Assessing the utility of satellite-based whitecap fraction to estimate sea spray production and CO2 transfer velocity

7th International Symposium on Gas Transfer at Water Surfaces

Anguelova, M.D.^1

Remote Sensing Division, Naval Research Laboratory, Washington

DC, United States^1

关键词: Coupled ocean-atmosphere response experiments;    Direct measurement;    In-situ observations;    Photographic measurements;    Radiometric measurements;    Satellite observations;    Transfer velocity;    Whitecap fractions;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/35/1/012002/pdf
DOI  :  10.1088/1755-1315/35/1/012002

来源: IOP

【 摘 要 】

The utility of a satellite-based whitecap database for estimates of surface sea spray production and bubble-mediated gas transfer on a global scale is presented. Existing formulations of sea spray production and bubble-mediated CO2transfer velocity involve whitecap fraction parametrization as a function of wind speed at 10 m reference height W(U10) based on photographic measurements of whitecaps. Microwave radiometric measurements of whitecaps from satellites provide whitecap fraction data over the world oceans for all seasons. Parametrizations W(U10) based on such radiometric data are thus applicable for a wide range of conditions and can account for influences secondary to the primary forcing factor, the wind speed. Radiometric satellite-based W(U10) relationship was used as input to: (i) the Coupled Ocean-Atmosphere Response Experiment Gas transfer (COAREG) algorithm to obtain CO2transfer velocity and total CO2flux; and (ii) the sea spray source function (SSSF) recommended by Andreas in 2002 to obtain fluxes of sea spray number and mass. The outputs of COAREG and SSSF obtained with satellite-based W(U10) are compared with respective outputs obtained with the nominal W(U10) relationship based on photographic data. Good comparisons of the gas and sea spray fluxes with direct measurements and previous estimates imply that the satellite- based whitecap database can be useful to obtain surface fluxes of particles and gases in regions and conditions difficult to access and sample in situ. Satellite and in situ estimates of surface sea spray production and bubble-mediated gas transfer thus complement each other: accurate in situ observations can constrain radiometric whitecap fraction and mass flux estimates, while satellite observations can provide global coverage of whitecap fraction and mass flux estimates.