13:45 〜 14:00
[ACG38-07] Interannual variation of the intraseasonal variability at 1000m depth in the eastern tropical Pacific Ocean
キーワード：季節内変動、赤道波
It has been shown that the intraseasonal variability (ISV) in the eastern tropical Pacific Ocean at an intermediate depth (~1000 m depth) has large amplitude along the equator with zonally uniform structure. However, the origin and detailed characteristics of the ISV at an intermediate depth are still open questions. In this study, we use the 10-day mean horizontal velocity obtained from drift data of the Argo floats and the temperature data from Tropical Atmosphere-Ocean (TAO) moored array in the equatorial Pacific for a period from 2010 to 2022 to evaluate interannual modulation of the equatorial ISV at the depth of 1000 m and its relation to the ISV in the upper layer.
Based on the Argo float drift, we evaluate the meridional component of eddy kinetic energy (V-EKE) at 1000 m depth, which depicts large intraseasonal variability with a period of about 30 days in the eastern tropical Pacific. The V-EKE shows a significant seasonality with its maximum in boreal winter. In addition, the V-EKE in winter indicates a clear interannual variation with the standard deviation of 16 cm2 s-2 and the largest amplitude appeared in 2016. The TAO moored temperature time series above 500 m depth shows the large amplitude ISV along the equator with the meridionally anti-symmetric structure, whose phase propagates upward implying downward energy transport based on linear wave theory. The upper-layer ISV signal also indicates significant interannual variation in its magnitude, which is consistent with the results from Argo-based analysis. These results suggest that the ISV and the interannual variation of the ISV magnitude at a depth of 1000 m is strongly influenced by the ISV in the upper layer.
Based on the Argo float drift, we evaluate the meridional component of eddy kinetic energy (V-EKE) at 1000 m depth, which depicts large intraseasonal variability with a period of about 30 days in the eastern tropical Pacific. The V-EKE shows a significant seasonality with its maximum in boreal winter. In addition, the V-EKE in winter indicates a clear interannual variation with the standard deviation of 16 cm2 s-2 and the largest amplitude appeared in 2016. The TAO moored temperature time series above 500 m depth shows the large amplitude ISV along the equator with the meridionally anti-symmetric structure, whose phase propagates upward implying downward energy transport based on linear wave theory. The upper-layer ISV signal also indicates significant interannual variation in its magnitude, which is consistent with the results from Argo-based analysis. These results suggest that the ISV and the interannual variation of the ISV magnitude at a depth of 1000 m is strongly influenced by the ISV in the upper layer.