1. Seminar, National Taiwan University, Taipei, 15 April 2011 Robert Houze University of Washington The tropical convective cloud population

2. What do we know? What role have radars played? What comes next? The tropical convective cloud population

3. Before Satellites

4. Small cumulus Cumulus congestus Cumulonimbus Visual Observation

5. Radiosonde data in the tropics Riehl & Malkus 1958 “Hot tower hypothesis”

6. GCM grid Convective parameterization

7. Satellite Observations: an “inconvenient truth”

8. Large cloud shields

9. Satellite view of the tropical cloud population Explained satellite pictures Retained the hot tower notion Included smaller clouds Early 1970’s

10. Radars: The second “inconvenient truth”

11. GATE 1974

12. 1974 40 ships! 12 aircraft! 1974 40 ships! 12 aircraft! 4 shipborne scanning digital C-band radars

13. More Field Projects to Study Convection BoB 1979 JASMINE 1999 EPIC 2001 TEPPS 1997 (Dashed: No sounding network) Ground, ship, & airborne cm radars

14. Houze et al. (1980) Post-GATE view of the tropical cloud population MESOSCALE CONVECTIVE SYSTEMS (MCSs) STRATIFORM RAIN GCM grid Hot Tower

15. Houze 1982 Heating and cooling processes in an MCS

16. Simplified MCS Heating Profiles Schumacher et al. 2004 Height (km) Deg K/day Convective Stratiform

17. MCS Net Heating Profiles Height (km) Deg K/day 0% stratiform 40% stratiform 70% stratiform Schumacher et al. 2004

18. Precipitation Radar in Space

19. The TRMM Satellite Ka-band Radar Low altitude, low inclination orbit

20. Combined satellite rainfall July 2000 TRMM plus passive microwave sensors + other Combined satellite rainfall July 2000 TRMM plus passive microwave sensors + other Rainfall mapping revolutionized!

21. TRMM Satellite Instrumentation Kummerow et al, 1998  = 2 cm Important! PR measures 3D structure of radar echoes

22. How tropical rain is distributed by cloud size and type

23. Schumacher & Houze 2003 2 Years of TRMM PR data Large Cbs MCSs Small isolated Cbs

24. Traditional conceptual view of mean meridional distribution of tropical convection Simpson 1992

25. Cu congestus Small Cb “Trimodal distribution” Suggested by TOGA COARE radiosonde data Johnson et al. 1999

26. Cloud Radars

27. “Trimodal” distribution Hollars et al. 1999 Evidence from Manus ARM cloud radar observations X MANUSMANUS

28. Cloud Radar in Space

29. Anvils of Mesoscale Convective Systems (MCSs) Yuan and Houze 2010

30. MCSs Over the Whole Tropics Yuan and Houze 2010 (< 12000 km 2 ) (> 40000 km 2 )

31. Morphology of MCS anvils in different parts of the tropics CloudSat data Yuan and Houze 2010

32. Internal structure of MCS anvils shown by CloudSat Yuan, Houze, and Heymsfield 2011 AfricaIndian Ocean

33. Internal structures of MCS anvils Cetrone & Houze 2011 and also Yuan et al. 2011-CloudSat Data from MCSs seen by ARM W-band radar in Niamey, Niger Height (km) Reflectivity (dBZ)

35. Addu Atoll Five radars on a tiny island

36. HUMIDITY DUAL WAVELENGTH Water vapor CM-WAVELENGTH Precipitation MM-WAVELENGTH Non-precipitating Cumulus MM-WAVELENGTH Anvil cloud * POLARIMETRY Microphysics DOPPLER Air motions Radar Supersite Approach Will document many aspects of the convective population

37. Summary & Conclusions

38. Timeline of progress Pre-satellite era  Hot towers and smaller clouds Radars in field projects  MCSs, squall lines, stratiform precipitation Precipitation radar in space  Global patterns—convective, stratiform, shallow, MCSs Cloud radars  ARM—layers, trimodality, anvils of MCSs  CloudSat—global distributions of MCSs, anvils,... Dual wavelength  Water vapor

39. 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

40. 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

41. 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

42. Internal structure of “thick” anvils shown by CloudSat Yuan, Houze, and Heymsfield 2011 Indian Ocean Africa