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subroutine da_calculate_grady_rad( iv, re, jo_grad_y ) 1,2
!------------------------------------------------------------------------------
! Purpose: Calculate Gradient_y for radiance data.
!
! METHOD: grad_y = -R^-1 (d - H delta_x ).
!
! HISTORY: 08/2005 - Creation Zhiquan Liu
!
!------------------------------------------------------------------------------
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, i
if (trace_use_dull) call da_trace_entry
("da_calculate_grady_rad")
do i =1, iv%num_inst
if ( iv%instid(i)%num_rad < 1 .or. iv%instid(i)%rad_monitoring == monitor_on ) cycle
do n=1, iv%instid(i)%num_rad
do k=1, iv%instid(i)%nchan
if ( iv%instid(i)%tb_qc(k,n) < obs_qc_pointer) re%instid(i)%tb(k,n) = 0.0
jo_grad_y%instid(i)%tb(k,n) = -re%instid(i)%tb(k,n) / (iv%instid(i)%tb_error(k,n) * iv%instid(i)%tb_error(k,n))
end do
end do
end do
if (trace_use_dull) call da_trace_exit("da_calculate_grady_rad")
end subroutine da_calculate_grady_rad