Recent developments on the assessment of gas transfer velocities derived using satellite inputs with the COARE gas transfer model

Understanding the processes and rate of exchange of gases between the atmosphere and global oceans is of vital importance to the climate community. The goal of our study is to assess the accuracy of the physically-based COARE gas transfer model of carbon dioxide, ozone, and DMS using satellite inputs and to construct a global-scale set of observations and error estimates of transfer velocity. Several satellite inputs are used for the COARE model including sea surface temperature, downward solar and infrared radiation, and near-surface wind speed, humidity (Qa), and temperature (Ta). We will present recent updates to the satellite algorithms of Ta and Qa used as input to the COARE model. The updated multi-sensor technique includes a higher resolution data set of 0.25 degree, improved limb correction technique for AMSU-A, and inclusion of multiple AMSU-A satellites. These updated satellites inputs were used to derive transfer velocities and compared with ship-derived COARE transfer velocities and direct covariance observations. Results indicate good agreement between the satellite-derived carbon dioxide COARE transfer velocities and ship-derived transfer velocities with a bias of less than 1 cm/hr and RMS differences of approximately 7 cm/hr. Comparisons of the ozone and DMS satellite and ship-derived transfer velocities will also be presented. Errors from the satellite-derived modeled transfer velocities are analyzed using a propagation of errors model which gives the sources of error in the modeled transfer velocity due to errors from the satellite inputs. Development of a multi-year global-scale data set of transfer velocity and error estimates computed from the error model will be presented. The global distribution, seasonal, and interannual variation of the transfer velocity observations and error estimates from the error model will be discussed.