Remote sensing of day/night sea surface temperature difference related to phytoplankton blooms

The diurnal sea surface temperature (D-SST, which is the daytime SST minus the night-time SST) and its relationship with heavy phytoplankton blooms were observed using satellite and in situ data. Two phytoplankton bloom events covering large areas in the East China Sea (ECS) were analysed to investigate the reactions among D-SST, chlorophyll-a (chl-a) concentration, suspended sediment (SS), coloured dissolved organic matter (CDOM), wind speed (WS) and solar radiation (SR). The results showed a positive relationship between D-SST and chl-a concentration in phytoplankton bloom areas. Further analyses of 12 major phytoplankton bloom events (total area 1000 km2) occurring between 2000 and 2005 in the ECS, accompanied by in situ observation data in Daya Bay, confirmed a positive correlation between chl-a concentration and D-SST. These results showed that an increase in D-SST may be found in heavy phytoplankton bloom areas. The present study represents an important step for understanding the influence of phytoplankton on ocean conditions.