| 1 | ! |
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| 2 | ! $Id: top_bound.F 1793 2013-07-18 07:13:18Z emillour $ |
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| 3 | ! |
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| 4 | SUBROUTINE top_bound(vcov,ucov,teta,masse,dt,ducov) |
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| 5 | IMPLICIT NONE |
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| 6 | c |
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| 7 | #include "dimensions.h" |
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| 8 | #include "paramet.h" |
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| 9 | #include "comconst.h" |
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| 10 | #include "comvert.h" |
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| 11 | #include "comgeom2.h" |
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| 12 | |
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| 13 | |
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| 14 | c .. DISSIPATION LINEAIRE A HAUT NIVEAU, RUN MESO, |
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| 15 | C F. LOTT DEC. 2006 |
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| 16 | c ( 10/12/06 ) |
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| 17 | |
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| 18 | c======================================================================= |
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| 19 | c |
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| 20 | c Auteur: F. LOTT |
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| 21 | c ------- |
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| 22 | c |
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| 23 | c Objet: |
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| 24 | c ------ |
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| 25 | c |
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| 26 | c Dissipation linéaire (ex top_bound de la physique) |
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| 27 | c |
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| 28 | c======================================================================= |
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| 29 | |
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| 30 | ! top_bound sponge layer model: |
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| 31 | ! Quenching is modeled as: A(t)=Am+A0*exp(-lambda*t) |
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| 32 | ! where Am is the zonal average of the field (or zero), and lambda the inverse |
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| 33 | ! of the characteristic quenching/relaxation time scale |
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| 34 | ! Thus, assuming Am to be time-independent, field at time t+dt is given by: |
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| 35 | ! A(t+dt)=A(t)-(A(t)-Am)*(1-exp(-lambda*dt)) |
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| 36 | ! Moreover lambda can be a function of model level (see below), and relaxation |
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| 37 | ! can be toward the average zonal field or just zero (see below). |
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| 38 | |
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| 39 | ! NB: top_bound sponge is only called from leapfrog if ok_strato=.true. |
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| 40 | |
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| 41 | ! sponge parameters: (loaded/set in conf_gcm.F ; stored in comconst.h) |
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| 42 | ! iflag_top_bound=0 for no sponge |
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| 43 | ! iflag_top_bound=1 for sponge over 4 topmost layers |
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| 44 | ! iflag_top_bound=2 for sponge from top to ~1% of top layer pressure |
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| 45 | ! mode_top_bound=0: no relaxation |
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| 46 | ! mode_top_bound=1: u and v relax towards 0 |
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| 47 | ! mode_top_bound=2: u and v relax towards their zonal mean |
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| 48 | ! mode_top_bound=3: u,v and pot. temp. relax towards their zonal mean |
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| 49 | ! tau_top_bound : inverse of charactericstic relaxation time scale at |
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| 50 | ! the topmost layer (Hz) |
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| 51 | |
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| 52 | |
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| 53 | #include "comdissipn.h" |
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| 54 | #include "iniprint.h" |
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| 55 | |
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| 56 | c Arguments: |
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| 57 | c ---------- |
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| 58 | |
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| 59 | real,intent(inout) :: ucov(iip1,jjp1,llm) ! covariant zonal wind |
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| 60 | real,intent(inout) :: vcov(iip1,jjm,llm) ! covariant meridional wind |
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| 61 | real,intent(inout) :: teta(iip1,jjp1,llm) ! potential temperature |
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| 62 | real,intent(in) :: masse(iip1,jjp1,llm) ! mass of atmosphere |
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| 63 | real,intent(in) :: dt ! time step (s) of sponge model |
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| 64 | real,intent(out) :: ducov(iip1,jjp1,llm) ! increment on ucov due to sponge |
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| 65 | |
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| 66 | c Local: |
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| 67 | c ------ |
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| 68 | |
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| 69 | REAL massebx(iip1,jjp1,llm),masseby(iip1,jjm,llm),zm |
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| 70 | REAL uzon(jjp1,llm),vzon(jjm,llm),tzon(jjp1,llm) |
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| 71 | |
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| 72 | integer i |
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| 73 | REAL,SAVE :: rdamp(llm) ! quenching coefficient |
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| 74 | real,save :: lambda(llm) ! inverse or quenching time scale (Hz) |
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| 75 | |
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| 76 | LOGICAL,SAVE :: first=.true. |
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| 77 | |
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| 78 | INTEGER j,l |
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| 79 | |
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| 80 | if (first) then |
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| 81 | if (iflag_top_bound.eq.1) then |
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| 82 | ! sponge quenching over the topmost 4 atmospheric layers |
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| 83 | lambda(:)=0. |
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| 84 | lambda(llm)=tau_top_bound |
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| 85 | lambda(llm-1)=tau_top_bound/2. |
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| 86 | lambda(llm-2)=tau_top_bound/4. |
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| 87 | lambda(llm-3)=tau_top_bound/8. |
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| 88 | else if (iflag_top_bound.eq.2) then |
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| 89 | ! sponge quenching over topmost layers down to pressures which are |
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| 90 | ! higher than 100 times the topmost layer pressure |
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| 91 | lambda(:)=tau_top_bound |
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| 92 | s *max(presnivs(llm)/presnivs(:)-0.01,0.) |
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| 93 | endif |
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| 94 | |
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| 95 | ! quenching coefficient rdamp(:) |
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| 96 | ! rdamp(:)=dt*lambda(:) ! Explicit Euler approx. |
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| 97 | rdamp(:)=1.-exp(-lambda(:)*dt) |
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| 98 | |
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| 99 | write(lunout,*)'TOP_BOUND mode',mode_top_bound |
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| 100 | write(lunout,*)'Sponge layer coefficients' |
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| 101 | write(lunout,*)'p (Pa) z(km) tau(s) 1./tau (Hz)' |
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| 102 | do l=1,llm |
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| 103 | if (rdamp(l).ne.0.) then |
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| 104 | write(lunout,'(6(1pe12.4,1x))') |
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| 105 | & presnivs(l),log(preff/presnivs(l))*scaleheight, |
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| 106 | & 1./lambda(l),lambda(l) |
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| 107 | endif |
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| 108 | enddo |
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| 109 | first=.false. |
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| 110 | endif ! of if (first) |
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| 111 | |
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| 112 | CALL massbar(masse,massebx,masseby) |
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| 113 | |
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| 114 | ! compute zonal average of vcov and u |
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| 115 | if (mode_top_bound.ge.2) then |
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| 116 | do l=1,llm |
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| 117 | do j=1,jjm |
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| 118 | vzon(j,l)=0. |
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| 119 | zm=0. |
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| 120 | do i=1,iim |
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| 121 | ! NB: we can work using vcov zonal mean rather than v since the |
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| 122 | ! cv coefficient (which relates the two) only varies with latitudes |
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| 123 | vzon(j,l)=vzon(j,l)+vcov(i,j,l)*masseby(i,j,l) |
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| 124 | zm=zm+masseby(i,j,l) |
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| 125 | enddo |
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| 126 | vzon(j,l)=vzon(j,l)/zm |
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| 127 | enddo |
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| 128 | enddo |
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| 129 | |
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| 130 | do l=1,llm |
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| 131 | do j=2,jjm ! excluding poles |
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| 132 | uzon(j,l)=0. |
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| 133 | zm=0. |
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| 134 | do i=1,iim |
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| 135 | uzon(j,l)=uzon(j,l)+massebx(i,j,l)*ucov(i,j,l)/cu(i,j) |
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| 136 | zm=zm+massebx(i,j,l) |
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| 137 | enddo |
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| 138 | uzon(j,l)=uzon(j,l)/zm |
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| 139 | enddo |
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| 140 | enddo |
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| 141 | else ! ucov and vcov will relax towards 0 |
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| 142 | vzon(:,:)=0. |
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| 143 | uzon(:,:)=0. |
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| 144 | endif ! of if (mode_top_bound.ge.2) |
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| 145 | |
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| 146 | ! compute zonal average of potential temperature, if necessary |
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| 147 | if (mode_top_bound.ge.3) then |
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| 148 | do l=1,llm |
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| 149 | do j=2,jjm ! excluding poles |
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| 150 | zm=0. |
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| 151 | tzon(j,l)=0. |
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| 152 | do i=1,iim |
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| 153 | tzon(j,l)=tzon(j,l)+teta(i,j,l)*masse(i,j,l) |
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| 154 | zm=zm+masse(i,j,l) |
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| 155 | enddo |
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| 156 | tzon(j,l)=tzon(j,l)/zm |
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| 157 | enddo |
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| 158 | enddo |
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| 159 | endif ! of if (mode_top_bound.ge.3) |
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| 160 | |
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| 161 | if (mode_top_bound.ge.1) then |
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| 162 | ! Apply sponge quenching on vcov: |
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| 163 | do l=1,llm |
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| 164 | do i=1,iip1 |
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| 165 | do j=1,jjm |
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| 166 | vcov(i,j,l)=vcov(i,j,l) |
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| 167 | & -rdamp(l)*(vcov(i,j,l)-vzon(j,l)) |
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| 168 | enddo |
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| 169 | enddo |
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| 170 | enddo |
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| 171 | |
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| 172 | ! Apply sponge quenching on ucov: |
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| 173 | do l=1,llm |
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| 174 | do i=1,iip1 |
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| 175 | do j=2,jjm ! excluding poles |
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| 176 | ducov(i,j,l)=-rdamp(l)*(ucov(i,j,l)-cu(i,j)*uzon(j,l)) |
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| 177 | ucov(i,j,l)=ucov(i,j,l) |
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| 178 | & +ducov(i,j,l) |
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| 179 | enddo |
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| 180 | enddo |
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| 181 | enddo |
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| 182 | endif ! of if (mode_top_bound.ge.1) |
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| 183 | |
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| 184 | if (mode_top_bound.ge.3) then |
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| 185 | ! Apply sponge quenching on teta: |
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| 186 | do l=1,llm |
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| 187 | do i=1,iip1 |
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| 188 | do j=2,jjm ! excluding poles |
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| 189 | teta(i,j,l)=teta(i,j,l) |
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| 190 | & -rdamp(l)*(teta(i,j,l)-tzon(j,l)) |
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| 191 | enddo |
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| 192 | enddo |
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| 193 | enddo |
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| 194 | endif ! of if (mode_top_bound.ge.3) |
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| 195 | |
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| 196 | END |
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