Seasonal changes and controlling factors of sea surface pCO2 in the Yellow Sea

Sea surface partial pressure of carbon dioxide (pCO2) is an important parameter in the ocean carbon cycle system. By using accurate global sea surface pCO2 data, we can directly estimate the ratio of net CO2 uptake of global ocean, which can provide a support for further research of global carbon cycle. This article mainly discussed the seasonal changes of sea surface pCO2 and the relationships of pCO2 with sea surface temperature (SST) and chlorophyll-a concentration (Chla) in the Yellow Sea during winter, spring and summer, based on the data obtained by the shipboard measurements in February, May and August 2010. The results showed that the correlations of pCO2 with SST and Chla were different in different seasons. SST and pCO2 had a strong positive correlation in the range of higher SST for both spring and summer, and a relative weak correlation in winter,which can be fitted by a quadratic curve in each season. There was a linear correlation between pCO2 and Chla in each season. The data of pCO2 and Chla showed a negative correlation during winter and summer, and a positive one during spring. Based on the correlation analyses, we proposed a regression equation of pCO2 with SST and Chla as two parameters in the Yellow Sea for summer, which showed a root mean squared error (RMSE) of 16.68μatm when the shipboard-observed data were used. By using the satellite-observed SST and Chla instead of the field data, the RMSE of the result is 21.46μatm.