! *****************************COPYRIGHT******************************* ! (C) Crown copyright Met Office. All rights reserved. ! For further details please refer to the file COPYRIGHT.txt ! which you should have received as part of this distribution. ! *****************************COPYRIGHT******************************* ! Description: ! Parameter values for surface routines. ! Code Description: ! Language: FORTRAN 90 ! This code is written to UMDP3 v8.2 programming standards. MODULE surf_param USE c_epslon, ONLY : repsilon USE c_lheat, ONLY : lc,lf USE c_r_cp, ONLY : cp USE c_g, ONLY : g IMPLICIT NONE SAVE !----------------------------------------------------------------------- ! Latent heat of sublimation. REAL, PARAMETER :: & ls=lc+lf ! Latent heat of sublimation (J per kg). !----------------------------------------------------------------------- ! Parameters for heat capacity of vegetation. REAL :: & hleaf = 5.7e4 & ! Specific heat capacity of leaves ! (J / K / kg Carbon). ,hwood = 1.1e4 ! Specific heat capacity of wood ! (J / K / kg Carbon). !----------------------------------------------------------------------- ! Parameters for leaf conductance and photosynthesis. REAL :: & beta1 = 0.83 & ! Coupling coefficients for co-limitation. ,beta2 = 0.93 & ! Coupling coefficients for co-limitation. ! Factors in expressions for limitation of photosynthesis by transport ! of products, for C3 and C4 respectively ,fwe_c3 = 0.5 & ,fwe_c4 = 20000.0 & ,q10_leaf = 2.0 ! Q10 factor for plant respiration. REAL, PARAMETER :: & ratio=1.6 ! Ratio of leaf resistance for CO2 to leaf ! resistance for H2O. REAL, PARAMETER :: ratio_o3 = 1.67 ! Ratio of leaf resistance for O3 to leaf ! resistance for H2O. !----------------------------------------------------------------------- ! Parameters used for stomatal conductance. INTEGER, PARAMETER :: & iter = 3 ! Number of iterations to ! determine the canopy climate. REAL, PARAMETER :: & o2 = 0.23 ! Atmospheric concentration of ! oxygen (kg O2/kg air). !----------------------------------------------------------------------- ! Parameters for soil respiration. REAL :: & kaps = 0.5e-8 & ! Specific soil respiration rate at 25 degC ! and optimum soil moisture (/s). ,kaps_roth(4) & ! Specific soil respiration rate for RothC ,q10_soil = 2.0 ! Q10 factor for soil respiration. DATA kaps_roth / 3.22e-7, 9.65e-9, 2.12e-8, 6.43e-10 / !----------------------------------------------------------------------- ! Parameters for surface transfer coefficients. INTEGER, PARAMETER :: & n_its=5 ! Number of iterations for Monin-Obukhov length ! and stability functions. REAL, PARAMETER :: & beta=0.08 & ! Tunable parameter in the surface layer scaling ! velocity formula (multiplying the turbulent ! convective scaling velocity). ,third=1./3. ! One third. REAL, PARAMETER :: BETA_cndd = 0.04 ! ! Tunable parameter in the surface layer scaling ! ! velocity formula multiplying the turbulent ! ! convective scaling velocity (halved from the ! ! value in the original scheme to compensate for ! ! the convective contribution). REAL, PARAMETER :: cnst_cndd_0 = 1.0 ! ! Constant in formula for convective gustiness REAL, PARAMETER :: cnst_cndd_1 = 6.004e+02 / g ! ! Constant in formula for convective gustiness REAL, PARAMETER :: cnst_cndd_2 = -4.375e+03 / g**2 ! ! Constant in formula for convective gustiness REAL, PARAMETER :: min_wind = 1.0e-3 ! ! minimum windspeed for iteration convergence REAL, PARAMETER :: min_ustar = min_wind / 50.0 ! ! corresponding friction velocity !----------------------------------------------------------------------- ! Constants used in the Beljaars and Holtslag stable stability functions REAL, PARAMETER :: & a = 1.0 & ,b = 2.0/3.0 & ,c = 5.0 & ,d = 0.35 & ,c_over_d = c/d !----------------------------------------------------------------------- ! Parameters for calculation of aerodynamic resistance. REAL, PARAMETER :: & ah = 10.0 & ! Stability parameter. ,cz = 4.0 ! Stability parameter. !----------------------------------------------------------------------- ! Parameters used for calculation of saturated specific humidity. REAL, PARAMETER :: & one_minus_epsilon = 1.0 - REPSILON & ! ONE MINUS THE RATIO OF THE ! MOLECULAR WEIGHTS OF WATER AND DRY AIR ,t_low = 183.15 & ! LOWEST TEMPERATURE FOR WHICH LOOK-UP TABLE OF ! SATURATION WATER VAPOUR PRESSURE IS VALID (K) ,t_high = 338.15 & ! HIGHEST TEMPERATURE FOR WHICH LOOK-UP TABLE OF ! SATURATION WATER VAPOUR PRESSURE IS VALID (K) ,delta_t = 0.1 ! TEMPERATURE INCREMENT OF THE LOOK-UP ! TABLE OF SATURATION VAPOUR PRESSURES INTEGER, PARAMETER :: & n = ((t_high - t_low + (delta_t*0.5))/delta_t) + 1.0 ! SIZE OF LOOK-UP TABLE OF SATURATION WATER VAPOUR ! PRESSURES. With T_LOW = 183.15, T_HIGH = 338.15 and ! DELTA_T = 0.1, this gives n=1551. !----------------------------------------------------------------------- ! Parameters used in diagnosis of screen T or q. REAL, PARAMETER :: & grcp = g / cp ! ratio of acceleration due to gravity to ! specific heat of dry air at constant ! pressure ( K/m) !----------------------------------------------------------------------- ! Parameters used in interpolation of wind, T and q. REAL, PARAMETER :: & !DSM z_obs_tq = 1.5 & z_obs_tq = 2.0 & ! Height of screen observations of temperature ! and humidity. ,z_obs_wind = 10.0 ! Height of surface wind observations. LOGICAL, PARAMETER :: & eff_int = .FALSE. ! switch for orographic roughness in ! calculation of 10m wind speed. ! .TRUE. orographic roughness included ! .FALSE. orographic roughness NOT included INTEGER, PARAMETER :: ip_scrndecpl1 = 1 ! Diagnose the screen temperature using ! surface similarity theory, but allow ! decoupling in very stable conditions ! based on the quasi-equilibrium radiative ! solution. INTEGER, PARAMETER :: ip_scrndecpl2 = 2 ! Diagnose the screen temperature using ! including transient effects and radiative ! cooling !----------------------------------------------------------------------- ! Parameters used to calculate blending height. REAL, PARAMETER :: & h_blend_max=1000.0 & ! Maximum blending height (m). ,h_blend_min=0.0 ! Minimum blending height (m). !----------------------------------------------------------------------- ! Roughness lengths for sea ice. REAL :: & z0miz = 1.0e-1 & ! roughness length for heat, moisture and ! momentum over the Marginal Ice Zone (m). ,z0sice = 3.0e-3 ! roughness length for heat, moisture and ! momentum over sea-ice (m). !----------------------------------------------------------------------- !----------------------------------------------------------------------- ! Other variables used in surface calculations !----------------------------------------------------------------------- REAL, ALLOCATABLE :: & diff_frac(:) ! The fraction of radiation that is diffuse REAL, PARAMETER :: & kn = 0.78 ! Nitrogen Allocation coefficient: ! Tellus 59B, 553-565 (2007), page 555. #if !defined(UM_RUN) !----------------------------------------------------------------------- ! START Variables not needed to be defined in UM !----------------------------------------------------------------------- REAL :: & seasalinityfactor = 1.0 ! Factor allowing for the effect ! of the salinity of sea water ! on the evaporative flux. !----------------------------------------------------------------------- ! END Variables not needed to be defined in UM !----------------------------------------------------------------------- #endif !----------------------------------------------------------------------- ! Set up a namelist to allow the scalars to be set via io !----------------------------------------------------------------------- NAMELIST /jules_surf_param/ hleaf,hwood,beta1,beta2,fwe_c3, & fwe_c4,q10_leaf,kaps,kaps_roth, & q10_soil,z0miz,z0sice END MODULE surf_param