© crown copyright met office assessing microphysics schemes with the 1d kinematic driver (kid)...

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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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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