Friction velocity is commonly derived from wind speed profiles in the atmospheric surface layer models. A new retrieval algorithm of friction velocity is formulated without using wind speed data over land surfaces. The proposed model is built on the Monin-Obukhov similarity equations (MOSE) and the maximum entropy production (MEP) model of surface heat fluxes. The extremum solution of the MOSE allows friction velocity directly related to sensible heat flux, which may be parameterized using the MEP model in terms of net radiation, surface temperature, and/or humidity. The model is tested using field observations at multiple sites with contrasting vegetation covers, geographic and climatic conditions. The modeled friction velocities agree closely with the observations at diurnal and seasonal scales. Tests using daily inputs demonstrate the potential of the model in estimating friction velocity at daily scale when sub-daily data are not available. This proof-of-concept study provides a possibility of remote sensing of surface or near surface wind speed over land surfaces.
Wang, J., Y. Tang, and Y. Deng (2018): Retrieval of Friction Velocity from Sensible Heat Flux Parameterized Using MEP Model over Land Surfaces (invited). American Geophysical Union Fall Meeting, Washington, DC, December 10-14, 2018.
This Paper/Book acknowledges NSF CZO grant support.