SLIMCAT

SLIMCAT is the variant of TOMCAT which uses isentropic levels in the stratosphere and calculations of the diabatic heating rate to calculate the vertical tracer transport.

Early simulations with the new TOMCAT 3D CTM had a number of technical challenges. First, in the 1990s, simulations were computationally expensive for the machines of the time. Second, the slow stratospheric tracer circulation produced by the meteorological analyses then available produced too-rapid and noisy vertical transport. SLIMCAT solved these problems.

The first version of SLIMCAT (see Chipperfield et al., 1996) was created to produce cheap, seasonal (winter-spring) simulations of polar chemistry on a single isentropic level. This inspired the acronym 'Single Level Isentropic Model of Chemistry and Transport', which also conveyed the idea of a 'slimmed down' version of the full TOMCAT 3D CTM.

While the 'single level' model was useful, it became clear that a 3D version over multiple isentropic levels could be created with calculated diabatic heating rates for the vertical transport. This would allow full multiannual simulations with a better description of vertical tracer transport than analysed vertical winds. At this point SLIMCAT became a name rather than an accurate acronym!

The SLIMCAT variant shares alot of core code with TOMCAT and they are part of the same model library (Chipperfield, 2006).

Example publications

Chipperfield, M.P., Multiannual Simulations with a Three-Dimensional Chemical Transport Model, J. Geophys. Res., 104, 1781-1805, doi:10.1029/98JD02597, 1999.

Chipperfield, M.P., New version of the TOMCAT/SLIMCAT off-Line chemical transport model: Intercomparison of stratospheric tracer experiments,
Q. J. R. Meteorol. Soc., 132, 1179-1203, doi:10.1256/qj.05.51, 2006.

Chipperfield, M.P., M.L. Santee, L. Froidevaux, G.L. Manney, W.G. Read, J.W. Waters, A.E. Roche and J.M. Russell, Analysis of UARS data in the southern polar vortex in September 1992 using a chemical transport model, J. Geophys. Res., 101, 18861-18881, doi:10.1029/96JD00936, 1996.