MODULE etat0_dcmip4_mod
  USE icosa
  IMPLICIT NONE
  PRIVATE
  
  REAL(rstd),PARAMETER :: eta0=0.252
  REAL(rstd),PARAMETER :: etat=0.2
  REAL(rstd),PARAMETER :: ps0=1e5
  REAL(rstd),PARAMETER :: u0=35
  REAL(rstd),PARAMETER :: T0=288
  REAL(rstd),PARAMETER :: DeltaT=4.8e5
  REAL(rstd),PARAMETER :: Rd=287
  REAL(rstd),PARAMETER :: Gamma=0.005
  REAL(rstd),PARAMETER :: up0=1
  REAL(rstd),PARAMETER :: lonc=Pi/9, latc=2*Pi/9, latw=2*Pi/9
  REAL(rstd),PARAMETER :: pw=34000
  REAL(rstd),PARAMETER :: q0=0.021
  
  INTEGER,SAVE :: testcase
  !$OMP THREADPRIVATE(testcase)  
  
  PUBLIC getin_etat0, compute_etat0

CONTAINS

  SUBROUTINE getin_etat0
    USE mpipara, ONLY : is_mpi_root
    IF(nqtot<2) THEN
       IF (is_mpi_root)  THEN
          PRINT *, "nqtot must be at least 2 for test case DCMIP4"
       END IF
       STOP
    END IF
    testcase=1
    CALL getin("dcmip4_testcase",testcase)
  END SUBROUTINE getin_etat0

  SUBROUTINE compute_etat0(ngrid,lon,lat, phis,ps,temp,ulon,ulat,q)
    USE icosa
    USE disvert_mod
    USE omp_para
    INTEGER, INTENT(IN) :: ngrid
    REAL(rstd),INTENT(IN) :: lon(ngrid)
    REAL(rstd),INTENT(IN) :: lat(ngrid)
    REAL(rstd),INTENT(OUT) :: phis(ngrid)
    REAL(rstd),INTENT(OUT) :: ps(ngrid)
    REAL(rstd),INTENT(OUT) :: temp(ngrid,llm)
    REAL(rstd),INTENT(OUT) :: ulon(ngrid,llm)
    REAL(rstd),INTENT(OUT) :: ulat(ngrid,llm)
    REAL(rstd),INTENT(OUT) :: q(ngrid,llm,nqtot)
    
    INTEGER :: l,ij
    REAL(rstd) :: etal, etavl, etas, etavs, sinlat, coslat, &
         Y, Tave, T, phis_ave, vort, r2, utot, &
         dthetaodeta_ave, dthetaodeta, dthetaodlat, duodeta, K, r
    
    etas=ap(1)/preff+bp(1)
    etavs=(etas-eta0)*Pi/2
    phis_ave=T0*g/Gamma*(1-etas**(Rd*Gamma/g))
    
    DO ij=1,ngrid
       sinlat=SIN(lat(ij))
       coslat=COS(lat(ij))
       phis(ij)=phis_ave+u0*cos(etavs)**1.5*( (-2*sinlat**6 * (coslat**2+1./3) + 10./63 )*u0*cos(etavs)**1.5  &
            +(8./5*coslat**3 * (sinlat**2 + 2./3) - Pi/4)*radius*Omega )
       ps(ij)=ps0
    ENDDO
    
    DO l=ll_begin,ll_end
       etal = 0.5 *( ap(l)/preff+bp(l) + ap(l+1)/preff+bp(l+1) )
       etavl=(etal-eta0)*Pi/2
       
       Tave=T0*etal**(Rd*Gamma/g)
       dthetaodeta_ave = T0 *( Rd*Gamma/g - kappa)* etal**(Rd*Gamma/g-kappa-1)
       IF (etat>etal) THEN
          Tave=Tave+DeltaT*(etat-etal)**5
          dthetaodeta_ave = dthetaodeta_ave - DeltaT * ( 5*(etat-etal)**4 * etal**(-kappa)  &
               + kappa * (etat-etal)**5 * etal**(-kappa-1))
       END IF
       
       DO ij=1,ngrid
          sinlat=SIN(lat(ij))
          coslat=COS(lat(ij))
          
          K=sin(latc)*sinlat+cos(latc)*coslat*cos(lon(ij)-lonc)
          r=radius*acos(K)
          utot=u0*cos(etavl)**1.5*sin(2*lat(ij))**2 + up0*exp(-(r/(0.1*radius))**2)
          ulon(ij,l) = utot
          ulat(ij,l) = 0.
          Y = ((-2*sinlat**6*(coslat**2+1./3)+10./63)*2*u0*cos(etavl)**1.5     &
               + (8./5*coslat**3*(sinlat**2+2./3)-Pi/4)*radius*Omega)
          T = Tave + 0.75*(etal*Pi*u0/Rd)*sin(etavl)*cos(etavl)**0.5 * Y
          temp(ij,l)=T
          
          IF (testcase==1) THEN
             q(ij,l,1)=T*etal**(-kappa)
             IF(nqtot>2) q(ij,l,3)=1.
             dthetaodeta=dthetaodeta_ave + 3./4. * Pi * u0/Rd*(1-kappa)*etal**(-kappa)*sin(etavl)*cos(etavl)**0.5 * Y & 
                  + 3/8. * Pi**2*u0/Rd * etal**(1-kappa) * cos(etavl)**1.5 * Y                    & 
                  - 3./16. * Pi**2 * u0 /Rd * etal**(1-kappa) * sin(etavl)**2 * cos(etavl)**(-0.5) *Y &
                  - 9./8.  * Pi**2 * u0 /Rd * etal**(1-kappa) * sin(etavl)**2 * cos(etavl)   &
                  * (-2*sinlat**6*(coslat**2+1./3.)+10./63.) 
             dthetaodlat=3./4.*Pi*u0/Rd*etal**(1-kappa)*sin(etavl)*cos(etavl)**0.5                                   &
                  *( 2*u0*cos(etavl)**1.5 * ( -12 * coslat*sinlat**5*(coslat**2+1./3.)+4*coslat*sinlat**7) &
                  + radius*omega*(-24./5. * sinlat * coslat**2 * (sinlat**2 + 2./3.) + 16./5. * coslat**4 * sinlat))
             
             duodeta=-u0 * sin(2*lat(ij))**2 * 3./4.*Pi * cos(etavl)**0.5 * sin(etavl)
             
             vort = -4*u0/radius*cos(etavl)**1.5 * sinlat * coslat * (2.-5.*sinlat**2)                  & 
                  + up0/radius*exp(-(r/(0.1*radius))**2) * (tan(lat(ij))-2*(radius/(0.1*radius))**2 * acos(K) * (sin(latc)*coslat &
                  -cos(latc)*sinlat*cos(lon(ij)-lonc))/(sqrt(1-K**2)))
             q(ij,l,2)=ABS(g/preff*(-1./radius*duodeta*dthetaodlat-(2*sinlat*omega+vort)*dthetaodeta))
             IF(nqtot>3) q(ij,l,4)=cos(lon(ij))*coslat
          ELSE IF (testcase==2) THEN
             q(ij,l,1)=q0*exp(-(lat(ij)/latw)**4)*exp(-((etal-1)*preff/pw)**2)
          END IF
       END DO
    END DO
    
  END SUBROUTINE compute_etat0
  
END MODULE etat0_dcmip4_mod