GENIE:Igcm

GENIE-IGCM is an (I)ntermediate complexity (G)eneral (C)irculation (M)odel of atmospheric dynamics.

History
The ICGM was initially developed in the department of Meteorology, University of Reading. In Reading the IGCM went through three versions:


 * IGCM1 : Portable version of the original adiabatic baroclinic model (Hoskins & Simmons, 1975), with an option for Newtonian forcing and Rayleigh drag to obtain a stable climate.
 * IGCM2 : Includes advected trace species, simplified moist parameterizations and a cheap "radiation scheme" (constant tropospheric cooling!).
 * IGCM3 : Intermediate climate model which includes more sophisticated radiation and real-Earth surface conditions. IGCM3 was developed in the mid 1990s, mainly by Piers Forster, Robin Glover and Suzanne Rosier, for climate sensitivity studies.

IGCM3 is currently being used for research at Reading (sometimes refered to as RUGCM). Mike Blackburn is the current point of contact at Reading. Details of the Reading IGCM can be found at: http://www.met.rdg.ac.uk/~mike/dyn_models/igcm/

Model structure
The IGCM is a spectral model. Typically run at T21 there have been attempts to run it at T42 also.

In the code the main division in the dynamics is between diabatic and adiabatic processes. The top level structure of GENIE-IGCM is:



Convection
The original convection scheme used in GENIE-IGCM is the Betts Miller scheme and was developed by Mike Blackburn. A description of this scheme can be found here: http://www.met.reading.ac.uk/~mike/betts_miller.html

In response to poor precipitation values in a tuning exercise (Annan et al, 2005) the Betts Miller scheme is no longer the only convection scheme in GENIE-IGCM. The second convection scheme (implemented by David Cameron and with a cloud diagnostic added by John Hughes) is the Tiedtke convection scheme. Initial results look promising that this will dramatically improve the prediction of precipitation.

Having two different convection schemes is also highly interesting since it allows comparison studies in which the only change is a change of the convection scheme.



Published work completed using the IGCM
GENIE and non-GENIE work to be described here.