Time series of in situ surface seawater partial pressure of CO2 (pCO2) data collected between 2005 and 2017, together with other environmental variables from field or satellite measurements, along the coasts of the United States of America and its territories at different latitudes, are analyzed to separate the temperature effect from the remaining non-temperature effects (i.e., biological and other physical effects) on driving surface pCO2. Similar to the findings in the open ocean, on seasonal time scales, the temperature effect (pCO2_T) tends to override the non-temperature effect (pCO2_nonT) in modulating surface pCO2 in tropical and subtropical oceanic waters. However, the balance between pCO2_T and pCO2_nonT tends to shift towards pCO2_nonT in temperate zone waters, with a few exceptions in some specific oceanic environments. On interannual time scales, both atmospheric pCO2 and surface pCO2 show significant increasing trends over short time scales (i.e., <10 years) except for a few outliers. In tropical and subtropical waters, the interannual changes of surface pCO2 are mainly controlled by the non-temperature effect (through air-sea CO2 exchange). In temperate regions, these changes are primarily driven by the temperature effect (through increased SST). Considering that temperature is commonly included in remote sensing algorithms of surface pCO2, this study suggests that, to better capture the seasonal and interannual signals in surface pCO2 from satellites, atmospheric pCO2 must be considered in the surface pCO2 remote sensing algorithms especially in tropical and subtropical waters. The non-temperature effect on surface pCO2, especially the biological effect (e.g., algal blooms), needs further investigation.
Chen, S., & Hu, C. (2019). Environmental controls of surface water pCO2 in different coastal environments: Observations from marine buoys. Continental Shelf Research, 183, 73–86. https://doi.org/10.1016/j.csr.2019.06.007