Post on 20-Dec-2015
Seminar, National Taiwan University, Taipei, 15 April 2011
Robert HouzeUniversity of Washington
The tropical convective cloud population
What do we know?
What role have radars played?
What comes next?
The tropical convective cloud population
Satellite view of the tropical cloud population
•Explained satellite pictures •Retained the hot tower notion •Included smaller clouds
Early 1970’s
197440 ships!
12 aircraft!
197440 ships!
12 aircraft!
4 shipborne scanning digital
C-band radars
4 shipborne scanning digital
C-band radars
More Field Projects to Study Convection
BoB 1979
JASMINE1999
EPIC 2001
TEPPS1997
(Dashed: No sounding network)
Ground, ship, & airborne cm radars
Houze et al. (1980)
Post-GATE view of the tropical cloud population
MESOSCALE CONVECTIVE SYSTEMS (MCSs)
STRATIFORMRAINGCM grid
Hot Tower
Simplified MCS Heating Profiles
Schumacher et al. 2004
He
igh
t (km
)
Deg K/day
Convective
Stratiform
MCS Net Heating Profiles
He
igh
t (km
)
Deg K/day
0% stratiform
40% stratiform
70% stratiform
Schumacher et al. 2004
The TRMM SatelliteThe TRMM Satellite
Ka-band RadarKa-band Radar
Low altitude, low inclination orbitLow altitude, low inclination orbit
Combined satellite rainfall July 2000TRMM plus passive microwave sensors + other
Combined satellite rainfall July 2000TRMM plus passive microwave sensors + other
Rainfall mapping revolutionized!Rainfall mapping revolutionized!
TRMM Satellite InstrumentationTRMM Satellite Instrumentation
Kummerow et al, 1998
λ= 2 cmImportant! PR measures 3D structure of radar echoes
Cu congestusSmall Cb
“Trimodal distribution”“Trimodal
distribution”
Suggested by
TOGA COARE radiosonde data
Johnson et al. 1999
“Trimodal” distribution
Hollars et al. 1999
Evidence
from Manus ARM cloud radar
observations
XMANUSMANUSMANUSMANUS
Internal structure of MCS anvils shown by CloudSat
Yuan, Houze, and Heymsfield 2011
Africa Indian Ocean
Internal structures of MCS anvils
Cetrone & Houze 2011and also
Yuan et al. 2011-CloudSat
Data from MCSs seen by ARM
W-band radar in Niamey, Niger
Hei
ght
(km
)
Reflectivity (dBZ)
HUMIDITY
DUAL WAVELENGTHWater vapor
CM-WAVELENGTHPrecipitation
MM-WAVELENGTHNon-precipitating
Cumulus
MM-WAVELENGTHAnvil cloud
POLARIMETRYMicrophysics
DOPPLERAir motions
Radar Supersite ApproachWill document many aspects of the convective population
Timeline of progress
Pre-satellite eraHot towers and smaller clouds
Radars in field projects
MCSs, squall lines, stratiform precipitation
Precipitation radar in space
Global patterns—convective, stratiform, shallow, MCSs
Cloud radarsARM—layers, trimodality, anvils of MCSsCloudSat—global distributions of MCSs, anvils, ...
Dual wavelengthWater vapor
Spectrum of convective cloud types and sizes covers a wide range of types and sizes of convective entities
• Mesoscale systems with stratiform rain• Top-heavy heating profiles• Multimodal size distributions• Shallow isolated cells• Structures of large anvil clouds• Global variability of the population
What we’ve learned
Where we are going
How does convective population project onto larger-scale dynamics?
• Latent heating profiles• Radiative heating profiles in anvils of MCSs • Nonprecipitating convective clouds• Relation between humidity field and cloud
population evolution • Role of clouds in MJO, ENSO, monsoon, & coupled
equatorial waves
End
This research was supported by NASA grants NNX07AD59G, NNX07AQ89G, NNX09AM73G, NNX10AH70G, NNX10AM28G,
NSF grants, ATM-0743180, ATM-0820586, DOE grant DE-SC0001164 / ER-6