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RTMA applications: calculate a "synthetic" cloud fraction #1367

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812a7a9
Slight refactor: use params_mod to declare the value of "cloud_def_p"
jaymes-kenyon Nov 13, 2025
306e7d3
Reintroduce a previous algorithm to create a "synthetic" cloud-fracti…
jaymes-kenyon Nov 13, 2025
caee2e7
Within the synthetic cloud-fraction calculation, reduce the search ra…
jaymes-kenyon Dec 2, 2025
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7 changes: 3 additions & 4 deletions sorc/ncep_post.fd/CLDRAD.f
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,7 @@
!> | logic, rather than a dedicated parameter number.
!> 2025-05-05 | Ben Blake | Add sanity checks for RRFSv1 implementation
!> 2025-05-08 | Jaymes Kenyon | For FV3 and MPAS applications, prevent cloud base from being diagnosed as below ground
!> 2025-11-13 | Jaymes Kenyon | Minor refactoring: the value of "cloud_def_p" (constant) is now set in params_mod
!>
!> @author Russ Treadon W/NP2 @date 1993-08-30
!---------------------------------------------------------------------------------
Expand Down Expand Up @@ -123,7 +124,7 @@ SUBROUTINE CLDRAD
PWAT,DUSTPM10,MAOD,NO3CB,NH4CB,aqm_aod550
use masks, only: LMH, HTM
use params_mod, only: TFRZ, D00, H99999, QCLDMIN, CFRmin_BASE_TOP, &
SMALL, D608, H1, ROG, &
CLOUD_DEF_P, SMALL, D608, H1, ROG, &
GI, RD, QCONV, ABSCOEFI, ABSCOEF, STBOL, PQ0, A2, &
A3, A4
use ctlblk_mod, only: JSTA, JEND, SPVAL, MODELNAME, SUBMODELNAME, &
Expand Down Expand Up @@ -156,7 +157,7 @@ SUBROUTINE CLDRAD
CLDP, CLDZ, CLDT, CLDZCu
REAL,dimension(lm) :: RHB, watericetotal, pabovesfc
REAL :: watericemax, wimin, zcldbase, zcldtop, zpbltop, &
rhoice, coeffp, exponfp, const1, cloud_def_p, &
rhoice, coeffp, exponfp, const1, &
pcldbase, rhoair, vovermd, concfp, betav, &
vertvis, tx, tv, pol, esx, es, e, zsf, zcld, frac
integer nfog, nfogn(7),npblcld,nlifr, k1, k2, ll, ii, ib, n, jj, &
Expand Down Expand Up @@ -1892,8 +1893,6 @@ SUBROUTINE CLDRAD
end do
npblcld = 0
Cloud_def_p = 0.0000001
DO J=JSTA,JEND
DO I=ISTA,IEND
!
Expand Down
62 changes: 59 additions & 3 deletions sorc/ncep_post.fd/INITPOST.F
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,9 @@
!> 2002-08-15 | H CHuang | Unit correction and generalize projection options
!> 2021-03-11 | Bo Cui | Change local arrays to dimension (im,jsta:jend)
!> 2023-01-24 | Sam Trahan | Comment-out wordy debug writes
!> 2025-11-13 | J Kenyon | Reintroduce a previous algorithm to create a
!> | "synthetic" cloud-fraction field, intended for
!> | RTMA applications
!>
!> @author Russ Treadon W/NP2 @date 1993-11-10
SUBROUTINE INITPOST
Expand Down Expand Up @@ -64,7 +67,7 @@ SUBROUTINE INITPOST
trdsw, theat, tclod, tprec, nprec, alsl, im, jm, lm, grib, &
prec_acc_dt1, submodelname
use params_mod, only: capa, g, rd, d608, tfrz, ad05, cft0, stbol, &
p1000, pi, rtd, lheat, dtr, erad
p1000, pi, rtd, lheat, dtr, erad, cloud_def_p
use lookup_mod, only: thl, plq, ptbl, ttbl, rdq, rdth, rdp, rdthe, pl, &
qs0, sqs, sthe, the0, ttblq, rdpq, rdtheq, stheq, the0q
use gridspec_mod, only: gridtype, dxval, latstart, latlast, lonstart, &
Expand Down Expand Up @@ -118,6 +121,7 @@ SUBROUTINE INITPOST
integer, external :: iw3jdn
real sun_zenith,sun_azimuth, ptop_low, ptop_mid, ptop_high
real delta_theta4gust
real watericetotal, radius, totcount, cloudcount
!
!
!***********************************************************************
Expand Down Expand Up @@ -1145,8 +1149,11 @@ SUBROUTINE INITPOST
end do
end do

! WRF EM outputs 3D cloud cover now
! Assign the cloud-fraction array (CFR)
IF(MODELNAME == 'RAPR')THEN
IF(SUBMODELNAME /= 'RTMA')THEN
! For non-RTMA RAPR applications (e.g., RAP, HRRR):
! Assign the CFR array using the model-state cloud fraction.
VarName='CLDFRA_BL'
call getVariable(fileName,DateStr,DataHandle,VarName,DUM3D, &
IM+1,1,JM+1,LM+1,IM,JS,JE,LM)
Expand All @@ -1157,7 +1164,56 @@ SUBROUTINE INITPOST
end do
end do
end do
ELSE
ELSE
! For RTMA: since cloud fraction is not an analysis
! variable, assign the CFR array by creating a "synthetic"
! cloud fraction. Namely, use the resolved cloud-water
! and cloud-ice fields surrounding each grid volume to
! calculate a neighborhood fraction of exceedance.
!
! --J Kenyon (13 Nov 2025): This fraction-of-exceedance
! algorithm was reintroduced to support 3DRTMA requirements.
! It essentially replicates previous code that was used for
! earlier RAP/HRRR versions.

radius = 16100. ! Use a horizontal neighborhood search of 16.1 km / 10 mi (arbitrary)
call ext_ncd_get_dom_ti_real(DataHandle,'DX',tmp, &
1,ioutcount,istatus)
dxval= nint(tmp)
numr = nint(radius/dxval)

do k = 1,lm
do j = jsta_2l, jend_2u
do i = 1, im
dummy(i,j)=QQW(i,j,k)
dummy2(i,j)=QQI(i,j,k)
enddo ! i
enddo ! j

call AllGETHERV(dummy)
call AllGETHERV(dummy2)

do j = jsta_2l, jend_2u
do i = 1, im
totcount =0.
cloudcount =0.
CFR(i,j,k) =0.
do ic = max(1,I-numr),min(im,I+numr)
do jc = max(1,J-numr),min(jm,J+numr)
totcount = totcount+1.
watericetotal = dummy(ic,jc) + dummy2(ic,jc)
if (watericetotal .gt. cloud_def_p) &
cloudcount=cloudcount+1.
! Note that the value of cloud_def_p is also arbitrary
enddo ! jc
enddo ! ic
CFR(i,j,k) = min(1.,cloudcount/totcount)
enddo ! i
enddo ! j
enddo ! k

ENDIF ! SUBMODELNAME
ELSE ! MODELNAME
VarName='CLDFRA'
call getVariable(fileName,DateStr,DataHandle,VarName,DUM3D, &
IM+1,1,JM+1,LM+1,IM,JS,JE,LM)
Expand Down
1 change: 1 addition & 0 deletions sorc/ncep_post.fd/params.F
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Expand Up @@ -93,6 +93,7 @@ module params_mod
#else
real, parameter :: QCLDmin=1.E-5 !< Minimum cloud mixing ratio - was 1.E-6
#endif
real, parameter :: CLOUD_DEF_P=1.E-7 !< Cloud water + ice mixing ratio (qc + qi) threshold used by some GSL diagnostics
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@GangZhao-NOAA GangZhao-NOAA Dec 3, 2025

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@jaymes-kenyon
Here CLOUD_DEF_P=1.E-7. I noticed that in GSI cloud analysis "gsdcloudanalysis.F90",
at line 208
data cloud_def_p / 0.000001_r_kind/
which is 1.0E-6. You did mentioned that "the value of cloud_def_p is also arbitrary" in INITPOST.F. I just want to confirm with you that this inconsistency is just a trivial thing, since it could be arbitrary.

Thank you!
-Gang

real, parameter :: CFRmin_BASE_TOP=0.02 !< Minimum cloud fraction for cloud base and top (used by GSL starting in 2023)
real, parameter :: NLImin=1.E3 !< Minimum number concentrations (m**-3) of large ice (snow/graupel/sleet)
! move definition of NLImax and T_ICE to MICROINIT 2012012018
Expand Down