anchor.diff:    double precision, intent(in)    :: g_vec(layers)
     integer,          intent(in)    :: nx, ny, layers, n
   
  +  ! barotropic velocity components (for pressure solver)
     double precision :: ub(nx+1, ny)
     double precision :: vb(nx, ny+1)
     double precision :: etastar(0:nx+1, 0:ny+1)
  
positive.code:   double precision, dimension(:,:,:), allocatable :: dudtold
    double precision, dimension(:,:,:), allocatable :: dudtveryold
    double precision, dimension(:,:,:), allocatable :: unew
    ! barotropic velocity components (for pressure solver)
    double precision, dimension(:,:), allocatable :: ub
    ! for initialisation
    double precision, dimension(:,:,:), allocatable :: uhalf
    ! for saving average fields
  
negative.code:   double precision, dimension(:,:,:), allocatable :: dvdtold
    double precision, dimension(:,:,:), allocatable :: dvdtveryold
    double precision, dimension(:,:,:), allocatable :: vnew
    ! for initialisation
    double precision, dimension(:,:,:), allocatable :: vhalf
    ! for saving average fields
  