!copyright (C) 2001 MSC-RPN COMM %%%RPNPHY%%%
***s/r calcalb1 - compute surface albedo considering vegetation and snow.
*
subroutine calcalb1(alb, veg, sno, anal, ni) 2
*
#include "impnone.cdk"
*
integer ni
real alb(ni),veg(ni),sno(ni),
+ anal(ni)
*
*Author
* B. Brasnett/A. Methot - CMC - March 1996 (from GEM)
*
*Revision
* 001 N. Brunet (Fall 1999) - routine moved to "physics" library
* (adaptation)
* 002 B. Dugas (July 2000) - restrict to soil
*
*Language
* Fortran 77
*
*Object
* Compute surface albedo considering vegetation, ice, snow
* and a background albedo.
* According to the value of bkgalb the background albedo
* is taken from climatological file ( bkgalb=true)
* or from a table of background albedo for each vegetation
* type (given within this subroutine).
*
* The routine modifies this background albedo considering both
* the snow depth analysis and a table of snow masking depths
* for each vegetation type ( given in this subroutine ).
*
* Albedo over ice and snow is 0.8.
*
*Arguments
*
* - Input -
* ALB climatological "no snow" albedos
* VEG coded vegetation types
* SNO snow depth (metres)
* ICE ice cover (0. - 1.)
* MASK land-sea mask
* NI first working dimension of all fields
*
* - Output -
* ANAL final albedo values
*
*NOTES
* 1) THE METHOD USED TO CALCULATE THE ALBEDO WITH SNOW HAS BEEN
* ADOPTED FROM A. HENDERSON-SELLERS AND J. GRAHAM COGLEY,
* TRENT U. TECHNICAL NOTE 85-1, OBTAINED FROM CCRN.
*
* 2) This subroutine expects snow depth (INPUT) in metres.
*
***
*
*
INTEGER I,ICODE,MG2,IFACTR,M,G,GG2 ,J,VG2,AG2,A
REAL MASKDP(0:24)
real albveg(0:24)
REAL ALBSNO
real pralg, albgbar
REAL ISNO
*
#include "options.cdk"
* NOT USED WATER
DATA albveg(0), albveg(1) / 0.06, 0.06/
* GLACIAL ICE INLAND LAKES
DATA albveg(2),albveg(3) / 0.80, 0.06 /
* EVERGREEN NEEDLELEAF EVERGREEN BROADLEAF
DATA albveg(4),albveg(5) / 0.14, 0.14/
* DECIDUOUS NEEDLELEAF DECIDUOUS BROADLEAF
DATA albveg(6),albveg(7) / 0.13, 0.13/
* TROPICAL BROADLEAF DROUGHT DECIDUOUS
DATA albveg(8),albveg(9) / 0.13, 0.13/
* EVERGREEN SHRUB BROADLEAF SHRUB
DATA albveg(10),albveg(11)/ 0.17, 0.16/
* THORN SHRUB SHORT GRASS, FORBS
DATA albveg(12),albveg(13)/ 0.16, 0.19/
* LONG GRASS ARABLE
DATA albveg(14),albveg(15)/ 0.20, 0.20/
* RICE SUGAR
DATA albveg(16),albveg(17)/ 0.12, 0.17/
* MAIZE COTTON
DATA albveg(18),albveg(19)/ 0.19, 0.19/
* IRRIGATED CROP URBAN
DATA albveg(20),albveg(21)/ 0.25, 0.18/
* TUNDRA SWAMP
DATA albveg(22),albveg(23)/ 0.15, 0.12/
* SANDY DRY SOIL
DATA albveg(24) / 0.35 /
*
*
*
* NOT USED WATER
DATA MASKDP(0), MASKDP(1) / 0.01, 0.01/
* GLACIAL ICE INLAND LAKES
DATA MASKDP(2),MASKDP(3) / 0.01, 0.01/
* EVERGREEN NEEDLELEAF EVERGREEN BROADLEAF
DATA MASKDP(4),MASKDP(5) / 12.00, 8.00/
* DECIDUOUS NEEDLELEAF DECIDUOUS BROADLEAF
DATA MASKDP(6),MASKDP(7) / 8.00, 8.00/
* TROPICAL BROADLEAF DROUGHT DECIDUOUS
DATA MASKDP(8),MASKDP(9) / 8.00, 4.00/
* EVERGREEN SHRUB BROADLEAF SHRUB
DATA MASKDP(10),MASKDP(11)/ 2.00, 1.00/
* THORN SHRUB SHORT GRASS, FORBS
DATA MASKDP(12),MASKDP(13)/ 1.00, 0.10/
* LONG GRASS ARABLE
DATA MASKDP(14),MASKDP(15)/ 0.15, 0.10/
* RICE SUGAR
DATA MASKDP(16),MASKDP(17)/ 0.10, 0.10/
* MAIZE COTTON
DATA MASKDP(18),MASKDP(19)/ 0.10, 0.10/
* IRRIGATED CROP URBAN
DATA MASKDP(20),MASKDP(21)/ 0.10, 4.00/
* TUNDRA SWAMP
DATA MASKDP(22),MASKDP(23)/ 0.02, 0.01/
* SANDY DRY SOIL
DATA MASKDP(24) / 0.01 /
*
*
DATA ALBSNO/0.8/
***********************************************************************
*
* isno = 1 centimetre
ISNO = 0.01
DO 10 I=1,ni
ICODE = MAX(MIN(24,NINT(VEG(I))),1)
* compute albedo over ground considering snow and vegetation
if ( bkgalb ) then
albgbar = alb(i)
else
albgbar = albveg(icode)
endif
IF ( sno(i) .GT. ISNO ) THEN
IF ( sno(i) .LE. MASKDP(ICODE) ) THEN
pralg = albgbar + (sno(i)/maskdp(icode)) *
% (albsno-albgbar)
ELSE
pralg = albsno
ENDIF
ELSE
pralg = albgbar
ENDIF
*
anal(i) = pralg
10 CONTINUE
*
RETURN
END