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This update provides an overview of the Rapid Update Cycle (RUC) model and its operational use at NCEP. The focus is on the impact of TAMDAR aircraft observations on the forecast skill of the RUC model. The evaluation phases, key dates for analysis/quality control changes, and improvements in temperature, wind, and humidity forecasts are discussed.
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Stan Benjamin, Bill Moninger, Tracy Lorraine Smith, Brian Jamison, and Barry SchwartzNOAA Earth System Research Laboratory (ESRL), Global Systems Division (GSD)Boulder, CO TAMDAR aircraft impact experiments with the RUC -- update - 13 April 2006
Purpose for Rapid Update Cycle (RUC) model run operationally at NCEP • Provide high-frequency (hourly) mesoscale analyses, short-range model forecasts • Assimilate all available observations • Users: • aviation/transportation • severe weather forecasting • general public forecasting • Focus on 1-12 hour forecast range KEY QUESTION: Can TAMDAR add to forecast skill for RUC model competing with other obs?
Observation needs for aviation NWP addressed by deployment of automated weather data from regional carriers • Improved forecasts for aviation hazards – • Icing, low ceiling conditions, precipitation forecasts • Convective environment, especially for convective initiation (T, RH, V all important) • Lower tropospheric wind profiles (e.g.,CTAS) • via • High density (regional airports) high-frequency (>6-8 soundings/day) • temperature and moisture profiles • winds from ascent/descent, enroute • => Examine 850-500mb T/RH/V forecast skill
Real-time TAMDAR impact experiment design • Parallel 20km RUC 1-h cycles • Uses latest code in RUC13 (but at 20km) • Dev cycle – all obs data but no TAMDAR • Dev2 cycle – dev + TAMDAR data • Lateral boundary conditions – same for Dev and Dev2 • Control design • Initialize Dev and Dev2 runs at exact same time – same observations used (except TAMDAR) • Reset dev and dev-2 background field at 1000z every • 48 h • Ensure against any computer logistics differences
Dev-Dev2 difference – 0h analysis Init 1800z 24 Aug 2005 – 500 mb 1000-1800z
Verification regions for GSD-RUC TAMDAR impact Large region (eastern half of US) -- 38 RAOB sites Small region (Great Lakes) includes 14 RAOBs
TAMDAR evaluation phases • 9 Feb – 21 April 2005 • Winter/early spring – lower vertical resolution • 22 April – 1 June • Spring – higher vertical resolution • 2 June – 22 July • Summer – higher vertical resolution • 23 July – 24 August • Summer – lower vertical resolution • 25 August – Jan 2006 – lower vert res • 31 March 2006 – onward – back to higher vertical resolution
Key dates for RUC analysis/QC changes • 8 June 2005 - Introduction of improved aircraft reject list • 1 Sept 2005 – Updated reject list • 15 Sept 2005 – Incorporate RUC13 moisture analysis • 15 Nov 2005 – Add new QC step in RUC analysis using ob-background difference – (important for isolated observations) • 1 Dec 2005 – Revised aircraft RH observation error to higher value (now same as raob, was previously “overfitting” TAMDAR RH data) • 15 Dec 2005 – Flag TAMDAR winds on descent • 15-30 March 2006 – Incorrect use of TAMDAR-RH in dev2. Corrected on 31 March.
Temp errors vs. raobs – 850-700-500 mb avg • 3h fcsts • Valid 00z • Gt.Lakes region • Running 30-day avg Dev –no TAMDAR Dev2- w/TAMDAR • Consistent improvement from TAMDAR • Increasing in winter 05-06
Temp errors vs. raobs – 850 mb only • 3h fcsts • Valid 00z • Gt.Lakes region • Running 30-day avg Dev –no TAMDAR Dev2- w/TAMDAR • Strongest effect at this level – 0.25 C improvement • inversions, cloud/thunderstorms/CAPE/CIN, etc.
Temp errors vs. raobs – 850 mb only – eastern US • 3h fcsts • Valid 00z • Gt.Lakes region • Running 30-day avg • 3h fcsts • Valid 00z • Eastern US domain – 38 raobs • Running 30-day avg Dev –no TAMDAR Dev2- w/TAMDAR • About 0.15 C improvement overall over eastern US
Temp errors vs. raobs – 850-700-500 mb avg • 3h fcsts • Valid 00z • Gt.Lakes region • Running 30-day avg Dev –no TAMDAR Dev2- w/TAMDAR 3h persistence –dev2 • Consistent improvement from TAMDAR • Increasing in winter 05-06
Wind errors vs. raobs – 850-700-500 mb avg • 3h fcsts • Valid 00z • Gt.Lakes region • Running 30-day avg Dev –no TAMDAR Dev2- w/TAMDAR • Consistent improvement from TAMDAR
Wind errors vs. raobs – 850-700-500 mb avg • 3h fcsts • Valid 00z • Gt.Lakes region • Running 30-day avg Dev –no TAMDAR Dev2- w/TAMDAR 3h persistence –dev2 • Consistent improvement from TAMDAR
RH errors vs. raobs – 850-700-500 mb avg • 3h fcsts • Valid 00z • Gt.Lakes region • Running 30-day avg Dev –no TAMDAR Dev2- w/TAMDAR Dev2 improvement • Positive impact from TAMDAR in last 2 months • Irregular in 2005
Dev –no TAMDAR Dev2- w/TAMDAR 3h persistence –dev2 RH errors vs. raobs – 850-700-500 mb avg • 3h fcsts • Valid 00z • Gt.Lakes region • Running 30-day avg Dev2 improvement • Positive impact from TAMDAR in last 4 months • Irregular in 2005
3h fcsts • Valid 00z • Gt.Lakes region • Running 7-day avg Dev –no TAMDAR Dev2- w/TAMDAR RH errors vs. raobs – 850-700-500 mb avg
3h fcsts • Valid 00z • Gt.Lakes region • No avg - ~1% RH reduced error w/ TAMDAR in April Dev –no TAMDAR Dev2- w/TAMDAR RH errors vs. raobs – 850 mb only
Overall GSD-RUC TAMDAR impact experiment results – updated 13 April 2006 • Results (TAMDAR impact) have improved during continued TAMDAR shakedown phase • Impact in cases often much larger than overall statistics • Recent results – Jan-April 2006 • Temperature impact • strongest (best) at 850 mb • 25% reduction of 3h forecast error (0.25K) • 20% on average – 850-700-500 mb • RH impact – 10% reduction RMS error (last 4 months – Dec05-Apr06) (15-20% reduction – 850mb, April06) • Better Temp/RH impact w/ higher vert resolution • Wind impact – ~10% reduction of 3h fcst errors in 850-700-500mb layer • Heading accuracy w/ Saab/Mesaba winds • Use along-track winds only? Maybe. • Increase turboprop wind obs errors? Definitely.
