Mixed Layer Convective Turbulence Theory with First International Satellite‐Land Surface Climatology Project Field Experiment Data

Abstract

The convective turbulence theory (CTT) [Stull, 1994] has several advantages over traditional bulk atmospheric boundary layer similarity formulations for the surface momentum and sensible heat fluxes under free convection. In particular, in CTT surface fluxes at scales of 101–102 km are parameterized directly from surface and mixed layer measurements, without regard to the surface layer profiles or surface roughness. The equations of CTT are tested with the First International Satellite‐Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) data set; the theory is extended so that geostrophic winds may be used in place of mixed layer winds; the formulation is applied to satellite‐derived surface temperature data; and Stull's [1994] mixed convection interpolation formula is tested. The scatter on graphs of the mixed layer transfer coefficients for momentum and sensible heat is greater for the FIFE data than for the Boundary‐Layer Experiment 1983 (BLX83) data used by Stull [1994], and the mean coefficient values are greater, probably because of the use of radiosonde data at FIFE and spatially averaged aircraft data at BLX83. Surface momentum and sensible heat flux estimated on the basis of CTT produced reasonable results but provided little or no improvement over a direct correlation between the reference fluxes and the mixed layer wind speed or the surface‐to‐mixed layer temperature difference. The geostrophic version of CTT provided results comparable to the original CTT. Remotely sensed surface temperatures used with geostrophic CTT allowed reasonable estimates of the surface sensible heat flux.