Turbulence kinetic energy budgets and dissipation rates in disturbed stable boundary layers

Numerical simulations of the stable atmospheric boundary layer are challenging due to the wide variety of phenomena which can affect a stable boundary, including density currents, breaking Kelvin-Helmoltz waves, and gravity waves, among others. To improve the simulations required by numerical weather prediction models, several new parameterizations have recently been proposed by Cheng, Canuto, and Howard (2002) and Freedman and Jacobson (2003), among others.

We evaluate turbulent kinetic energy (TKE) budgets, the TKE dissipation rate, and the TKE dissipation length over a range of stability regimes represented by a developing stable boundary layer, intrusions (by a cold front and by a density current) into the stable boundary layer, and post-intrusion restabilization, using data from the MICROFRONTS and CASES-99 field experiments. The observations are compared with standard (Louis, 1979) and more recent parameterizations (Freedman and Jacobson, 2003; Cheng, Canuto, and Howard, 2002).

Support for MP from the Atmospheric Sciences Division, Mesoscale Dynamics Program of the National Science Foundation, under grant ATM-9903645, is acknowledged. The LLNL component of this work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.