Seasonal Variability of Eddy Kinetic Energy in the Central Indian Ocean: POLYGON-67 Revised

IF 0.7 Q4 OCEANOGRAPHY
G. Shapiro, J. Gonzalez-Ondina
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引用次数: 1

Abstract

Purpose. The main goal of this study is to analyse the seasonal variability of meso-scale eddy activity in the north tropical Indian Ocean. The selected area coincides with the location of POLYGON-67 (P67) experiment where the mesoscale eddies of the open ocean were first discovered. Methods and results. The variability of mesoscale eddy kinetic energy in surface ocean layer, enstrophy of larger scale circulation, spatial and temporal patterns of surface currents and surface winds are jointly analysed using a 20-year long daily time series of eddy-resolving ocean reanalysis data obtained from EU Copernicus Marine Environment Monitoring Service and climatic wind data from US National Oceanographic and Atmospheric Administration. The fast mesoscale and slow large-scale processes are separated using a Savitsky – Golay filter with the cut-off time of 103 days which corresponds to a local minimum in the full kinetic energy power spectrum. In contrast to other parts of the tropical ocean, the seasonal variability of EKE exhibits 2 maxima – the largest being in April, and the secondary being in October which are related to the maxima in enstrophy of larger scale currents. Conclusions. The double peak variability in EKE corresponds to the seasonal variability of large scale enstrophy and monsoon wind circulation and supports a hypothesis that the main mechanism of EKE generation is barotropic instability of larger scale currents. The EKE variability within P67 is mostly controlled by advection of energy from neighbouring areas, and to a lesser extent by local generation.
中印度洋涡旋动能的季节变化:POLYGON-67修正
意图本研究的主要目的是分析北热带印度洋中尺度涡旋活动的季节变化。所选区域与POLYGON-67(P67)实验的位置一致,在该实验中首次发现了公海的中尺度涡旋。方法和结果。海洋表层中尺度涡动能的变化、大尺度环流的自养,使用欧盟哥白尼海洋环境监测服务中心获得的涡旋解析海洋再分析数据和美国国家海洋和大气管理局的气候风数据,联合分析了地表流和地表风的空间和时间模式。使用Savitsky–Golay滤波器分离快速中尺度过程和慢速大尺度过程,截止时间为103天,对应于全动能功率谱中的局部最小值。与热带海洋的其他部分相比,EKE的季节变化表现出2个最大值——最大值在4月,第二个在10月,这与大尺度洋流的自养最大值有关。结论。EKE的双峰变率对应于大尺度自养和季风环流的季节变率,并支持EKE产生的主要机制是大尺度洋流的正压不稳定性的假设。P67内的EKE变化主要由邻近地区的能量平流控制,在较小程度上由局部发电控制。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Physical Oceanography
Physical Oceanography OCEANOGRAPHY-
CiteScore
1.80
自引率
25.00%
发文量
8
审稿时长
24 weeks
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