The 13th Symposium on Boundary Layers and Turbulence

P2B.19
CONVECTIVE TRANSPORT THEORY FOR SURFACE FLUXES, TESTED DURING BOUNDARY-LAYER EXPERIMENT 1996 (BLX96)

Edi Santoso, Univ. of British Columbia, Vancouver, Canada; and R. B. Stull

Statically unstable atmospheric boundary layers contain buoyant thermals with undiluted cores that transport air vertically across large distances. The rate of convective transport defines a buoyancy velocity, which is used to parameterize surface turbulent fluxes. Convective transport theory (CTT) proposed by Stull (1994) parameterizes surface fluxes based on differences between mean variables at the surface skin and in the uniform layer (UL) in the mid-mixed layer. Stull's (1994) derivation of the mixed-layer (ML) parameterization for surface fluxes results in expression containing empirical convective-transport coefficients. The values of the coefficients were derived in that paper from data collected from BLX83 and were validated independently using data collected from Koorin experiment.
New data collected from BLX96, conducted over three sites in Oklahoma with different land use and aerodynamic roughness, are used to test CTT and its empirical parameters. There were 33 low level horizontal flight legs, each between 68 and 75 km length, from 12 flights of King Air aircraft flown during 15 July - 13 August 1996. Downward-looking infrared radiation thermometers on the aircraft remotely measured surface skin temperature. The aircraft also made in situ measurements of variables in the mid-ML. The results confirm the free convective form of CTT for the surface fluxes. The values of the convective-transport coefficients are within the standard-deviation error bars previously reported by Stull (1994).

The 13th Symposium on Boundary Layers and Turbulence