Model Change Bulletin

                                    MCB#6                        

                             ISCST3 (dated 98356)

    This Model Change Bulletin documents changes made to the Industrial
Source Complex Short Term (ISCST3) Dispersion Model (see Code Changes below).

[NOTE:  New ISC3 users are urged to read ISC3 MCB#1, Amendment #1 for
important information.  In addition, this change to the ISCST3 model does
not address the anomalous behavior of the dry deposition algorithm described
in MCB#2 and MCB#5.]

CODE CHANGES

    Changes from ISCST3 (dated 98348) include the following:

1.  A correction to an error with the new post-1997 PM10 routines.
    The error occurred when only 24-hour averages were calculated
    (no ANNUAL averages) for a multiple year period.  The multi-year
    average of the H4H 24-Hour values was not computed correctly in
    those cases.

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                           *   IMPORTANT   *
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    This program will henceforth be identified by its name and a Julian date,
i.e.: ISCST3 (dated 98356).  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 contents 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 SCRAM ALERTS section of this website.