Regional Bowen ratio controls on afternoon moist convection: A large eddy simulation study

摘要: This study examines the effect of regional Bowen ratio β, domain-averaged surface sensible heat flux (SHF) to latent (LHF), on afternoon moist convection. With a temporally evolving but spatially uniform available energy over mesoscale domain under weak capping inversion, we run large eddy simulation convective boundary layer (CBL). We first prescribe small β 0.56 (a wet surface) and then reversed 1.80 dry by switching SHF LHF fields. The perturbation fields fluxes are prescribed with Fourier spectra κ− 3 (κ is horizontal wave number; strong heterogeneity) κ0 (homogeneity). cases have vertical buoyancy produce more vigorous updrafts. In heterogeneous, case, removal inhibition subdomain SHF, deep convection develops. clouds develop do not progress into precipitating homogeneous cases, randomly distributed shallow significantly thicker in case. (Co)spectral analyses confirm turbulent thermals reveal that moisture advection heterogeneity-induced flows makes correlation between temperature perturbations change from negative positive, which facilitates pool high relative humidity air just above CBL top, necessary condition for