1. 2006(-07)TAMDAR aircraft impact experiments for RUC humidity, temperature and wind forecasts Stan Benjamin, Bill Moninger, Tracy Lorraine Smith, Brian Jamison, Ed Szoke, Tom Schlatter NOAA Earth System Research Laboratory (ESRL), Global Systems Division (GSD) Boulder, CO

2. 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 RH/T/V forecast skill in RUC model competing with other obs? Purpose for Rapid Update Cycle (RUC) model run operationally at NCEP

3. Observation needs for aviation NWP addressed by deployment of automated weather data from regional carriers Goal: 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 tropospheric profile of T/RH/V forecast skill

4. 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 processing differences between dev and dev2 cycles

5. 1000-1800z Dev-Dev2 difference – 0h analysis Init 1800z 24 Aug 2005 – 500 mb

6. Verification regions for GSD-RUC TAMDAR impact Large region (eastern half of US) -- 38 RAOB sites Small region (Great Lakes) includes 14 RAOBs

7. 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 (O-B) difference – (important for isolated observations) 1 Dec 2005 – Revised aircraft RH observation error to higher value (4% to 12%, 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 June 2006 – Further improvement in O-B QC

8. Figure 3a. RMS RH at 500 hPa for 3h forecasts for the old verification system (centered at 15% RH). Figure 3b. RMS RH at 500 hPa for 3h forecasts for the new verification system (centered at 19% RH). New verification software – Bill Moninger - verify every 10mb, not just at mandatory levels - use all raob data, no QC screening Example - More improvement in 500mb RH forecasts from TAMDAR from including all obs.

9. Temp errors vs. raobs – 850 mb 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 Slightly improved in 2006

10. Temp errors vs. raobs – 1000-800 mb avg 3h fcsts Valid 00z Gt.Lakes region Running 7-day avg Most accurate results in 2006 since mid-Nov Dev –no TAMDAR Dev2- w/TAMDAR Diff – dev-dev2

11. Wind errors vs. raobs – 850-700-500 mb avg 3h fcsts Valid 00z Gt.Lakes region Running 30-day avg Consistent improvement from TAMDAR Dev –no TAMDAR Dev2- w/TAMDAR 3h persistence –dev2

12. RH errors vs. raobs – 850-700-500 mb avg Consistently positive since Jan 2006 3h fcsts Valid 00z Gt.Lakes region Running 30-day avg Dev –no TAMDAR Dev2- w/TAMDAR 3h persistence –dev2

13. RH errors vs. raobs – 850 mb 3h fcsts Valid 00z Gt.Lakes region Running 30-day avg Consistent positive impact from TAMDAR in 2006, unlike in 2005 Dev –no TAMDAR Dev2- w/TAMDAR

14. RH errors vs. raobs – sfc-800 mb avg Positive impact throughout 2006 Average 1% in 1000-800mb layer 3h fcsts Valid 00z Gt.Lakes region Running 7-day avg Dev –no TAMDAR Dev2- w/TAMDAR 3h persistence –dev2

15. RH errors vs. raobs – 900-500 mb avg Increased impact in last 3 months 3h fcsts Valid 00z Gt.Lakes region Running 7-day avg Dev –no TAMDAR Dev2- w/TAMDAR 3h persistence –dev2

16. Temperature wTAM noTAM April-October 2006 Warm season + transition Dec06-Jan07 Cold season wTAM noTAM

17. Relative humidity wTAM noTAM April-October 2006 Warm season + transition Dec06-Jan07 Cold season wTAM noTAM

18. Wind wTAM noTAM April-October 2006 Warm season + transition wTAM noTAM Dec06-Jan07 Cold season

19. TAMDAR impact study with RUC parallel cycles 2005-2007 (ongoing) Further improvement in RH, temperature, wind Forecast errors – RUCdev (no TAMDAR), RUCdev2 (w/ TAMDAR) noTAM wTAM Temp RH Wind wTAM noTAM

20. GSD-RUC TAMDAR impact experiment results – updated 17Jan 2007 Recent results – 2006 RH impact improved in 2006 – Consistent 1-2%RH reduction of RMS error (20-30% reduction – peaks at 900- 800mb, 600-400mb Temperature impact strongest from 950-800mb layer – inversion top! 25% reduction of 3h forecast error (0.25K) Better temp impact apparent w/ higher vert resolution (Nov06-current) Wind impact – ~10% reduction of 3h fcst errors in 850- 700-500mb layer. About same as in 2005. Heading accuracy w/ Saab/Mesaba winds Increase turboprop wind obs errors? (now used in devRUC13). Results (TAMDAR impact) have improved during continued TAMDAR evaluation