Impact of observations on Impact of observations on Bureau of Meteorology Bureau of Meteorology
SystemsSystems
Peter Steinle, Bob Seaman, John LeMarshall,
Yi Xiao, ….
(A) Australian upper air stations 1994-2007
(B) AMV’s & ACCESS 4dVAR
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opImpact of Aust. mainland upper air Impact of Aust. mainland upper air stations on NWP wind analysesstations 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)
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X
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Aust. mainland upper air networkAust. mainland upper air network
X
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Important stationsImportant stations
Most influential & Very influential
• Remoteness
• Tropics Retuned B in 1999
• Greater influence tropics
Influential at upper levels
• Near sub-tropical jet
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Stations with least relative impactStations with least relative impact
Impact reduced post enhanced satellite data usage
• Significant drop in influence post 1998
Rarely influential Never influential
• Aircraft data
• Obs density
• Downstream
• Some wind only stations
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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
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AMV’s in ACCESS 4dVARAMV’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
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Tropical AMV coverageTropical AMV coverage
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UK typical of global NWP systems UK typical of global NWP systems
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1. Forecasts from 12Z 14th 2. AusLAM vs Global minor effect3. No bogussing
UK global Extra AMV JTWC
18Z 14th 16.1 120.1 15.8 120.5 16.2 120.2
00Z 15th 16.2 119.9 15.8 119.8 15.7 119.7
06Z 16.5 119.5 16.0 119.6
12Z 16.6 119.2 16.1 119.0 16.4 118.8
18Z 17.4 118.9 16.1 118.7 16.7 118.3
00Z 16th 17.6 118.9 16.5 118.7 16.9 118.1
06Z 18.1 118.9 17.3 118.5 16.9 118.0
12Z 18.8 119.1 17.8 118.3 17.7 117.5
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UK typical of global NWP systems UK typical of global NWP systems
OA
AO
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Parallel TrialParallel Trial
No AMV
AMV (6hr)
AMV std
AMV 6hr
No AMV
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FC diffNo AMV
AMV
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Still a need for AMVs Occasional high impact …although often minor impact Scope for improving existing data Tropics- wind, wind (& moisture)
5th WMO Data Assimilation Symposium
Melbourne,
5-9 October 2009
