Model Change Bulletin              
              
                                   MCB#3                         7/18/91

                           CTDMPLUS (dated 91107)


     This Model Change Bulletin documents the changes made to the CTDMPLUS 
model and its associated programs since the version dated 91051.  In earlier
model versions, the effective stack height was not being reset to its initial
value.  This occurred after finishing calculations for receptors utilizing
transitional plume rise.  These changes correct that problem.  Concentration
results should vary from previous model version results depending upon the
height of the receptor with respect to the plume height.  Also several
improvements have been made to the menu driven program used in running the
model.


Model Changes Implemented:
=========================

CTDMPLUS: 

1.   In the main program, CTDMPLUS, two of the header lines were changed to
reflect the new CTDMPLUS julian date and model change bulletin number.  The
following two lines were changed from:

C                          CTDMPLUS (DATED 91051)                           *
C             *** SEE CTDMPLUS MODEL CHANGE BULLETIN MCB#2 ***              *

to:

C                          CTDMPLUS (DATED 91107)                           *
C             *** SEE CTDMPLUS MODEL CHANGE BULLETIN MCB#3 ***              *


2.  In the DAYCALC.FOR subroutine, the following changes were made to 
correctly model situations in which transitional plume rise is used.

        a) The coding was changed from:

C  RISE, XFIN ARE RETURNED

to:

C  ADDED FLAG ITRANPR - A 1 MEANS THAT TRANPR WAS CALLED.  THIS IS 
C  NECESSARY BECAUSE IF WE RESET THE EFFECTIVE STACK HEIGHT ARRAY,
C  WE NEED TO RESET IT AFTER OUR CALCULATIONS FOR THIS RECEPTOR ARE
C  COMPLETED -DJB 4/16/91

C  RISE, XFIN ARE RETURNED


        b) The coding was changed from:

       IF (XP .GE. XF .OR. FB .EQ. 0.0) THEN
         TRISE = -999.0

to:

       IF (XP .GE. XF .OR. FB .EQ. 0.0) THEN
         ITRANPR = 0
         TRISE = -999.0


        c) The coding was changed from:

       ELSE 
         CALL TRANPR(XP,TRISE)

to:

       ELSE 
         ITRANPR = 1
         CALL TRANPR(XP,TRISE)


        d) The coding was changed from:

         IF (RISE .NE. TRISE) XF = XP
         HPL = HS + RISE
         EFFSH(1) = HPL
         EFFSH(2) = HPL
         EFFSH(3) = 2.0*XMH - HPL
         EFFSH(4) = 2.0*XMH - HPL
         EFFSH(5) = 2.0*XMH + HPL
         EFFSH(6) = 2.0*XMH + HPL
       ENDIF            

to:

         IF (RISE .NE. TRISE) XF = XP
         HPLTR = HS + RISE
         EFFSH(1) = HPLTR
         EFFSH(2) = HPLTR
         EFFSH(3) = 2.0*XMH - HPLTR
         EFFSH(4) = 2.0*XMH - HPLTR
         EFFSH(5) = 2.0*XMH + HPLTR
         EFFSH(6) = 2.0*XMH + HPLTR
       ENDIF            


        e) The coding was changed from:

260    CONTINUE

to:

C IF WE CALLED TRANPR (ITRANPR = 1) THE RESET THE EFFSH ARRAY USING
C FINAL PLUME HEIGHT (HPL) FOR NXT RECEPTOR 
        IF (ITRANPR .GT. 0) THEN
          EFFSH(1) = HPL
          EFFSH(2) = HPL
          EFFSH(3) = 2.0*XMH - HPL
          EFFSH(4) = 2.0*XMH - HPL
          EFFSH(5) = 2.0*XMH + HPL
          EFFSH(6) = 2.0*XMH + HPL
        ENDIF

260    CONTINUE


3.  In the PAGE.FOR subroutine the CTDMPLUS julian date was updated to reflect 
the model update. The coding was changed from: 

6010   FORMAT('1','CTDMPLUS Dated(91051)',T72,'PAGE',1X,I3/)

to:

6010   FORMAT('1','CTDMPLUS Dated(91107)',T72,'PAGE',1X,I3/)

DRIVEIT :

1.  The code was modified to better trap and display run-time errors returned 
by the FORTRAN programs. 

2.  The use of batch files to run the FORTRAN programs was eliminated; the DOS 
commands are issued directly from the menu driver now.

3.  The program tests for the existence of the PSCRAT file and deletes it if 
it exists.

4.  The program now determines the location of the COMMAND.COM file instead of 
assuming it to be in the root directory.

RECGEN:

1.  A format statement used in writing to the DUMMY.PDF scratch file was 
changed to eliminate problems encountered with large numbers that overran the 
field size.