1. EUMETSAT04 04/2004 © Crown copyright Use of EARS in Global and Regional NWP Models at the Met Office Brett Candy, Steve English, Roger Saunders and Amy Doherty Satellite Applications, Met Office

2. EUMETSAT04 05/2004 © Crown copyright Introduction Operational forecast model data cutoff Impact of lost ATOVS data Results of experiments Use of EARS data at the Met Office Plans for the future

3. EUMETSAT04 05/2004 © Crown copyright Met Office NWP Models Global –Global ATOVS from NESDIS –110 min cutoff (main run) UK Mesoscale –Local ATOVS reception from West Freugh, Scotland –120 min cutoff European Mesoscale –Global ATOVS from NESDIS –180 min cutoff (currently)

4. EUMETSAT04 05/2004 © Crown copyright Percentage of data used for each observation type in a global model main run %

5. EUMETSAT04 05/2004 © Crown copyright Arrival Times of Data North Atlantic Region Six-hour window 25/02/2004 09:00- 15:00 window Main Run Update Run First Overpass

6. EUMETSAT04 05/2004 © Crown copyright No Cutoff Experiment All available ATOVS data were used in the Global model and results compared to a control run in which no data arriving after the cutoff were assimilated. Results showed the positive impact of the missing data.

7. EUMETSAT04 05/2004 © Crown copyright RMS Error reduces when all ATOVS data are used. Large peak seen in the T+24 forecasts is less pronounced.

8. EUMETSAT04 05/2004 © Crown copyright T+48 pressure forecast error difference plots

9. EUMETSAT04 05/2004 © Crown copyright Case Study 26th May 2003 North Pacific Cyclone No cutoff experiment predicts a deeper cyclone, closer match to verifying analysis (979 hPa) 982 hPa 978 hPa

10. EUMETSAT04 05/2004 © Crown copyright EARS Station Coverage 24 hours of data

11. EUMETSAT04 05/2004 © Crown copyright Using EARS in the Global Model Trial ran for 3 weeks from the 24 th February 2002 NOAA15 & 16 EARS data from seven stations

12. EUMETSAT04 05/2004 © Crown copyright Example of the Extra Data Global data assimilated in main run EARS and Global data assimilated in main run NOAA16 & NOAA15 NOAA16

13. EUMETSAT04 05/2004 © Crown copyright Difference in Analysis Increments from the Main Forecast Runs

14. EUMETSAT04 05/2004 © Crown copyright Forecast Impact Overall Neutral Benefit in the NH Extra-Tropics Positive Benefit when significant extra data assimilated

15. EUMETSAT04 05/2004 © Crown copyright Use in Operational NWP Ears included in latest package of changes to operational system Initially using 3 stations: –Tromsø (Norway), Maspalomas (Canaries), Edmonton (Canada). Package also includes: –First use of AIRS radiances –Other ATOVS processing changes »Introduce AMSU radiances from AQUA »Move to RTTOV-7 forward model »More data over land Pre-op trial indicates rise of 3 % on a global index (equivalent to yearly improvement from all NWP changes)

16. EUMETSAT04 05/2004 © Crown copyright Conclusions The use of late satellite data can occasionally have large forecast impacts. Using the EARS data to fill in voids from the global data results in positive forecast benefit. Near future: use of EARS data in Euro model. Additional application: AMSU precipitation imagery for duty forecasters.