Mesoscale Convective Systems in AMMA What has been learned from previous campaigns? GATE—off the coast of west Africa COPT81—over 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?

Pre-GATE view of tropical cloud population

Houze et al. (1980) Post-GATE view of tropical cloud population

GATE & COPT 81: MCS water, mass, and heat budgets

GATE (Gamache & Houze 1983).60R.40R 1.17R.41R.29R.37R 0.13R.16R COPT81 (Chong & Hauser 1989) Water Budget of a West African Mesoscale Convective System over ocean (GATE) and land (COPT81)

Height (km) Deg K/day Convective Assumed heating profiles MCS heating profiles seen in GATE & elsewhere

Height (km) Deg K/day Convective Stratiform Assumed heating profiles MCS heating profiles seen in GATE & elsewhere

Height (km) Deg K/day Assumed heating profiles 0% stratiform Assumed heating profiles

Height (km) Deg K/day Assumed heating profiles 0% stratiform 40% stratiform Assumed heating profiles

Height (km) Deg K/day Assumed heating profiles 0% stratiform 40% stratiform 70% stratiform Assumed heating profiles

TRMM: Global mapping of MCSs

Nesbitt, Zipser & Cecil (2000) Contribution of convective system type to rainfall AFRICAS. AMER.E. PAC.W. PAC.

Schumacher and Houze (2003) TRMM precipitation radar rain amount subdivided into convective and stratiform components Total rain Convective rain Stratiform rain Stratiform rain fraction

TRMM PR Jan-Apr 1998 El Niño precipitation, observed % stratiform, El Niño basic state 250 mb stream function, 400 mb heating K/day Schumacher, Houze, and Kracunas (2003)

TOGA COARE: Implications of tropical MCSs for momentum transport in large-scale waves

1000 km TOGA COARE MCS momentum transport in strong westerlies Moncrieff & Klinker 1997 plan view cross section AB AB

strong westerly regionwesterly onset region TOGA COARE: Ship and aircraft radar data relative to Kelvin-Rossby wave structure Houze et al. 2000

SWNE Houze et al TOGA COARE: Strong Westerly case of 11 February 1993 stratiform echo Downward momentum transport

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. What’s missing? We haven’t 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.

Technology in GATE & COPT81 Upper-air sondes in GATE—poor 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 GATE—mostly 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

NSF/NCAR S-pol radar Polarimetric Doppler S-band, 10.7 cm Z h, V r, Z dr, K dp, L dr Portable—Deployed successfully in TRMM/LBA (Brazil), MAP (Italian Alps) and other difficult sites

Integrated Sounding Systems UHF Doppler wind profiler (~ 0.1 – 7 km agl) Radio-Acoustic T v profiler (~0.2 – 2 km agl) GPS rawinsonde sounding system Automated surface met obs Seatainer packaged Soundings, > 2/day + event-based

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

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

Convection, microphysics, & lightning in AMMA S. 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.

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.

= East regime 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

Hydrometeor Identification-Example from STEPS 2000

Retrieve mixing ratio estimates from polarimetric data

Performance of the S-POL radar rainfall estimate relative to rain gauges for February 1999 TRMM-LBA MethodBIASSTANDARD ERROR S-POL Optimal -4.8%14.4% S-POL Median-10.7%17.9% S-POL Closest-11.1%20.6% Using polarimetric techniques, accurate rain rates can be calculated and used for budget calculations and hydrological applications

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 lightning—aerosol may affect both S-band polarimetric radar provides the basic tool for pursuing this work