
                        Model Change Bulletin

                                MCB#6                      12/19/2011

                        AERMOD (dated 11353)

This Model Change Bulletin (MCB) documents changes made to the AERMOD
Dispersion Model. A brief description of the changes is provided
below.  Additional details are available in the Fortran source code.
No changes to the user instructions were required for update.


This revised version of AERMOD (dated 11353) includes the following
modifications relative to the previous version (dated 11103):

--  Bug Fixes:

    1.  Modified subroutines METEXT, MAXD_METEXT, ALLRESULT to fix the
        MAXDCONT option for URBAN applications. Source contributions 
        reported in MAXDCONT files generated by the previous version
        could be erroneous for applications involving URBAN sources.

    2.  Modified subroutine OUTQA to include logical variable PLFILE 
        for PLOTFILEs in the check for output file options that use
        the FILEFORM keyword specifying whether fixed-format or 
        exp-format is used. Previous versions erroneously issued 
        warning message W399 if PLOTFILE was the only relevant output 
        option used with the FILEFORM keyword.

    3.  Modified subroutine O3VALS to corret the test for number of 
        parameters to be .GE. 4 to allow for the ANNUAL option.

    4.  Modified subroutine METEXT to only increment hour index and 
        year index if MAXDCONT option is being used. This change avoids 
        unnecessary runtime error if the met data file includes a single 
        hour (or more) beyond the maximum number of years specified by the 
        NYEARS PARAMETER, which is initialized to 5 in the MAIN1 module.

    5.  Modified subroutine PRTO3VALS to use the O3FLAG variable which
        identifies the user-specified option for defining temporally-
        varying background ozone concentrations. The previous version 
        erroneously referenced the BFLAG variable associated with 
        user-specified BACKGROUND concentrations. This error would not
        have affected modeled concentrations based on the previous 
        version of the model, but could result in a runtime error due 
        to an array subscript out-of-bounds for some applications, or 
        could result in skipping the summary of user-specified ozone
        values in the output file for some applications.


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                        *   IMPORTANT   *
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This program will henceforth be identified by its name and a Julian date,
i.e.: AERMOD (dated 11353).  Future changes to this model will be identified
by an updated Julian date found at the beginning of the model source code
and followed by a reference to a SCRAM Model Change Bulletin (MCB#n)
which will explain the nature and content of the changes.  All Model Change
Bulletins for this program will always be available for back reference on
this website.  In the future, notification of changes (MCBs) to this program
will be made in the Recent Additions section of the SCRAM website.
