[e200b7a] | 1 | subroutine hanna(z) |
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| 2 | ! i |
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| 3 | !***************************************************************************** |
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| 4 | ! * |
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| 5 | ! Computation of \sigma_i and \tau_L based on the scheme of Hanna (1982) * |
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| 6 | ! * |
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| 7 | ! Author: A. Stohl * |
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| 8 | ! * |
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| 9 | ! 4 December 1997 * |
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| 10 | ! * |
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| 11 | !***************************************************************************** |
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| 12 | ! * |
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| 13 | ! Variables: * |
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| 14 | ! dsigwdz [1/s] vertical gradient of sigw * |
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| 15 | ! ol [m] Obukhov length * |
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| 16 | ! sigu, sigv, sigw standard deviations of turbulent velocity fluctuations * |
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| 17 | ! tlu [s] Lagrangian time scale for the along wind component. * |
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| 18 | ! tlv [s] Lagrangian time scale for the cross wind component. * |
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| 19 | ! tlw [s] Lagrangian time scale for the vertical wind component. * |
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| 20 | ! ust, ustar [m/s] friction velocity * |
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| 21 | ! wst, wstar [m/s] convective velocity scale * |
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| 22 | ! * |
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| 23 | !***************************************************************************** |
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| 24 | |
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| 25 | use par_mod |
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| 26 | use com_mod |
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| 27 | use hanna_mod |
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| 28 | |
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| 29 | implicit none |
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| 30 | |
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| 31 | real :: corr,z |
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| 32 | |
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| 33 | |
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| 34 | |
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| 35 | !********************** |
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| 36 | ! 1. Neutral conditions |
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| 37 | !********************** |
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| 38 | |
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| 39 | if (h/abs(ol).lt.1.) then |
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| 40 | ust=max(1.e-4,ust) |
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| 41 | corr=z/ust |
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| 42 | sigu=1.e-2+2.0*ust*exp(-3.e-4*corr) |
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| 43 | sigw=1.3*ust*exp(-2.e-4*corr) |
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| 44 | dsigwdz=-2.e-4*sigw |
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| 45 | sigw=sigw+1.e-2 |
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| 46 | sigv=sigw |
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| 47 | tlu=0.5*z/sigw/(1.+1.5e-3*corr) |
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| 48 | tlv=tlu |
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| 49 | tlw=tlu |
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| 50 | |
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| 51 | |
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| 52 | !*********************** |
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| 53 | ! 2. Unstable conditions |
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| 54 | !*********************** |
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| 55 | |
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| 56 | else if (ol.lt.0.) then |
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| 57 | |
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| 58 | |
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| 59 | ! Determine sigmas |
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| 60 | !***************** |
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| 61 | |
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| 62 | sigu=1.e-2+ust*(12-0.5*h/ol)**0.33333 |
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| 63 | sigv=sigu |
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| 64 | sigw=sqrt(1.2*wst**2*(1.-.9*zeta)*zeta**0.66666+ & |
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| 65 | (1.8-1.4*zeta)*ust**2)+1.e-2 |
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| 66 | dsigwdz=0.5/sigw/h*(-1.4*ust**2+wst**2* & |
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| 67 | (0.8*max(zeta,1.e-3)**(-.33333)-1.8*zeta**0.66666)) |
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| 68 | |
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| 69 | |
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| 70 | ! Determine average Lagrangian time scale |
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| 71 | !**************************************** |
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| 72 | |
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| 73 | tlu=0.15*h/sigu |
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| 74 | tlv=tlu |
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| 75 | if (z.lt.abs(ol)) then |
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| 76 | tlw=0.1*z/(sigw*(0.55-0.38*abs(z/ol))) |
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| 77 | else if (zeta.lt.0.1) then |
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| 78 | tlw=0.59*z/sigw |
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| 79 | else |
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| 80 | tlw=0.15*h/sigw*(1.-exp(-5*zeta)) |
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| 81 | endif |
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| 82 | |
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| 83 | |
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| 84 | !********************* |
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| 85 | ! 3. Stable conditions |
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| 86 | !********************* |
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| 87 | |
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| 88 | else |
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| 89 | sigu=1.e-2+2.*ust*(1.-zeta) |
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| 90 | sigv=1.e-2+1.3*ust*(1.-zeta) |
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| 91 | sigw=sigv |
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| 92 | dsigwdz=-1.3*ust/h |
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| 93 | tlu=0.15*h/sigu*(sqrt(zeta)) |
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| 94 | tlv=0.467*tlu |
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| 95 | tlw=0.1*h/sigw*zeta**0.8 |
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| 96 | endif |
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| 97 | |
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| 98 | |
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| 99 | tlu=max(10.,tlu) |
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| 100 | tlv=max(10.,tlv) |
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| 101 | tlw=max(30.,tlw) |
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| 102 | |
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| 103 | if (dsigwdz.eq.0.) dsigwdz=1.e-10 |
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| 104 | |
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| 105 | end subroutine hanna |
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