Simulated response of the marine atmospheric boundary layer in the westernPacific warm pool region to surface flux forcing

The atmospheric boundary layer (ABL) response to surface fluxes and prescri bed advective and radiative forcings is tested in a column ABL model. Obser vations are used to run an ABL model in a marine tropical convective regime . The influence of surface fluxes and prescribed advective and radiative fo rcings potential temperature and specific humidity throughout tile ABL is e xamined. The manner by which the different ABL processes interact with each other is investigated in light of recently demonstrated sensitivity of the simulated general circulation to flux parameterizations. Simulated near-su rface temperature and sensible heat fluxes are in close agreement with obse rvations, with both the advection and the sensible heat flux contributing a pproximately equally to ABL warming. Simulated nearsurface humidity and hum idity profiles are dryer than observed. The model exhibits very vigorous no nlocal ABL mixing that self-regulates the flux response in its surface flux formulation by reducing humidity gradients and subsequent evaporation. The total time-averaged simulated heat flux for two surface flux parameterizat ions tested is within the Tropical Ocean Global Atmosphere Coupled Ocean At mosphere Experiment (TOGA-COARE) required accuracy. When decoupled from mod el response, tile ABL model formulation overpredicts (underpredicts) latent heat fluxes modestly. ABL depth is dominated by nonlinear terms involving interaction between different surface fluxes and the ABL turbulent mixing a nd between these fluxes and advective and radiative forcing. Simulations in coarse vertical resolution typical of General Circulation Models (GCMs) re sult in significant ABL deepening and drying over observed values but also in better agreement between the time-averaged simulated and observed surfac e heat fluxes.