Detecting Chlorophyll a Concentration and Bloom Patterns at Upwelling Area in South Central Vietnam by High Resolution Multi-satellite Data

Abstract

Study on Chlorophyll a (Chl. a) distribution and bloom patterns is essential in the upwelling areas that constitute the main fishery grounds of Vietnam. Based on high resolution satellite imagery and monthly in-situ data in period from 2007 to 2008, the spatial and temporal variations of Chl. a in the upwelling region including algal blooms have been detected. Anomalies of higher Chl. a concentration and bloom patterns occurred at different periods, locations, and bloom shapes in coastal waters of Southern Center of Vietnam. The appearances of these bloom are related to four difference reasons, such as: (i) Their locations coincided to main center of upwelling phenomena that usually occur during southwest monsoon (SWM); (ii) Effect of northeast monsoon (NEM) that brings and attaches the nutrient into the coast and created “floating” algae bloom patches in coastal zones; (iii) The algae blooms can be potentially associated with Harmful Algae Bloom (HAB) during the SWM or local eddies during NEM and (iv) Their appearances are also as a result of distinctive nutrient inflow from Mekong delta and pumping of nutrients by internal waves in coastal shallow waters