the three-dimensional structure of convective storms
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Thorwald Stein ([email protected]). The three-dimensional structure of convective storms. Robin Hogan John Nicol Robert Plant Peter Clark Kirsty Hanley Carol Halliwell Humphrey Lean. (UK Met Office). The DYMECS approach: beyond case studies. - PowerPoint PPT PresentationTRANSCRIPT
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The three-dimensional structure of convective storms
Robin HoganJohn NicolRobert PlantPeter Clark
Kirsty HanleyCarol HalliwellHumphrey Lean
Thorwald Stein ([email protected])
(UK Met Office)
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The DYMECS approach: beyond case studies
NIMROD radar network rainfall
Track storms in real time
and automatically
scan Chilbolton radar
Derive properties of hundreds of storms on ~40 days:Vertical velocity3D structureRain & hailIce water contentTKE & dissipation rate
Evaluate these properties in model varying:ResolutionMicrophysics schemeSub-grid turbulence parametrization
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Storm structure from radarStorm structure from radar
Distance east (km)
Dis
tance
nort
h
(km
)
Radar
reflect
ivit
y
(dB
Z)
40 dBZ
0 dBZ
20 dBZ
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“Shallow”
“Deep”
Observations UKV 1500m 200m
Median storm diameter Median storm diameter with heightwith height
Lack of anvils?
Drizzle from nowhere?
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Vertical profiles ofVertical profiles ofreflectivity reflectivity
1.5-km 1.5-km + graupel
200-m 500-m Observations
Conditioned on average reflectivity at 200-1000m below 0oC.
Reflectivity distributions forprofiles with thismean Z 40-45 dBZ are shown.
Model:High rainfall rate from
shallow storms.Or ice cloud dBZ<0
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Observations UKV 1500m 200m
Missing anvils?Missing anvils?• Define anvil as cloud above 6km with
diameter larger than storm diameter at 3km.
• More than 40% of storms above 6km have anvil (model and observations).
A selection of individual profiles shows anvil factors will be small (close to 1)
6
3
z
T=0oC
R
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Missing anvils?Missing anvils?
PDF of anvil factorDmax/D3km
6
3
z
T=0oC
R
• Define anvil as cloud above 6km with diameter larger than storm diameter at 3km.
Dmax
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Updraft Updraft retrievalretrieval
• Hogan et al. (2008)– Track features in radial
velocity from scan to scan
Chapman & Browning (1998)– In quasi-2D features (e.g.
squall lines) can assume continuity to estimate vertical velocity