Mesoscale Parallel Experiment Change Log

Experiment Name:  Eta-32 with modified shallow convection parameterization

When Who What
2004/9/1/00/ Ferrier
  • The maximum depth of shallow convection is limited to 200 hPa, even if the (entraining) parcel temperature is more than 2C warmer than the environment at cloud top (see 3rd bullet in 2004/7/27/12 entry). This change is intended to reduce the amount of stabilization in the parallel and reduce the low precipitation bias.
  • 2004/8/27/00/ Ferrier
  • Revert to operational versions of routines MIXLEN and PRODQ2 (see 6/29/04 entry)
  • 2004/8/21/00/ Ferrier
  • The fraction of ambient air mixed at cloud top was increased from 20% to 30% (see 2004/8/3/12 entry)
  • 2004/8/6/12/ Ferrier
  • Fixed a bug in the shallow convection which caused the code to abort in extremely dry conditions when calculated cloud base got too low.
  • 2004/8/3/12/ Ferrier
  • The amount of lifting of parcels to reach their condensation level (LCL) was removed as a criteria for convective triggering.
  • The fraction of ambient air mixed at cloud top was decreased from 30% to 20%.
  • 2004/7/29/00 Ferrier
  • Increased the maximum lift of the parcels back to 100 hPa.
  • 2004/7/28/12 Ferrier
  • Restricted the triggering of shallow convection by:
    1. Reducing the maximum lift of parcels from 100 hPa to 50 hPa.
    2. Including in the parcel ascent the lifting of air to reach the lifting condensation level (LCL).
  • Changed some of the code logic to avoid unnecessary calculations.
  • EDAS restarted from ETAV control
  • 2004/7/27/12 Ferrier
  • Fixed a bug associated with a 3D storage array of saturation pressures.
  • Increased the amount of cloud-top entrainment from 5% to 30%.
  • Changed the default maximum depth of shallow convection from 400 hPa to 200 hPa under most circumstances. But if the (entraining) parcel temperature is more than 2C warmer than the environment at cloud top, then the maximum depth of shallow convection can extend up to 300 hPa.
  • The entire shallow convection section was modifed and rewritten to consider upward transports of heat and moisture. These changes include different methods for calculating the reference profiles of temperature and moisture.
  • Shallow convection is aborted only if there is a decrease in column-integrated entropy. All other criteria for aborting shallow convection have been removed.
  • EDAS restarted from ETAV control
  • 2004/6/29/12 Ferrier, Freedman, Janjic, Ek, Mitchell
  • DIFCOF.F & TURBL.F changed: In very stable conditions when the PBL depth is diagnosed as the lowest Eta model level above the surface, impose a lower limit on eddy diffusivity (Km,Kh) of 0.5 m^2/s up to (and one level above) the inversion height in order to maintain atmospheric turbulent mixing at least above this nominally small value.
  • Subroutine SFCDIF was changed : For the profile functions for the very stable boundary layer (z/L=>1), impose a consistent limit on z0/L.
  • Changes to subroutines MIXLEN and PRODQ2 which removes mixing length limits under stable conditions -- should increase (downward) turbulent heat mixing in stable conditions.
  • EDAS restarted from ETAV control
  • Page Last Modified: August 3, 2004