1
2
3      SUBROUTINE PENFCT
4!***********************************************************************
5!             PENFCT Module of the AMS/EPA Regulatory Model - AERMOD
6!
7!   PURPOSE: Calculate the plume penetration factor
8!
9!   PROGRAMMER: Roger Brode and Jim Paumier, PES, Inc.
10!
11!   DATE:    September 30, 1993
12!
13!   REVISED: To use VPTGZI = 0.01 for Base Case model. R.Brode, PES - 12/7/94
14!
15!   INPUTS:  Stability, STABLE/UNSTAB
16!            Buoyancy flux, FB
17!            Wind speed at release height, UP (computed in METINI)
18!            Potential temperature at ZI
19!            Potential temperature gradient above ZI, VPTGZI (from
20!            AERMET)
21!
22!   OUTPUTS: Plume penetration factor, PPF
23!
24!   CALLED FROM:   PCALC
25!
26!   Assumptions:
27!
28!   References:   "Plume Penetration of the CBL and Source 3: Source
29!                 Strength and Plume Rise", J. Weil, 9/1/93
30!                 "A Dispersion Model for the Convective Boundary Layer",
31!                 J. Weil, 8/17/93
32!
33!***********************************************************************
34
35!     Variable Declarations
36      USE MAIN1
37      IMPLICIT NONE
38      CHARACTER MODNAM*12
39
40      SAVE
41      REAL BVZI2
42
43      MODNAM = 'PENFCT'                                                 !   9132
44
45      IF ( STABLE ) THEN
46         PPF = 0.0                                                      !   7638
47
48      ELSEIF ( UNSTAB .AND. (HS.GE.ZI) ) THEN
49         PPF = 1.0                                                      !     40
50
51      ELSE
52!        Compute the square of the Brunt-Vaisala frequency at ZI, BVZI2
53
54         BVZI2 = G/PTATZI*VPTGZI                                        !   1454
55
56!        Compute the value of PsubS, Eq. 26b in the 2nd reference
57         PSUBS = FB/(UP*BVZI2*(ZI-HSP)*(ZI-HSP)*(ZI-HSP))
58
59!        Compute the ratio of delta(Hsub_e)/delta(Hsub_h), HEDHH
60!        (Eq. 25 in the 2nd ref.
61!        NOTE: 17.576 = (2.6)**3 and 0.296296 is (2/3)**3
62         HEDHH = (17.576*PSUBS+0.296296)**0.333333
63
64!        Check the value of HEDHH and compute the plume penetration, P
65         IF ( HEDHH.LT.0.666667 ) THEN
66            PPF = 0.0                                                   !    498
67
68         ELSEIF ( HEDHH.GT.2.0 ) THEN
69            PPF = 1.0                                                   !     78
70
71         ELSE
72            PPF = 1.5 - (1.0/HEDHH)                                     !    878
73
74         ENDIF
75
76      ENDIF
77
78      CONTINUE                                                          !   9132
79      END


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