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Impact of observations on Bureau of Meteorology Systems

Impact of observations on Bureau of Meteorology Systems. Peter Steinle, Bob Seaman, John LeMarshall, Yi Xiao, …. (A) Australian upper air stations 1994-2007 (B) AMV’s & ACCESS 4dVAR. Impact of Aust. mainland upper air stations on NWP wind analyses. Seaman, (2007), AMM Impact on analyses

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Impact of observations on Bureau of Meteorology Systems

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  1. Impact of observations on Bureau of Meteorology Systems Peter Steinle, Bob Seaman, John LeMarshall, Yi Xiao, …. (A) Australian upper air stations 1994-2007 (B) AMV’s & ACCESS 4dVAR

  2. Impact of Aust. mainland upper air stations on NWP wind analyses • Seaman, (2007), AMM • Impact on analyses • Difference (ms-1) with & without individual soundings • Ranking / Relative impact overcomes system changes • Divide into 4 ~equal groups each analysis • Changes in ranking due to • Observing schedules • Changes in amount & use of other data (e.g. satellites) • Started in 1994 • Also have data for SYNOP, BUOY etc. (Seaman, AMM,1994) 4th Obs Impact Workshop

  3. Aust. mainland upper air network X X X X 4th Obs Impact Workshop X X X X X X X

  4. Important stations • Most influential & • Very influential • Remoteness • Tropics • Retuned B in 1999 • Greater influence tropics 4th Obs Impact Workshop • Influential at upper levels • Near sub-tropical jet

  5. Stations with least relative impact • Impact reduced post enhanced satellite data usage • Significant drop in influence post 1998 4th Obs Impact Workshop • Rarely influential • Never influential • Aircraft data • Obs density • Downstream • Some wind only stations

  6. Remote stations most important • Macquarie Island most significant! • Importance of tropical stations • Limited wind information from satellites • Influence of aircraft data etc. • Some wind only stations never have significant impact 4th Obs Impact Workshop

  7. AMV’s in ACCESS 4dVAR • Australian Community Climate and Earth System Simulator • Centre for Australian Weather & Climate Research • Partnership between ABM & CSIRO • Atmospheric model: UM + 4dVAR • N144 (~80km) global, L50 • VAR at N108L50 • 37.5km & 12.5km Regional • AIRS (but not IASI yet) • JLM winds • TC Nicholas case study & 16day trial • Focus on Aus region 4th Obs Impact Workshop

  8. Tropical AMV coverage 4th Obs Impact Workshop

  9. UK typical of global NWP systems 4th Obs Impact Workshop

  10. 1. Forecasts from 12Z 14th 2. AusLAM vs Global minor effect3. No bogussing 4th Obs Impact Workshop

  11. UK typical of global NWP systems A O A O 4th Obs Impact Workshop

  12. Parallel Trial No AMV AMV (6hr) AMV std 4th Obs Impact Workshop AMV 6hr No AMV

  13. AN AMV 4th Obs Impact Workshop No AMV FC diff

  14. Still a need for AMVs • Occasional high impact • …although often minor impact • Scope for improving existing data • Tropics- wind, wind (& moisture) 4th Obs Impact Workshop 5th WMO Data Assimilation Symposium Melbourne, 5-9 October 2009

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