[Ncep.list.fv3-announce] News: NEMSfv3gfs and FV3 git repository updates 20191002

Jun Wang - NOAA Federal jun.wang at noaa.gov
Wed Oct 2 15:04:23 UTC 2019

Dear all,

Following changes were committed to the NEMSfv3gfs/FV3 repositories:

Ticket #68678 <https://vlab.ncep.noaa.gov/redmine/issues/68678> For GFS.v16
implementation: A final branch for merging all physics changes and netcdf
I/O changes into master
A new "EMC FV3" branch, gfsv16_physupdt_netcdf, has been created to merge
all physics updates and I/O changes made in a few different branches into
one, and prepare for the commit to the master for gfs.v16 implementation.
The changes include:

Ticket #68694 <https://vlab.ncep.noaa.gov/redmine/issues/68694>: Update
Unified gravity wave drag; optimize physics driver clean up and reduce
unnecessary code.
-Major update is related to Unified Gravity Wave Physics (UGWP) in the
physics driver and the UGW driver code ugwp_driver_v0.f. The change
involves the capability to combine the original GFS orographic gravity wave
drag (GWD) and mountain blocking scheme with the new non-stationary gravity
wave drag parameterization.
-Additional enhancement to the non-stationary UGW is added by making it
possible to optionally modulate the original source function based on
vertically integrated turbulent kinetic energy (TKE) or precipitation
(which is equivalent to vertically integrated heating via convection and
-The upward long wave in the routine dcyc2.f is upgraded to be the sum of
the upward long wave computed on each fractional grid component (water or
ice in GFS) instead of computed through mean temperature.
-A minor upgrade to the original GWD is also made by following the approach
of UGWP in computing the vertically integrated Brunt-Vaisala frequency
-SfcProp%hprim in gfs physics driver is removed as this is the same as
-WIND (wind speed) is now computed once in the physics drives and it is
passed to all routines previously used to calculate it independently.
-Averaging of surface stress between water and ice is added to sfc_cice.f
-Namelist parameters min_seaice and min_lakeice are added to enable
different thresholds for sea and lake ice
-Some small update is made to sfcsub.F in time averaging by making the
second weight as 1.0 - first weight to make sure sub of the two weights is
exactly one
-The computation of Julian date for Noah MP is now moved to GFS_driver, and
some unnecessary local arrays are eliminated.
-The routine assign_importdata is updated to be more efficient and the
precip unit error is fixed in atmos_model.F90.

Ticket #68141 <https://vlab.ncep.noaa.gov/redmine/issues/68141>: cold bias
reduction related changes and a mask interpolation bug fix
The cold bias reduction related changes include: 1)the code changes from
GFDL is integrated to NEMSfv3gfs source code. 2) Ice terminal velocity is
reduced and 3) the temperature instead of the liquid frozen temperature is
used in the saturation mixing ratio calculation in the GFDLMP PDF cloud
cover. A bug is fixed to make mask interpolation off as expected, by
setting the logical variable lmask be false, for a land surface variable.

Ticket #68128 <https://vlab.ncep.noaa.gov/redmine/issues/68128>: Update of
scale-aware TKE-based moist EDMF scheme and inclusion of canopy heat
storage parameterization in the Noah-MP
The sa-TKE-EDMF is updated to address the increased negative wind speed
bias in upper troposphere and large reduction of stratocumulus clouds over
nearshore regions in the eastern Pacific and Atlantic Oceans, and to
further improve the prediction of low-level inversion. Other changes
include the reduction of the minimum and maximum characteristic mixing
lengths, reduction of core downdraft and updraft fractions, and change of
updraft top height calculation. To further improve the prediction of
low-level inversion, in the update the background diffusivity has been
further decreased with increasing surface layer stability. Three tuning
parameters are now moved to physics namelist. The simple heat storage
parameterization over forest canopies which was developed for Noah-LSM is
included in the Noah-MP as an option.

Ticket #67925 <https://vlab.ncep.noaa.gov/redmine/issues/67925>: A bug fix
in interpolation of substrate climatology in GFS
The interpolation of the substrate climatology (a coarse resolution) to the
model resolution is updated to not use surface mask for interpolation

Ticket #68982 <https://vlab.ncep.noaa.gov/redmine/issues/68982>: Negative
Delta-z Analysis Increments
NEMSfv3gfs currently flips the sign of delta-z field in order to output
positive delz in history file. However the sign is not flipped when reading
in the delta-z increments from the GSI and this inconsistency causes the
model to blow up with delta-z increment. The delz sign flip is now removed
in the model when outputting the field to history file.

Ticket #68487 <https://vlab.ncep.noaa.gov/redmine/issues/68487>: enable
compressed netcdf gaussian_grid files in write component
The zlib compression (lossless and lossy) for netcdf gaussian_grid files is
enabled in the model for sequential netcdf output history files. A
configuration variable ideflate is added to model_configure to enable this
lossless compression. The default value of ideflate is zero meaning no
compression, values 1-9 are valid compression levels. When ideflate > 0,
HDF5 files are created instead of old NETCDF_CLASSIC binary format. This is
transparent for clients as long as a version of the netcdf c library with
HDF5 support is linked.
Another configuration variable nbits is added to model_configure to enable
the lossy compression. The default value of nbits is zero, which means
lossless compression. Values between 1 and 32 are valid lossy compression
level. An extra variable attribute "max_abs_compression_error" is added
which is the error introduced by this quantization.

The code changes alter model results. New baselines were created on
supported platforms. Regression test passed on hera and wcoss phase1/2,
cray and dell.


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