NCEP Operational Air Quality Forecast Change Log


AQF Operational Run Forecasts



Model Run


2015-2016 Changes
March 15, 2017  12 UTC
  • NAM V4 scheduled to be promoted to operations
Feb. 4, 2016  12 UTC CMAQ V4.7.2 Implemented (EPA Version number 4.6)
May 1, 2015  12 UTC
Jan. 29, 2015 12 UTC
  • V4.6.5 CB05/AERO-4 CMAQ
    • CB05: 51 species with  156 reactions,  (Sarwar et al., 2013 and 2008).
    • AERO-4: Represent size distribution by log normal distributions of φ, geometric diameter of the particles: Aitken (φ <0.1 μm), accumulation (0.1<φ <2.5μm) and coarse (2.5<φ <10μm). New particle formation: gas conversion and nucleation. (Binkowski and Rosselle, 2003)
    • Heterogeneous hydrolysis reaction of N2O5 ( key linkage between gas and aerosol phase reactions, includes temperature and humidity impact).
    • ISORROPIA V1.7  gas-particle partitioning:  Partitioning between inorganic gas and particulate species due to thermodynamic equilibrium (v1.7 increased stability).
    • NTR, organic nitrate, biases high and influenced ozone production. It is now photolyzed and removed quicker (Dickerson et al., 2014) by shortening NTR lifetime by a factor of 10.
    • Update NOx emissions with satellite data (Pan, et al., 2014).
    • Modulate fugitive dust emission with a binary switch: whenever there is ice/snow suppress emission.
    • Incorporate NESIDS Hazard Mapping System “observed” wild fire  near real-time smoke emissions  (24-48 hrs old fire ponts)
    • Layer specific time step was added to speed up code.
    • Deposition velocity calculation over trees  were adjusted as VOCs and ozone were overpredicted
    • Increased  the minimum PBL to 50 m where high pollutants were noted esp. over marine boundary layers
    • Implemented  a hybrid lateral boundary condition where GEOS-Chem 2006 climatological LBCs were used up to 7 km.
    • Updated emissions using 2005 base year while extrapolating to 2013 by using:
    • Updated CEM point source data to 2012.
    • Updated DOE projection factors to 2014. 

2014 Changes

August 12, 2014  12 UTC
  • NAM  upgraded and implemented in production.  All CMAQ runs driven by upgraded NAM.
May 1, 2014   12 UTC
  • Point, area and mobile emissions  for CB04 chemistry mechanism continue to use recent EPA National Emissions Inventory (NEI,  2005) but projected for the current year.  EGU sources use 2012 CEM data projected for 2014.

2011-2013 Changes

April 1, 2013

12 UTC

June 1, 2012

 12 UTC

October 18, 2011

12 UTC

  • The North American Model (NAM) was upgraded to the National Environmental Modeling System (NEMS) framework Non-hydrostatic Multi-scale Model (NMMB).  The NAM provides hourly meteorological predictions at 12 km to drive CMAQ.

June 1, 2011

 12 UTC

2009-2010  Changes

July 6, 2010

12 UTC

  • Corrected powert plant emissions were incorporated; from our
    evaluations the impact is a minor reduction in predicted ground-level ozone (a few ppb)

September 30, 2010

12 UTC

  • EMC modified POST3 codes to produce both day 1 and day 2 ozone daily maximum predictions.
  • Implementation of Daily Maximum Day 1 ozone GRIB2 NDGD files 

May 1, 2010

12 UTC

  • Point, area and mobile emissions  for CB04 chemistry mechanism continue to use recent EPA National Emissions Inventory (NEI,  2005) but projected for the current year.  EGU sources use 2008 CEM data projected for 2010.

August 12, 2009

12 UTC

  • NAM-CMAQ production AQF model capability declared operational on NCEP IBM Power 6 Computing platform

  May 01, 2009

12 Z

  • Point, area and mobile emissions  for CB04 chemistry mechanism upgraded based upon recent EPA National Emissions Inventory (NEI,  2005) and then projected for the current year.  EGU sources will use 2007 CEM data projected for 2009.  
  • For mobile sources, the  EPA Office of  Transportation and Air Quality (OTAQ ) estimates will be used in addition to 2005 NEI v1 emission data sets.  

2008  Changes

December 16, 2008


Changes to the NAM  driving meteorological model forecast system:

  1. The background for the first (tm12) analysis in each NDAS run is now from the GDAS instead of the previous NDAS run (so-called "partial cycling"). Land states are still fully cycled from the previous NDAS cycle.
  2. WRF-NMM Model changes (also implemented into the DGEX):
    1. The PBL/turbulance schemes were modified to mix each hydrometeor species in the vertical.
    2. To apply vertical diffusion for separate water species, the model was changed so that (a) it can apply vertical diffusion to an arbitrary number of species, (b) the counter gradient option can be applied to some or all of the species if desired, and (c) option to set to zero some or all of the surface fluxes is also made available.
    3. In the radiation parameterization, the absorbtion coefficients for water and ice have been doubled to 1600 and 1000, respectively
    4. Changes to land-sfc physics:
      1. Let the potential evaporation decrease linearly with Bulk Richardson number under stable condition, and weighted by snow coverage.
      2. Let the slope of saturated humidity function wrt temperature decrease linearly with snow coverage.
  3. Changes to GSI analysis
    1. Use latest (1Q 2008) version of the GSI analysis code
    2. Assimilate METOP radiance data
    3. Assimilate TAMDAR/AMDAR aircraft data
    4. New version of Communitity Radiative Transfer Model
  4. Use AFWA 1/16 bedient snow depth analysis
  5. Use WPS (instead of WRF-SI) codes to process GDAS first guess input files, which are used as a first guess to the first (tm12) GSI analysis in the NDAS

May 13, 2008

     12Z Run

  • Point, area and mobile emissions  upgraded based upon recent EPA National Emissions Inventory (NEI,  2005) and then projected for the current year.  EGU sources will use 2006 CEM data projected for 2008.  
  • For mobile sources, the  EPA Office of  Transportation and Air Quality (OTAQ ) estimates will be used in addition to 2005 NEI v1 emission data sets.  Use of OTAQ on-road emission estimates is a departure from the temperature dependent regression approach used in previous years.

March 31, 2008

12Z Run

  Changes to the NAM WRF-NMM weather forecast model implemented.  Impact on AQ specific weather and ozone predictions are shown here.

  • Expanded the Computational domain by 18%
  • Gravity wave mountain drag parameterization implemented
  • Modified horizontal advection for improved mass conservation
  • Improved Surface Longwave radiation calculation
  • Upgraded GSI data assimilation with NMM based backgroun error covariances
  • Improved assimilation of AIRS radiances, GOES single field of view radiances, MODIS and surface Mesonet winds
  • Use of NAM forecast precip to drive soil moisture calculations outside CONUS where precip observations are lacking
  • Increased terrain smoothing

September 18, 2007

     12Z run

  Experimental CONUS CMAQ gas-phase only forecast system moved to NCO Operational slot:

  • Expanded domain (5X) to cover Continental U.S.
  • Common WRF-NMM hybrid sigma-P vertical coordinate
  • NAM clear sky radiation prediction used to scale CMAQ photolysis
  • Asymmetric Convective Model used to drive CMAQ moist convection mixing
  • Asymmetric Convective Model-2 used to drive CMAQ PBL mixing
  • Constant, static Ozone Lateral Boundary conditions for all CMAQ levels (turned off use of GFS ozone at CMAQ Lateral boundary top)
  • Updates to CMAQ V4.6 with bug corrections to deposition, optimized advection scheme and plume rise
  • Special California NEI 2002 Non-Road mobile emissions

Eastern U.S. Operational Run Change Log (2005-Sept. 2007)

July 3, 2007

    12Z Run

CMAQ Point source emission files updated with 2007 projections.

May 16, 2007

     00Z Run

CMAQ static  area emissions updated with 2007 projections.

September 5, 2006

    12Z Run

CMAQ now driven by updates to NAM model (additional NAM-Y changes implemented) that include increase to horizontal diffusion and corrections to SST initial conditions.

       August 22, 2006

    18Z Run

CRISIS Fix:  PREMAQ array bounds corrections implemented. Very small improvement in ozone predictions.

August 15, 2006

    12 Z Run

CMAQ now driven by NAM-Y meteorology  which was implemented into NAM slot.  NAM-Y had corrections to vertical and horizontal diffusion and lake SST initialization which resulted in more realistic warmer,dryer boundary layers that increase production of ozone.  The NAM-Y impact on CMAQ forecasts can be seen from Tsidulko analysis.

       August 01, 2006

    12Z Run

CRISIS Fix:  Some Point  Source Emissions were still configured for 2005 .  These emissions files were updated for 2006 projections.

July 28, 2006

    18Z Run

CRISIS FIX:  The WRF post code  interpolates WRF outputs from the WRF hybrid vertical  coordinate systems to CMAQ sigma levels and  uses simple interpolation for all  elements except temperature.  For temperature,  to be consistent  with hydrostatic balance, it first computes geopotential heights  for upper and lower boundaries (using the hydrostatic equation) and then computes temperature at desired sigma level using the hydrostatic equation again. This algorithm doesn't work in the first model layer, and in this case temperature is extrapolated from the upper layers.  In case of an inversion, since the algorithm involves several upper layers, the bottom sigma temperature happens to be higher then the first model layer temperature. To fix the problem for   loose coupling,. temperature is simply interpolated  (just like all other elements) for the lowest model layer, while using hydrostatically derived temperature for all the upper layers. Impact of these changes can be seen here.

June 20, 2006

   12Z Run

Operational CMAQ Eastern U.S. ozone run driven by operational NAM-WRF.
12 km CMAQ gas w/ reduced CB4 gas  phase chemistry forecasts run twice/day(06 and 12Z) to 48 hours.  WRF outputs interpolated to CMAQ sigma verfical coordinate for loose vertical coupling.

  • 6 hour CMAQ cycling for initial conditions
  • Lateral Boundaries are static except at CMAQ top layer where GFS ozone is specified
  • Above-cloud downward convective mixing turned off
  •  Point/Area Source Emissions  for 2006

April 4, 2006

  18 Z cycle

 Eastern U.S. (3X) run initiated with NAM-WRF parallel run.  WRF outputs interpolated to CMAQ sigma verfical coordinate for loose vertical coupling for 6 hour cycling.  Operational CMAQ NAM-Eta and NAM-WRF 3X domain runs are viewed here 

   August 31, 2005

  00 Z cycle

 NE operational forecasts replaced with Eastern U.S. (3X)  Experimental runs.
Click here for more info on Eastern U.S. configuration
The 3X operational forecasts were the same as the NE U.S. runs except:

  • Larger CMAQ domain: 268x259x22
  • Lateral Boundaries are static except at CMAQ top layer where GFS ozone is specified
  • Above-cloud downward convective mixing turned off

N.E. U.S. Operational Run Change Log (2004-2005)

   June 10, 2005

  00 Z Run

 A bug was corrected in the interpolation  of ozone from the new GFS T382 to the CMAQ 12 km grid.  This has helped reduce ozone overpredictions found in runs from  May 31-June 10, 2005.

  May 31, 2005

  12 Z GFS Upgrade

The NCEP Global Forecast System (GFS) was upgraded to T382 (~35 km).
In addition, the following implementations were changed:

  • A new land/sea ice physics
  • Reduced vertical diffusion
  • Enhanced mountain blocking
  • assimilation of AIRS satellite data

GFS ozone is used to prescribe the CMAQ lateral Boundary Conditions above 6 km.

  May 3, 2005

  12 Z NAM-12 CMAQ Operational (1X domain)

  Upgraded NAM-12.   Upgraded CMAQ  :
   PREMAQ updated to use NAM-12 1 km landuse data
    Minor CMAQ updates to version 4.4
    2002 Point/Area Source Emissions projected for 2005
    Updated Mobile 6 source emissions
    GFS ozone for CMAQ LBCs above 6 km


  September 15, 2004

   00 Z

  N.E. U.S. Run declared operational

May 1, 2004

12 Z Eta-12

CMAQ Experimental

Implemented Experimental System

2002  Point/Area Source Emissions Projected for 2004

Updated Mobile 6 mobile source emissions

6 hour initial condition cycling

Use of GFS ozone predictions for CMAQ upper Lateral Boundary Conditions

March 2004 Eta-12 implementation

48 hour forecasts for both 06 and 12 UTC runs

May 5, 2004

12 Z Experimental

Correction to 6 hour Cycling system. Now turned on.

May 17, 2004

12 Z Experimental

Correction to GFS ozone LBC ingest.  Now working.

May 26, 2004

12z Experimental

Sfc ozone Grib files now available on /com/aqm/prod

July 20, 2004  


1. Limited  GFS LBC  ozone ingest to above 6 km AGL (CMAQ sigma lvl 18)
2. Specification of  a minimum mixing coefficiant (Kz) in CMAQ pbl routines
   *  Allows for lower Kz in rural areas than urban at night :  reduces  nightime O3 overprediction in rural  areas
   * Prevents precursor concentrations in urban areas becoming too large at night and
     thereby reduces overtitration in urban areas (more mixing in urban areas at nght)



NCEP FVS verification system



System Component


June 1, 2005

 Grid2obs VSDB records

 VSDB exceedence records (FHO) now being produced for daily maximum 1 and 8 hour ozone predictions.

March 25, 2005

Grid2obs VSDB

 VSDB file generation turned on for 2005 Ozone season:
Backward averaged convention used for both Airnow bufr and cmaq forecasts
L1L2 and FHO statistics now computed (except daily maximums)

 2004 FVS VSDB File changes

May 31, 2004

Grid2obs VSDB records  

VSDB records (L1,L2) begun for NE domain on 146 grid using forward averaged BUFR observations

June 9-June 20

BUFR generation

BUFR software changed at EPA to produce backward averages. 
VSDB records not produced

June 21, 2004

BUFR Generation

BUFR softward changed at EPA to produce foreward averages for NCO data tanks.
Bufr tanks and VSDB records for June 9-20 recreated with foreward avging

July 12, 2004

VSDB records

VSDB records are now computed for East US domain on Grid 146, 142
Subdomain records computed for all grids (eg: NEC, SEC,APL...)

July 22, 2004     

3X VSDB Records      

VSDB records computed for developmental 3x domain (Grid 142) over full domain, and subregions, and over 1 x domain

August 1, 2004

VSDB records

VSDB subdomains updated to new FVS regions.  MDW, GMC and  LMV now
replace NMW, SMW (midwest) subregions.

August 1, 2004

FHO VSDB records

Began creating  1h & 8 h VSDB FHO records for events :
1hr ozone > 20, 40, 65, 85, 105, 125 ppb
8h avg ozone > 20, 40, 65, 85 ppb





Summer 2003 North East Domain Forecasts



Model Run


June 25, 2003

12 Z Eta-12 – CMAQ Experimental

Implemented Experimental System with 24 hour ozone initialization cycling.

Used Spring 2003 Eta-12 implementation

July 23-24

12 Z Experimental

CMAQ Archives lost

July 31- August 4

12 Z Experimental

Cold Start Runs…No cycling

August 5

12 Z NCO run


Transfer to NCO

Cold Start…no cycling

August 5

06Z Experimental

06Z implemented

6 hour cycling (6z only)

August 15

06 Z Experimental

Cold Start

August 20

06 Z NCO

12 Z NCO

Transfer of 6 hour cycling to NCO for 6 and 12 Z runs.

Cold Start

September 9

06 Z, 12 Z NCO

Eta-Post:  landuse, soiltype variable packing fixed.  Previously landuse values incorrectly packed to equal 0 (Ocean) or 10.