Transcript Operational Use of the Rapid Update Cycle

Operational Use of the
Rapid Update Cycle
Stan Benjamin - NOAA/FSL
[email protected]
http://maps.fsl.noaa.gov - RUC web page
COMAP Symposium 99-1
20 May 1999
What Runs Where
• Rapid Update Cycle (RUC)
– Operational Version at NCEP
• Mesoscale Analysis and Prediction System
(MAPS)
– Experimental Version at NOAA/ERL/FSL
(Essentially the same software.
New capabilities tested first in MAPS at FSL)
RUC/MAPS Purpose
• Provide high-frequency mesoscale analyses
and short-range forecasts for:
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aviation
severe weather forecasting
forecasts for public
other transportation
agriculture
The 1-h Version of the RUC
Data cutoff - +20 min, 2nd run at +55 min at 0000, 1200 UTC
NCEP Operational Models
Model
RUC
Eta
Name of Duration
Run
RUC
12 hr
Freq.
Domain
Where Develop.
1 hr
CONUS FSL/U. of Miami
Eta
36/48 hr
6/9 hr
N.Amer.+
NCEP/U. of
Belgrade
Global
Spectral
AVN
72 hr
6 hr
Global
NCEP
Global
Spectral
MRF
240 hr
24 hr
Global
NCEP
Global
NCEP
Coupled
Seasons
Key Personnel -- RUC-2
Development/Implementation
Stan Benjamin
John Brown
Kevin Brundage
Dezso Devenyi
Georg Grell
Barry Schwartz
Tanya Smirnova
Tracy Lorraine Smith
Tom Schlatter
Analysis/model dev, mgmt
Model dev, parameterizations
NCEP impl., WWW, graphics
3-d VAR development
Model dev., parameterizations
Obs ingest, obs sensitivity studies
Land-sfc processes
Obs ingest, obs sensitivity studies
Interaction w/ NCEP
Geoff Manikin
Geoff DiMego
NCEP liaison for RUC, impl.
Interaction w/ NCEP/NCO, NWS
Uses of the RUC
• Explicit Use of Short-Range Forecasts
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Aviation Weather Center - airmets, sigmets
Storm Prediction Center - severe weather watches
FAA
Dept. of Transportation - air traffic management
National Weather Service Forecast Offices
Airline Forecasting Offices
NASA Space Flight Centers
• Monitoring Current Conditions with Hourly
Analyses
• Evaluating Trends of Longer-Range Models
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RUC1 vs RUC2 Characteristics
RUC-1
RUC-2
Assimiliation 3 hr
1 hr, unified 3-d /surface cycle
Analysis
OI - hybrid-b
OI with new data, cycled cloud
variables, soil moisture, temp.,
and snow cover
Model
Hybrid-b, 60 km, 25
levels
Hybrid-b/MM5, 40 km, 40
levels, larger domain
Moist
Physics
Supersaturation
removal
Cloud microphysics (MM5) explicit fcsts of cloud water, rain
water, snow, ice, graupel, number
concentration - ice particles
RUC-1 versus RUC-2, cont.
Surface
Processes
Radiation
RUC-1
RUC-2
SFC fluxes (Pan)
Sfc fluxes with multi-level
soil/vegetation model with snow
accumulation/melting
Full atmos. radiation - influenced
by hydrometeors (MM5)
Level 3.0 (Burk-Thompson) with
explicit TKE forecast
Digital filter with optimal filter
Sfc energy budget,
clouds = f(RH)
Turbulence
Mellor - Yamada
level 2.0
Initialization Adiabatic digital
filter
Surface
Land use, SST Conditions
Clima. no snow
cover
Improved land use, vegetation
class, daily SST/LST snow,
cycled soil moisture/temp./snow
Hourly Data for 40 km MAPS/RUC-2
Data Type
~Number
Rawinsonde (inc. special obs)
WPDN/NPN profilers 405 MHz
Boundary layer profilers 915 MHz
RASS (WPDN + Bound.Layer
80
/ 12 h NCEP and FSL
31
/1h
NCEP and FSL
15
15
/1h
/1h
FSL only
FSL only
/ 1h
/1h
/1h
/1h
NCEP and FSL**
NCEP and FSL
NCEP and FSL
NCEP and FSL
VAD (velocity azimuth
display) winds (WSR-88D)
110-130
Aircraft (ACARS)(wind,temp) 700-2800
Surface - land (wind,psfc,T,Td) 1500-1700
Buoy
100-200
Yellow items new for RUC-2
Freq. Use
**not used since 1/99
pending QC issues
Hourly Data for 40 km MAPS/RUC-2,
cont.
Data Type
GOES precipitable water
GOES high-density cloud
drift winds
(IR, VIS, WV cloud top)
SSM/I precipitable water
Ship reports
Reconnaissance
dropwinsonde
~Number
1000-2500
Freq.
/1h
Use
NCEP and FSL
1000-2500
1000-4000
10s
/3h
/ 2-6 h
/3h
NCEP and FSL
NCEP only
NCEP only
a few
/ variable NCEP only
Yellow items new for RUC-2
Real-time observation counts at http://maps.fsl.noaa.gov for RUC-2
and 40-km MAPS
Advantages of q Coords for
Data Assimilation
Analysis
- adaptive 3-d correlation structures and
analysis increments, esp. near baroclinic zones
- improved coherence of obs near fronts for QC
Forecast Model
- reduced vertical flux thru coordinate surfaces,
leading to reduced vertical dispersion -- much of
vertical motion implicit in 2-d horiz. Advection
- conservation of potential vorticity
- reduced spin-up problems (Johnson et al. 93
MWR)
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RUC-2 Time Availability vs. RUC-1
Improvements due to the 1-hr cycle and earlier data cut-off time
RUC-2 Analysis
• QC - buddy check, removal of VADs w/ possible
bird contamination problems
• 3-part analysis (all using optimal interpolation)
1) univariate precipitable water (PW) analysis - using
satellite PW obs - update mixing ratio field
2) z/u/v 3-d multivariate analysis - update qv based on
height/thickness analysis increment, update
psfc from height increment at sfc, update u/v at
all levels
RUC-2 Analysis, cont.
3) univariate analysis of condensation pressure at all
levels, qv at all levels. Also update u/v near
sfc and psfc with univariate analysis with
smaller correlation lengths
• Update soil temp at top 2 levels to maintain (Tskin
- T1-atmos)
• Pass through soil moisture, cloud mixing ratios,
snow cover/temperature (will alter these fields at
future time)
RUC-2 Analysis, cont.
• Vertical spreading (correlation of forecast
error) based on potential temperature
separation (not pressure separation as w/ other models)
• Analysis in generalized vertical coordinate
(code applicable to pressure, sigma, or eta
analysis) except for adjustment at end to
reference potential temperatures and new psfc
• Background is usually previous 1 hr RUC
forecast
Raob sounding
RUC2 sounding
Close fit to observations in RUC2 analysis
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Raob
RUC after fix
RUC before fix
7 April 99 significant-level fix in RUC-2
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RUCS 60 km Hourly Surface
Analyses
• Draws fairly closely to data
• Persistence background field (1 hr previous
analysis
– some QC problems
– no consistency with terrain
• MAPS sea-level pressure, (Benjamin &
Miller, 1990 MWR)
• Blending to data-void region from NGM
Surface Analyses/Forecasts
in RUC-2
• integrated with 3-d 40 km 1 hr cycle
• dynamic consistency with model forecast
=> accounts for:
– land/water, mtn circulations, sea/lake breezes,
snow cover, vegetation…
• improved quality control - model forecast
background prevents runaway bullseyes
• forecasts out to 12 hr in addition to hourly
analyses
Surface Analyses/Forecasts in
RUC-2, cont.
• Same fields as in 60 km RUCS, plus all
fields available in 3-d system
RUC-2 sfc files (GRIB)
0.3 MB / output time
all variables from RUCS plus
precip
precip type
stability indices
RUC-2 use of surface data
All winds, sfc pressure obs used
T/Td used if abs (Pstation - Pmodel) < 70 mb
- about 90% west of 105ºW, 99% east of 105ºW
|pmodel - pstn|
ID
Eta-48
Eta-29 RUC-40
FGZ
0*
18
10 (FLG)
TUS
60
13*
44
SLC
59*
68
59*
MFR
109
48*
67
OAK
18*
15*
25
** w/I 5 mb of closest fit
SAN
12
5*
23
DRA
42
29*
34*
GJT
98
105
65*
RIW
104
27
16*
GEG
4*
11
1*
GTF
26
4*
14
UIL
14*
9*
11*
RUC-2 Model
• Prognostic variables
– Dynamic - (Bleck and Benjamin, 93 MWR)
• qv, p between levels, u, v
– Moisture - (MM5 cloud microphysics)
• q v, qc, qr, qi, qs, qg, Ni (no. conc. ice particles)
– Turbulence - (Burk-Thompson, US Navy, 89 JAS)
– Soil - temperature, moisture - 6 levels (down to 3 m)
– Snow - water equivalent depth, temperature
(soil/snow/veg model - Smirnova et al., 1997 MWR)
RUC-2 Model, cont.
• Numerics
– Continuity equation
• flux-corrected transport (positive definite)
– Advection of qv, all q (moisture) variables
• Smolarkiewicz (1984) positive definite scheme
– Horizontal grid
• Arakawa C
– Vertical grid
• Non-staggered, generalized vertical coordinate
currently set as isentropic-sigma hybrid
RUC-2 Model, cont.
• Cumulus parameterization
– Grell (Mon.Wea.Rev., 1993)
– simplified (1-cloud) Arakawa-Schubert
– includes effects of downdrafts
• Digital filter initialization (Lynch and
Huang, 93 MWR)
– +/- 40 min adiabatic run before each forecast
MM5 Level 4 Microphysics
• Predicts mixing ratios of water vapor, cloud
water, rain water, cloud ice, snow, graupel and
number concentration of cloud ice
• Ongoing improvements in collaboration with
NCAR/RAP
• Continuous cycling of liquid and solid
hydrometeors
• NCEP C-90 CPU usage (12 hr forecast):
– 10% microphysics
– 15% advection of hydrometeors
Montreal ice storm - 9h RUC2 forecast valid 2100 9 Jan 98.
N-S cross sections of RUC2 microphysics
| YUL
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RUC
Land-surface
Process
Parameterization
(Smirnova et al.
1997, MWR)
Ongoing cycle
of soil moisture,
soil temp, snow
cover/depth/temp)
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Fields From Soil/Snow Model
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•
Soil temperature at 6 levels
Soil moisture at 6 levels
Surface runoff
Sub-surface runoff
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Direct evaporation from bare soil
Evapotranspiration
Evaporation of canopy water
Condensation of water
Canopy water
Water dripping from the canopy
Fields From Soil/Snow Model,
cont.
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Snow depth
Snow temperature
Accumulation of snow
Amount of melted snow
Flux of snow phase change heat
– Predicted soil variables cycled since April 1996
– Predicted snow variables cycled since March 1997
RUC - 2 Output Files
• Isobaric main (25 mb, 212 grid)
– 6 3-d variables (ht, temp, RH, u/v, vv)
– 80 2-d variables (prec, indices, spec. level, …)
– ~7 MB / output time
• Surface fields (212 grid)
– 25 2-d variables (p, T, TD, u/v, 3-h dp, precip,
indices…)
– ~0.3 MB / output time
RUC - 2 Output Files, cont.
• 211 isobaric/sfc grids (will add vert. Vel.)
• BUFR hourly soundings - same format as Eta
– ~290 stations
– ~1.5 MB for 12-h fcst, all stations (week of 12/8/97)
• Native – ~10 MB / output time
40 km MAPS versus 32 km Eta
Apr-Jul
1998
40 km MAPS versus 32 km Eta, cont.
RUC vs. Eta - 12h fcsts - 7 April - 10 May 1999
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Improvements in 40-km RUC-2
over RUC-1
• Wind analyses/forecasts - improved skill at all times
• Temperature improved skill, much
reduced bias
• RH improved skill, much
reduced bias
• Turbulence – sharp, coherent structures near frontal zones
Improvements in 40-km RUC-2
• Icing – explicit microphysics with cloud water/rain/snow/ice/graupel
• Surface forecasts – substantial improvement from addition of surface physics
(multi-level soil/vegetation model, snow physics), clouds,
improved radiation
• Precipitation – much better especially in orographic precip and heavy precip
events
Directions for Future RUC-2
Improvements
(suggested by precipitation verification)
• Improve cloud/moisture analysis.
– Use of advanced microphysics in RUC-2 means that initial
cloud errors can lead to underforecasting. Work is underway
to add satellite, radar and surface data to forecast cloud
fields.
• Introduce fractional cloudiness into the model
– Allow supersaturation at <100% RH within 40 km grid boxes
• Convective parameterization (Grell, includes effect of
downdrafts)
– Gives reasonable performance but still needs
tuning/improvement
Dec 98 change bundle for RUC-2
• Y2K fixes
• Analysis changes
– smaller horiz. error correlation near sfc for T/Td,
slightly less dependence on stability => improved sfc
T/Td fit in mtns
– fix to use of cloud drift winds => will have much more
effect (over water only)
– better fit to sfc obs
• Model changes
– fixes to sfc physics - reduction of cool bias in daytime
– fixes to radiation - more cooling at night, slightly more
heating in daytime
– less convective precip over warm water
Dec 98 change bundle for RUC-2,
cont.
• Diagnostic fixes
– CAPE/CIN - mix lowest 30-40 mb - less
jumpiness from analysis to 1h fcst
– tropopause level fix
• GRIB table fixes
– Allow soil cycling with adequate precision
• Boundary condition fix to account for Eta
change in RH as of 11/3/98
Apr 99 emergency change for RUC2
• Correctly uses raob sig-level temp/dewpoint
data now.
• Previously, missed sig-level T/Td data
(TTBB) and forced in linearly interpolated
structures between mandatory levels.
• Significant improvement in RUC grid
sounding structures and in overall RUC
performance
May 99 post-proc fixes for RUC2
• Bug/consistency fixes for diagnosis of sfc T/Td in RUC2.
(fix to lapse rate range)
– Biases in west US for T/Td reduced, 2 °C  0
– s.d. temps over US from 2.0  1.4 °C
(verification against METAR obs)
• CAPE- searches lowest 300 mb, not 180 mb
• More smoothing of isobaric winds in lower troposphere,
near tropopause
• Use of NESDIS ice field
• Much faster running of RUC - 10 procs for all runs
RUC-2 Weaknesses
• Still some precip spin-up problem, despite cycling of
cloud/precip variables, esp. for light precip/overrunning (1-3 hr
late)
• Fix: Add cloud analysis - 1999 - 1st version, allow for
cloud at RH < 100%
• Too much precip over warm oceans, too little near SE coast in
cold season
• Dec 98 fix package helped some - work underway on fixing
tendencies input to Grell convective parameterization
• Daytime convective precip in summer too widespread
• Upcoming fix on tendencies input to Grell scheme
RUC-2 Weaknesses, cont.
• Convective precip forecasts miss many small areas, underforecast
peak amounts.
– Lower equitable threat score than Eta
– more detailed than Eta
• Too much graupel near 0ºC
• Fix: with 20-km RUC, collaboration with FSL and NCAR
on microphysics fixes
• Diurnal cycle of surface temperature a little too weak
– a little too warm at night
• Dec 98 fix package - sfc flux change, radiation fix, GRIB
precision to allow proper soil moisture cycling
• May 99 fix - improve diagnosis of sfc temp/Td diagnosis -significant reduction in bias
RUC-2 Weaknesses, cont.
• Detailed (noisy?) output compared to other models, especially
vertical velocity
– Detail is probably realistic over terrain
• Analysis near coastlines
– does not account for land/sea contrast
– analysis increments over coast extrapolated over sea
Fix: Account for lower horizontal correlation in analysis
when crossing coastline
Fixed RUC-2 Weaknesses
• Analysis sounding structure
– irregular near ground if only sfc data assimilated
Fix: analysis tuning (Dec 98)
Fix: sig-level bug fix (Apr 99) *****************
• CAPE/CIN
– analysis values previously too high in high CAPE areas
– jump between analysis and 1-h forecasts
Fix: CAPE software (Dec 98)
(May 99 - parcel search now in lowest 300 mb, not 180 mb
layer)
RUC-2 Strengths
• Surface fields, esp. surface winds
– sfc files
• analysis and forecast
• small
• standard sfc fields plus precip, stability, precip type
• Topographically induced circulations
– sea/lake breezes (scale too large but they’re there)
– mtn/valley circulations
– differential friction effects
RUC-2 Strengths, cont.
• Precipitation fields
– more detailed than Eta (lower FAR but lower POD)
• Snow accumulation
– explicit, not diagnosed (from MM5 microphysics)
• Precip. type
– uses explicit hydrometeor mixing ratios/fall rates
• Upper-level features
– hybrid q/ coordinate
– winds, PV, temps, fronts, more coherent vorticity
structures on isobaric surfaces
RUC-2 Strengths, cont.
• Lower tropospheric temp/RH
– good fcst sounding structure (esp. after 4/99 fix)
– hybrid coordinate
• Soil/hydro fields
– soil moisture - cycled in 6-level soil model
– surface runoff, canopy water, dew formation, etc.
• Vertical velocity
– available in RUC-2
– good mtn wave depiction, frontal features
• Hourly analyses
– available much sooner than RUC-1 grids
– (4/99 speed-up in RUC processing at NCEP, 12h fcsts
available 30 min sooner, analyses available 8-10 min sooner)
RUC/MAPS Web Resources
• Main RUC/MAPS home page
– http://maps.fsl.noaa.gov
• RUC2 discussion forum
– maps.fsl.noaa.gov/forum/eval
• RUC2 real-time data inventory
– maps.fsl.noaa.gov/final.ruc_data.html
• RUC2 Tech. Proc. Bulletin
– maps.fsl.noaa.gov/ruc2.tpb.html
RUC/MAPS Web Resources,
cont.
• RUC-2 diagnosed variables - explanation of each
– maps.fsl.noaa.gov/vartxt.cgi
• RUC-2 evaluation from Nov 97 - Jan 98 field test
– maps.fsl.noaa.gov/ruc2.evalsum.html
• Experimental 36h fcsts run at FSL
• Parallel cycle w/ latest experiments (e.g., cloud analysis)
• AFDs/SFDs using RUC (http://maps.fsl.noaa.gov/sfd)
– used to monitor NWS use of RUC
The Future of the RUC
• Transfer of current 40km RUC2 to IBM SP-2 - July 1999
– faster, distributed post-processing
• 20 km 1 hr version on IBM SP-2
– Probably in early 2000
– 3-d variational analysis
– Cloud/hydrometeor analysis using satellite, radar,
surface, aircraft combined with explicit cloud fcsts in
RUC-2
• Later, assimilation of new data sets: sat. cloudy/clear
radiances (GOES/POES), hourly precipitation analyses,
WSR-88D radial winds, lightning, GPS precipitable water,
sat water vapor winds
The Future of the RUC, cont.
– Improved physical parameterizations, including cloud
microphysics (freezing drizzle), surface physics (frozen
soil, high-resolution soil and surface data sets), and
turbulence physics
• Higher resolution versions
– 15-20 km/60 level - expanded domain - early 2001
– trade-off between resolution and domain?
20km RUC
topography
- early 2000
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The Future of the RUC, cont.
• Non-hydrostatic -z model under development
– Generalized vertical coordinate
– Nudging of coordinate surfaces toward “grid generator”
• can be set as smoothed quasi-isentropic hybrid coordinate
– treats sub~20km variations (convective clouds, breaking mountain
waves) w/ quasi-horizontal coordinates
– treats >20km variations w/ -z coordinates
– Collaboration between University of Miami (Rainer Bleck,
Zuwen He), FSL (John Brown, Stan Benjamin), and NCAR
(Bill Skamarock)
– Part of WRF model (Weather Research and Forecast NCAR/FSL/NCEP/CAPS) effort - a generalized vertical
coordinate option.
– WRF-based RUC probably by 2005-6 at 5-10km scale
– 30-min cycle or finer?
Feedback
• Send feedback/questions on RUC
performance to the RUC discussion forum.
• Invite us to workshops.
http://maps.fsl.noaa.gov/forum/eval
303-497-6387
[email protected]