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This commit has a fix for a problem of cloud-radiation coupling with the use of MYNN PBL. #349

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merged 1 commit into from
Nov 1, 2019
Merged

This commit has a fix for a problem of cloud-radiation coupling with the use of MYNN PBL. #349

merged 1 commit into from
Nov 1, 2019

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tanyasmirnova
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The problem: the first call to the radiation happens before
the first call to MYNN PBL, therefore CLDFRA_BL=0 in the first call to mynnrad_pre,
and zero values are sent to array cldcov(:,:).
When cloud cover is zero, the RRTMG radiation thinks that there are no clouds at all.
The erroneous cloud-free LW and SW downward radiation fluxes affect the first
hour of itegration, and cause siginificant cooling in the ploar regions, and too warm
land surface temperature from cloud-free SW radiation.
The fix: the fist call to mynnrad_pre should be skipped, so that cloud cover - cldcov(:,:) - is not
overwritten by zero values of MYNN subgrid-clouds. In this case the initial cloud cover
is computed in progcld5 from initial cloud water mixing ratio,
relative humidity and specific humidity in the layer.
Starting with the second call to the rrtmg radiation, the MYNN subgrid clouds are used.
Attached are SW and LW downward fluxes before fix (left) and after fix (right)
Screen Shot 2019-11-01 at 11 16 09 AM
Screen Shot 2019-11-01 at 11 16 29 AM

@tanyasmirnova
This commit has a fix for a problem of cloud-radiation coupling with the
e4d291e 
use of MYNN PBL.
The problem: the first call to the radiation happens before
the first call to MYNN PBL, therefore CLDFRA_BL=0 in the first call to mynnrad_pre,
and zero values are sent to array cldcov(:,:).
When cloud cover is zero, the RRTMG radiation thinks that there are no clouds at all.
The erroneous cloud-free LW and SW downward radiation fluxes affect the first
hour of itegration, and cause siginificant cooling in the ploar regions, and too warm
land surface temperature from cloud-free SW radiation.
The fix: the fist call to mynnrad_pre should be skipped, so that cloud cover - cldcov(:,:) - is not
overwritten by zero values of MYNN subgrid-clouds. In this case the initial cloud cover
is computed in progcld5 from initial cloud water mixing ratio,
relative humidity and specific humidity in the layer.
Starting with the second call to the rrtmg radiation, the MYNN subgrid clouds are used.
climbfuji
climbfuji approved these changes Nov 1, 2019
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This change is straightforward and can be merged without running through all the regression tests. Thanks for identifying and fixing this issue!

@climbfuji climbfuji merged commit e0d5f16 into NCAR:gsd/develop Nov 1, 2019
climbfuji added a commit to climbfuji/ccpp-physics that referenced this pull request Nov 26, 2019
@climbfuji
Merge gsd/develop into dtc/develop, squashed commit of the following:
73bbc9f 
commit 7f530ed
Merge: e0d5f16 b492f2e
Author: Dom Heinzeller <dom.heinzeller@icloud.com>
Date:   Thu Nov 21 15:40:20 2019 -0700

    Merge pull request NCAR#356 from tanyasmirnova/ruc_land_ice_v1

    Added the capability to use climatological LAI in RUC LSM

commit b492f2e
Merge: bd32702 e0d5f16
Author: tanyasmirnova <tanya.smirnova@noaa.gov>
Date:   Wed Nov 20 20:36:42 2019 +0000

    Merge branch 'gsd/develop' of https://github.com/NCAR/ccpp-physics into ruc_land_ice_v1

commit bd32702
Author: tanyasmirnova <tanya.smirnova@noaa.gov>
Date:   Wed Nov 20 20:29:42 2019 +0000

    Added the capability to use a Leaf Area Index (LAI) climatology in RUC LSM.
    Variables xlaixy and rdlai are added to the argument list of lsm_ruc_run.
    If rdlai=.true. in the physics namelist, then the LAI climatology will be passed into
    the RUC LSM and used instead of look-up table value for a given vegetation type.

commit e0d5f16
Merge: 660ede7 e4d291e
Author: Dom Heinzeller <dom.heinzeller@icloud.com>
Date:   Sat Nov 2 05:47:40 2019 +0900

    Merge pull request NCAR#349 from tanyasmirnova/ruc_land_ice_v1

    This commit has a fix for a problem of cloud-radiation coupling with the use of MYNN PBL.

commit e4d291e
Author: tanyasmirnova <tanya.smirnova@noaa.gov>
Date:   Fri Nov 1 16:47:58 2019 +0000

    This commit has a fix for a problem of cloud-radiation coupling with the
    use of MYNN PBL.
    The problem: the first call to the radiation happens before
    the first call to MYNN PBL, therefore CLDFRA_BL=0 in the first call to mynnrad_pre,
    and zero values are sent to array cldcov(:,:).
    When cloud cover is zero, the RRTMG radiation thinks that there are no clouds at all.
    The erroneous cloud-free LW and SW downward radiation fluxes affect the first
    hour of itegration, and cause siginificant cooling in the ploar regions, and too warm
    land surface temperature from cloud-free SW radiation.
    The fix: the fist call to mynnrad_pre should be skipped, so that cloud cover - cldcov(:,:) - is not
    overwritten by zero values of MYNN subgrid-clouds. In this case the initial cloud cover
    is computed in progcld5 from initial cloud water mixing ratio,
    relative humidity and specific humidity in the layer.
    Starting with the second call to the rrtmg radiation, the MYNN subgrid clouds are used.

commit 660ede7
Merge: 4a17324 db9742d
Author: Dom Heinzeller <dom.heinzeller@icloud.com>
Date:   Mon Oct 28 12:38:54 2019 +0900

    Merge pull request NCAR#344 from tanyasmirnova/ruc_land_ice_v1

    Sync RUC LSM code with the version used in RAP/HRRR

commit db9742d
Author: tanyasmirnova <tanya.smirnova@noaa.gov>
Date:   Thu Oct 24 22:14:13 2019 +0000

    Sync the RUC LSM code with the version in RAPv5/HRRRv4.
    Some clean-up in sfc_drv_ruc.F90.

commit 27eb089
Merge: fa3c1d3 4a17324
Author: tanyasmirnova <tanya.smirnova@noaa.gov>
Date:   Thu Oct 24 22:03:14 2019 +0000

    Merge branch 'gsd/develop' of https://github.com/NCAR/ccpp-physics into ruc_land_ice_v1

commit 4a17324
Merge: 543f640 3a28055
Author: Dom Heinzeller <dom.heinzeller@icloud.com>
Date:   Thu Oct 24 10:53:19 2019 +0900

    Merge pull request NCAR#338 from haiqinli/gsd/develop-hli

    "to include GF updates in GSDv0beta4"

commit 3a28055
Author: Haiqin.Li <Haiqin.Li@noaa.gov>
Date:   Wed Oct 23 21:13:25 2019 +0000

    "update to pass the ccpp_gsd_noah_repro regression test case"

commit 0711b82
Author: Haiqin.Li <Haiqin.Li@noaa.gov>
Date:   Sun Oct 20 04:54:18 2019 +0000

    "update to pass ccpp_gsd regression test"

commit fa3c1d3
Author: tanyasmirnova <tanya.smirnova@noaa.gov>
Date:   Thu Oct 17 16:28:55 2019 +0000

    1. Use fraction of frozen precipitation SR directly from Thompson MP.
    2. Bug fix in liquid precipitation and frozen fraction  - SRFLAG. This
       bug was producing 1.e-3 factor maller values of SRFLAG.
    3. Modification to comment for precipitation in sfc_drv_ruc.F90

commit a59d416
Author: Haiqin.Li <Haiqin.Li@noaa.gov>
Date:   Sun Oct 13 20:40:44 2019 +0000

    "clean the code"

commit 4ca463c
Author: Haiqin.Li <Haiqin.Li@noaa.gov>
Date:   Sun Oct 13 20:35:36 2019 +0000

    "update input of imfdeepcnv following Dom's suggestions"

commit 14c1c5b
Author: Haiqin.Li <Haiqin.Li@noaa.gov>
Date:   Fri Sep 27 18:04:33 2019 +0000

    "to include GF updates in GSDv0beta4"
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