subroutine uv2div (lon,lat, ubar,vbar, div )
	dimension ubar(lon,lat),vbar(lon,lat), y(37),cy(37)
	dimension dux(lon,lat),dvy(lon,lat)
	dimension div(lon,lat)

	pi = 4.*atan(1.)
	er = 6370000.0
	detx=2.*pi/144.
	dety=pi/72.
	do j=1,37 
	   y(j)= float(j-1)*dety
	   cy(j)=cos(y(j))
	end do

	do j=2,lat-1
	do i=2,lon-1
	   dux(i,j)=(ubar(i+1,j)-ubar(i-1,j))/2./detx/er/cy(j)
	   dvy(i,j)=(vbar(i,j+1)-vbar(i,j-1))/2./dety/er
	end do
	   dux(1,j)=(ubar(2,j)-ubar(144,j))/2./detx/er/cy(j)
	   dvy(1,j)=(vbar(1,j+1)-vbar(1,j-1))/2./dety/er
	   dux(144,j)=(ubar(1,j)-ubar(143,j))/2./detx/er/cy(j)
	   dvy(144,j)=(vbar(144,j+1)-vbar(144,j-1))/2./dety/er
	end do

	do j=2,lat-1
	do i=1,144
 	   div(i,j) = dux(i,j) + dvy(i,j)
	end do
	end do

	return
	end