subroutine hanna1(z) ! i !***************************************************************************** ! * ! Computation of \sigma_i and \tau_L based on the scheme of Hanna (1982) * ! * ! Author: A. Stohl * ! * ! 4 December 1997 * ! * !***************************************************************************** ! * ! Variables: * ! dsigwdz [1/s] vertical gradient of sigw * ! ol [m] Obukhov length * ! sigu, sigv, sigw standard deviations of turbulent velocity fluctuations * ! tlu [s] Lagrangian time scale for the along wind component. * ! tlv [s] Lagrangian time scale for the cross wind component. * ! tlw [s] Lagrangian time scale for the vertical wind component. * ! ust, ustar [m/s] friction velocity * ! wst, wstar [m/s] convective velocity scale * ! * !***************************************************************************** use par_mod use com_mod use hanna_mod implicit none real :: z,s1,s2 !********************** ! 1. Neutral conditions !********************** if (h/abs(ol).lt.1.) then ust=max(1.e-4,ust) sigu=2.0*ust*exp(-3.e-4*z/ust) sigu=max(sigu,1.e-5) sigv=1.3*ust*exp(-2.e-4*z/ust) sigv=max(sigv,1.e-5) sigw=sigv dsigw2dz=-6.76e-4*ust*exp(-4.e-4*z/ust) tlu=0.5*z/sigw/(1.+1.5e-3*z/ust) tlv=tlu tlw=tlu !*********************** ! 2. Unstable conditions !*********************** else if (ol.lt.0.) then ! Determine sigmas !***************** sigu=ust*(12-0.5*h/ol)**0.33333 sigu=max(sigu,1.e-6) sigv=sigu if (zeta.lt.0.03) then sigw=0.96*wst*(3*zeta-ol/h)**0.33333 dsigw2dz=1.8432*wst*wst/h*(3*zeta-ol/h)**(-0.33333) else if (zeta.lt.0.4) then s1=0.96*(3*zeta-ol/h)**0.33333 s2=0.763*zeta**0.175 if (s1.lt.s2) then sigw=wst*s1 dsigw2dz=1.8432*wst*wst/h*(3*zeta-ol/h)**(-0.33333) else sigw=wst*s2 dsigw2dz=0.203759*wst*wst/h*zeta**(-0.65) endif else if (zeta.lt.0.96) then sigw=0.722*wst*(1-zeta)**0.207 dsigw2dz=-.215812*wst*wst/h*(1-zeta)**(-0.586) else if (zeta.lt.1.00) then sigw=0.37*wst dsigw2dz=0. endif sigw=max(sigw,1.e-6) ! Determine average Lagrangian time scale !**************************************** tlu=0.15*h/sigu tlv=tlu if (z.lt.abs(ol)) then tlw=0.1*z/(sigw*(0.55-0.38*abs(z/ol))) else if (zeta.lt.0.1) then tlw=0.59*z/sigw else tlw=0.15*h/sigw*(1.-exp(-5*zeta)) endif !********************* ! 3. Stable conditions !********************* else sigu=2.*ust*(1.-zeta) sigv=1.3*ust*(1.-zeta) sigu=max(sigu,1.e-6) sigv=max(sigv,1.e-6) sigw=sigv dsigw2dz=3.38*ust*ust*(zeta-1.)/h tlu=0.15*h/sigu*(sqrt(zeta)) tlv=0.467*tlu tlw=0.1*h/sigw*zeta**0.8 endif tlu=max(10.,tlu) tlv=max(10.,tlv) tlw=max(30.,tlw) end subroutine hanna1