INVESTIGATION OF THE IMPACT
OF MICROPHYSICS OPTIONS ON
IDEALIZED WRF SUPERCELL
Catrin M. Mills
Sara T. Strey-Mellema
MICROPHYSICS
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Kessler:
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Thompson:
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Warm rain – no ice
Idealized microphysics (read- simple)
Time-split rainfall
Replacement of Thompson et al. (2007)
6-class microphysics with graupel with ice and rain number
concentrations (rather than idealized)
predicted (double-moment ice)
Time-split fall terms
Millbrandt:
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New in Version 3.2
7-class microphysics with separate graupel and hail
Number concentrations predicted for all six species
water/ice species (double-moment) – 12
Time-split fall terms
HYPOTHESIS
The microphysics scheme that best represents ice
particles will have the strongest updrafts and
strongest mesocyclone
 Model studies have shown that simulating ice
effects storm dynamics, such that vertical
vorticity is enhanced throughout the storm
 We expect that the more sophisticated schemes
are necessary in generating cold pools that can
generate horizontal vorticity and downdrafts that
can tilt it into the vertical
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ADVECTION TERM: THOMPSON VS. KESSLER
DIVERGENCE TERM: THOMPSON VS.
KESSLER
TILTING TERM: THOMPSON VS. KESSLER
ADVECTION TERM: THOMPSON VS. KESSLER
W- WIND
kessler
thompson
millbrandt