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QTCM - Quasi-equilibrium Tropical Circulation Model

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QTCMs are models of intermediate complexity suitable for the modeling of tropical climate and its variability. It occupies a niche among climate models between complex general circulation models and simple models.

The primitive-equation-based dynamical framework is constructed using analytical solutions from the quasi-equilibrium convective parameterization as the first basis function in a Galerkin representation of vertical structure. A uniqueness of the QTCM is its balanced treatment of dynamics and physical parameterizations. It includes a linearized longwave radiation scheme, simple cloud prediction and shortwave radiation schemes, and the Simple-Land (SLand) land model.

QTCM1 (version 2.2):
Anomalous precipitation from a simulation forced by observed sea surface temperatures 1982-1998.


QTCM2 includes an explicit, prognostic atmospheric boundary layer of fixed depth beneath a free troposphere (FT). The primitive equations are projected onto basis functions confined to either the ABL or FT. In the ABL, dry static energy, moisture, and velocity are vertically uniform, while in the FT temperature, moisture, and velocity follow approximately QTCM1-like structure, i.e., one mode each for temperature and moisture and (approximately) barotropic and baroclinic modes for velocity.


QTCM1 includes a single deep convective mode in the vertical thermodynamic structure and two components (baroclinic and barotropic) in the vertical structure of velocity. It is computationally light (5min on a Sun Ultra2 at 5.625x3.75 resolution and 1.5 minutes on a Pentium-4/Linux workstation) and easy to diagnose.

QTCM1 Version 2.3 (August 2002)

Unofficial, non-released QTCM versions

Archive of released versions

Archive of sample figures


Initial QTCM1 Publications