Mesoscale Convective Systems in AMMA

1. 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?

2. Pre-GATE view of tropical cloud population

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

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

5. 0 .13R .37R 1.17R .41R COPT81(Chong & Hauser 1989) .16R .29R .60R .40R Water Budget of a West African Mesoscale Convective Systemover ocean (GATE) and land (COPT81) GATE(Gamache & Houze 1983)

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

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

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

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

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

11. TRMM: Global mapping of MCSs

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

13. TRMM precipitation radar rain amount subdivided intoconvective and stratiform components Total rain Schumacherand Houze (2003) Convective rain Stratiform rain Stratiform rain fraction

14. 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

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

16. A A B B plan view TOGA COARE MCS momentum transport in strong westerlies Moncrieff &Klinker 1997 1000 km 1000 km cross section

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

18. SW NE TOGA COARE: Strong Westerly case of 11 February 1993 stratiformecho Downward momentumtransport Houze et al. 2000

19. 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.

20. 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

21. NSF/NCAR S-pol radar • Portable—Deployed successfully in TRMM/LBA (Brazil), MAP (Italian Alps) and other difficult sites • Polarimetric • Doppler • S-band, 10.7 cm • Zh, Vr, Zdr, Kdp, Ldr

22. 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 , > 2/day + event-based

23. 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

24. 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

25. 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.

26. 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.

27. = 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

28. Hydrometeor Identification-Example from STEPS 2000

29. Retrieve mixing ratio estimates from polarimetric data

30. Method BIAS STANDARD ERROR S-POL Optimal -4.8% 14.4% S-POL Median -10.7% 17.9% S-POL Closest -11.1% 20.6% 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

31. 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