A Study on the Mesoscale Eddies In the Northern Indian Ocean and the Concentration of Its Inner Chlorophyll-a

Abstract This paper uses the observation data set of the interaction among the atmosphere, ocean, and organisms caused by the global mesoscale eddy and the data of chlorophyll-a in the tertiary sea surface (OC-CCI 5.0 version) to make month-on-month and year-on-year statistical analysis on the life cycle, movement trajectory and generation number of mesoscale eddies in the North Indian Ocean (5°N-30°N, 45°E-100°E) from 2009 to 2019. It also summarizes the spatiotemporal variation characteristics of chlorophyll concentration inside the mesoscale eddies in this sea area and makes a brief analysis accordingly. The analysis results show that the life cycle, spatial distribution, and frequency distribution of the number of cyclone and anticyclone vortices in the North Indian Ocean are relatively consistent, and they all move westward. The average lifespan of the cyclone vortex is 7.94 weeks, slightly longer than that of the anticyclone vortex, which is 7.87 weeks. The monthly average number of cyclone vortices is 9, more than the monthly average number of anticyclone vortices of 8. There are obvious seasonal differences. Cyclonic eddies will increase the sea surface Chl-a concentration, while anticyclonic eddies will reduce the sea surface Chl-a concentration. And the concentration distribution of Chl-a may be affected by the seasonality of mesoscale eddies.