Propagation of uncertainty analysis of CO2 transfer velocities derived from the COARE gas transfer model using satellite inputs

Abstract

A propagation of uncertainty method is developed to describe gas transfer uncertainties for carbon dioxide (CO2) using the National Oceanic and Atmospheric Administration-Coupled Ocean Atmosphere Response Experiment (NOAA-COARE) gas transfer model (COAREG). The uncertainty model assesses the impact uncertainties in satellite inputs to COAREG have on the resulting carbon dioxide gas transfer velocities. The model impact of 10 m temperature, 10 m specific humidity, 10 m wind speed, sea surface temperature, longwave and shortwave downward surface flux are investigated. Nine years of gas transfer velocities and their uncertainties were constructed and analyzed. The climatological mean transfer velocities were found to have standard errors of less than 15%. Spatial and temporal variations of the uncertainties from these inputs are presented and the percentage variance explained for each input was dominated by uncertainties in wind speed. Uncertainty due to the covariance between air temperature and wind speed and the uncertainties in the 10 m air temperature at low wind speed conditions were found to be significant. Additionally, the likelihood air temperature uncertainties affect the gas transfer uncertainty is greatest in regions where air temperature exceeds sea surface temperature. Buoyancy-driven transfer in COAREG increases gas transfer velocities uncertainties under these conditions. These conditions most typically occur in regions along the equatorial cold tongue region east of South America and in the North Pacific and North Atlantic. © 2014. American Geophysical Union. All Rights Reserved.