[Ncep.list.fv3-announce] NEMSfv3gfs and FV3 git repository updates 20180606

Jun Wang - NOAA Federal jun.wang at noaa.gov
Wed Jun 6 15:29:25 UTC 2018

Dear all,

The second commit of fixing the excessive cooling at cloud top is made into
NEMSfv3gfs and FV3 repositories.

Task #51114 <https://vlab.ncep.noaa.gov/redmine/issues/51114>: Modification
of convection schemes to reduce too much cooling at the cloud top

Occasional model crashes have occurred when stochastic physics is turned on
in FV3GFS runs. It was found that in those cases there were too much
convective cooling and heating tendencies near the cumulus top which are
amplified by stochastic physics. To reduce too much convective cooling at
the cloud top, the convection schemes have been modified for the rain
conversion rate, entrainment and detrainment rates, overshooting layers,
and maximum allowable cloud base mass flux. SCM and 3D FV3GFS tests
indicate that the modified schemes largely reduce the too much convective
cooling and heating near the cloud top. And there is no indication of model
crash with the modified schemes. FV3GFS medium-range forecast experiments
show that the modified convection schemes slightly improves forecast skill
for 500 hPa height anomaly correlation while it has a neutral impact on
CONUS precipitation forecast skill

The code changes alter model results. New baseline was created on support
platforms, regression test passed on wcoss cray, phase1/2, theia and jet.

A new tag nemsfv3gfs_beta_v1.0.4 was created after the commit.

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