Global ocean mesoscale eddy identification algorithm extracted on basis of HOG characteristics

Abstract

The invention relates to a global ocean mesoscale eddy identification algorithm extracted on the basis of HOG characteristics. The algorithm uses satellite altimeter data. The method extracted on the basis of the HOG characteristics comprises detecting the maximum rotating speed characteristic line of an eddy, determining an area where the eddy exists, determining the eddy center and an eddy boundary through iteration of an inward contraction and outward expansion mode, applying a limit of an eddy property in an iteration process, determining a spatial position and scale of the eddy then, and completing identification of the ocean mesoscale eddy. The method takes an HOG characteristic value of an altimeter image as a parameter of the eddy identification, prevents result inaccuracy caused by an influence of a Coriolis force when the eddy identification is performed nearby the equator, and improves accuracy and efficiency of the eddy identification.

Description

technical field [0001] The invention belongs to the field of feature extraction and ocean visualization, and specifically relates to a global ocean mesoscale eddy identification algorithm based on HOG (Histogram of Oriented Gradient, histogram of oriented gradient). Background technique [0002] Since the 1970s, the research on mesoscale eddies has increasingly become a focus and focus of physical oceanographers. Since the mesoscale vortex can cause changes in the vertical positions of thermoclines and haloclines, it has high research value and significance in both theoretical research such as ocean dynamics and practical applications such as national defense and military affairs. [0003] There are many methods for identifying and extracting oceanic mesoscale eddies. Currently, common eddy identification methods include Sea Surface Height (SSH) method, Okubo-Weiss (OW) method, Vector Geometry (VG) method and Hybrid Detection (HD) method. Wait. [0004] (1) SSH method: Thi...

AI Technical Summary

Problems solved by technology

The OW method defines the criteria from the physical properties of mesoscale vortices, which can better reveal the physical nature of mesoscale vortices, but it has obvious defects.

First, the Coriolis force tends to 0 near the equator, so the OW parameters calculated by SLA, Coriolis force and gravity acceleration are incorrect

Second, the W field will generate a lot of noise, which is often misjudged as a vortex

Third, the results obtained by different thresholds fluctuate greatly

[0008] In the vortex identification using the above methods, the geostrophic flow velocity must be added as a factor to determine the vortex, and when the geostrophic flow velocity is calculated based on the altimeter data, the Coriolis force parameter is added, and the Coriolis force is close to the equator. Therefore, the geostrophic flow rate calculated from the altimeter data near the equator is inaccurate, which causes errors in the vortex identification results

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