source: palm/tags/release-3.8/SOURCE/calc_liquid_water_content.f90 @ 4343

Last change on this file since 4343 was 668, checked in by suehring, 11 years ago

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1 SUBROUTINE calc_liquid_water_content
2
3!------------------------------------------------------------------------------!
4! Current revisions:
5! -----------------
6!
7! Former revisions:
8! -----------------
9! $Id: calc_liquid_water_content.f90 668 2010-12-23 13:22:58Z oliver.maas $
10!
11! 667 2010-12-23 12:06:00Z suehring/gyschka
12! nxl-1, nxr+1, nys-1, nyn+1 replaced by nxlg, nxrg, nysg, nyng
13!
14! 95 2007-06-02 16:48:38Z raasch
15! hydro_press renamed hyp
16!
17! 19 2007-02-23 04:53:48Z raasch
18! Old comment removed
19!
20! RCS Log replace by Id keyword, revision history cleaned up
21!
22! Revision 1.5  2005/03/26 15:22:06  raasch
23! Arguments for non-cyclic boundary conditions added to argument list of
24! routine exchange_horiz,
25! ql calculated for the ghost points, exchange of ghost points removed
26!
27! Revision 1.1  2000/04/13 14:50:45  schroeter
28! Initial revision
29!
30!
31!
32! Description:
33! ------------
34! Calculation of the liquid water content (0%-or-100%-scheme)
35!------------------------------------------------------------------------------!
36
37
38    USE arrays_3d
39    USE cloud_parameters
40    USE constants
41    USE grid_variables
42    USE indices
43    USE pegrid
44
45    IMPLICIT NONE
46
47    INTEGER :: i, j, k
48
49    REAL :: alpha, e_s, q_s, t_l
50
51    DO  i = nxlg, nxrg
52       DO  j = nysg, nyng
53          DO  k = nzb_2d(j,i)+1, nzt
54
55!
56!--          Compute the liquid water temperature
57             t_l = t_d_pt(k) * pt(k,j,i)
58
59!
60!--          Compute saturation water vapor pressure at t_l
61             e_s = 610.78 * EXP( 17.269 * ( t_l - 273.16 ) / &
62                                          ( t_l - 35.86 ) )
63
64!
65!--          Compute approximation of saturation humidity
66             q_s = 0.622 * e_s / ( hyp(k) - 0.378 * e_s )
67
68!
69!--          Correction factor
70             alpha = 0.622 * l_d_r * l_d_cp / ( t_l * t_l )
71
72!
73!--          Correction of the approximated value
74!--          (see: Cuijpers + Duynkerke, 1993, JAS, 23)
75             q_s = q_s * ( 1.0 + alpha * q(k,j,i) ) / ( 1.0 + alpha * q_s )
76
77!
78!--          Compute the liquid water content
79             IF ( ( q(k,j,i) - q_s ) > 0.0 ) THEN
80                ql(k,j,i) = q(k,j,i) - q_s
81             ELSE
82                ql(k,j,i) = 0.0 
83             ENDIF
84
85          ENDDO
86       ENDDO
87    ENDDO
88   
89 END SUBROUTINE calc_liquid_water_content
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