!!----------------------------------------------------------------------
   !! NEMO/OPA 3.3 , NEMO Consortium (2010)
   !! $Id$
   !! Software governed by the CeCILL licence (NEMOGCM/NEMO_CeCILL.txt)
   !!----------------------------------------------------------------------

   REAL(KIND=wp) FUNCTION grt_cir_dis( pa1, pa2, pb1, pb2, pc1, pc2 )
      !!----------------------------------------------------------------------
      !!                     *** FUNCTION grt_cir_dis ***
      !!
      !! ** Purpose : Great circle distance between pts (lat1,lon1) 
      !!               & (lat2,lon2)
      !!                   
      !! ** Method   : Geometry.
      !!
      !! History :
      !!        !  1995-12 (G. Madec, E. Durand, A. Weaver, N. Daget) Original 
      !!        !  2006-03 (A. Vidard) Migration to NEMOVAR 
      !!        !  2006-10 (A. Weaver) Cleanup
      !!----------------------------------------------------------------------
      
      !! * Arguments
      REAL(KIND=wp) :: pa1   !  sin(lat1)
      REAL(KIND=wp) :: pa2   !  sin(lat2)
      REAL(KIND=wp) :: pb1   !  cos(lat1) * cos(lon1)
      REAL(KIND=wp) :: pb2   !  cos(lat2) * cos(lon2)
      REAL(KIND=wp) :: pc1   !  cos(lat1) * sin(lon1)
      REAL(KIND=wp) :: pc2   !  cos(lat2) * sin(lon2)

      grt_cir_dis = &
         &  ASIN( SQRT( 1.0 - ( pa1 * pa2 + pb1 * pb2 + pc1 * pc2 )**2 ) )
      
   END FUNCTION grt_cir_dis