the noaa rapid update cycle (ruc) 1-h assimilation cycle
DESCRIPTION
Stan Benjamin Steve Weygandt John Brown NOAA Forecast Systems Lab – Boulder CO, USA. The NOAA Rapid Update Cycle (RUC) 1-h assimilation cycle. GOAL: Provide high-frequency (1h) mesoscale 3-d analyses and short-range (1-12+h) forecasts for aviation, severe weather, hydrology, …. - PowerPoint PPT PresentationTRANSCRIPT
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The NOAA Rapid Update Cycle (RUC) 1-h assimilation cycle
WWRP Symposium -- Nowcasting & Very Short Range Forecasting – 8 Sept 2005 – Toulouse, France
Stan BenjaminSteve WeygandtJohn Brown
NOAAForecast Systems Lab – Boulder CO, USA
RUC web site - http://ruc.fsl.noaa.gov
GOAL:
• Provide high-frequency (1h) mesoscale 3-d analyses and short-range (1-12+h) forecasts for aviation, severe weather, hydrology, …
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RUC Hourly Assimilation Cycle
11 12 13 14 15 16 Time (UTC)
1-hrfcst
Background
Fields
Analysis
Fields
1-hrfcst
1-hrfcst
3DVAR
Obs
1-hrfcst
3DVAR
Obs
3DVAR
Obs
3DVAR
Obs
3DVAR
Obs
1-hrfcst
1-hrfcst
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RUC Hourly Assimilation Cycle + Forecasts > 1h
11 12 13 14 15 16 Time (UTC)
9-hrfcst
Background
Fields
Analysis
Fields
9-hrfcst
9-hrfcst
3DVAR
Obs
9-hrfcst
12-hfcst
12-hfcst
3DVAR
Obs
3DVAR
Obs
3DVAR
Obs
3DVAR
Obs
Run-time at NCEP for RUC 12h fcst – 17 min
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Data type ~ Number Frequency
Rawinsonde ~85 /12h+spec
Aircraft 1600-6000 /1h
NOAA profiler 32 /1h
VAD winds ~125 /1h
PBL profilers 25 /1h
Surface METAR 1600-1800 /1h
Mesonet ~6000 /1h
Buoy/ship 100-1500 /1h
GOES precip water 1500-3000 /1h
SSM/I precip water 1000-4000 /6h
GPS precip water ~280 /1h
GOES cloud-drift wind 1000-2500 /1h
GOES cloud-top (p,T) ~10km /1h
Radar ref / /lightning 1km13km /1h
RUCObsSources
- experimental13km RUC-- As of 6 Sept 05
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RUC20Wind forecastAccuracy
-Sept-Dec2002
Verification against rawinsonde data over RUC domainRMS vector difference (forecast vs. obs)
RUC is able to use recent obs to improve forecast skill down to 1-h projection for winds
6 8 10 12 (kts)
1 3 6 912
Analysis~ ‘truth’
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Application of Digital Filter Initialization (DFI) in RUC Model
• Critical for 1-h assimilation cycle• 45 min forward, 45 min backward – no physics• Average over DFI period• Applicable for diabatic application, nudging to radar obs during DFI ‘pre-forecast’
Noise in surface presat 1h forecast is much lower with DFI
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Vert Coord Hybrid isentropic-sigma – 50 levels
Stable clouds, NCAR mixed-phase (cloud Precipitation water, rain water, snow,
graupel, ice, ice particle number. concen.
Sub-grid Grell-Devenyi ens schemeprecipitation (144 members, closure/CIN
Land-surface RUC LSM - 6-level soil/veg
model, 2-layer snow model
- Smirnova
Rapid Update Cycle Model
Current operational RUC: 13-km
9-12-hrfcst
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Recent changes to RUC13 3DVAR analysis(among many):
1. Use of surface obs throughout PBL (NCEP Fall 2004)
2. Cloud analysis (GOES, METAR ceiling/vis/curr-wx)
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PBL-based METAR assimilation -- create additional obs corrections thru PBLUse METAR data through PBL depth from 1h fcst
RUC oper analysis18z 3 Apr 02IAD
x xxx
Effect of PBL-basedMETAR assimilation
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RUC enhancements:
1. Use of METAR obs throughboundary-layer depth (Sept 04)
2. Assimilation of GPS precipitable
water observations (RUC13 - ~Jun05)
CAPE impact from two RUC enhancements
3h fcst WITHenhancements
3h fcstOPERATIONAL
0000 UTC 21 Apr 2004
Severe reports
NWS SPCNorman, OK
Tornadoes
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Use GOES CTP, radar reflectivity, lightning, METAR (clouds,wx,vis) to modify 1h fcst 3-d q* fields
• Clear/build (change qc, qi, qv) with logical arrays
• Safeguards for pressure-level assignment problems
(marine stratus, convective clouds)
• Use nationwide mosaic radar data to modify water
vapor, hydrometeor fields – in testing, crude
• Lightning data used as a proxy for radar reflectivity
• Feedback to cumulus parameterization scheme – bypass convective inhibition via radar/lightning, GOES ECA
RUC Cloud Analysis
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GOES cloud top
pressureRadar/lightning data
100
200
300
400
500
600
700
800
900
999
PRES
Qv
Qc
RH
Cloudwater, water vapor and relative humidity before ( )and after (----) GOES Cloud-top pressure adjustment
Rainwater, snow, cloud ice and reflectivity before ( ) and after (----) GOES radar/lightning adjustment
100
200
300
400
500
600
700
800
900
999
PRES
Qr
Qs
QidBZ
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IFRLIFR VFR CLR MVFR
Sample ceiling analysis impact
Ceiling from RUC hydrometeors
AnalysisWITH
cld/wx/vis obs
AnalysisNO
cld/wx/vis obs
Aviation Flight Rules
cloud ceiling height (meters)
1800 UTC 17 Nov 2003
Observations
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Data type ~ Number3-d reflectivity data NSSL mosaicked
data
NASA Langley experimental GOES cloud products
TAMDAR aircraft regional carriers – T/V/RH – lower-mid troposphere
65 aircraft
Radar radial wind 120 WSR-88D radars
GPS zenith wet delay(replacing prec water retrievals)
280, increasing
QC’d mesonet data 6000, but many not usable due to poor siting and lack of QC monitoring/metadata
Experimental or future RUC ObsSources
To be added in next 6 months to experimental13km RUC
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Radar reflectivity assimilation - experimental RUC13 init 09z - 3-6h precipValid 12-15 UTC 6 Sept 2005
Control – oper RUC
Exp RUC13W/ rad ref assim
Obs – 1345 UTC
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Sample 3DVAR analysis with radial velocity
500 mb Height/Vorticity
*Amarillo, TX
DodgeCity, KS
*
*
AnalysisWITHradial
velocity
**
Cint =2 m/s
**
Cint =1 m/s
K = 15wind
Vectors
and speed
0800 UTC 10 Nov 2004
Dodge City, KS
Vr
Amarillo, TX
Vr
*
*
Analysisdifference
(WITH radial
velocity minus
without)
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Current RUC CONUS domain
Planned Rapid Refresh domain
Goals:Hourly NWP update in
- Alaska- Wider E. Pacific-- Canada- Caribbean Sea
Rapid Refresh-replace RUC – 2007-08- 13km resolution - use WRF model
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The RUC by 2008, testing in 2006
• “Rapid Refresh”• Simple more complex assimilation of radar reflectivity and radial winds• Improved use of sat data, GPS, aircraft, surface/mesonet• Use of WRF model w/ RUC-like physics• Use of NCEP data assimilation (GSI) with RUC-specific enhancements – use of sfc data, cloud analysis• North American coverage