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subroutine da_varbc_adj (cv_size, cv, iv, y) 1,2
!---------------------------------------------------------------------------
! PURPOSE: Apply bias correction to radiance innovations.
!
! Called from da_transform_vtoy_adj
!
! HISTORY: 10/27/2007 - Creation Tom Auligne
!---------------------------------------------------------------------------
implicit none
integer, intent(in) :: cv_size ! Size of cv array.
real, intent(inout) :: cv(1:cv_size) ! control variables.
type (iv_type), intent(inout) :: iv ! O-B structure.
type (y_type), intent(in) :: y ! y = h (xa)
integer :: inst, i, k, num_rad, n, npred
real, allocatable :: varbc_param_adj(:)
real :: cv_local
if (trace_use) call da_trace_entry
("da_varbc_adj")
do inst = 1, iv%num_inst ! loop for sensor
num_rad = iv%instid(inst)%num_rad
allocate(varbc_param_adj(iv%instid(inst)%varbc_info%npredmax))
do k=1,iv%instid(inst)%nchan ! loop for channel
npred = iv%instid(inst)%varbc(k)%npred
if (npred <= 0) cycle ! VarBC channels only
!---------------------------------------------------------------
! Adjoint to bias correction through linear regression
!---------------------------------------------------------------
varbc_param_adj(:) = 0.0
if (num_rad >0) then
do n = 1, num_rad ! loop for pixel
if (iv%instid(inst)%tb_qc(k,n) <= qc_varbc_bad) cycle ! good obs only
if (.not. iv%instid(inst)%info%proc_domain(1,n)) cycle ! do not sum up HALO data
varbc_param_adj(1:npred) = varbc_param_adj(1:npred) + &
y%instid(inst)%tb(k,n) * &
iv%instid(inst)%varbc_info%pred( &
iv%instid(inst)%varbc(k)%ipred(1:npred),n )
end do
end if
!---------------------------------------------------------------
! Change of variable (preconditioning) + sum across processors
!---------------------------------------------------------------
do i = 1, npred
cv_local = SUM(varbc_param_adj(1:npred) * iv%instid(inst)%varbc(k)%vtox(i,1:npred))
cv(iv%instid(inst)%varbc(k)%index(i)) = cv(iv%instid(inst)%varbc(k)%index(i)) + &
wrf_dm_sum_real(cv_local)
end do
end do
deallocate(varbc_param_adj)
end do ! end loop for sensor
if (trace_use) call da_trace_exit("da_varbc_adj")
end subroutine da_varbc_adj