activities. The eddy kinetic energy(EKE) are dominant in the whole ocean energy. This study is aimed to explore the mechanism of the spatio-temporal variation of EKE in this region. 【Method】 From the original energy equation, the EKE's spatiotemporal variation was studied, based on Estimating the Circulation and Climate of the Ocean II(ECCO2) data(1991―2017) and Sea Level Anormaly(SLA) data(1993―2018). 【Result and Conclusion】 The result shows that Eddy Kinetic Energy(EKE) had low level and shallow vertical influence during December to March, while high level and deep vertical influence during June to August. In this paper, the EKE high value region in the southwest Pacific was divided into three small regions(region A: 150° ―160° E, 28° ―36° S; region B: 150° ―160° E, 28° ―32° S;region C: 150° ―160° E, 32° ―36° S). To start with the energy equation, we analyzed the lead-lag correlativity between Barotropic(BT), Baroclinic(BC), Wind Stress Work(WW) and EKE and found that BT was the major factor which manuplated EKE. Region A and C had a positive correlation of0.70 and 0.58 with BT lagging by one month, and region B had a positive correlation of 0.53, varing in the same period with BT. In order to find out how vertical velocity sheer(ud) and large-scale climate change work on EKE, this paper analyzed the correlativity between EKE and ud, Nino3.4 index and Southern Annular Mode(SAM) index. The analysis of lead-lag correlativity between the EKE spatiotemporal variation and these factors, indicated that the EKE had a positive correlation of 0.57 with Nino3.4 index lagging by 6 months, and Nino3.4 index may be the major factor affecting EKE variation in this sea area through the vertical shear of the currents.