WMO International Cloud Modeling Workshop, 12-16 July 2004 A two-moment microphysical scheme for...

WMO International Cloud Modeling Workshop, 12-16 July 2004WMO International Cloud Modeling Workshop, 12-16 July 2004

A two-moment microphysical scheme

for mesoscale and microscale

cloud resolving models

Axel Seifert

National Center for Atmospheric Research


Motivation

• Aerosol-Cloud interactions can be a strong feedback in the climate system

• Quantitative precipitation forecasts suffer from oversimplified microphysical models

• Many ongoing projects on weather modification,but little scientific knowledge

improved microphysical models are necessary


Microphysical models:

x = particle mass


Generalized Gamma Distribution

x = particle mass, = shape parameter, = tail parameter

D in m D in m


Use mass and numberconcentrations to getan explicit size information

4 Variables

A two-moment warm phase scheme

(Seifert and Beheng 2001, Atmos. Res.)


A two-moment mixed-phase cloud scheme


What happend so far ....• Comparison with bin microphysics

• Sensitivity study showed that especially high CAPE, low wind shear convective systems are sensitive to aerosols/CCN

• Simulation of isolated observed thunderstorms

• Severe storms during BAMEX

• WRF, MM5 and LM implementation


Comparison within HUCM


BIN BULK

CONT

MARI

Timeseries of maximum mass concentrations


Total grid averaged precipitation


CCN effects on different storm types

Weisman and Klemp (1982)sensitivity study, but nowincluding CCN as a third external parameter:

Variation of 1. CAPE 2. vertical wind shear3. CCN concentration

Effects on total precipitation?(Seifert and Beheng 2003, submitted)


Total 3h-precipitation

supercell convection

multicell conv.


Total 3h-precipitationand rel. change for cont. CCN


WRF simulation of a CRYSTAL-FACE storm

(100x80 km, 250 m resolution, warm bubble, single sounding)


Observations vs. WRF simulationX-band reflectivity


Observations vs. WRF simulationW-band reflectivity


Attenuation by liquid water


Composite NEXRAD Radar

4 km BAMEX forecast 36 h Reflectivity

4 km BAMEX forecast 12 h Reflectivity

Valid 6/10/03 12Z

Real-time WRF 4 km BAMEX Forecast


BAMEX 10 June 00 UTC + 09h

WRF’s Lin-type scheme

Reisner-Thompson scheme

Seifert-Beheng scheme

Column max. reflectivity (WRF)






Accumulated precip during 23 h


Acknowledgements:Klaus D. Beheng, KarlsruheUli Blahak, KarlsruheMichael Baldauf, KarlsruheJochen Förstner, KarlsruheAlexander Khain, JerusalemAndrei Pokrovsky, JerusalemBill Hall, NCARAndy Heymsfield, NCARMorris Weisman, NCARGerry Heymsfield, NASA

Scientific Computing Centers at Karlsruhe and NCAR


Various one- and two-moment schemes


Maximum vertical velocities (HUCM)


Coupling of microphysics and dynamics!

WMO International Cloud Modeling Workshop, 12-16 July 2004 A two-moment microphysical scheme for...

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