1. Impact of observations on Bureau of Meteorology Systems
Peter Steinle, Bob Seaman, John LeMarshall,
Yi Xiao, ….
(A) Australian upper air stations
(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 networkX 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. UK global
Extra AMV
JTWC
18Z 14th
16.1
120.1
15.8
120.5
16.2
120.2
00Z 15th
119.9
119.8
15.7
119.7
06Z
16.5
119.5
16.0
119.6
12Z
16.6
119.2
119.0
16.4
118.8
18Z
17.4
118.9
118.7
16.7
118.3
00Z 16th
17.6
16.9
118.1
18.1
17.3
118.5
118.0
18.8
119.1
17.8
17.7
117.5
4th Obs Impact Workshop
1. Forecasts from 12Z 14th 2. AusLAM vs Global minor effect 3. No bogussing

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

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

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

14. 5th WMO Data Assimilation Symposium
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