Mesoscale Convective Systems in AMMA

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Mesoscale Convective Systems in AMMA

• What has been learned from previous campaigns?
• GATEoff the coast of west Africa
• COPT81over the west African continent
• What has been learned since these campaigns?
• TOGA COARE
• TRMM
• What can we learn from AMMA?
• How can we learn it?
• How can this new MCS knowledge help the overall
  goals of AMMA?

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Pre-GATE view of tropical cloud population
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Post-GATE view of tropical cloud population
Houze et al. (1980)
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GATE COPT 81 MCS water, mass, and heat budgets
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Water Budget of a West African Mesoscale
Convective Systemover ocean (GATE) and land
(COPT81)
GATE(Gamache Houze 1983)
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MCS heating profiles seen in GATE elsewhere
Assumed heating profiles
Height (km)
Convective
Deg K/day
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MCS heating profiles seen in GATE elsewhere
Assumed heating profiles
Stratiform
Height (km)
Convective
Deg K/day
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Assumed heating profiles
Assumed heating profiles
Height (km)
0 stratiform
Deg K/day
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Assumed heating profiles
Assumed heating profiles
40 stratiform
Height (km)
0 stratiform
Deg K/day
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Assumed heating profiles
Assumed heating profiles
70 stratiform
40 stratiform
Height (km)
0 stratiform
Deg K/day
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TRMM Global mapping of MCSs
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Contribution of convective system type to rainfall
Nesbitt, Zipser Cecil (2000)
AFRICA
S. AMER.
E. PAC.
W. PAC.
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TRMM precipitation radar rain amount subdivided
intoconvective and stratiform components
Total rain
Schumacherand Houze (2003)
Convective rain
Stratiform rain
Stratiform rain fraction
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TRMM PR Jan-Apr 1998 El Niño precipitation,
observed stratiform, El Niño basic state
Schumacher, Houze, and Kracunas (2003)
K/day
250 mb stream function, 400 mb heating
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TOGA COARE Implications of tropical MCSs for
momentum transport in large-scale waves
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plan view
TOGA COARE MCS momentum transport in strong
westerlies Moncrieff Klinker 1997
1000 km
1000 km
cross section
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TOGA COARE Ship and aircraft radar data relative
to Kelvin-Rossby wave structure
Houze et al. 2000
strong westerly region
westerlyonset region
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TOGA COARE Strong Westerly case of 11 February
1993
stratiformecho
Downward momentumtransport
Houze et al. 2000
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• Where do we stand now with west African MCSs?
• GATE COPT81 showed us the existence and
  prominent importance of the MCSs in the west
  African phenomenology
• TOGA COARE TRMM have shown us the global
  importance of mesoscale organization (esp. sf
  regions) in water budgets, vertical distribution
  of heating and momentum transports.
• Whats missing?
• We havent determined the mechanisms of
  interaction on the meso-to-synoptic scales.
• Why AMMA?
• AMMA is best place to use latest technology to
  see better how the meso-to-synoptic scale
  interaction occurs, esp in the context of AEJ and
  AEW.
• AMMA not only will allow this fundamental
  interaction to be studied but will allow the
  downstream effects on hurricane formation to be
  determined.

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• Technology in GATE COPT81
• Upper-air sondes in GATEpoor quality winds
• Ship radar in GATE--precip only, no Doppler, no
  polarimetry, no S-band
• Land radar in COPT81 --dual-Doppler, no
  polarimetry, limited coverage, no S-band, no
  large-scale context
• Aircraft in GATEmostly in situ flight track met
  obs, some dropsondes, photos out the window
• Technology available for AMMA
• Better rawinsondes, ISS (integrated sounding
  systems), profilers
• Mobile S-band for land deployment, with
  polarimetry
• Doppler radar on ship
• Airborne Doppler radar
• Long range dropsondes, driftsondes
• Doppler lidars
• More diverse set of satellites

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NSF/NCAR S-pol radar

• PortableDeployed successfully in TRMM/LBA
  (Brazil), MAP (Italian Alps) and other difficult
  sites

• Polarimetric
• Doppler
• S-band, 10.7 cm
• Zh, Vr, Zdr, Kdp, Ldr

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Integrated Sounding Systems

• UHF Doppler wind profiler ( 0.1 7 km agl)
• Radio-Acoustic Tv profiler (0.2 2 km agl)
• GPS rawinsonde sounding system
• Automated surface met obs
• Seatainer packaged
• Soundings , gt 2/day event-based

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Proposed Use of the R/V Ronald H. Brown During
AMMA

• Instruments
• Radar (Scanning C-band Doppler Vertically
  pointing Ka-band Doppler)
• Rawinsonde
• 915 MHz wind profiler
• DIAL/Mini-MOPA LIDAR
• Multi-spectral radiometers
• Air-sea flux system
• Meteorological observation (T,RH, P), rain gauges
  and ceilometer
• Oceanographic measurements including SST, CTD and
  ADCP

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Summary MCSs in AMMA

• GATE COPT81 showed that mesoscale organization
  was an important part of the tropical cloud
  population, both on land and offshore
• Since GATE COPT81, the mesoscale organization
  of tropical cloud populations has been seen to
  have global significance, esp. via TRMM TOGA
  COARE
• Water budgets precipitation
• Heating profiles
• Momentum transports
• AMMA is the best place to use new technology to
  understand the meso-synoptic scale connection,
  since the interaction ofwest African MCSs
  larger-scale dynamics is so robust
• AEJ AEWs
• Saharan air layer
• Tropical cyclone formation
• These meso-synoptic scale linkages are essential
  to the overall picture of the west African
  monsoon sought by AMMA

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Convection, microphysics, lightning in AMMAS.
A. Rutledge
AMMA domain is a natural laboratory to study
aerosol/cloud interactions and associated
feedbacks to cloud dynamics. Lightning Recent
work from TRMM-LBA (Brazil) suggests that
aerosols may exert a fundamental control on flash
rate and cloud dynamics. This issue can be
further evaluated in AMMA. Precipitation
microphysics Need to understand the
microphysical aspects of the formation of the
stratiform anvil precipitation. Overarching
issue Microphysical aspects of African
convective systems virtually unexplored.
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Global frequency and distribution of lightning as
observed from space Christian, Hugh J. , Richard
J. Blakeslee, Dennis J. Boccippio, William L.
Boeck, Dennis E. Buechler, Kevin T. Driscoll,
Steven J. Goodman, John M. Hall, William J.
Koshak, Douglas M. Mach, and Michael F. Stewart,
Global frequency and distribution of lightning as
observed from space by the Optical Transient
Detector, J. Geophys. Res., accepted, 2002.
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Brazilian Lightning Detection Network (BLDN)
Oscillations apparent East (west) anomalies
more (less) lightning.
CCN higher in east regime argued to lead to more
lightning a competing hypothesis is that CAPE
is higher in East regime compared to West
regime
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Hydrometeor Identification-Example from STEPS 2000
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Retrieve mixing ratio estimates from polarimetric
data
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Performance of the S-POL radar rainfall estimate
relative to rain gauges for February 1999
TRMM-LBA
Using polarimetric techniques, accurate rain
rates can be calculated and used for budget
calculations and hydrological applications
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Summary Convection, microphysics, lightning
in AMMA S. A. Rutledge
West Africa is the best place to study aerosol
effects on tropical convection Ice phase
microphysics are critical in both the MCS
stratiform anvil precipitation and in
lightningaerosol may affect both S-band
polarimetric radar provides the basic tool for
pursuing this work