module module_bl_gwdo
contains
   subroutine gwdo(u3d,v3d,t3d,qv3d,p3d,p3di,pi3d,z, &
                  rublten,rvblten, &
                  dtaux3d,dtauy3d,dusfcg,dvsfcg, &
                  var2d,oc12d,oa2d1,oa2d2,oa2d3,oa2d4,ol2d1,ol2d2,ol2d3,ol2d4, &
                  znu,znw,p_top, &
                  cp,g,rd,rv,ep1,pi, &
                  dt,dx,kpbl2d,itimestep, &
                  ids,ide, jds,jde, kds,kde, &
                  ims,ime, jms,jme, kms,kme, &
                  its,ite, jts,jte, kts,kte)
   implicit none
  integer, intent(in ) :: ids,ide, jds,jde, kds,kde, &
                                     ims,ime, jms,jme, kms,kme, &
                                     its,ite, jts,jte, kts,kte
  integer, intent(in ) :: itimestep
  real, intent(in ) :: dt,dx,cp,g,rd,rv,ep1,pi
  real, dimension( ims:ime, kms:kme, jms:jme ) , &
            intent(in ) :: qv3d, &
                                                                          p3d, &
                                                                         pi3d, &
                                                                          t3d, &
                                                                             z
  real, dimension( ims:ime, kms:kme, jms:jme ) , &
            intent(in ) :: p3di
  real, dimension( ims:ime, kms:kme, jms:jme ) , &
            intent(inout) :: rublten, &
                                                                      rvblten
  real, dimension( ims:ime, kms:kme, jms:jme ) , &
            intent(inout) :: dtaux3d, &
                                                                      dtauy3d
  real, dimension( ims:ime, kms:kme, jms:jme ) , &
             intent(in ) :: u3d, &
                                                                          v3d
  integer, dimension( ims:ime, jms:jme ) , &
             intent(in ) :: kpbl2d
  real, dimension( ims:ime, jms:jme ) , &
             intent(inout ) :: dusfcg, &
                                                                       dvsfcg
  real, dimension( ims:ime, jms:jme ) , &
             intent(in ) :: var2d, &
                                                                        oc12d, &
                                                      oa2d1,oa2d2,oa2d3,oa2d4, &
                                                      ol2d1,ol2d2,ol2d3,ol2d4
  real, dimension( kms:kme ) , &
            optional , &
            intent(in ) :: znu, &
                                                                          znw
  real, optional, intent(in ) :: p_top
  real, dimension( its:ite, kts:kte ) :: delprsi, &
                                                                          pdh
  real, dimension( its:ite, kts:kte+1 ) :: pdhi
  real, dimension( its:ite, 4 ) :: oa4, &
                                                                          ol4
  integer :: i,j,k,kdt,kpblmax
   do k = kts,kte
     if(znu(k).gt.0.6) kpblmax = k + 1
   enddo
   do j = jts,jte
      do k = kts,kte+1
        do i = its,ite
           if(k.le.kte)pdh(i,k) = p3d(i,k,j)
           pdhi(i,k) = p3di(i,k,j)
        enddo
      enddo
      do k = kts,kte
        do i = its,ite
          delprsi(i,k) = pdhi(i,k)-pdhi(i,k+1)
        enddo
      enddo
        do i = its,ite
            oa4(i,1) = oa2d1(i,j)
            oa4(i,2) = oa2d2(i,j)
            oa4(i,3) = oa2d3(i,j)
            oa4(i,4) = oa2d4(i,j)
            ol4(i,1) = ol2d1(i,j)
            ol4(i,2) = ol2d2(i,j)
            ol4(i,3) = ol2d3(i,j)
            ol4(i,4) = ol2d4(i,j)
        enddo
      call gwdo2d(dudt=rublten(ims,kms,j),dvdt=rvblten(ims,kms,j) &
              ,dtaux2d=dtaux3d(ims,kms,j),dtauy2d=dtauy3d(ims,kms,j) &
              ,u1=u3d(ims,kms,j),v1=v3d(ims,kms,j) &
              ,t1=t3d(ims,kms,j),q1=qv3d(ims,kms,j) &
              ,del=delprsi(its,kts) &
              ,prsi=pdhi(its,kts) &
              ,prsl=pdh(its,kts),prslk=pi3d(ims,kms,j) &
              ,zl=z(ims,kms,j),rcl=1.0 &
              ,kpblmax=kpblmax &
              ,dusfc=dusfcg(ims,j),dvsfc=dvsfcg(ims,j) &
              ,var=var2d(ims,j),oc1=oc12d(ims,j) &
              ,oa4=oa4,ol4=ol4 &
              ,g=g,cp=cp,rd=rd,rv=rv,fv=ep1,pi=pi &
              ,dxmeter=dx,deltim=dt &
              ,kpbl=kpbl2d(ims,j),kdt=itimestep,lat=j &
              ,ids=ids,ide=ide, jds=jds,jde=jde, kds=kds,kde=kde &
              ,ims=ims,ime=ime, jms=jms,jme=jme, kms=kms,kme=kme &
              ,its=its,ite=ite, jts=jts,jte=jte, kts=kts,kte=kte )
   enddo
   end subroutine gwdo
   subroutine gwdo2d(dudt,dvdt,dtaux2d,dtauy2d, &
                    u1,v1,t1,q1, &
                    del, &
                    prsi,prsl,prslk,zl,rcl,kpblmax, &
                    var,oc1,oa4,ol4,dusfc,dvsfc, &
                    g,cp,rd,rv,fv,pi,dxmeter,deltim,kpbl,kdt,lat, &
                    ids,ide, jds,jde, kds,kde, &
                    ims,ime, jms,jme, kms,kme, &
                    its,ite, jts,jte, kts,kte)
   implicit none
   integer :: kdt,lat,latd,lond,kpblmax, &
                            ids,ide, jds,jde, kds,kde, &
                            ims,ime, jms,jme, kms,kme, &
                            its,ite, jts,jte, kts,kte
   real :: g,rd,rv,fv,cp,pi,dxmeter,deltim,rcl
   real :: dudt(ims:ime,kms:kme),dvdt(ims:ime,kms:kme), &
                            dtaux2d(ims:ime,kms:kme),dtauy2d(ims:ime,kms:kme), &
                            u1(ims:ime,kms:kme),v1(ims:ime,kms:kme), &
                            t1(ims:ime,kms:kme),q1(ims:ime,kms:kme), &
                            zl(ims:ime,kms:kme),prsl(its:ite,kts:kte), &
                            prslk(ims:ime,kms:kme)
   real :: prsi(its:ite,kts:kte+1),del(its:ite,kts:kte)
   real :: oa4(its:ite,4),ol4(its:ite,4)
   integer :: kpbl(ims:ime)
   real :: var(ims:ime),oc1(ims:ime), &
                            dusfc(ims:ime),dvsfc(ims:ime)
   real,parameter :: ric = 0.25
   real,parameter :: dw2min = 1.
   real,parameter :: rimin = -100.
   real,parameter :: bnv2min = 1.0e-5
   real,parameter :: efmin = 0.0
   real,parameter :: efmax = 10.0
   real,parameter :: xl = 4.0e4
   real,parameter :: critac = 1.0e-5
   real,parameter :: gmax = 1.
   real,parameter :: veleps = 1.0
   real,parameter :: factop = 0.5
   real,parameter :: frc = 1.0
   real,parameter :: ce = 0.8
   real,parameter :: cg = 0.5
   integer,parameter :: kpblmin = 2
   integer :: i,k,lcap,lcapp1,nwd,idir, &
                            klcap,kp1,ikount,kk
   real :: rcs,rclcs,csg,fdir,cleff,cs,rcsks, &
                            wdir,ti,rdz,temp,tem2,dw2,shr2,bvf2,rdelks, &
                            wtkbj,tem,gfobnv,hd,fro,rim,temc,tem1,efact, &
                            temv,dtaux,dtauy
   logical :: ldrag(its:ite),icrilv(its:ite), &
                            flag(its:ite),kloop1(its:ite)
   real :: taub(its:ite),taup(its:ite,kts:kte+1), &
                            xn(its:ite),yn(its:ite), &
                            ubar(its:ite),vbar(its:ite), &
                            fr(its:ite),ulow(its:ite), &
                            rulow(its:ite),bnv(its:ite), &
                            oa(its:ite),ol(its:ite), &
                            roll(its:ite),dtfac(its:ite), &
                            brvf(its:ite),xlinv(its:ite), &
                            delks(its:ite),delks1(its:ite), &
                            bnv2(its:ite,kts:kte),usqj(its:ite,kts:kte), &
                            taud(its:ite,kts:kte),ro(its:ite,kts:kte), &
                            vtk(its:ite,kts:kte),vtj(its:ite,kts:kte), &
                            zlowtop(its:ite),velco(its:ite,kts:kte-1), &
                            coefm(its:ite)
   integer :: kbl(its:ite),klowtop(its:ite)
   logical :: iope
   integer,parameter :: mdir=8
   integer :: nwdir(mdir)
   data nwdir/6,7,5,8,2,3,1,4/
   real,parameter :: frmax = 10.
   real,parameter :: olmin = 1.0e-5
   real,parameter :: odmin = 0.1
   real,parameter :: odmax = 10.
   real,parameter :: erad = 6371.315e+3
   integer :: komax(its:ite)
   integer :: kblk
   real :: cd
   real :: zblk,tautem
   real :: pe,ke
   real :: delx,dely,dxy4(4),dxy4p(4)
   real :: dxy(its:ite),dxyp(its:ite)
   real :: ol4p(4),olp(its:ite),od(its:ite)
   real :: taufb(its:ite,kts:kte+1)
   rcs = sqrt(rcl)
   cs = 1. / sqrt(rcl)
   csg = cs * g
   lcap = kte
   lcapp1 = lcap + 1
   fdir = mdir / (2.0*pi)
   delx = dxmeter
   dely = dxmeter
   dxy4(1) = delx
   dxy4(2) = dely
   dxy4(3) = sqrt(delx*delx + dely*dely)
   dxy4(4) = dxy4(3)
   dxy4p(1) = dxy4(2)
   dxy4p(2) = dxy4(1)
   dxy4p(3) = dxy4(4)
   dxy4p(4) = dxy4(3)
   dtaux = 0.0
   dtauy = 0.0
   do i = its,ite
     klowtop(i) = 0
     kbl(i) = 0
   enddo
   do i = its,ite
     xn(i) = 0.0
     yn(i) = 0.0
     ubar (i) = 0.0
     vbar (i) = 0.0
     roll (i) = 0.0
     taub (i) = 0.0
     taup(i,1) = 0.0
     oa(i) = 0.0
     ol(i) = 0.0
     ulow (i) = 0.0
     dtfac(i) = 1.0
     ldrag(i) = .false.
     icrilv(i) = .false.
     flag(i) = .true.
   enddo
   do k = kts,kte
     do i = its,ite
       usqj(i,k) = 0.0
       bnv2(i,k) = 0.0
       vtj(i,k) = 0.0
       vtk(i,k) = 0.0
       taup(i,k) = 0.0
       taud(i,k) = 0.0
       dtaux2d(i,k)= 0.0
       dtauy2d(i,k)= 0.0
     enddo
   enddo
   do i = its,ite
     taup(i,kte+1) = 0.0
     xlinv(i) = 1.0/xl
   enddo
   taufb(its:ite,kts:kte+1) = 0.0
   komax(its:ite) = 0
   do k = kts,kte
     do i = its,ite
       vtj(i,k) = t1(i,k) * (1.+fv*q1(i,k))
       vtk(i,k) = vtj(i,k) / prslk(i,k)
       ro(i,k) = 1./rd * prsl(i,k) / vtj(i,k)
     enddo
   enddo
   do i = its,ite
     zlowtop(i) = 2. * var(i)
   enddo
   do i = its,ite
     kloop1(i) = .true.
   enddo
   do k = kts+1,kte
     do i = its,ite
       if(kloop1(i).and.zl(i,k)-zl(i,1).ge.zlowtop(i)) then
         klowtop(i) = k+1
         kloop1(i) = .false.
       endif
     enddo
   enddo
   do i = its,ite
     kbl(i) = max(kpbl(i), klowtop(i))
     kbl(i) = max(min(kbl(i),kpblmax),kpblmin)
   enddo
   komax(:) = kbl(:)
   do i = its,ite
     delks(i) = 1.0 / (prsi(i,1) - prsi(i,kbl(i)))
     delks1(i) = 1.0 / (prsl(i,1) - prsl(i,kbl(i)))
   enddo
   do k = kts,kpblmax
     do i = its,ite
       if (k.lt.kbl(i)) then
         rcsks = rcs * del(i,k) * delks(i)
         rdelks = del(i,k) * delks(i)
         ubar(i) = ubar(i) + rcsks * u1(i,k)
         vbar(i) = vbar(i) + rcsks * v1(i,k)
         roll(i) = roll(i) + rdelks * ro(i,k)
       endif
     enddo
   enddo
   do i = its,ite
     wdir = atan2(ubar(i),vbar(i)) + pi
     idir = mod(nint(fdir*wdir),mdir) + 1
     nwd = nwdir(idir)
     oa(i) = (1-2*int( (nwd-1)/4 )) * oa4(i,mod(nwd-1,4)+1)
     ol(i) = ol4(i,mod(nwd-1,4)+1)
     ol4p(1) = ol4(i,2)
     ol4p(2) = ol4(i,1)
     ol4p(3) = ol4(i,4)
     ol4p(4) = ol4(i,3)
     olp(i) = ol4p(mod(nwd-1,4)+1)
     od(i) = olp(i)/max(ol(i),olmin)
     od(i) = min(od(i),odmax)
     od(i) = max(od(i),odmin)
     dxy(i) = dxy4(MOD(nwd-1,4)+1)
     dxyp(i) = dxy4p(MOD(nwd-1,4)+1)
   enddo
   do k = kts,kte-1
     do i = its,ite
       ti = 2.0 / (t1(i,k)+t1(i,k+1))
       rdz = 1./(zl(i,k+1) - zl(i,k))
       tem1 = u1(i,k) - u1(i,k+1)
       tem2 = v1(i,k) - v1(i,k+1)
       dw2 = rcl*(tem1*tem1 + tem2*tem2)
       shr2 = max(dw2,dw2min) * rdz * rdz
       bvf2 = g*(g/cp+rdz*(vtj(i,k+1)-vtj(i,k))) * ti
       usqj(i,k) = max(bvf2/shr2,rimin)
       bnv2(i,k) = 2.0*g*rdz*(vtk(i,k+1)-vtk(i,k))/(vtk(i,k+1)+vtk(i,k))
       bnv2(i,k) = max( bnv2(i,k), bnv2min )
     enddo
   enddo
   do i = its,ite
     ulow(i) = max(sqrt(ubar(i)*ubar(i) + vbar(i)*vbar(i)), 1.0)
     rulow(i) = 1./ulow(i)
   enddo
   do k = kts,kte-1
     do i = its,ite
       velco(i,k) = (0.5*rcs) * ((u1(i,k)+u1(i,k+1)) * ubar(i) &
                                + (v1(i,k)+v1(i,k+1)) * vbar(i))
       velco(i,k) = velco(i,k) * rulow(i)
       if ((velco(i,k).lt.veleps) .and. (velco(i,k).gt.0.)) then
         velco(i,k) = veleps
       endif
     enddo
   enddo
   do i = its,ite
     ldrag(i) = velco(i,1).le.0.
   enddo
   do k = kpblmin,kpblmax
     do i = its,ite
       if (k .lt. kbl(i)) ldrag(i) = ldrag(i).or. velco(i,k).le.0.
     enddo
   enddo
   do k = kts,kpblmax
     do i = its,ite
       if (k .lt. kbl(i)) ldrag(i) = ldrag(i).or. bnv2(i,k).lt.0.
     enddo
   enddo
   do i = its,ite
     wtkbj = (prsl(i,1)-prsl(i,2)) * delks1(i)
     bnv2(i,1) = wtkbj * bnv2(i,1)
     usqj(i,1) = wtkbj * usqj(i,1)
   enddo
   do k = kpblmin,kpblmax
     do i = its,ite
       if (k .lt. kbl(i)) then
         rdelks = (prsl(i,k)-prsl(i,k+1)) * delks1(i)
         bnv2(i,1) = bnv2(i,1) + bnv2(i,k) * rdelks
         usqj(i,1) = usqj(i,1) + usqj(i,k) * rdelks
       endif
     enddo
   enddo
   do i = its,ite
     ldrag(i) = ldrag(i) .or. bnv2(i,1).le.0.0
     ldrag(i) = ldrag(i) .or. ulow(i).eq.1.0
     ldrag(i) = ldrag(i) .or. var(i) .le. 0.0
   enddo
   do k = kpblmin,kpblmax
     do i = its,ite
       if (k .lt. kbl(i)) usqj(i,k) = usqj(i,1)
     enddo
   enddo
   do i = its,ite
     if (.not.ldrag(i)) then
       bnv(i) = sqrt( bnv2(i,1) )
       fr(i) = bnv(i) * rulow(i) * 2. * var(i) * od(i)
       fr(i) = min(fr(i),frmax)
       xn(i) = ubar(i) * rulow(i)
       yn(i) = vbar(i) * rulow(i)
     endif
   enddo
   do i = its,ite
     if (.not. ldrag(i)) then
       efact = (oa(i) + 2.) ** (ce*fr(i)/frc)
       efact = min( max(efact,efmin), efmax )
       cleff = sqrt(dxy(i)**2. + dxyp(i)**2.)
       cleff = 3. * max(dxmeter,cleff)
       coefm(i) = (1. + ol(i)) ** (oa(i)+1.)
       xlinv(i) = coefm(i) / cleff
       tem = fr(i) * fr(i) * oc1(i)
       gfobnv = gmax * tem / ((tem + cg)*bnv(i))
       taub(i) = xlinv(i) * roll(i) * ulow(i) * ulow(i) &
                * ulow(i) * gfobnv * efact
     else
       taub(i) = 0.0
       xn(i) = 0.0
       yn(i) = 0.0
     endif
   enddo
   do k = kts,kpblmax
     do i = its,ite
       if (k .le. kbl(i)) taup(i,k) = taub(i)
     enddo
   enddo
   do k = kpblmin, kte-1
     kp1 = k + 1
     do i = its,ite
       if (k .ge. kbl(i)) then
         icrilv(i) = icrilv(i) .or. ( usqj(i,k) .lt. ric) &
                               .or. (velco(i,k) .le. 0.0)
         brvf(i) = max(bnv2(i,k),bnv2min)
         brvf(i) = sqrt(brvf(i))
       endif
     enddo
     do i = its,ite
       if (k .ge. kbl(i) .and. (.not. ldrag(i))) then
         if (.not.icrilv(i) .and. taup(i,k) .gt. 0.0 ) then
           temv = 1.0 / velco(i,k)
           tem1 = coefm(i)/dxy(i)*(ro(i,kp1)+ro(i,k))*brvf(i)*velco(i,k)*0.5
           hd = sqrt(taup(i,k) / tem1)
           fro = brvf(i) * hd * temv
           tem2 = sqrt(usqj(i,k))
           tem = 1. + tem2 * fro
           rim = usqj(i,k) * (1.-fro) / (tem * tem)
           if (rim .le. ric) then
             if ((oa(i) .le. 0.).or.(kp1 .ge. kpblmin )) then
               temc = 2.0 + 1.0 / tem2
               hd = velco(i,k) * (2.*sqrt(temc)-temc) / brvf(i)
               taup(i,kp1) = tem1 * hd * hd
             endif
           else
             taup(i,kp1) = taup(i,k)
           endif
         endif
       endif
     enddo
   enddo
   if(lcap.lt.kte) then
     do klcap = lcapp1,kte
       do i = its,ite
         taup(i,klcap) = prsi(i,klcap) / prsi(i,lcap) * taup(i,lcap)
       enddo
     enddo
   endif
   do i = its,ite
     if(.not.ldrag(i)) then
        kblk = 0
        pe = 0.0
        do k = kte, kpblmin, -1
          if(kblk.eq.0 .and. k.le.komax(i)) then
            pe = pe + bnv2(i,k)*(zl(i,komax(i))-zl(i,k))*del(i,k)/g/ro(i,k)
            ke = 0.5*((rcs*u1(i,k))**2.+(rcs*v1(i,k))**2.)
            if(pe.ge.ke) then
              kblk = k
              kblk = min(kblk,kbl(i))
              zblk = zl(i,kblk)-zl(i,kts)
            endif
          endif
        enddo
        if(kblk.ne.0) then
          cd = max(2.0-1.0/od(i),0.0)
          taufb(i,kts) = 0.5 * roll(i) * coefm(i) / dxy(i)**2 * cd * dxyp(i) &
                         * olp(i) * zblk * ulow(i)**2
          tautem = taufb(i,kts)/float(kblk-kts)
          do k = kts+1, kblk
            taufb(i,k) = taufb(i,k-1) - tautem
          enddo
          taup(i,:) = taup(i,:) + taufb(i,:)
        endif
     endif
   enddo
   do k = kts,kte
     do i = its,ite
       taud(i,k) = 1. * (taup(i,k+1) - taup(i,k)) * csg / del(i,k)
     enddo
   enddo
   do klcap = lcap,kte
     do i = its,ite
       taud(i,klcap) = taud(i,klcap) * factop
     enddo
   enddo
   do k = kts,kpblmax-1
     do i = its,ite
       if (k .le. kbl(i)) then
         if(taud(i,k).ne.0.) &
         dtfac(i) = min(dtfac(i),abs(velco(i,k) &
                   /(deltim*rcs*taud(i,k))))
       endif
     enddo
   enddo
   do i = its,ite
     dusfc(i) = 0.
     dvsfc(i) = 0.
   enddo
   do k = kts,kte
     do i = its,ite
       taud(i,k) = taud(i,k) * dtfac(i)
       dtaux = taud(i,k) * xn(i)
       dtauy = taud(i,k) * yn(i)
       dtaux2d(i,k) = dtaux
       dtauy2d(i,k) = dtauy
       dudt(i,k) = dtaux + dudt(i,k)
       dvdt(i,k) = dtauy + dvdt(i,k)
       dusfc(i) = dusfc(i) + dtaux * del(i,k)
       dvsfc(i) = dvsfc(i) + dtauy * del(i,k)
     enddo
   enddo
   do i = its,ite
     dusfc(i) = (-1./g*rcs) * dusfc(i)
     dvsfc(i) = (-1./g*rcs) * dvsfc(i)
   enddo
   return
   end subroutine gwdo2d
end module module_bl_gwdo