Surface Layer Forced Marine Atmospheric Boundary Layer Convective Eddies

摘要

Boundary layer convective eddies (BLCE) observed via synthetic aperture radar(SAR) on 17 June 1993 during the Hi-Res 2 field experiment are investigated using a three dimensional nonlinear spectral model derived from the shallow Boussinesq equations. Boundary conditions are appropriate for marine atmospheric boundary layer (MABL) flow and allow for heat and momentum fluxes across the lower boundary, as is required to determine sea surface stress patterns. Enhancements made to the model for this study include the addition of an inversion layer, an unstable surface layer and weighted nonlinear numerical dissipation. A more numerically accurate integration scheme is also incorporated. A linear stability analysis of Hi-Res 2 data finds maximum growth rates for disturbances having horizontal wavelengths that match those determined from the 17 June 1993 SAR image. Desirable by products of the analysis include the determination of physically plausible mean horizontal wind profiles and inversion strengths. Two model integrations are performed using identical measured atmospheric input values and initial conditions, but with different dissipation weights.