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NOAA COARE Gas Transfer parameterization: Update Using Wave Parameters C. W. Fairall* NOAA Earth Science Research Laboratory, Boulder, CO, USA Ludovic Bariteau and Jeffrey Hare** CIRES, University of Colorado, Boulder, CO, USA Detlev Helmig INSTAAR, University of Colorado, Boulder, CO, USA Wade McGillis LDEO Concept: Change from windspeed-driven parameterizations to scaling models based on physics of the processes

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Background On Flux – Transfer Velocity Relationships The flux, F x, of trace gases between the atmosphere and ocean: X w =concentration in the water, X a =concentration in air r subscript reference height/depth z r s subscript at interface k x =transfer velocity for X More general form of k includes water- side and air-side transfer processes expressed as RESISTANCES, R Gases reactive in water –‘Chemical enhancement factor β –If enhancement is large, transfer velocity usually called deposition velocity

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Do You Feel Lucky? k=cu 2

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Basic Budget Equation For Gas Concentration X In One Fluid Source term in flux form Near the surface we can use an eddy diffusion representation of turbulent flux Total Flux=Sum of transport and reaction/source effects In dynamic equilibrium F x is independent of z If S x =0, we can relate the flux to the change in X from the surface, s, to some reference height/depth in the fluid, z=z r

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COARE MODEL HISTORY 1996 Bulk Meteorological fluxes (k u =u*C d ) –Update 2003 (8000 eddy covariance obs) –Oceanic cool skin module – molecular sublayer 2000 CO2 2004 DMS 2006 Ozone

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Air-Sea transfer coefficients as a function of wind speed: latent heat flux (upper panel) and momentum flux (lower panel). The red line is the COARE algorithm version 3.0; the circles are the average of direct flux measurements from 12 ETL cruises (1990-1999); the dashed line the original NCEP model.

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NOAA COARE Gas Transfer Algorithm: COARE Turbulent-Molecular Physics and Woolf Bubble Physics Bubbles enhance transfer on ocean side Atmos Resistance Ocean Resistance A is adjustable constant, phi a buoyancy function Woolf bubble xfer velocity B is adjustable constant W b is whitecap fraction *a from COARE3.0 bulk flux algorithm: U *a from COARE3.0 bulk flux algorithm: Windspeed or wave-based u * relationships

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GASEX-I, GASEX-II, and DMS Field Programs: Difference in CO2 and DMS from Solubility-Bubble Effect THIS IS THE DATA

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Whitecap - Fetch Effects

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Energy Of Wave Breaking Wave Model –p computed from wave spectral model Energy flux from atmosphere Both u *w and W b coupled to p Coupled atmosphere-wave model Fan et al. 2007

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Whitecap Parameterizations: Wind Speed, Wave parameters, Wave Breaking Monahan Mellville Woolf URI and UM Wave Models

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Spread of Energy at Fixed Wind Speed

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Present Plans NOAA COARE GAS: CO2, DMS, and Ozone Produce new version for use with wave parameters Tune it to wind-speed version Observations? Ozone cruises, SOLAS, GASEX III

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