Changeset 1795 in lmdz_wrf for trunk/tools/module_ForDiagnosticsVars.f90

Timestamp:

Mar 12, 2018, 3:37:19 PM (7 years ago)

Author:

lfita

Message:

Adding:

`psl_ecmwf': sea-level pressure computation following ECMWF

File:

• trunk/tools/module_ForDiagnosticsVars.f90 (modified) (2 diffs)

trunk/tools/module_ForDiagnosticsVars.f90

@@ -28 +28 @@
 ! var_cllmh: low, medium, high-cloud [0,1]
 ! var_clt: total cloudiness [0,1]
+! var_psl_ecmwf: sea level pressure using ECMWF method following Mats Hamrud and Philippe Courtier [Pa]
 ! var_zmla_generic: Subroutine to compute pbl-height following a generic method
 ! var_zwind: Subroutine to extrapolate the wind at a given height following the 'power law' methodology
@@ -127 +128 @@
   END FUNCTION var_clt
 
+  SUBROUTINE var_psl_ecmwf(PRPRESS, hgt, PTB, PRESBH, PRESBF, psl)
+    ! Subroutine to compute sea level pressure using ECMWF method following Mats Hamrud and Philippe Courtier
+    !   method found in LMDZ in phylmd/pppmer.F90 in combination with phylmd/ctsar.F90
+
+!        IMPLICIT ARGUMENTS :  CONSTANTS FROM YOMCST,YOMGEM,YOMSTA.
+!        --------------------
+
+    IMPLICIT NONE
+
+    REAL, INTENT(in)                                     :: PRPRESS, hgt, PTB, PRESBH, PRESBF 
+    REAL, INTENT(out)                                    :: psl
+
+! Local
+    REAL                                                 :: ghgt, PTSTAR, PT0, ZTSTAR
+    REAL                                                 :: ZALPHA, POROG
+    REAL                                                 :: ZDTDZSG, ZOROG, ZT0, ZTX, ZTY, ZX, ZY, ZY2
+    REAL, PARAMETER                                      :: RDTDZ1 = -gammav
+
+!!!!!!! Variables
+! PRPRESS: Surface pressure [Pa]
+! hgt: Terrain height [m]
+! PTB: Temperature first half-level [K]
+! PRESBH: Pressure first half-level [Pa]
+! PRESBF: Pressure second full-level [Pa]
+! psl: sea-level pressure
+
+    fname = 'var_psl_ecmwf'
+    
+    ! Height by gravity
+    POROG = hgt*g
+
+    !* 1. COMPUTES SURFACE TEMPERATURE
+    !*   THEN STANDARD SURFACE TEMPERATURE.
+
+    ZDTDZSG=-RDTDZ1/g
+    ZALPHA=ZDTDZSG*r_d
+
+    PTSTAR=PTB*(1.0+ZALPHA*(PRESBH/PRESBF-1.0))
+    PT0=PTSTAR+ZDTDZSG*POROG
+
+    !* 2.    POST-PROCESS MSL PRESSURE.
+    !  --------------------------
+
+    !* 2.1   COMPUTATION OF MODIFIED ALPHA AND TSTAR.
+
+    ZTX=290.5
+    ZTY=255.0
+
+    IF (PTSTAR < ZTY) THEN
+      ZTSTAR=0.5*(ZTY+PTSTAR)
+    ELSEIF (PTSTAR < ZTX) THEN
+      ZTSTAR=PTSTAR
+    ELSE
+      ZTSTAR=0.5*(ZTX+PTSTAR)
+    ENDIF
+
+    ZT0=ZTSTAR+ZDTDZSG*POROG
+    IF (ZTX > ZTSTAR .AND. ZT0 > ZTX) THEN
+      ZT0=ZTX
+    ELSEIF (ZTX <= ZTSTAR .AND. ZT0 > ZTSTAR) THEN
+      ZT0=ZTSTAR
+    ELSE
+      ZT0=PT0
+    ENDIF
+
+    ZOROG=SIGN(MAX(1.0,ABS(POROG)),POROG)
+    ZALPHA=r_d*(ZT0-ZTSTAR)/ZOROG
+
+    !* 2.2   COMPUTATION OF MSL PRESSURE.
+
+    IF (ABS(POROG) >= 0.001) THEN
+      ZX=POROG/(r_d*ZTSTAR)
+      ZY=ZALPHA*ZX
+      ZY2=ZY*ZY
+
+      psl=PRPRESS*EXP(ZX*(1.0-0.5*ZY+1.0/3.*ZY2))
+    ELSE
+      psl=PRPRESS
+    ENDIF
+
+    RETURN
+
+  END SUBROUTINE var_psl_ecmwf
 
   SUBROUTINE compute_psl_ptarget4d2(press, ps, hgt, ta, qv, ptarget, psl, d1, d2, d3, d4)