The NOAA Rapid Update Cycle (RUC) 1-h assimilation cycle WWRP Symposium -- Nowcasting & Very Short Range Forecasting – 8 Sept 2005 – Toulouse, France Stan Benjamin Steve Weygandt John Brown NOAA Forecast 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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The NOAA Rapid Update Cycle (RUC) 1-h assimilation cycle
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 Presentation
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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, …
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
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
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
- 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