Model Change Bulletin                  6/19/96

			   MCB#3

		  PLUVUE II (dated 96170)

     This Model Change Bulletin initiates the use of the
PLUVUE II model (dated 96170).  This version supersedes the
previous version (dated 92243).  The revisions to the PLUVUE
II model are identified in an Addendum to the User's Manual
for the Plume Visibility Model, PLUVUE II (Revised), dated
June 1996.

     The revised PLUVUE II model (dated 96170) corrects
several errors found in the previous version of the model
and makes some minor refinements.  A detailed explanation of
these changes is provided in Section 2.1.8 of the Addendum
to the User's Manual.  As noted below, some of these changes
have not been fully tested and are not recommended for
regulatory use at this time.

      Specific changes to the PLUVUE II model (dated 96170):

1. A missing term was included in the calculation of the
     apparent radiance in subroutine BACKOBJ.
2. The default reflectance of the black and white terrain
     objects was modified from 0.0 and 1.0 to 0.1 and 0.9,
     respectively.
3. A second calculation for the contrast of a plume viewed
     against a terrain background was included, assuming
     that the eye was accommodated to the radiance of the
     horizon sky.  This option has not been evaluated at
     this time.  The output from PLUVUE II for the eye
     accommodated to the sky SHOULD NOT BE USED FOR
     REGULATORY PURPOSES.
     ***NOTE*** The user must select horizontal views with a
     sky background as well as views with terrain background
     to obtain numbers for the eye accommodated to the sky.
     Asterisks will be printed for those values otherwise.
4. A term for diffuse skylight was added to SUBROUTINE
     BACOBJ to correct for problems encountered in the
     calculations when the sun was low in the sky.
5. Corrections were made to the calculation of primary
     particle emissions that are carbon and non-carbon.
6. Some integer variables were replaced with character
     variables to comply with FORTRAN 90 Compilers.
7. A check was added at the top of the program to determine
     if the correct values were being returned from FUNCTION
     CLOCK and program execution is terminated with a
     warning message if incorrect values occur.  (Various
     versions of the LAHEY FORTRAN compiler have had
     problems with mixed mode division; these versions of
     the compiler should not be used to compile this model
     without obtaining updated fix files from LAHEY,
     therefore, this check was inserted to trap that
     problem.)
8. A check was added to ensure that the sun is above the
     horizon.  A maximum zenith angle (ZMAX) is specified in
     the code (currently 88 degrees).  If the zenith angle
     is greater than ZMAX, the time is adjusted until the
     zenith angle becomes less than ZMAX.  The maximum time
     adjustment is limited to one hour.  A warning message
     is printed if adjustments occur.
9. An informational message is printed if the user specifies
     non-horizontal views of the sky and the angle BETA is
     less than 5 degrees.  The model will not calculate non-
     horizontal views for BETA less than 5 degrees; this
     feature was not well documented, so the informational
     message was inserted to avoid confusion.

     The User's Manual for the Plume Visibility Model
continues to be the primary source of documentation for the
PLUVUE II model.  Revisions to the PLUVUE II model (dated
96170) are identified in an Addendum to the User's Manual for
the Plume Visibility Model, PLUVUE II (Revised), dated June
1996.  The user should replace the related items in the
user's manual with the following page numbers from the
Addendum:
1. Revise the Title page and Table of Contents (pages iii
     and iv)
2. Chapter 1.0 Introduction (pages 1 through 3)
3. Chapter 2.0, Pages 6,9,18,19,31,32,33, 33a,33b,33c,
    36, and 54 
4. Chapter 4, References, page 106 and 107

	Note that the input and output files shown in 
Figure 10 and 11 of the User's Manual contain different
values than those used in the revised TEST.INP and TEST.OUT
shown in the README.TXT file.  However, the information
in the user's manual continues to be useful in illustrating
 how to interpret model results.
     
	Also, note that Appendix A, Comparison of the Original
Version of PLUVUE II with the Revised Version for Different
Stability Classes, in the user's manual is deleted.


		     ******************
		     * Important Note *
		     ******************

     This program will henceforth be identified by its name
and a Julian date, i.e., PLUVUE II (dated 96170).  Future
changes to this model will be identified by an updated
Julian date found after the first few lines of the model
source code and followed by a reference to a SCRAM BBS Model
Change Bulletin Number (MCB#n)which will explain the nature
and contents of the changes.  All MCB's for this program
will always be available for back reference on this BBS.  In
the future, notification of changes to this program will be
made in the SCRAM ALERTS section of this BBS immediately
following the LOGON procedure.  A new Model Change Bulletin
will ONLY be issued when there is a change to the model
source code.  Changes to test cases that are included in the
archived file will be addressed and appropriately identified
in an amendment to the model's latest MCB with notification
posted in the SCRAM ALERTS section of the BBS.




			 ADDENDUM  --  9/11/96
			***********************

      The 9/11/96 modifications made to the file RUNPLUVU.ZIP 
involved the relinking of the PC executable modules to avoid problems
with memory allocation on DOS/Windows machines.  There were no changes
made to the code, therefore, the model date has not been changed.