anchor.diff:  
     ! Free surface (eta)
     double precision, dimension(:,:), allocatable :: eta
  -  double precision, dimension(:,:), allocatable :: etastar
     double precision, dimension(:,:), allocatable :: etanew
     ! for saving average fields
     double precision, dimension(:,:), allocatable :: etaav
  
positive.code:   double precision, dimension(:,:,:), allocatable :: dvdtold
    double precision, dimension(:,:,:), allocatable :: dvdtveryold
    double precision, dimension(:,:,:), allocatable :: vnew
    ! barotropic velocity components (for pressure solver)
    double precision, dimension(:,:), allocatable :: vb
    ! for initialisation
    double precision, dimension(:,:,:), allocatable :: vhalf
    ! for saving average fields
  
negative.code:   double precision, dimension(:,:,:), allocatable :: dudtold
    double precision, dimension(:,:,:), allocatable :: dudtveryold
    double precision, dimension(:,:,:), allocatable :: unew
    ! for initialisation
    double precision, dimension(:,:,:), allocatable :: uhalf
    ! for saving average fields
  