Tropical Cumulus Convection and Upward-Propagating Waves in Middle-Atmospheric GCMs

• DOI: 10.1175/1520-0469(2003)060<2765:tccauw>2.0.co;2
• Publication Date: 2003-11-04T18:49:07Z
• Authors: T. Horinouchi; S. Pawson; K. Shibata; U. Langematz; E. Manzini; M. A. Giorgetta; F. Sassi; R. J. Wilson; K. Hamilton; J. de Grandpré; A. A. Scaife
• Keywords: Quasi-biennial oscillation; Forcing (mathematics); Wavenumber; Atmospheric Circulation

It is recognized that the resolved tropical wave spectrum can vary considerably among general circulation models (GCMs) and these differences have an important impact on simulated climate. A comprehensive comparison of low-latitude waves presented for December–January–February period using high-frequency data from nine GCMs participating in GCM Reality Intercomparison Project Stratospheric Processes Their Role Climate (GRIPS; SPARC). Quantitative measures wavenumber-frequency structure their impacts zonal mean are given. Space–time spectral analysis reveals throughout middle atmosphere linked to variability convective precipitation, which determined by parameterized convection. The precipitation differs more than order magnitude models, with additional changes distribution (especially frequency). These be explained primarily choice different cumulus parameterizations: quasi-equilibrium mass-flux schemes tend produce small variability, while moist-convective adjustment scheme most active. Comparison observational estimates suggests model values scattered around estimates. Among only those largest reproduce equatorial quasi-biennial oscillation (QBO). This implies real atmosphere, forcing waves, resolvable typical resolutions present-day GCMs, insufficient drive QBO. Parameterized convection also nonmigrating tides region. In momentum transport diurnal mesosphere comparable or larger planetary-scale Kelvin being significant has been thought. shown westerly accelerations semi-annual examined driven mainly gravity periods shorter 3 days, some contribution wavenumber-1 negligible. results provide a state-of-the-art assessment links between parameterizations middle-atmospheric middle-atmosphere climate models.