! ! $Id: top_bound.f90 5312 2024-11-01 12:22:08Z abarral $ ! SUBROUTINE top_bound(vcov,ucov,teta,masse,dt) USE iniprint_mod_h USE comgeom2_mod_h USE comdissipn_mod_h USE comconst_mod, ONLY: iflag_top_bound, mode_top_bound, & tau_top_bound USE comvert_mod, ONLY: presnivs, preff, scaleheight USE dimensions_mod, ONLY: iim, jjm, llm, ndm USE paramet_mod_h IMPLICIT NONE ! ! .. DISSIPATION LINEAIRE A HAUT NIVEAU, RUN MESO, ! F. LOTT DEC. 2006 ! ( 10/12/06 ) !======================================================================= ! ! Auteur: F. LOTT ! ------- ! ! Objet: ! ------ ! ! Dissipation lin�aire (ex top_bound de la physique) ! !======================================================================= ! top_bound sponge layer model: ! Quenching is modeled as: A(t)=Am+A0*exp(-lambda*t) ! where Am is the zonal average of the field (or zero), and lambda the inverse ! of the characteristic quenching/relaxation time scale ! Thus, assuming Am to be time-independent, field at time t+dt is given by: ! A(t+dt)=A(t)-(A(t)-Am)*(1-exp(-lambda*t)) ! Moreover lambda can be a function of model level (see below), and relaxation ! can be toward the average zonal field or just zero (see below). ! NB: top_bound sponge is only called from leapfrog if ok_strato=.true. ! sponge parameters: (loaded/set in conf_gcm.F ; stored in comconst_mod) ! iflag_top_bound=0 for no sponge ! iflag_top_bound=1 for sponge over 4 topmost layers ! iflag_top_bound=2 for sponge from top to ~1% of top layer pressure ! mode_top_bound=0: no relaxation ! mode_top_bound=1: u and v relax towards 0 ! mode_top_bound=2: u and v relax towards their zonal mean ! mode_top_bound=3: u,v and pot. temp. relax towards their zonal mean ! tau_top_bound : inverse of charactericstic relaxation time scale at ! the topmost layer (Hz) ! Arguments: ! ---------- real,intent(inout) :: ucov(iip1,jjp1,llm) ! covariant zonal wind real,intent(inout) :: vcov(iip1,jjm,llm) ! covariant meridional wind real,intent(inout) :: teta(iip1,jjp1,llm) ! potential temperature real,intent(in) :: masse(iip1,jjp1,llm) ! mass of atmosphere real,intent(in) :: dt ! time step (s) of sponge model ! Local: ! ------ REAL :: massebx(iip1,jjp1,llm),masseby(iip1,jjm,llm),zm REAL :: uzon(jjp1,llm),vzon(jjm,llm),tzon(jjp1,llm) integer :: i REAL,SAVE :: rdamp(llm) ! quenching coefficient real,save :: lambda(llm) ! inverse or quenching time scale (Hz) LOGICAL,SAVE :: first=.true. INTEGER :: j,l if (iflag_top_bound.eq.0) return if (first) then if (iflag_top_bound.eq.1) then ! sponge quenching over the topmost 4 atmospheric layers lambda(:)=0. lambda(llm)=tau_top_bound lambda(llm-1)=tau_top_bound/2. lambda(llm-2)=tau_top_bound/4. lambda(llm-3)=tau_top_bound/8. else if (iflag_top_bound.eq.2) then ! sponge quenching over topmost layers down to pressures which are ! higher than 100 times the topmost layer pressure lambda(:)=tau_top_bound & *max(presnivs(llm)/presnivs(:)-0.01,0.) endif ! quenching coefficient rdamp(:) ! rdamp(:)=dt*lambda(:) ! Explicit Euler approx. rdamp(:)=1.-exp(-lambda(:)*dt) write(lunout,*)'TOP_BOUND mode',mode_top_bound write(lunout,*)'Sponge layer coefficients' write(lunout,*)'p (Pa) z(km) tau(s) 1./tau (Hz)' do l=1,llm if (rdamp(l).ne.0.) then write(lunout,'(6(1pe12.4,1x))') & presnivs(l),log(preff/presnivs(l))*scaleheight, & 1./lambda(l),lambda(l) endif enddo first=.false. endif ! of if (first) CALL massbar(masse,massebx,masseby) ! ! compute zonal average of vcov and u if (mode_top_bound.ge.2) then do l=1,llm do j=1,jjm vzon(j,l)=0. zm=0. do i=1,iim ! NB: we can work using vcov zonal mean rather than v since the ! cv coefficient (which relates the two) only varies with latitudes vzon(j,l)=vzon(j,l)+vcov(i,j,l)*masseby(i,j,l) zm=zm+masseby(i,j,l) enddo vzon(j,l)=vzon(j,l)/zm enddo enddo do l=1,llm do j=2,jjm ! excluding poles uzon(j,l)=0. zm=0. do i=1,iim uzon(j,l)=uzon(j,l)+massebx(i,j,l)*ucov(i,j,l)/cu(i,j) zm=zm+massebx(i,j,l) enddo uzon(j,l)=uzon(j,l)/zm enddo enddo else ! ucov and vcov will relax towards 0 vzon(:,:)=0. uzon(:,:)=0. endif ! of if (mode_top_bound.ge.2) ! ! compute zonal average of potential temperature, if necessary if (mode_top_bound.ge.3) then do l=1,llm do j=2,jjm ! excluding poles zm=0. tzon(j,l)=0. do i=1,iim tzon(j,l)=tzon(j,l)+teta(i,j,l)*masse(i,j,l) zm=zm+masse(i,j,l) enddo tzon(j,l)=tzon(j,l)/zm enddo enddo endif ! of if (mode_top_bound.ge.3) if (mode_top_bound.ge.1) then ! ! Apply sponge quenching on vcov: do l=1,llm do i=1,iip1 do j=1,jjm vcov(i,j,l)=vcov(i,j,l) & -rdamp(l)*(vcov(i,j,l)-vzon(j,l)) enddo enddo enddo ! ! Apply sponge quenching on ucov: do l=1,llm do i=1,iip1 do j=2,jjm ! excluding poles ucov(i,j,l)=ucov(i,j,l) & -rdamp(l)*(ucov(i,j,l)-cu(i,j)*uzon(j,l)) enddo enddo enddo endif ! of if (mode_top_bound.ge.1) if (mode_top_bound.ge.3) then ! ! Apply sponge quenching on teta: do l=1,llm do i=1,iip1 do j=2,jjm ! excluding poles teta(i,j,l)=teta(i,j,l) & -rdamp(l)*(teta(i,j,l)-tzon(j,l)) enddo enddo enddo endif ! of if (mode_top_bound.ge.3) END SUBROUTINE top_bound