General order for discussion
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Transcript of General order for discussion
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General order for discussion
• Does balance matter?• What kinds of metric should be used to
measure imbalance? • Algorithm details• Other types of balance• What about unbalanced flow?• Use of “toy models”.• Anything else?
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Metrics
• What kind of metric should be used to measure imbalance?– Separate by scale?
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Measuring gravitational “noise”
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Does balance matter?
• Does a balanced analysis matter, or can we just initialise?
• Does a balanced background matter?– Used to estimate background error
covariances
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Algorithm details
• Are some flavours of EnKF inherently better for balance?– Perturbed obs, single vs double, ETKF vs
EnSRF vs EAKF, sequential vs all-at-once, …
• Are some control variable choices better for balance in Var systems?
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Other types of balance
• Balance issues concerning moisture
• Balances on the mesoscale
• Tropical cyclones
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Convection and Gravity-Wave Generation
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What about unbalanced flow?
• Models can simulate several regimes, e.g
• Mesosphere
• Mesoscale
• Tropics
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Koshyk et al. (1999)
troposphere
stratosphere
mesosphere
Rot KE Div KE
RotKE = DivKE around n=20
RotKE = DivKE around n=10
Kinetic energy spectrum Kinetic energy spectrum changes with heightchanges with height
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Toy models
• What are the desirable properties of a toy model for studying balance in an assimilation system?
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Anything else?
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Forecast and obs error variances increase with height
Nezlin et al. (2008)
CMAM ens-based T forecast error std
T profiles over one night from lidar
http://pcl.physics.uwo.ca/science/temperature/R.J. Sica (U Western Ontario)
42.9 N, 81.4 W