1
2
3      SUBROUTINE TGINIT()
4!=======================================================================
5!                TGINIT module of the AERMOD Dispersion Model
6!
7!   Purpose:     To compute the temperature scaling parameter and
8!                gradient at 5 m for the stable atmosphere
9!
10!   Input:       Friction velocity, Obukhov length, ambient temperature,
11!                surface roughness length
12!
13!   Output:      THETA_STAR and dTHETA/dZ at TREFHT
14!
15!   Assumptions:
16!
17!   Called by:   GRDPTG
18!
19!   Programmer:  Jim Paumier (PES, Inc.)              30 Sept 1993
20!
21!   Revision history:
22!     JOP  March 14, 1995  The initial gradient is now stored in
23!                          TG4PFL rather than the first level of
24!                          profiled gradients
25!
26!   References:  Model Coding Abstract for the Met Interface dated
27!                August 6, 1992 and all subsequent addenda/corrigenda
28!
29!-----------------------------------------------------------------------
30!
31!---- Variable declarations
32!
33      USE MAIN1
34      IMPLICIT NONE
35      CHARACTER MODNAM*12
36
37      SAVE
38
39      REAL , PARAMETER :: TGMINHT = 2.0 , TGMAXHT = 100.0
40      INTEGER :: LVL
41      REAL :: REFLVL
42
43      MODNAM = 'TGINIT'                                                 !   3044
44      PATH = 'MX'
45
46!---- Variable initializations
47
48
49!     The computations are made only for a stable atmosphere
50
51      IF ( STABLE ) THEN
52
53         REFLVL = -99.0                                                 !   2546
54         LVL = 1
55         DO WHILE ( REFLVL.LT.0.0 .AND. LVL.LE.NTGLVL )
56
57            IF ( PFLTGZ(LVL).GT.SFCZ0 ) THEN                            !   2546
58               REFLVL = PFLTGZ(LVL)                                     !      0
59
60            ELSE
61               LVL = LVL + 1                                            !   2546
62
63            ENDIF
64
65         ENDDO
66
67         IF ( REFLVL.GT.0.0 .AND. REFLVL.LE.100.0 ) THEN                !   2546
68            THSTAR = PFLTG(LVL)*VONKAR*PFLTGZ(LVL)                      &
69     &               /(1.0+5.0*PFLTGZ(LVL)/OBULEN)
70
71         ELSE
72            THSTAR = USTAR**2/(G*VONKAR*OBULEN/TA)                      !   2546
73
74         ENDIF
75
76!        Determine the reference level for computing a temperature
77!        gradient for profiling
78
79!        Compute DTHETA/dZ at TREFHT
80
81         TG4PFL = (THSTAR/(VONKAR*TGMINHT))*(1.0+5.0*TGMINHT/OBULEN)    !   2546
82         TG4XTR = (THSTAR/(VONKAR*TGMAXHT))*(1.0+5.0*TGMAXHT/OBULEN)
83
84      ELSE
85
86!        For the unstable case
87         THSTAR = -9.0                                                  !    498
88         TG4PFL = XVAL
89
90      ENDIF
91
92      CONTINUE                                                          !   3044
93      END


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