Speed-dependent Charnock parameter in COARE3.0?

[DesmetQuentin]

Hello Graziano,

In COARE3.0, is this normal that the speed-dependent Charnock parameter of Fairall et al. (2003) is not applied? They wrote in the article "alpha increases linearly from 0.011 at U_{10n} = 10ms^{-1} to 0.018 at U_{10n} = 18 ms^{-1}, and remains constant for lack of better information beyond this wind speed."

If ignoring this is not intended, I propose the simple modifications below. It compiles and works normally. In a short test I made over the Philippine Sea throughout September to get some tropical cyclone passing by, I compared with and without the speed-dependent Charnock parameter and it gave the figure below comparing the surface wind stress of SRF outputs (speed-dependent in the bottom pannel), where the highest wind stress is about 10% higher near the eye. It should make a difference in coupled experiments, I guess.

Cheers,
Quentin

References

Fairall, C.W., Bradley, E.F., Hare, J.E., Grachev, A.A., Edson, J.B., 2003. Bulk Parameterization of Air–Sea Fluxes: Updates and Verification for the COARE Algorithm. Journal of Climate 16, 571–591. DOI:10.1175/1520-0442(2003)016<0571:BPOASF>2.0.CO;2

[graziano-giuliani]

Accepted modification. Most users use the Zeng model, and this wind speed dependency didn't get to the COARE code. Thanks Quentin!