Mesoscale Parallel Experiment Change Log

Experiment Name:  Meso-08 HiResWindow Model

When Who What
2002/02/19/12 Janjic, Rogers
  • Changed parameter CFL_MAX in ADVE.F from 0.97 to 0.80. When vertical CFL=CFL_MAX is detected, the temperature and wind profiles between the levels in question are smoothed to prevent a violation of the CFL criteria.
  • Changed Z0MAX in INIT.F from 10 to zero; this eliminates using the standard deviation of the surface height to compute the roughness length.
  • 2002/02/22/12 Ek, Mitchell, Rogers
  • Begin use of new version of SFLX with modified thermal conducivity through snow cover which will soon be implemented in the operational Eta code.
  • 2002/02/26/00 Janjic, Rogers
  • Changed parameter CFL_MAX in ADVE.F from 0.80 to 0.66.
  • 2002/02/26/00 Chuang
  • Modified vertical interpolation algorthim in eta-to-hybrid preprocessor to interpolate heights using linear in ln(pressure) instead of quadratic in ln(pressure)
  • 2002/02/26/00 Chuang, Rogers
  • Fixed a bug in routine BNDLYR2 in the hybrid post-processor so that boundary layer mean fields (temperature, etc.) are calculated correctly.
  • Fixed a bug in INIT which was causing the the array TSHLTR in the initial condition restart file to be converted twice to potential temperature, causing 00-h 2-m temperatures to be too high.
  • Fixed an error which caused the 00-h 10-m wind speed to be smaller than the those from the 10-km Eta nests. In the 10-km Eta nest, the 00-h 10-m winds are set equal to the winds in the lowest Eta layer above ground. Changed the hybrid code to consistent with the Eta code at 00-h
  • 2002/03/05/12 Chuang
  • Fixed a bug in routine CALCAPE in the hybrid post-processor so that CAPE and CIN are calculated correctly.
  • 2002/03/05/12 Rogers
  • Reduced fundamental time step for 8 km runs from 20 sec to 18 sec to prevent code failure due to linear instability (occurred in 3/2-3/4 Eastern U.S. 8 km runs).
  • 2002/03/12/18 Janjic
  • Divergence damping parameter CODAMP increased from 6 to 15 for all 6 nested domains.
  • Lateral diffusion factor COAC decreased from 0.25 to 0.1 for all 6 nested domains.
  • Fundemental time step increased from 18 sec to 20 sec for all 8 km domains.
  • 2002/03/14/18 Janjic
  • Introduced slope factor variable SLOPHT which was used in HDIFF to turn off horizontal diffusion is the ground slope exceeds 5%. This was done to reduce large precipitation over high terrain in Hawaii.
  • 2002/03/18/12 Chuang, Janjic
  • Modified vertical interpolation algorthim in eta-to-hybrid preprocessor to interpolate heights and wind using cubic spline instead of linear ln(pressure).
  • 2002/03/25/12 Chuang
  • Fixed a problem in the cubic spline version of INTRST due to a mismatch between HTMI and LMHI (the input Eta-12 terrain masks) before spline interpolation is called. Because the horizontal interpolation is done before vertical interpolation, there was no "real" HTMI and LMHI over the output domain combined with input terrain. Therefore, HTMI was estimated from comaprison between output terrain and standard height while LMHI was estimated from where horizontally interpolated TI becomes zero.

    To fix the problem, changes were made to the specification of HTMI and LMHI so that they match each other in two different ways depending on whether input terrain is higher than output terrain.

  • 2002/03/27/12 Rogers
  • The 12Z 3/25/02 changes were pulled due to failures of the 8-km Eastern U.S. run.
  • 2002/04/01/12 Chuang
  • Always match htmoi (input Eta height mask) to lmhoi (first Eta level above ground) regardless how input terrain height compares to output terrain height. This ensures that geopotential height over the nested domain combined with input terrain would not be identical at any two layers which occurs when interpolated input temperature is zero and htmi=1 at any layer. The identical geopotential height at any two layers will cause the spline interpolation of surface pressure to fail.
  • The new surface pressure over the nested domain is specified to be identical to the output surface pressure when the terrain height difference between input and output domains is less than 10 cm. This change was made for the following two reasons:

    (1) To make sure that surface pressure over nest domain is identical to the surface pressure over 12 km domain over the ocean.

    (2) To avoid generating thin layers for extrapolation when input terrain is barely above the output terrain.

  • 2002/04/04/12 Janjic
  • Modified horizontal advection routine HAD2 so that there is no moisture transport up the hybrid surfaces when the slope is greater than 5%.
  • Modified HDIFF so that fluxes between any two points on hybrid surfaces are set to zero if the slope exceeds 5%.
  • The liquid water potential temperature has been introduced as a dependent variable in order to take into account the effects of phase changes on turbulence. In order to avoid using an inconsistent and/or oversimplified microphysics scheme, the redistribution between the water vapor and condensate after the vertical turbulent transports of these quantities is left to the model's gridscale precipitation scheme.

    The integral stability functions for stable regime have been replaced by the functions proposed by Holtslag and de Bruin. The new functions have better asymptotics in case of extremely stable surface layers. Also, the possibility of overestimating the surface fluxes in extremely stable situations due to computational constraints has been eliminated. Over water surfaces, the previously used approximate stability functions derived from a theoretical model have been replaced by stability functions based on observations. Iterative calculations of the parameters of the viscous sublayer over water have been introduced in order to improve the accuracy of the computations. The stability functions are specified using predefined look-up tables.

  • 2002/04/04/18 Chuang
  • Modified INTRST's computation of the initial surface pressure to be proportional to ln(p) instead of proportional to pressure. This eliminates erroneously high (> 50C) surface temperatures in the hybrid initial conditions.
  • 2002/04/08/12 Janjic
  • Set initial soil moisture in all 4 soil levels to 0.5 for all points above 2039 m elevation
  • Removed the pressure limit (currently = 200 mb) on adjusting moisture in CUCNVC
  • Changed SLOPHT from 0.05 to 0.001, and turned back on the passive scalar advection transports on sloping hybrid surfaces in HAD2.
  • 2002/04/10/12 Black
  • Turned on initialization of interpolated initial conditions from the Eta-12 using the Lynch digital filter for 3 iterations (1 iteration = 110 timesteps)
  • 2002/04/11/18 Black
  • Revised the distribution of the 60 hybrid vertical layers so that the lowest layer is 40 m thick instead of 20 m thick.
  • 2002/04/12/12 Black, Rogers
  • Reverted back to original hybrid level distribution. The 18Z 4/11 change will be reimplemented when the new vertical layer distribution is put into the hybrid boundary condition files generated from the operational Eta-12.
  • 2002/04/15/12 Black, Rogers
  • Hybrid lateral boundary condition files from the operational Eta changed to use new hybrib level distribution with 40 m thick layer over water. Parallel runs changed to use this new vertical layer distribution.
  • 2002/04/17/18 Chuang
  • Fixed an error in the interpolation of specific humidity from eta to hybrid layers to prevent input specific humidity values of zero to be used. If the eta specific humidity is zero, it is reset to the minimum default used in the model (1.0E-12) before the vertical interpolation is performed.
  • 2002/04/18/12 Janjic
  • Increased diffusion paramter COAC from 0.1 to 0.25. This increase allowed 2 failed runs (06Z 4/15 west US and 12Z 4/17 central US) with CFL violations to run to completion without CFL violations.
  • 2002/04/24/12 Rogers
  • Reverted to use of initial soil moisture from the eta-12 at elevations > 2039 m instead of setting it equal to 0.5 (see 12Z 4/8/02 change). This change caused several failed central US forecasts which failed to run to completion.
  • 2002/04/25/12 Rogers
  • Increased diffusion paramter COAC from 0.25 to 0.5. This increase allowed a failed forecast (12Z 4/25 central US) to run to completion.
  • 2002/04/30/12 Black
  • Began use of new hybrid surface orography files and z0eff files with fixes to some boundary points (inadvertently set to sea level). New terrain files are now being used in both INTRST and operational hybrid boundary generation job.
  • 2002/04/30/12 Janjic, Ferrier
  • Changed the grid-scale RH condensation threshold in the cloud microphysics to 100% instead of using the resolution-dependent formula in GSMCONST (which set the value to 97.8% for the 8 km grids)
  • 2002/05/02/12 Rogers
  • Modifed the pre-processor code INTRST so that the initial soil temperatures and fixed field TG are adjusted based on the terrain height difference between the eta-12 and the hybrid model terrain height. The standard atmosphere lapse rate of 6.5C / km is used for the adjustment.
  • 2002/05/15/12 Janjic
  • Replaced Adams-Bashfort vertical advection scheme with the damping Matsuno vertical advection scheme and set CFL threshold to 0.97 (was 0.66). Diffusion parameter COAC set to 0.25 (was 0.50).
  • 2002/05/24/12 Black, Rogers
  • Reduced physics timestep from 360 sec to 240 sec for the 8 km hybrid Meso forecast, and from 480 sec to 240 sec for the 10 km Alaska hybrid Meso forecast.
  • 2002/05/30/12 Rogers
  • Reverted back to the original physics timestep (360 sec for the 8 km runs, 480 sec for the 10 km Alaska run.
  • 2002/07/02/12 Rogers
  • Modified the radiation driver (RADTN) and short-wave radiation code (SWR93) by adding Ferrier's modifications to the operational Eta which removes small cloud water amounts in thin layers. This problem caused occasional failures in the operational Eta code.
  • Page Last Modified: April 25, 2002