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© Crown copyright Met Office
Assessing microphysics schemes with the 1D Kinematic Driver (KiD)Reading meetingBen Shipway 18th Nov 2009
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Acknowledgements
• Adrian Hill, Jonathan Wilkinson
• Hugh Morrison, Greg Thompson
• Brad Ferrier, Weiguo Wang
• Various other people working with the model.
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Segal’s Law:A man with a watch know what time it is. A man with two watches is never sure!
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KiD 1D driver code• Kinematic Driver code written with a simple interface to a common
dynamical core
• Developed to facilitate the testing of a range of microphysics schemes in a consistent way
• Several simple test cases are supplied to test a range of microphysical situations, e.g. deep convection, warm rain cumulus, drizzling stratocumulus, mixed-phase stratocumulus
Examples of current applications
• Comparison between CRM and hi-resolution operational microphysics schemes – enables fast detailed analysis of process rates.
• GCSS SHEBA intercomparison case – provides initial analysis of proposed sensitivity tests. Also highlights any significant differences in the processes of the different schemes.
• Development of microphysics codes – enables extensive testing of schemes over a wide parameter space, highlighting sensitivities and also bugs.
Warm case
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Surface precip. for 50 cm-3
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kg m
-2 s-
1
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kg m
-2 s-
1
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UM and graupelTest cases: deep1
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© Crown copyright Met Office
Contents
Microphysics Peak graupel mixing ratio (x10-3 kg/kg)
LEM SM 7.3
LEM DM 6.5
Morrison 10.2
Thompson 11.2
UM Ice+Snow 0.8
UM Snow 0.8
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graupel processes not included in UM
• Deposition and sublimation of graupel
• The wet mode of graupel growth.
• Collection of ice crystals (only collection of aggregates is assumed)
• Freezing of rain
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Same order of magnitude as LEM piacr_g. In UM this process produces more snow…
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SHEBA and ice processesTest cases: mixed1
Mixed-phase supercooled sc
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UCLA-LARC LEM
WSM6 UM
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1D model: mixed1
UCLA-LARC LEM
Modifying Morrison ice autoconversion scheme to not depend upon humidity and turning off droplet sedimentation can bring the two schemes into better agreement
Evaluation against observations
• Sheba (GCSS)
• Wave clouds
• Lagrangian descents (CONSTRAIN)
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Questions and answers