Recent Trends in Satellite-Derived Chlorophyll and Aerosol Optical Depth Together with Simulated Dimethylsulfide in the Eastern China Marginal Seas

The biogenic compound dimethylsulfide (DMS) produced by a range of marine biota is the major natural source of reduced sulfur to the atmosphere and plays a major role in the formation and evolution of aerosols, potentially affecting climate. The spatio-temporal distribution of satellite-derived chlorophyll_ a (CHL) and aerosol optical depth (AOD) for the recent years (2011–2019) in the Eastern China Marginal Seas (ECMS) (25°–40°N, 120°–130°E) are studied. The seasonal CHL peaks occurred during late April and the CHL distribution displays a clear zonal gradient. Elevated CHL was also observed along the northern and western coastlines during summer and winter seasons. Trend analysis shows that mean CHL decreases by about 10% over the 9-year study period, while AOD was higher in south and lower in north during summertime. A genetic algorithm technique is used to calibrate the key model parameters and simulations are carried out for 2015, a year when field data was available. Our simulation results show that DMS seawater concentration ranges from 1.56 to 5.88 nmol L −1 with a mean value of 2.76 nmol L −1 . DMS sea-air flux ranges from 2.66 to 5.00 µmol m −2 d −1 with mean of 3.80 µmol m −2 d −1 . Positive correlations of about 0.5 between CHL and AOD were found in the study region, with higher correlations along the coasts of Jiangsu and Zhejiang Provinces. The elevated CHL concentration along the west coast is correlated with increased sea-water concentrations of DMS in the region. Our results suggest a possible influence of DMS-derived aerosol in the local ECMS atmosphere, especially along the western coastline of ECMS.