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subroutine da_calculate_grady_polaramv(iv, re, jo_grad_y) 1,2
!-------------------------------------------------------------------------
! Purpose: Calculates Gradient of Polar AMVs Obs.
!-------------------------------------------------------------------------
implicit none
type (iv_type), intent(in) :: iv ! Innovation vector.
type (y_type), intent(inout) :: re ! Residual vector.
type (y_type), intent(inout) :: jo_grad_y ! Grad_y(Jo)
integer :: n , k
if (trace_use_dull) call da_trace_entry
("da_calculate_grady_polaramv")
do n=1, iv%info(polaramv)%nlocal
do k=1, iv%info(polaramv)%levels(n)
if (iv%polaramv(n)%u(k)%qc < obs_qc_pointer) then
re%polaramv(n)%u(k) = 0.0
end if
if (iv%polaramv(n)%v(k)%qc < obs_qc_pointer) then
re%polaramv(n)%v(k) = 0.0
end if
jo_grad_y%polaramv(n)%u(k) = -re%polaramv(n)%u(k) / &
(iv%polaramv(n)%u(k)%error * iv%polaramv(n)%u(k)%error)
jo_grad_y%polaramv(n)%v(k) = -re%polaramv(n)%v(k) / &
(iv%polaramv(n)%v(k)%error * iv%polaramv(n)%v(k)%error)
end do
end do
if (trace_use_dull) call da_trace_exit("da_calculate_grady_polaramv")
end subroutine da_calculate_grady_polaramv