Update sbcflx.F90

Remove 0.5 factor on zmod, already accounted for in ztx zty

src/OCE/SBC/sbcflx.F90

@@ -176,7 +176,7 @@ CONTAINS
       DO_2D( 0, 0, 0, 0 )
          ztx = ( utau(ji-1,jj  ) + utau(ji,jj) ) * 0.5_wp * ( 2._wp - MIN( umask(ji-1,jj  ,1), umask(ji,jj,1) ) )
          zty = ( vtau(ji  ,jj-1) + vtau(ji,jj) ) * 0.5_wp * ( 2._wp - MIN( vmask(ji  ,jj-1,1), vmask(ji,jj,1) ) )
-         zmod = 0.5_wp * SQRT( ztx * ztx + zty * zty ) * tmask(ji,jj,1)
+         zmod = SQRT( ztx * ztx + zty * zty ) * tmask(ji,jj,1)
          taum(ji,jj) = zmod
          wndm(ji,jj) = SQRT( zmod * zcoef )  !!clem: not used?
       END_2D