SUBROUTINE CANRES(SOLAR,SFCTMP,Q2,SFCPRS,SMC, & GC,RC,IVEG,ISOIL, & RSMIN,NROOTS,SMCWLT,SMCREF, & RCS,RCQ,RCT,RCSOIL) ! IMPLICIT NONE C ###################################################################### C SUBROUTINE CANRES C ----------------- C THIS ROUTINE CALCULATES THE CANOPY RESISTANCE WHICH DEPENDS ON C INCOMING SOLAR RADIATION, AIR TEMPERATURE, ATMOSPHERIC WATER C VAPOR PRESSURE DEFICIT AT THE LOWEST MODEL LEVEL, AND SOIL C MOISTURE (PREFERABLY UNFROZEN SOIL MOISTURE RATHER THAN TOTAL) C ---------------------------------------------------------------------- C SOURCE: JARVIS (1976), JACQUEMIN AND NOILHAN (1990 BLM) C ---------------------------------------------------------------------- C PROGRAM HISTORY LOG: C 03-01-17 M EK AND H CHUANG - LIFTED IT FROM MODEL FOR POST C ---------------------------------------------------------------------- C INPUT: SOLAR: INCOMING SOLAR RADIATION C CH: SURFACE EXCHANGE COEFFICIENT FOR HEAT AND MOISTURE C SFCTMP: AIR TEMPERATURE AT 1ST LEVEL ABOVE GROUND C Q2: AIR HUMIDITY AT 1ST LEVEL ABOVE GROUND C Q2SAT: SATURATION AIR HUMIDITY AT 1ST LEVEL ABOVE GROUND C SFCPRS: SURFACE PRESSURE C SMC: VOLUMETRIC SOIL MOISTURE C ZSOIL: SOIL DEPTH (NEGATIVE SIGN, AS IT IS BELOW GROUND) C NSOIL: NO. OF SOIL LAYERS C IROOT: NO. OF SOIL LAYERS IN ROOT ZONE (1.LE.NROOT.LE.NSOIL) C XLAI: LEAF AREA INDEX C SMCWLT: WILTING POINT C SMCREF: REFERENCE SOIL MOISTURE C (WHERE SOIL WATER DEFICIT STRESS SETS IN) C C RSMIN, RSMAX, TOPT, RGL, HS: CANOPY STRESS PARAMETERS SET IN C SUBROUTINE REDPRM C C (SEE EQNS 12-14 AND TABLE 2 OF SEC. 3.1.2 OF C CHEN ET AL., 1996, JGR, VOL 101(D3), 7251-7268) C C OUTPUT: PC: PLANT COEFFICIENT C RC: CANOPY RESISTANCE C GC: CANOPY CONDUCTANCE C ---------------------------------------------------------------------- C ###################################################################### INCLUDE "parmeta" INCLUDE "parmsoil" INCLUDE "params" INTEGER K ! INTEGER NROOT(13) INTEGER IROOT(13) INTEGER IVEG INTEGER ISOIL ! REAL SIGMA, RD, CP, SLV REAL SOLAR, CH, SFCTMP, Q2, SFCPRS REAL SMC(NSOIL), ZSOIL(NSOIL), PART(NSOIL) REAL SMWLT(9),SMREF(9),RSMN(13),RC,PC,Q2SAT,GC REAL TOPT,RSMAX,RGL(13),HS(13),XLAI,RCS,RCT,RCQ,RCSOIL,FF REAL P,QS,GX,TAIR4,ST1,SLVCP,RR,DELTA ! PARAMETER (CP=1004.5, SLV=2.501000E6) DATA XLAI /4.0/ DATA RSMAX /5000./ DATA TOPT /298.0/ DATA IROOT /4,4,4,4,4,4,3,3,3,2,3,3,2/ DATA ZSOIL /-0.1,-0.4,-1.0,-2.0/ C SSIB VEGETATION TYPES (DORMAN AND SELLERS, 1989; JAM) C C 1: BROADLEAF-EVERGREEN TREES (TROPICAL FOREST) C 2: BROADLEAF-DECIDUOUS TREES C 3: BROADLEAF AND NEEDLELEAF TREES (MIXED FOREST) C 4: NEEDLELEAF-EVERGREEN TREES C 5: NEEDLELEAF-DECIDUOUS TREES (LARCH) C 6: BROADLEAF TREES WITH GROUNDCOVER (SAVANNA) C 7: GROUNDCOVER ONLY (PERENNIAL) C 8: BROADLEAF SHRUBS WITH PERENNIAL GROUNDCOVER C 9: BROADLEAF SHRUBS WITH BARE SOIL C 10: DWARF TREES AND SHRUBS WITH GROUNDCOVER (TUNDRA) C 11: BARE SOIL C 12: CULTIVATIONS (THE SAME PARAMETERS AS FOR TYPE 7) C 13: GLACIAL (THE SAME PARAMETERS AS FOR TYPE 11) DATA RSMN /150.0, 100.0, 125.0, 150.0, 100.0, 70.0, * 40.0, 300.0, 400.0, 150.0, 400.0, 40.0, * 150.0/ DATA RGL /30.0, 30.0, 30.0, 30.0, 30.0, 65.0, * 100.0, 100.0, 100.0, 100.0, 100.0, 100.0, * 100.0/ DATA HS /41.69, 54.53, 51.93, 47.35, 47.35, 54.53, * 36.35, 42.00, 42.00, 42.00, 42.00, 36.35, * 42.00/ C SOIL TYPES ZOBLER (1986) COSBY ET AL (1984) (quartz cont.(1)) C 1 COARSE LOAMY SAND (0.82) C 2 MEDIUM SILTY CLAY LOAM (0.10) C 3 FINE LIGHT CLAY (0.25) C 4 COARSE-MEDIUM SANDY LOAM (0.60) C 5 COARSE-FINE SANDY CLAY (0.52) C 6 MEDIUM-FINE CLAY LOAM (0.35) C 7 COARSE-MED-FINE SANDY CLAY LOAM (0.60) C 8 ORGANIC LOAM (0.40) C 9 GLACIAL LAND ICE LOAMY SAND (NA using 0.82) DATA SMREF /0.283, 0.387, 0.412, 0.312, 0.338, 0.382, & 0.315, 0.329, 0.283/ DATA SMWLT /0.029, 0.119, 0.139, 0.047, 0.100, 0.103, & 0.069, 0.066, 0.029/ C ---------------------------------------------------------------------- C INITIALIZE CANOPY CONDUCTANCE TERMS C ---------------------------------------------------------------------- RCS = 0.0 RCT = 0.0 RCQ = 0.0 RCSOIL = 0.0 RC = 0.0 C ---------------------------------------------------------------------- C SET SMCWLT, SMCREF, RSMIN, NROOTS VALUES C ---------------------------------------------------------------------- SMCWLT = SMWLT(ISOIL) SMCREF = SMREF(ISOIL) RSMIN = RSMN(IVEG) NROOTS = IROOT(IVEG) C ---------------------------------------------------------------------- C CONTRIBUTION DUE TO INCOMING SOLAR RADIATION C ---------------------------------------------------------------------- FF = 0.55*2.0*SOLAR/(RGL(IVEG)*XLAI) RCS = (FF + RSMIN/RSMAX) / (1.0 + FF) RCS = MAX(RCS,0.0001) RCS = MIN(RCS,1.0) C ---------------------------------------------------------------------- C CONTRIBUTION DUE TO AIR TEMPERATURE AT FIRST MODEL LEVEL ABOVE GROUND C ---------------------------------------------------------------------- RCT = 1.0 - 0.0016*((TOPT-SFCTMP)**2.0) RCT = MAX(RCT,0.0001) RCT = MIN(RCT,1.0) C ---------------------------------------------------------------------- C CONTRIBUTION DUE TO VAPOR PRESSURE DEFICIT AT FIRST MODEL LEVEL. C ---------------------------------------------------------------------- c P = SFCPRS C Insert QSAT computation used in ETA2P TBLO=SFCTMP Q2SAT=PQ0/SFCPRS*EXP(A2*(TBLO-A3)/(TBLO-A4)) QS = Q2SAT C RCQ EXPRESSION FROM SSIB RCQ = 1.0/(1.0+HS(IVEG)*(QS-Q2)) c RCQ = MAX(RCQ,0.01) RCQ = MAX(RCQ,0.0001) RCQ = MIN(RCQ,1.0) C ---------------------------------------------------------------------- C CONTRIBUTION DUE TO SOIL MOISTURE AVAILABILITY. C DETERMINE CONTRIBUTION FROM EACH SOIL LAYER, THEN ADD THEM UP. C ---------------------------------------------------------------------- GX = (SMC(1)-SMCWLT)/(SMCREF-SMCWLT) IF (GX .GT. 1.) GX = 1. IF (GX .LT. 0.) GX = 0. C#### USING SOIL DEPTH AS WEIGHTING FACTOR PART(1) = (ZSOIL(1)/ZSOIL(NROOTS)) * GX C#### USING ROOT DISTRIBUTION AS WEIGHTING FACTOR CC PART(1) = RTDIS(1) * GX DO K = 2, NROOTS GX = (SMC(K)-SMCWLT)/(SMCREF-SMCWLT) IF (GX .GT. 1.) GX = 1. IF (GX .LT. 0.) GX = 0. C#### USING SOIL DEPTH AS WEIGHTING FACTOR PART(K) = ((ZSOIL(K)-ZSOIL(K-1))/ZSOIL(NROOTS)) * GX C#### USING ROOT DISTRIBUTION AS WEIGHTING FACTOR CC PART(K) = RTDIS(K) * GX END DO DO K = 1, NROOTS RCSOIL = RCSOIL+PART(K) END DO RCSOIL = MAX(RCSOIL,0.0001) RCSOIL = MIN(RCSOIL,1.0) C ---------------------------------------------------------------------- C DETERMINE CANOPY RESISTANCE DUE TO ALL FACTORS. C CONVERT CANOPY RESISTANCE (RC) TO PLANT COEFFICIENT (PC). C ---------------------------------------------------------------------- CC/98/01/05/........RC = RCMIN/(RCS*RCT*RCQ*RCSOIL) c RC = RCMIN(IVEG)/(XLAI*RCS*RCT*RCQ*RCSOIL) RCMIN = RSMIN/XLAI RCMAX = RSMAX/XLAI RC = RCMIN/(RCS*RCT*RCQ*RCSOIL) RC = MAX(RCMIN,MIN(RC,RCMAX)) GC = 1./RC RETURN END