Water-side Turbulence Enhancement of Ozone Deposition to the ...

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 Background On Flux Transfer Velocity Relationships The flux, Fx, of trace gases between the atmosphere and ocean:

Xw=concentration in the water, Xa=concentration in air r subscript reference height/depth zr kx=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

If enhancement is large, transfer velocity usually called deposition velocity Fx w' x' x k x ( X wr / x X ar ) x X ws / X as s subscript at interface k x [ R xw x R xa ] 1 x Fx X ar Vdx X ar Rxa Do You Feel Lucky? k=cu2

Basic Budget Equation For Gas Concentration X In One Fluid [ w' x' Dx X / z ] [ w' x' Dx X / z S x ] X / t U X Qsource z z Source term in flux form S x Qx ( z )dz Near the surface we can use an eddy diffusion representation of turbulent flux w' x' K ( z ) Total Flux=Sum of transport and

reaction/source effects In dynamic equilibrium Fx is independent of z If Sx=0, we can relate the flux to the change in X from the surface, s, to some reference height/depth in the fluid, z=zr z X z F x [ Dx K ( z )] X Sx z Fx X

z K ( z ) Dx dx F X s X r X ( z r ) Fx x Fx Rx Dx K ( z ) V x COARE MODEL HISTORY 1996 Bulk Meteorological fluxes (ku=u*Cd) Update 2003 (8000 eddy covariance obs) Oceanic cool skin module molecular sublayer 2000 CO2 2004 DMS 2006 Ozone 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.

NOAA COARE Gas Transfer Algorithm: COARE Turbulent-Molecular Physics and Woolf Bubble Physics Bubbles enhance transfer on ocean side 1 k x [( Rwx k b ) 1 x Rax ] 1 Atmos Resistance 1/ 2 u*a Rax [ha S ca C d 1 / 2 5 ln(S ca /( 2 ))] Ocean Resistance 1/ 2 u*a Rwx w / a [hw S cw ln( z wr / uw )] A is adjustable constant, phi a

buoyancy function Woolf bubble xfer velocity 13.3 hw A kb Vo 1/ 2 1/ n n W b x 1 [1 (e x S cw ) ] B B is adjustable constant Wb is whitecap fraction Wb 3.8 *10 6 U 3.4 U*a from COARE3.0 bulk flux algorithm: Windspeed or wave-based u* relationships

GASEX-I, GASEX-II, and DMS Field Programs: Difference in CO2 and DMS from Solubility-Bubble Effect THIS IS THE DATA Whitecap - Fetch Effects Energy Of Wave Breaking Wave Model p computed from wave spectral model Energy flux from atmosphere Both u*w and Wb coupled to p 1 P E j U j u i u jU i 2S ij a

a E ( z ) ( P w2 )W ( wu U )U w a a z E w (0) Cwave wave U 0 ( total wave ) p E w Cwave wave p 3.2 a u 3.5 *a Coupled atmosphere-wave model Fan et al. 2007 Whitecap Parameterizations: Wind Speed, Wave parameters, Wave Breaking Whitecap Functions: Hurricane Wave Model Results

1 Monahan 10 Wb 3.8 * 10 6 U 3.4 10*Wp 0 Woolf URI and UM Wave Models Wa 6 *10 U u H Wb 4 *10 7 *a

Wa p / w Mon 10 3. 0 Woolf 0.96 Whitecap Fraction Mellville 7 10*Mellvile -1 10

-2 10 -3 10 -4 10 0 10 1 10 Wind Speed (m/s)

2 10 Spread of Energy at Fixed Wind Speed 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