Transcript 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 &

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,
4th Obs Impact Workshop
(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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Aust. mainland upper air network
X
X
X
X
X
X
X
X
X
X
X
Important stations

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
Most influential &
Very influential
• Remoteness
• Tropics

Retuned B in 1999
• Greater influence tropics

Influential at upper
levels
• Near sub-tropical jet
Stations with least relative impact
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
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
 Remote
stations most important
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• Macquarie Island most significant!
 Importance
of tropical stations
• Limited wind information from satellites
 Influence
 Some
of aircraft data etc.
wind only stations never have
significant impact
4th Obs Impact Workshop
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
Tropical AMV coverage
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UK typical of global NWP systems
4th Obs Impact Workshop
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
1. Forecasts from 12Z 14th
2. AusLAM vs Global minor effect
3. No bogussing
4th Obs Impact Workshop
UK typical of global NWP systems
A
A
O
O
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Parallel Trial
No AMV
AMV (6hr)
AMV std
AMV 6hr
No AMV
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AN
No AMV
AMV
FC diff
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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