Transcript MMB Briefing on Clouds etc. 19 May 2005 Brad Ferrier

MMB Briefing on Clouds etc.
19 May 2005
Brad Ferrier
 Status on WRF codes for clouds & radiation
 Version 1.3 (V1.3) for ARW in NCO prod runs
 V2 for NMM & ARW
 Miscellaneous physics issues
 Summary of 1 March 2005 NE snowstorm reruns
 Frequency of physics calls => RH vs. precip fields
 Preliminary feedback from ’05 SPC Spring Program
 Brief summary of JCSDA Workshop on Satellite
Assimilation of Clouds & Precipitation


Mesoscale dynamics issue
Cloud verification issue
WRF V1.3 code for clouds & radiation
 Recent change to WRF “nest” runs for June
 DX ~ 5 – 6 km for NMM, ARW – w/o convection
 6-member WRF ensemble in SREF later in year
 Timing tests by Matt
 Original plan to run Lin or NCEP5 microphysics
in ARW
 Took too much CPU time … go with “Ferrier”
 Bug in running “Ferrier” in ARW, providing
total condensate as input into Dudhia
radiation, YSU PBL rather than cloud water,
ice, & rain

Working on fix thanks to help from Dudhia
WRF V2 code for clouds & radiation
 Bug fix for SW↓ rather than SWnet into LSM made
in versions 1,2
 Dan’s making progress in putting GFS radiation into
WRF
 Status on NAMX changes


Gave updated Ferrier microphysics to Tom (T_ice=-30C)
Cloud-radiation changes have been coded and it runs, but
need to make changes to the WRF post to preview impacts
on 3D cloud fractions, Cu precip rate, & visibility
 Ferrier is the only microphysics scheme that works
in NMM, while all other schemes but Ferrier work in
ARW => V1.3 solution from Jimy will help here

Propose a flag for advecting total condensate vs. individual
hydrometeor species, independent of core & microphysics
Summary of 28 Feb/1 Mar snowstorm reruns
 Many WRF NMM V2 eastern nest runs using
2005022712 initial conditions (NAM ICs+LBCs)
 NAM fcst Low too close to coast, high QPF
 WRF NMM slightly better, but still bad
 WRF NMM runs had better L track off coast with
 SAS Cu + YSU PBL
 KF Cu
 YSU PBL
 Much better forecast with GFS ICs+LBCs
 Thanks
to Matt, was able to run with mixed ICs &
LBCs => GFS ICs most important
NAM IC+LBC
GFS IC+LBC
GFS IC
NAM LBC
GFS IC
NAM LBC
24-h WRF NMM runs valid 2005022812
NAM IC+LBC
GFS IC+LBC
NAM IC
GFS LBC
GFS IC
NAM LBC
36-h WRF NMM runs valid 2005030100
NAM IC+LBC
GFS IC+LBC
GFS IC
NAM LBC
GFS IC
NAM LBC
48-h WRF NMM runs valid 2005030112
Initial Surface Pressure at 2005022712
NAM
GFS
• Much lower surface pressure over Gulf of Mexico in GFS;
time series of HPC analyses suggests intensifying storm
Frequency of physics calls => RH vs. precip fields
 Several WRF “blogs” => 20050420
 More frequent physics calls will reduce supersaturations,
but …
 Could also increase high bias in QPF (Dan’s runs)
 May need to revisit downward flux of precipitation …
storage vs. fall out through bottom of grid cell
 If this is the problem, then may require more CPU
resources to resolve
 Evaluation using other microphysical schemes will be
helpful
 Slow down hydrologic cycle by delaying or turning off
accretion of cloud water by rain & precip ice (thx Dan)
 Zavisa’s latest changes to convection strongly impact
triggering of deep, shallow Cu
Preliminary Feedback from SPC
 Focusing on 4-5 km ARW & NMM runs w/o convection, 2-km
ARW/CAPS runs, though they also look at 8-km ARW, NMM,
NMMGFS
 Excellent web page for 2005 Spring Program
 From sounding diagnostics page, the NMM is to be too
moist at lower levels (sfc, PBL)
 From model verification page, radar reflectivities from the
NMM never exceed 50 dBZ while they frequently exceed
50 dBZ from ARW (examples to follow)
 Can explain this if dBZ is due to rain, where a fixed
mean Dr is assumed for rain contents >1 g m-3 from
tropical oceanic rain DSD studies
 May not apply over continents in warm season,
especially if rain is formed from melting of large
graupel and hail
24-h fcst of 1-km dBZ at 2005051800
(base reflectivity)
24-h fcst of Composite (column-maximum)
dBZ at 2005051800
Base reflectivity at 2005051800
(base dBZ)
Large ice
(1-h max base dBZ
2300 – 0000)
JCSDA Workshop on Satellite Assimilation
of Clouds & Precipitation (May 2-4)
 Program with links to talks
 Links to modeling group report, draft talk by
Ohring presented at last week’s GMoB mtg
 Improved draft will be presented by Ohring at
ITOVS mtg in China
 Benefits:
 Issues
with ISCCP clds exposed by new algorithm
using MODIS, also seen from CLAVR
 Viewing clouds from bottom (sfc) vs. top (sats)
 Collaboration between Chang & Li (UMD) w/
Heidinger (UW) for joint JCSDA work
JCSDA Workshop (2 of 3)
 Salient modeling issues for MMB
 Higher resolutions will not solve our problems
 Convection … a big headache .. treat as
nonlocal mixing+ transport w/o making sfc
precip?
 What % of compensating subsidence from
gravity waves in grid?; downdrafts?
 Tripoli: most important impact of convection is
transport of momentum “after dust settles”
 Me: what about heating/cooling ala Pandya &
Durran?
 Get views from Dave Raymond (next month),
Greg, others?
JCSDA Workshop (3 of 3)
 Recommendations for future work
 Compare
4D statistical properties of T, Q, &
cloud+precip fields in time, space
 Onset of “A-train” & GPM will provide great
opportunities for cld+precip satellite obs
 Ensembles of CRMs from GCSS WGs?
 Include radiances from single-column modeling
using ARM data, other “supersites”?
 Linearize, simplify physics for assimilation?
 High quality, independent cloud & precip data
sets for verification (sats + rads + gauges)
 Work on convection, more resources for some
NWP centers (hint hint)
Global Cloud Climatologies
(PATMOS is Heidinger’s successor to CLAVR)