Effects of Typhoon Chanthu on Marine Chlorophyll a, Temperature and Salinity

A typhoon is a severe weather process in tropical oceans. Typhoon transit is often accompanied by strong convective weather, such as gales and rainstorms, which threatens fishery, property, and human safety. In this study, the effects of typhoon Chanthu on chlorophyll a (Chl a), temperature, and ocean surface salinity are analyzed using remote sensing data. The results illustrate that before the transit of Chanthu (6-12 September), the mean concentration of Chl a and sea surface salinity (SSS) are low (0.74 mg/m3, 30.59 psu, respectively), while the mean sea surface temperature (SST) is high (29.01 degrees C). After the typhoon transits (13-30 September), the mean Chl a concentration and salinity increase (1.29 mg/m3, 30.87 psu respectively), while the mean SST decrease (27.43 degrees C). The Ekman pumping transports nutrients from the deep ocean to the surface layer, promotes the photosynthesis of surface phytoplankton, and increases the concentration of sea surface Chl a. Typhoon Chanthu causes the mixing and entrainment of the upper ocean, which causes the deep cold water of the ocean to rise into the mixed layer and cause the SST to decrease. Severe vertical mixing transports deep high-salt water to the surface, causing SSS to rise. The results of this study have important scientific significance and application value for developing coastal economy, aquaculture, and fishery.