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Bin resolved modeling of ice microphysics

Workshop on Measurement Problems in Ice Clouds Zurich, Switzerland July 5-6, 2013. Bin resolved modeling of ice microphysics. Wolfram Wobrock, Andrea Flossmann. Ice microphysics in clouds. Cotton et al, 2011. MODEL Configuration in 3D. a 3D cloud model with detailed microphysics.

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Bin resolved modeling of ice microphysics

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  1. Workshop on Measurement Problems in Ice Clouds Zurich, Switzerland July 5-6, 2013 Bin resolvedmodeling of icemicrophysics Wolfram Wobrock, Andrea Flossmann

  2. Icemicrophysics in clouds Cotton et al, 2011

  3. MODEL Configuration in 3D a 3D cloud model with detailed microphysics Example: a cumulonimbus cloud Necessity to followateverygridpoint env. 40 classes per cat. => Limitsregarding computer time and storage, in particular for meso-scalemodels

  4. Bulkschemes • 1 Moment schemes: Walko et al (1995): pristineice, snow, aggregates, graupel and hail, 3D Straka, Mansell (2005): 10 icecategories : twoicecrystal habits (column and plate), rimedcloudice, snow (icecrystalaggregates), threecategories of graupelwithdifferentdensities and intercepts, frozen drops, smallhail, and large hail, 3D • 2 Moment schemes: Meyers et al (1997): mixing ratio and number concentration of rain, pristineicecrystals, snow, aggregates, graupel and hail, 3D Seifert et al (2006): cloudice, snowkflakes, graupel, prescribedG distributions, 2D Morrison, Grabowski (2007): mixing ratio due to vapourdeposition, mixingratio due to riming, icenumberconcentration, 2D kinematic

  5. 200µm 500µm 500µm 500µm 500µm MIN-BIN-Configuration: • Drop numberdensity distribution: dN/d(log D), assumingsphericalform (D: equiv. diameter) • Iceparticlenumberdensity distribution: • Needsat least 2 informations, • instead of justdiameter! • Whichparametersto select? • 2 dimensions (largest, smallest?) • Mass + density? • Volume + surface? Currently: just one parameterused (e.g. dimension or mass); otherparameters are prescribed

  6. Bin icemicrophysicsmodels: • Radius coordiante: Hall (1980): 18 categoriesicecrystals, 10 for transistion, 23 for graupel, 2D Farleyand Orville (1986): hail Respondek et al (1995): icecrystals, graupel, 2D Khvorostyanov, Sassen (1998): icecrystals, mass equ. radius, 2D/3D • Mass coordinates: Reisin et al (1996): icecrystals, graupel, snow, 2D Ovtchinnokov, Kogan (2000): smallest15 categoriesare icecrystalswhile the largest 13 categoriesare graupel, 3D Flossmann, Wobrock (2010): sphericaliceparticles, 3D Khain et al (2011): icecrystals (plate-, columnar- and branch types), aggregates, graupel and hail, 2D

  7. Processes: • Nucleation: The onset temperatures and relative humidities for deposition/condensation freezing and immersion freezing for bioaerosols, solid ammonium sulphate and BC (soot) Adapted from Hoose and Möhler (2012). Whichparticlesformice (chemical composition, size) underwhichatmospherical conditions (temperature, humidity)?

  8. Processes: • Vapourdeposition: Mass growth as a funtion of the capacitance C of a correspondingconductor (information on form: spherical, disk, spheroid,..)

  9. Processes: • Sedimentation: Terminal velocity as a funtion of the selectedparameters ?

  10. Processes: • Riming and aggregation: Collection efficiencies as a funtion of the selectedparameters ?

  11. Processes: • Melting:

  12. gouttes cristaux Processes: • Radiation: Optical parameters as a funtion of the selected size and formparameters ?

  13. Conclusion: • Modelling of the ice phase in cloudsistrappedbetween: • Not enough information and • Toomuch information • What are the mostadaptedparameters and how do all processes relate to these (2?) parameters?

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