History of the recent versions of the UCLA AGCM
[Features are accumulative (unless optional) as the version number advances.]

Version 6.6
Version 6.61
Version 6.62
  • Shortwave radiation parameterization modified; Instead of using Katayama's ('72) formulations, shortwave absorption by ozone computed following Lacis and Hansen ('74) [Farrara, Kim and Mechoso '97]
Version 6.63
  • Shortwave radiation parameterization modified again; Instead of using Katayama's ('72) formulations, shortwave absorption by water vapor computed following Manabe and Moeller ('61) [Kim, Farrara and Mechoso '98]
Version 6.7
  • Vertical mixing of momentum in dry convectively unstable layers included [Farrara]
Version 6.8
  • Formulations of the vertical advection between the PBL and the free atmosphere improved (summary)
Version 6.9
  • Shortwave radiation parameterization switched from Katayama's ('72) to Harshvardhan et al.'s ('87)
Version 6.91
Version 6.92
  • Prognostic Arakawa-Schubert cumulus parameterization scheme (Pan and Randall, QJRMS '98)
  • Grid-scale precipitation computation procedure improved
  • Relaxed adjustment time scale (5 physics timesteps) applied to increments in water vapor mixing ratio and potential temperature from moist convective adjustment routine
Version 6.95
  • The layer cloud instability (LCI) process revised such that the effect of LCI on prognostic variables is added instantaneously rather than over the duration of one 'physics' timestep
  • The PBL cloud amount, which depends on the variance of the underlying topography, modified as described in Li and Arakawa ('98)
  • The method for calculating the optical depth of PBL clouds, which uses the diagnosed cloud liquid water of Suarez et al. ('83), modified for improvement
  • Several bugs fixed; the most significant being in the cumulus redistribution of momentum, such that this is done correctly now whereas previously it was underestimated by an order of magnitude or more
Version 6.98
  • Revised evaporation of large-scale precipitation; loosely based on Eq. 6.3.10 of Cheng and Arakawa ('97)
  • Modified 2.5 long. x 2 lat. version of topography to reduce steepness of slope (specifically don't allow slopes greater than 1/100) [Farrara]
  • Drag added to momentum in the PBL in regions where the slope of the topography is greater than 1/200. This drag is linearly proportional to the slope of the topography with a maximum coefficient of 1x10**-3 s**-1 [Farrara]
  • Minor modifications to the cumulus and large-scale precipitation parameterizations:
    If ( topographic variance > 10**5 ), do not apply the 95% PBL RH criterion for the occurrence of cumulus convection, and do not consider the nimbostratus case for large-scale precipitation from the PBL. [Farrara]
Version 7.0
  • Prognostic determination of cloud water and ice added
  • Effects of cumulus downdrafts included in the (prognostic) Arakawa-Schubert cumulus parameterization scheme [Cheng and Arakawa '97]
  • Calculation of PBL cloud optical properties modified per Li et al. (2002) [Li et al. '02]
Version 7.1
  • Bug fixed in prognostic cloud water/ice scheme
  • Code placed in CVS repository in the following directory: /cvsroot/camel_7.1p
Version 7.2
  • Added 'cumulus' clouds for every cloud type (layer) with positive cumulus cloud base mass flux. These clouds have the optical properties of cumulus clouds as specified in Harshvardhan (1987, 89) and replace any clouds predicted by the prognostic cloud water/ice scheme. [Spahr]
Version 7.3
  • Added Fu-Liou solar and terrestrial radiation parameterization as an option. If this option is exercised, this is considered to be version 7.3 [Gu/Farrara].
Version 8.0 (In progress)
  • Multi-Layer PBL [Konor and Arakawa]


For questions or comments, please contact Joseph Spahr
or John Farrara


Revised, 3 July 2003