Model Change Bulletin
              
                              MCB#2                       4/26/95

                      CAL3QHC  (Dated 93157)
                      CAL3QHCR (Dated 95116)


     Both CAL3QHC and CAL3QHCR are covered by this Model Change Bulletin. 
CAL3QHCR is an enhanced but separate version of CAL3QHC.  Both models will
retain their respective identifying Julian dates.

        No changes have been made to CAL3QHC (Dated 93157) and therefore, there is
no change to its Julian date.

     This Model Change Bulletin initiates the activities of CAL3QHCR (Dated
95116) under the CAL3QHC header.  CAL3QHCR is an enhanced version of CAL3QHC
(Dated 93157).  CAL3QHCR is capable of processing up to a year of
meteorological, and vehicle emissions, traffic volume and signalization data in
one run using the basic algorithms from CAL3QHC.  Daily to seasonal runs can
also be made.  Output from the model consists of calculated running 8-hour and
1-hour averaged CO or 24-hour and annual block averaged PM-10 concentrations. 
Model usage caveats are contained in the CAL3QHCR user's guide which is an
addendum to the CAL3QHC user's guide.

     CAL3QHCR will henceforth be identified by its respective name and Julian
date, i.e.: CAL3QHCR (Dated 95116).  Future changes to either of these two
programs will be identified by an updated Julian date found on the first line
of the model source code and followed by a reference to a CAL3QHC Model Change
Bulletin (MCB#n) on the SCRAM BBS.  A new Julian date will be assigned to a
model only when the source code for that model has been changed.  The nature
and contents of the changes to each model will be explained as was done in the
previous two paragraphs.  All Model Change Bulletins for these two models will
always be available for back reference on this BBS.  In the future,
notification of changes (MCBs) to either of these two models will be made in
the SCRAM ALERTS section of this BBS immediately following the LOGON procedure.

      The source code for these models have been compiled and tested on an IBM
PC computer.  A math coprocessor should be used.

                       ******************
                       * Important Note *  
                       ******************
   
      A new Model Change Bulletin will ONLY be issued when there
is a change to the source code for either of these two models.  Changes to test
cases and/or any pre and post processors that are included in the archived file
of either model will be addressed and appropriately identified in an amendment
to the models' latest MCB with notification posted in the SCRAM ALERTS section
of the BBS.