| 1 | !------------------------------------------------------------------------------- |
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| 2 | ! |
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| 3 | ! ###################################### |
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| 4 | REAL FUNCTION QSATSEAW_1D(PT,PP) |
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| 5 | ! ###################################### |
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| 6 | ! |
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| 7 | !!**** *QSATW * - function to compute saturation vapor humidity from |
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| 8 | !! temperature |
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| 9 | !! |
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| 10 | !! PURPOSE |
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| 11 | !! ------- |
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| 12 | ! The purpose of this function is to compute the saturation vapor |
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| 13 | ! pressure from temperature over saline seawater |
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| 14 | ! |
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| 15 | ! |
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| 16 | !!** METHOD |
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| 17 | !! ------ |
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| 18 | !! Given temperature T (PT), the saturation vapor pressure es(T) |
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| 19 | !! (FOES(PT)) is computed by integration of the Clapeyron equation |
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| 20 | !! from the triple point temperature Tt (XTT) and the saturation vapor |
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| 21 | !! pressure of the triple point es(Tt) (XESTT), i.e |
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| 22 | !! The reduction due to salinity is compute with the factor 0.98 (reduction of 2%) |
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| 23 | !! |
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| 24 | !! es(T)= 0.98*EXP( alphaw - betaw /T - gammaw Log(T) ) |
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| 25 | !! |
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| 26 | !! with : |
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| 27 | !! alphaw (XALPW) = LOG(es(Tt))+ betaw/Tt + gammaw Log(Tt) |
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| 28 | !! betaw (XBETAW) = Lv(Tt)/Rv + gammaw Tt |
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| 29 | !! gammaw (XGAMW) = (Cl -Cpv) /Rv |
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| 30 | !! |
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| 31 | !! Then, the specific humidity at saturation is deduced. |
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| 32 | !! |
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| 33 | !! |
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| 34 | !! EXTERNAL |
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| 35 | !! -------- |
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| 36 | !! NONE |
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| 37 | !! |
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| 38 | !! IMPLICIT ARGUMENTS |
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| 39 | !! ------------------ |
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| 40 | !! Module MODD_CST : comtains physical constants |
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| 41 | !! XALPW : Constant for saturation vapor pressure function |
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| 42 | !! XBETAW : Constant for saturation vapor pressure function |
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| 43 | !! XGAMW : Constant for saturation vapor pressure function |
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| 44 | !! |
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| 45 | !! REFERENCE |
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| 46 | !! --------- |
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| 47 | !! Book2 of documentation of Meso-NH |
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| 48 | !! Zeng, X., Zhao, M., and Dickinson, R. E., 1998 : Intercomparaison of bulk |
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| 49 | !! aerodynamic algorithm for the computation of sea surface fluxes using |
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| 50 | !! TOGA COARE and TAO data. Journal of Climate, vol 11, n�10, pp 2628--2644 |
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| 51 | !! |
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| 52 | !! |
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| 53 | !! AUTHOR |
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| 54 | !! ------ |
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| 55 | !! C. Lebeaupin * Meteo France * |
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| 56 | !! |
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| 57 | !! MODIFICATIONS |
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| 58 | !! ------------- |
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| 59 | !! Original 6/04/2005 |
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| 60 | !------------------------------------------------------------------------------- |
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| 61 | ! |
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| 62 | !* 0. DECLARATIONS |
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| 63 | ! ------------ |
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| 64 | ! |
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| 65 | USE MODD_CSTS |
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| 66 | USE dimphy |
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| 67 | USE indice_sol_mod |
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| 68 | |
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| 69 | IMPLICIT NONE |
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| 70 | |
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| 71 | !* 0.1 Declarations of arguments and results |
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| 72 | ! |
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| 73 | ! |
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| 74 | REAL, DIMENSION(klon), INTENT(IN) :: PT ! Temperature |
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| 75 | ! (Kelvin) |
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| 76 | REAL, DIMENSION(klon), INTENT(IN) :: PP ! Pressure |
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| 77 | ! (Pa) |
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| 78 | REAL, DIMENSION(SIZE(PT)) :: PQSAT ! saturation vapor |
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| 79 | ! specific humidity |
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| 80 | ! with respect to |
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| 81 | ! water (kg/kg) |
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| 82 | ! |
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| 83 | !* 0.2 Declarations of local variables |
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| 84 | ! |
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| 85 | REAL, DIMENSION(SIZE(PT)) :: ZFOES ! saturation vapor |
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| 86 | ! pressure |
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| 87 | ! (Pascal) |
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| 88 | ! |
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| 89 | INTEGER :: JJ ! loop index |
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| 90 | !REAL(KIND=JPRB) :: ZHOOK_HANDLE |
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| 91 | !------------------------------------------------------------------------------- |
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| 92 | ! |
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| 93 | !IF (LHOOK) CALL DR_HOOK('MODE_THERMOS:QSATSEAW_1D',0,ZHOOK_HANDLE) |
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| 94 | !DO JJ = 1, SIZE(PT) |
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| 95 | !* 1. COMPUTE SATURATION VAPOR PRESSURE |
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| 96 | ! --------------------------------- |
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| 97 | ! |
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| 98 | ZFOES = 0.98*EXP( XALPW - XBETAW/PT - XGAMW*LOG(PT) ) |
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| 99 | ! vapor pressure reduction of 2% over saline seawater could have a significant |
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| 100 | ! impact on the computation of surface latent heat flux under strong wind |
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| 101 | ! conditions (Zeng et al, 1998). |
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| 102 | ! |
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| 103 | !* 2. COMPUTE SATURATION HUMIDITY |
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| 104 | ! --------------------------- |
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| 105 | ! |
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| 106 | PQSAT = XRD/XRV*ZFOES/PP /(1.+(XRD/XRV-1.)*ZFOES/PP) |
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| 107 | ! |
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| 108 | !ENDDO |
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| 109 | !IF (LHOOK) CALL DR_HOOK('MODE_THERMOS:QSATSEAW_1D',1,ZHOOK_HANDLE) |
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| 110 | !------------------------------------------------------------------------------- |
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| 111 | ! |
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| 112 | END FUNCTION QSATSEAW_1D |
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| 113 | !------------------------------------ |
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