CALPUFF is an advanced non-steady-state meteorological and air quality modeling system developed by scientists at Exponent, Inc. It is maintained by the model developers and distributed by Exponent. The model has been listed by the U.S. Environmental Protection Agency (EPA) as an alternative model for assessing long range transport of pollutants and their impacts on Federal Class I areas and for certain near-field applications involving complex meteorological conditions when the selection and use occur in agreement with the appropriate reviewing authority and approval by the EPA Regional Office (see details on CALPUFF’s Regulatory Status).
The modeling system consists of three main components and a set of preprocessing and post-processing programs. The main components of the modeling system are CALMET (a diagnostic three-dimensional meteorological model), CALPUFF (an air quality dispersion model), and CALPOST (a post-processing package). In addition to these components, there are numerous other processors that may be used to prepare geophysical (land use and terrain) data in many standard formats; meteorological data (surface, upper air, precipitation, and buoy data); and interfaces to other models such as the Penn State/NCAR Mesoscale Model (MM5), the National Centers for Environmental Prediction (NCEP) Eta/NAM and RUC models, the Weather Research and Forecasting (WRF) model and the RAMS model.
Some examples of applications for which CALPUFF may be suitable include:
The CALPUFF Modeling System is available from Exponent without charge. The main models (CALMET, CALPUFF, and CALPOST), and related processors are available for download. You may also register to receive notices of model updates.
July 29, 2022
CALNO2 Version 7.0.0 is now available for download as part of the Version 7 CALPUFF codes. CALNO2 will allow a user to process one or more CALPUFF concentration files and calculate NO2 concentrations based on modeled NOx using either OLM or ARM methods.
February 6, 2020
CALPUFF Version 7.3.1 is currently being distributed under a BETA release heading. The code and related post-processors are available for public use and testing of the new SPRAY source type. Any comments or questions on this new release are appreciated and can be directed to rreiss@exponent.com. During this period, CALPUFF Version 7.2.1 remains available as part of our standard Version 7 code distribution.
October 1, 2019
CALPUFF Version 7.3.1 has been released. This version incorporates an agricultural spraying source type. In addition, several bugs were identified and fixed in Version 7.2.1 including issues with the use of multiple sub-hourly variable emissions files and processing missing layers in AERMET generated .PFL files. The only change from Version 7.2.1 to 7.2.2 was a bug fix related to the spray source.
The post-processors CALPOST (v7.2.0 to v7.3.0), CALSUM (v7.1.0 to v7.2.0) and POSTUTIL (v7.1.0 to v7.2.0) have also been updated to allow processing of the new spray source type.
CALWRF has been updated from v2.0.2 to v2.0.3 to correct a bug related to precipitation events which cross between multiple WRFOUT files.
July 26, 2016
The USEPA has approved an update of CALMET and CALPUFF from V5.8.4 (dated July 31, 2013) to V5.8.5 (dated December 14, 2015). This update includes code changes described in Model Change Bulletin H (MCB-H). These changes include fixes to bugs in the implementation of PRIME downwash, along with updates to eliminate specific compilation and list file errors.
June 22, 2015
CALPUFF Version 7 is released.
March 19, 2014
CALMET has been updated from v6.334 to v6.4.0 (level 121203). This update includes the enhancements of polar stereographic mapping, increased maximum number of 3D.DAT files, and a compressible liquid water content output file. In addition, several bugs were identified and fixed with v6.4.0 including improved time zone reads from input file headers, expanded input file version support, and updated logic for input file version assumptions.
CALSUM has been updated from v1.4 to v1.5.0 (level 121203). This update allows files with different time periods to be merged. With the update, it is assumed that times missing from one of the compared CALPUFF files have zero impact from the sources contained in other comparison files. That is, concentrations are assumed zero for those periods not in an “addend” file. In addition, v1.5.0 expands the version string to 12 characters.
METSERIES has been updated from v1.81 to v1.9.0 (level 121203). This update includes the enhancements of inclusion of surface pressure as an output parameter, a more explicit midnight convention, support for extracting precipitation data from PRECIP.DAT and 2D.DAT formatted files, and support for reading newest format AERMOD files (SURFACE, PROFILE data). In addition a bug was fixed to correctly address missing data in wind rose calculations.
SMERGE has been updated from v5.661 to v5.7.0 (level 121203). This update includes the enhancement of allowing more NCDC ISHWO data codes to be read. In addition, a bug was fixed to correctly address missing temperature observations and missing data flags.
BUOY has been updated from v1.251 to v1.3.0 (level 140116). This updates adds an enhancement of read functionality for the standard NDBC data format available at the time of this update.
Please note the updated programs above include the following two revised CALPUFF library files:
CALUTILS (CALPUFF library) has been updated from v2.58 to v.2.6.0 (level 140318). This update utilizes standard Fortran 95 intrinsic procedures for date and time (Subroutine DATETM). Obsolete compiler specific code removed for obtaining command line arguments (Subroutine COMLINE).
COORDLIB (CALPUFF library) has been updated from v1.98 to v1.10.0 (level 140313). This update fixes erroneous non-zero false Northing when converting Southern hemisphere locations to UTM-N coordinates. Also initialize various variables and work arrays to zero.
December 4, 2013 The USEPA has approved an update of CALMET and CALPUFF from V5.8 (dated June 23, 2007) to V5.8.4 (dated July 31, 2013). This update includes USEPA-approved portions of code changes described in Model Change Bulletin E (MCB-E), MCB-F and MCB-G. USEPA has approved only those portions of the Model Change Bulletins that are recognized as bug fixes. All other code changes (enhancements and new features) are not included at this time. A memo describing bug fixes versus enhancements is available on SCRAM. Note that the USEPA approved version of CALPOST remains V6.221 (level 080724).
August 13, 2013 CALWRF has been updated from v1.4 to v2.0.1 (level 130418), which includes support to process multiple WRF files, a precipitation rate bug fix, creation of 2D.DAT files, range checks for 2D/3D variables, 3D.DAT header correction, a map projection bug fix, blank string initialization routine, and idatenext loop bug fix, and updated Linux and Windows compiling instructions.
August 17, 2012 The USEPA-Approved version of CALPOST has been updated from version 5.6394 (level 070622) to version 6.221 (level 080724). Version 6.221 includes "Method 8" (MVISBK = 8, M8_MODE = 5, MVISCHECK = 1), which utilizes the revised IMPROVE equation per the Federal Land Managers' Air Quality Related Values Work Group (FLAG) revised October 2010 report. This update only effects CALPOST, and no other program in the CALPUFF System of programs. The USEPA-Approved version of CALPUFF remains version 5.8 (level 070623) and the USEPA-Approved version of CALMET is still version 5.8 (level 070623).
April 25, 2011. Version 6.42 of the model has been updated to include MCB-G.
April 14, 2011. Updates to the Nov 2010 Version 6 CALPUFF (v6.42) and CALPOST (v6.291) model codes. This release includes a new v6 CALMET release (v6.333) and new GUIs compatible with the updated v6 codes.
November 3, 2010. Two new chemistry options have been introduced into the latest Version 6 series of the CALPUFF modeling system. The new programs include CALPUFF (Version 6.4) and POSTUTIL (Version 1.64). The changes to the chemistry include modifications to the RIVAD chemical conversion algorithms for the transformation of SO2 to SO4 and NO/NO2 to HNO3 and NO3, addition of the ISORROPIA (Version 2.1) model for inorganic gas-particle equilibrium, addition of aqueous-phase transformation adapted from the RADM cloud implementation in CMAQ/SCICHEM and a new option for anthropogenic secondary organic aerosol (SOA) formation based on the CalTech SOA model implemented in CMAQ-MADRID. These changes are based on work by Karamchandani et al. (2008) with an earlier version of ISORROPIA and CALPUFF. Other changes in this release also include MCB-F updates as well as new model options such as a nested grid option in CALPUFF.
August 4, 2008. An implementation of the draft FLAG (2008) guidance on visibility has been added to a new beta Version 6 of CALPOST. The GUI has been enhanced to include a library of the f(RH) and background extinction values for each Class I area in the United States. Changes to Version 6 of CALMET and CALPUFF that do not affect results when running in regulatory mode have been included in this update.
June 27, 2008. Version 6 of the model has been updated to include all updates through MCB-E as well as the new regulatory switch used in Version 5.8 and settings recommended by the USEPA. An extensive set of new features has been added to the graphical user interface system and support processors.
June 29, 2007. The USEPA has approved an update in CALPUFF from V5.711a (dated July 16, 2004) to V5.8 (dated June 23, 2007). This update includes code changes described in Model Change Bulletin B (MCB-B), MCB-C and MCB-D. CALMET has been updated from V5.53a (dated July 16, 2004) to V5.8 (dated June 23, 2007). The new codes are based on the VISTAS-series codes (CALPUFF V5.756 and CALMET V5.726) with the main changes being the addition of a regulatory switch in CALMET and switch settings recommended by the USEPA to configure the models to be consistent with the prior regulatory versions. The model preprocessors and postprocessors in the USEPA-approved section have been updated to the VISTAS-series of the model codes.
August 4, 2006. Update of VISTAS Version 5 (CALMET, CALPUFF, CALPOST, POSTUTIL, CALMET GUI, and CALPro GUI).
CALMET v5.726 (dated August 1, 2006) includes corrections in the overwater buoyancy flux calculations, and modifications to correct run-time stoppages seen in specific configurations.June 15, 2006. The USEPA has approved an update to CALPUFF from v5.7 (dated April 2, 2003) to v5.711a (dated July 16, 2004) as described in Model Change Bulletin A (MCB-A).
April 14, 2006. Update of Version 6 (CALMET, CALPUFF, CALPOST, POSTUTIL, and CALPro GUI); Update of VISTAS Version 5 (CALMET, CALPUFF, POSTUTIL, BUOY, and CALPro GUI); VISTAS Sub-Regional Sample Files and Data Files available and new description of one-step ALM procedure.
April 3, 2006. Release of Version 6 of the CALPUFF modeling system.
March 30, 2006. Update of CALMM5 to eliminate possible duplicate hours being retained when using multiple MM5 output files from different MM5 runs with overlapping hours.
January 9, 2006. Model Change Bulletin B (MCB-B) has been added that addresses changes to the modeling system codes needed to update the current BETA-Test (MCB-A) release. These changes are posted here to provide users access to important updates prior to the next release of the system. Model Change Bulletin B(051216) identifies the changes in CALMET and CALPUFF and may be used to update the corresponding codes. Users who are currently running the BETA-Test (MCB-A) versions of these programs may download updated versions by going to the "Download" page. Note that a revised GUI installation for the BETA-Test (MCB-B) system is provided there as well, which contains the updated CALMET and CALPUFF executables.
May 25, 2005. A version of CALMM5 (MM5 V3) has been added to the Download BETA-Test page. This version of CALMM5 processes MM5 Version 3 output data directly.
July 16, 2004. A Model Change Bulletin (MCB) has been added that addresses changes to the modeling system codes needed to update the current BETA-Test release. These changes will be part of the next release of the system, but are posted here to provide users access to important updates in the interim. Model Change Bulletin A(040716) identifies the changes in CALMET,CALPUFF, READ62,and SMERGE, and may be used to update the corresponding codes. Users who are currently running the BETA-Test versions of these programs may download updated versions by going to the "Download" page. Note that a revised GUI installation for the BETA-Test system is provided there as well, which contains the updated CALMET and CALPUFF executables.
July 11, 2003. Changes to the official version of the CALPUFF modeling system are available for beta testing on the "Download" page. These modifications are not yet officially accepted by the USEPA, but they are provided for user testing.
April 17, 2003. A new version of the CALPUFF modeling system has been released. This version of the model is the USEPA-recommended version that should be used for regulatory application studies. It includes numerous upgrades and new features, including a “no-observations” option in CALMET allowing the model to be run with 3-D prognostic (e.g., MM5) meteorological data alone, introduction of the PRIME building downwash model, a generalized coordinate transformations, new self-documenting control (input) files for the preprocessors and postprocessors, and a set of new GUIs for running the preprocessing programs. The elements of the beta-test version that has previously been available are implemented into the new release. More information on the specific model updates are provided in the download area of the web page.
The Frequently Asked Questions (FAQ) pages, formerly available in the beta-test area, has been expanded and is now accessible on the main download pages, or by means of the FAQs link listed in the panel on your left.