CALPUFF Frequently Asked Questions (FAQs)

CModeling for PSD/NSR: The answers to questions provided here are not intended to replace or supercede recommendations provided in Appendix W to 40CFR Part 51 (Guideline on Air Quality Models). Applications of this modeling system for the purpose of PSD/NSR permits should be coordinated with appropriate State/Federal authorities.

1.0 Overview and GUI's

1.1 General

  1. When might I consider using a puff model instead of a plume model?
  2. I have input control file from an earlier version of CALPUFF, and want to use it with the most recent version. Will my control file be compatible with the new version? If not, what changes will I need to make to the inputs?
  3. Explain the rules for formatting the input option files for the different programs that make up the CALPUFF modeling system? Is the order of inputs in the input option file important?
  4. What is the maximum file size for CALMET/CALPUFF data, and is this limit compiler dependent?
  5. What criteria do I use to determine whether I should use UTM or Lambert Conformal coordinates for my application of CALPUFF?
  6. How are calm hours treated by the CALMET/CALPUFF modeling system, and if I have a large number of calm hours for one of my surface stations should I be concerned about how it will influence the results?
  7. I want to use CALMET/CALPUFF for a local-scale application involving complex flows. I also want the initial guess wind field to reflect mesoscale features, but do not have MM5 data available for the time period of interest. What options are available?
  8. What are the considerations in developing wind field characterizations (NWS+MM, NWS only, MM only) and what are the effects of these alternatives on modeled concentration and deposition values?
  9. Can CALMET/CALPUFF be used to simulate land/sea breeze circulations, and what special considerations exist for such an application?
  10. I am planning to use CALPUFF to simulate visibility and deposition impacts on a Class I area. What do I need to consider?
  11. Are there any applications for which I should select the option "Do not check selections against regulatory guidance" under the CALPUFF Run Information screen of the GUI?
  12. What extra steps are needed to compile a model or processor on a PC using a FORTRAN compiler other than the Lahey F95 compiler used for the distribution executables?
  13. What extra steps are needed to compile CALMET and CALPUFF on Unix/Linux systems?
  14. Will CALPUFF work with Windows 7 and 64-bit machines?


1.2 Graphical User Interfaces (GUI's)

  1. I switched to another application while running the GUI, and when I came back it was not on the same screen?
  2. How can I control the default directory settings and the default file extension settings?


1.3 Long Range Transport Screening Runs

  1. Where can I get a summary of the processing steps?
  2. How many years of meteorological data should be used when applying CALPUFF in a screening mode?
  3. Can I run CALPUFF with an ISC-type meteorological data file that contains five years of data, or do I need to parse the file into separate years first?
  4. Should I apply a non-zero minimum mixing height when running CALPUFF in a screening mode? If not, how will very low mixing heights affect my results?
  5. Is there a difference between CPRAMMET and the EPA's PCRAMMET meteorological preprocessors, and if so, when should I use CPRAMMET?



2.0 Meteorological Processing (CALMET)

2.1 Terrain Elevation Data Processing (TERREL)

  1. What data formats are supported?
  2. What are the web addresses for the various terrain elevation data sets, and steps necessary to process each?
  3. The 1-degree and 7.5-minute terrain height data files are compressed and have no record delimiters. How should we process these data files for use by the CALMET utility programs running on IBM PC's?
  4. How will I know whether my terrain elevation data is sufficiently resolved (i.e., small enough grid size) for my specific application?
  5. What do I do if my terrain data and/or meteorological domain cross different UTM zones?


2.2 Land Use Data Processing (CTGCOMP, CTGPROC)

  1. What data formats are supported in CTG and PRELND1?
  2. What are the web addresses for the various landuse data sets, and steps necessary to process each?
  3. The 1-degree and 7.5-minute land-use data files are compressed and have no record delimiters. How should we process these data files for use by the CALMET utility programs running on IBM PC's?
  4. What can go wrong when processing landuse data?
  5. Explain the QA threshold for processing of land use data.
  6. What do I do (or where do I go) if there is no land use data for my area of interest from the USGS website?


2.3 Upper Air Data Processing (READ62)

  1. What data formats are supported?
  2. What are the considerations in selecting UA sites a) for long-range transport applications, and b) for complex flow applications.
  3. How can I tell if critical data are missing?
  4. How can I deal with missing soundings, e.g., if lowest levels are missing, or if the soundings do not go high enough, or if complete soundings are missing?
  5. What do I do if my meteorological data stations and/or the meteorological domain cross different time zones?


2.4 Surface Observation Data Processing (METSCAN, SMERGE)

  1. What data formats are supported?
  2. What are the considerations in selecting surface sites, a) for long-range transport applications, and b) for complex flow applications?
  3. Can ASOS data be used with CALMET, and are there any drawbacks to using such data?
  4. How does CALMET handle missing surface data?
  5. How can I deal with missing data?
  6. Does CALMET define a day as hours 00 to 23 or as hours 01 to 24, and how does CALMET and it's preprocessors handle this issue for different types of input meteorological data?


2.5 Precipitation Data Processing (PXTRACT, PMERGE)

  1. What data formats are supported?
  2. What are the considerations in selecting precipitation sites, a) for long-range transport applications, and b) for complex flow applications?
  3. Can I use the hourly precipitation data from my SAMSON meteorological data file, and if so, how do I extract and merge the data with precipitation data from other stations?


2.6 Mesoscale Meteorological Data Processing (CALMM5)

  1. What data formats are supported?


2.7 Switch Settings/Options

  1. Which CALMET settings typically require expert judgement for tailoring the analysis for a specific application?
  2. What options are available for initializing the wind field in CALMET, and how do I determine the best option for a particular application?
  3. How do I select the appropriate grid spacing for my application of CALMET?


2.8 Listing and Review of Results (PRTMET)

  1. Can I use PRTMET to create a file that allows me to plot how meteorological conditions vary over time at a single receptor?
  2. Can I use PRTMET to create files that will allow me to plot how meteorological conditions vary over the entire domain (or some subdomain)?



3.0 Concentration and Deposition Simulation (CALPUFF)

3.1 Emission Data Processing

  1. How can I treat monthly or seasonal variations?
  2. How can I track the impact of one or more sources or source types?


3.2 Background Values for Ozone and Ammonia

  1. Where do I get background ozone data?
  2. How can I vary the background ozone for each grid square and hour?
  3. Where do I get background ammonia data?
  4. How can I vary the background ammonia value?


3.3 Switch Settings/Options

  1. Which CALPUFF settings typically require expert judgement for tailoring the analysis for a specific application?
  2. When should I use the slug option in the CALPUFF model?
  3. What criteria should I use to determine whether or not to allow puff splitting?
  4. What are the various options available for selecting dispersion coefficients, and can I select options that are similar to other dispersion models such ISCST3, AERMOD and CTDM?
  5. What criteria should I use to determine whether or not to use a) the CTSG option for subgrid-scale complex terrain, and b) the SGTIBL option for subgrid-scale coastal effects?
  6. CALPUFF chemistry. What are the tradeoffs and known limitations between use of RIVAD and MESOPUFF II, a) from the respect of setting model options and defining model input, and b) from the respect of effects on modeling results.
  7. How do I solve the problem of too many puffs in my CALPUFF run?



4.0 Auxiliary Intermediate Programs (CALSUM, APPEND, POSTUTIL)

4.1 CALSUM

  1. How can I splice together separate CALPUFF runs that are tracking separate sources or source types?
  2. Can I "adjust" source emission rates after CALPUFF has completed its run?

4.2 APPEND

  1. I need to split my CALMET run into smaller time periods due to file size limitations. How can I do this, and are there any special considerations (e.g., overlapping periods at beginning and end of each segment)?


4.3 POSTUTIL

  1. How can I get total Sulfur and total Nitrogen deposition fluxes?



5.0 Summary of Results (CALPOST)

5.1 Switch Setting/Options

  1. What are the differences and tradeoffs between the different options provided for computing regional visibility impacts?


5.2 Listing and Review of Results

  1. Can I use CALPOST to create a file that allows me to plot how concentrations vary over time at a single receptor?
  2. Can I use CALPOST to create files that will allow me to plot how concentrations vary over the entire domain (or some subdomain)?