HR: 09:45h
AN: A41E-08    [Abstracts]
TI: A Coupled 1-Dimensional Atmosphere/Ocean/Microphysical Model to Probe Sea Spray Heat and Moisture Fluxes During a North Atlantic Summer Gale
AU: * Kettle, A J
EM: anthony.kettle@uea.ac.uk
AF: School of Environmental Sciences, University of East Anglia, Norwich, NR4 6LR, United Kingdom
AB: Underway meteorological and oceanographic data recorded from the RRS Discovery (as part of the Atmospheric Chemistry Studies in the Ocean Environment, or ACSOE, experiment) during a summer gale south of Iceland in June, 1997 showed dramatic perturbations of air temperature and relative humidity, and near surface ocean temperature and salinity. The underwater ocean temperature decreased by about 1K and the salinity increased by 0.03 psu during the highest winds before decreasing by 0.1 psu. The atmospheric temperature decreased by 4K during the highest winds, and the relative humidity increased from 75 to 95 percent. The measured perturbations in both the oceanic and atmospheric boundary layers was due a combination of vertical advection and phase change effects associated with the production and evaporation of sea spray/aerosols, in addition to the conventional interfacial fluxes of heat and water vapor. The perturbations in the geophysical parameters are explored with a coupled 1-dimensional atmosphere/ocean/microphysical model. The oceanic boundary layer model is based on the PWP bulk mixed layer, and the atmospheric/microphysical model is based on MISTRA model with important modifications to take account of sea spray production during high winds. The oceanic model is initialized with measured profiles of temperature and salinity that were recorded from the RRS Discovery before the storm, and the atmospheric model is initialized with NCEP-NCAR re-analysis data. Known problems of temperature and humidity drift in the atmospheric model, associated with unbalanced surface heat and moisture fluxes, were overcome by relaxing the model predictions to the NCEP-NCAR data. The results from the forward model suggest that sea spray production and evaporation may have a profound impact on the temperature and moisture structure of the atmospheric boundary layer and may also have a measurable impact on upper ocean salinity. The coupled model may be used in an inverse mode to better constrain the sea spray volume production function, which is currently known only to within an order of magnitude. The spray fluxes derived from the inverse model indicate that the present estimates of the sea spray volume production function may have to be revised upward.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0312 Air/sea constituent fluxes (3339, 4504)
DE: 3307 Boundary layer processes
DE: 4504 Air/sea interactions (0312, 3339)
DE: 4576 Western boundary currents
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting