Kinetic Energy Cascade in the Frequency Domain from Satellite Products

Multiscale oceanic motions continuously transfer kinetic energy across various spatiotemporal scales through kinetic energy cascade. Satellite altimetry offers long-term daily ocean data at 0.25-degree resolution, enabling the analysis of energy cascades in both wavenumber and frequency domains. Whi...

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Main Authors: Qianqian Geng, Xin Su, Ru Chen, Gang Huang, Wanli Shi
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Remote Sensing
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Online Access:https://www.mdpi.com/2072-4292/17/5/877
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author Qianqian Geng
Xin Su
Ru Chen
Gang Huang
Wanli Shi
author_facet Qianqian Geng
Xin Su
Ru Chen
Gang Huang
Wanli Shi
author_sort Qianqian Geng
collection DOAJ
description Multiscale oceanic motions continuously transfer kinetic energy across various spatiotemporal scales through kinetic energy cascade. Satellite altimetry offers long-term daily ocean data at 0.25-degree resolution, enabling the analysis of energy cascades in both wavenumber and frequency domains. While energy cascade studies in the wavenumber domain are well-developed, frequency domain analyses remain limited. In this study, using 24 years of velocity data from satellite altimetry, we analyze the surface frequency-domain kinetic energy cascade primarily using the coarse-graining method. Compared to other approaches in literature, the coarse-graining approach shows superiority in diagnosing energy cascade in the frequency domain. Using this approach in the Kuroshio Extension region, we compare the spatiotemporal variability of energy cascades between the frequency and wavenumber domains. A pronounced low-frequency forward cascade, distinct from the wavenumber domain results, is identified. We propose a theory linking this low-frequency forward cascade with eddy generation through eddy–mean flow interactions. Significant variability is also observed in frequency domain energy cascades. Further analysis shows that wind forcing only plays a minor role in modulating the temporal variability of the energy cascade. Our findings are crucial for evaluating the model’s fidelity and advancing investigation of climate variability from the perspective of energy transfer.
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spelling doaj-art-3efde45fc3fd4777b49d5bd2896d5c5e2025-08-20T02:53:02ZengMDPI AGRemote Sensing2072-42922025-02-0117587710.3390/rs17050877Kinetic Energy Cascade in the Frequency Domain from Satellite ProductsQianqian Geng0Xin Su1Ru Chen2Gang Huang3Wanli Shi4Tianjin Key Laboratory for Marine Environmental Research and Service, School of Marine Science and Technology, Tianjin University, Tianjin 300072, ChinaTianjin Key Laboratory for Marine Environmental Research and Service, School of Marine Science and Technology, Tianjin University, Tianjin 300072, ChinaTianjin Key Laboratory for Marine Environmental Research and Service, School of Marine Science and Technology, Tianjin University, Tianjin 300072, ChinaNational Key Laboratory of Earth System Numerical Modeling and Application, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaTianjin Key Laboratory for Marine Environmental Research and Service, School of Marine Science and Technology, Tianjin University, Tianjin 300072, ChinaMultiscale oceanic motions continuously transfer kinetic energy across various spatiotemporal scales through kinetic energy cascade. Satellite altimetry offers long-term daily ocean data at 0.25-degree resolution, enabling the analysis of energy cascades in both wavenumber and frequency domains. While energy cascade studies in the wavenumber domain are well-developed, frequency domain analyses remain limited. In this study, using 24 years of velocity data from satellite altimetry, we analyze the surface frequency-domain kinetic energy cascade primarily using the coarse-graining method. Compared to other approaches in literature, the coarse-graining approach shows superiority in diagnosing energy cascade in the frequency domain. Using this approach in the Kuroshio Extension region, we compare the spatiotemporal variability of energy cascades between the frequency and wavenumber domains. A pronounced low-frequency forward cascade, distinct from the wavenumber domain results, is identified. We propose a theory linking this low-frequency forward cascade with eddy generation through eddy–mean flow interactions. Significant variability is also observed in frequency domain energy cascades. Further analysis shows that wind forcing only plays a minor role in modulating the temporal variability of the energy cascade. Our findings are crucial for evaluating the model’s fidelity and advancing investigation of climate variability from the perspective of energy transfer.https://www.mdpi.com/2072-4292/17/5/877kinetic energy cascadesatellite productsfrequency domainAVISOcoarse-graining approachspatiotemporal variability
spellingShingle Qianqian Geng
Xin Su
Ru Chen
Gang Huang
Wanli Shi
Kinetic Energy Cascade in the Frequency Domain from Satellite Products
Remote Sensing
kinetic energy cascade
satellite products
frequency domain
AVISO
coarse-graining approach
spatiotemporal variability
title Kinetic Energy Cascade in the Frequency Domain from Satellite Products
title_full Kinetic Energy Cascade in the Frequency Domain from Satellite Products
title_fullStr Kinetic Energy Cascade in the Frequency Domain from Satellite Products
title_full_unstemmed Kinetic Energy Cascade in the Frequency Domain from Satellite Products
title_short Kinetic Energy Cascade in the Frequency Domain from Satellite Products
title_sort kinetic energy cascade in the frequency domain from satellite products
topic kinetic energy cascade
satellite products
frequency domain
AVISO
coarse-graining approach
spatiotemporal variability
url https://www.mdpi.com/2072-4292/17/5/877
work_keys_str_mv AT qianqiangeng kineticenergycascadeinthefrequencydomainfromsatelliteproducts
AT xinsu kineticenergycascadeinthefrequencydomainfromsatelliteproducts
AT ruchen kineticenergycascadeinthefrequencydomainfromsatelliteproducts
AT ganghuang kineticenergycascadeinthefrequencydomainfromsatelliteproducts
AT wanlishi kineticenergycascadeinthefrequencydomainfromsatelliteproducts