1. The Tropical Cloud Population R. A. Houze Lecture, Indian Institute of Tropical Meteorology, Pune, 9 August 2010

2. Clouds in Low Latitudes Lecture Sequence 1.Basic tropical cloud types 2.Severe convection & mesoscale systems 3.Tropical cloud population 4.Convective feedbacks to large-scales 5.Monsoon convection 6.Diurnal variability 7.Clouds in tropical cyclones

3. Before Satellites

4. Small cumulus Cumulus congestus Cumulonimbus and mesoscale convective systems Visual Observation View from an aircraft flying over the South China Sea

5. “Hot tower hypothesis” of Riehl & Malkus 1958 Radiosonde Data

6. Satellite Observations

7. Large cloud shields

9. Circa 1970 Good: Explained satellite pictures Retained the hot tower notion Included smaller clouds Satellite view of the tropical cloud population Not good: Missing downdraft No stratiform rain Unrealistic scale separation

10. Radars

11. GATE 1974

12. GATE SHIP ARRAY

13. More Field Projects to Study Convection BoB 1979 JASMINE 1999 EPIC 2001 TEPPS 1997 (Dashed: No sounding network)

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

15. By the early 1980’s Idealized life cycle of tropical MCS Houze 1982

16. Precipitation Radar in Space

17. The TRMM Satellite TRM M Radar Low altitude, low inclination orbit

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

19. Knowledge of global rainfall before satellites measured rain from space

20. Combined satellite rainfall July 2000 TRMM plus passive microwave sensors + other Knowledge of global rainfall after TRMM & other satellites measured rain from space

21. How is tropical rain distributed by cloud size and type?

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

23. How do the environments of these regimes differ?

24. Trade Wind Regime

25. Stratocumulus Regime

26. Trade Wind Regime

27. Indo/Pacific Warm Pool

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

29. “Trimodal” distribution Johnson et al. 1999 Conceptual model based on TOGA COARE observations Cu congestus Small Cb

30. “Trimodal” distribution Johnson et al. 1999 Evidence from TOGA COARE sounding data

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

32. Tropical cloud population related to SST

33. SST Climatology (July) TRMM PR Deep Convective TRMM PR Shallow, Isolated Convective July SST

34. Land vs Ocean

35. TRMM view of Africa vis a vis the Atlantic Rain Stratiform Rain Fraction MCSs with large 85 GHz ice scattering Lightning

36. Cloud Radar in Space

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

38. 123 Three steps of analysis of multi-sensor data & (GEOPROF-2B) (TB11) Yuan and Houze 2010 (GEOPROF-2B) (TB11)

39. MODIS CloudSat Use MODIS and CloudSat to find threshold of thick high cloud Yuan and Houze 2010

40. 1-Find“cold centers” 2-Use AMSR-E to find rain areas Use 260 K threshold Locate 1 st closed contour Use 1 mm/h threshold for rain rate Yuan and Houze 2010 Associate pixels with nearest cold center

41. Define criterion for MCS that is reasonable for all these regions Yuan and Houze 2010

42. TB11 = 220 Area > 2000 km 2 account for most of the rainfall Colors show rain amount Size of cold cloud top Temperature defining cold center Yuan and Houze 2010

43. “Connected” and “Separated” MCSs Yuan and Houze 2010

44. MCSs Over the Whole Tropics Yuan and Houze 2010

45. MCSs Over the Whole Tropics Yuan and Houze 2010

46. Frequency of MCS anvils over tropics Yuan and Houze 2010

47. Comparison of MCS anvils in different parts of the tropics CloudSat data Yuan and Houze 2010

48. Milestones in determining the tropical cloud population Pre-satellite era  Hot towers and smaller clouds Radars in field projects  MCSs, squall lines, stratiform precipitation Precipitation radar in space  Patterns of convective, stratiform, shallow isolated  Relation to ocean & land Cloud radar in space  Global distributions of MCSs & anvils

49. Clouds in Low Latitudes Next Lecture Sequence 1.Basic tropical cloud types 2.Severe convection & mesoscale systems 3.Tropical cloud population 4.Convective feedbacks to large-scales 5.Monsoon convection 6.Diurnal variability 7.Clouds in tropical cyclones

50. This research was supported by NASA grants NNX07AD59G, NNX07AQ89G, NNX09AM73G, NNX10AH70G, NNX10AM28G, NSF grants, ATM-0743180, ATM-0820586, DOE grant DE-SC0001164 / ER-6