Abstract: Based on the method of the controlling factors analyses, a satellite remote sensing algorithm was developed to retrieve the aquatic pCO₂ in the Pearl River Estuary in summer time. The end members of the Pearl River water and Kuroshio water were applied to quantify the pCO₂ variations controlled by the water mass mixing and thermal dynamic effects, and a look-up table was generated to fulfill the calculation. Moreover, relationship between the a_CDM(443 nm) and surface layer water salinity was established to retrieve the salinity from ocean color satellite data. In addition, based on the underway measured pCO₂ and matchup satellite Chl-a data, the model for the biological effect on the pCO₂ was developed. Finally, the mixing and biological effects on the pCO₂ were combined to retrieve the pCO₂ from the satellite. Based on the established model, the comparisons between the retrieved pCO₂ and underway measured pCO₂ were carried out. The results show that if only considering the mixing and thermal dynamic effects it would overestimate the pCO₂, while if considering the biological effect additionally it would much improve the results not only on the magnitudes, but also the variations. The satellite-retrieved pCO₂ also reveals that in summer time, the coastal region in the Pearl River Estuary is a sink of the atmosphere CO₂, while the outer shelf is a weak source of CO₂.

Key words: Pearl River Estuary, aquatic pCO₂, remote sensing retrieval