Global Dstribution of Merger and Split of Oceanic Mesoscale Eddies

Hiromu Ishiyama, Hokkaido University, Faculty of Environmental Earth Science, Sapporo, Japan, Hiromichi Ueno, Hokkaido University, Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Japan, Masaru Inatsu, Hokkaido University, Sapporo, Japan and Sachihiko Itoh, Atmosphere and Ocean Research Institute University of Tokyo, Kashiwa, Japan
Abstract:
Oceanic mesoscale eddies are ubiquitous vortical structures. They have an important role in transferring energy and mass vertically and horizontally, stimulating phytoplankton blooms and also affecting atmospheric weather systems. In this study, we investigated the mesoscale eddies in detail from the viewpoint of eddy-eddy interaction. This is because eddy-eddy interactions are scarcely observed in the ocean and are still open question. In particular in this study, we investigated global distribution of mergers and splits of mesoscale eddy through analysis of 20-year time series of satellite altimeter data distributed by AVISO. Neighbor enclosed area tracking algorithm, which is able to detect mergers and splits of mesoscale eddies, was applied to track each eddy identified using Okubo-Weiss parameter. The frequency of mergers and splits of mesoscale eddies varied from area to area: both mergers and splits frequently occurred in the areas of western boundary currents and their extensions, subtropical counter currents, and Antarctic Circumpolar Current regions.
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