Influence of a tropical cyclone Gonu on phytoplankton biomass (chlorophyll a) in the Arabian Sea

Tropical cyclones could gradually affect the physical, chemical, and biological processes in the upper layer of the ocean. In terms of biological consequences, the cyclone wind field causes local mixing which results in the injection of nutrients into the upper layer of the ocean and triggering phytoplankton bloom (Subrahmanyam et al. 2002). In some cases, the magnitude of the hurricane-induced bloom could reach a gradual (30-fold) increase in the surface chlorophyll a concentration, as well as an increase in the primary production (Lin et al. 2003; Smitha et al. 2006). In the regions where cyclones often occur, their propagation could chiefly influence the annual productivity of the ocean. For example, an average of 14 cyclones pass over the South China Sea annually, which suggests the contribution of cyclones to annual production to be as much as 20-30% (Lin et al. 2003).