1. Introduction to tropical meteorology and deep convection Roger K. Smith University of Munich

2.  A satpix tour of the tropics  The zonal mean circulation (Hadley circulation), Inter- Tropical Convergence Zone (ITCZ)  Field experiments  Macroscale circulations, The Walker circulation, Monsoons  Synoptic scale weather systems, tropical waves  Moist convection and convective systems  The Madden-Julian Oscillation, Westerly wind bursts  Concluding remarks Topics

3. INDO IR 01010510

4. GMS IR 01022621

5. GOES IR 00112909

6. Principal land and ocean areas between 40°S and 40°N. The shaded areas show tropical highlands (over 1000 m). From Nieuwolt (1977)

7. How does one define the tropics? Tropic of Capricorn 23.5 o s Tropic of Cancer 23.5 o N Maritime continent

8.  A satpix tour of the tropics  The zonal mean circulation (Hadley circulation), Inter- Tropical Convergence Zone (ITCZ)  Field experiments  Macroscale circulations, The Walker circulation, Monsoons  Synoptic scale weather systems, tropical waves  Moist convection and convective systems  The Madden-Julian Oscillation, Westerly wind bursts  Concluding remarks Next topic

9. Radiative heat balance Zonally averaged components of the absorbed solar flux and emitted thermal infrared flux at the top of the atmosphere. (after Vonder Haar and Suomi, 1971, with modifications) F (W m  2 ) 100 0 200 300 90 50 30 10 0 10 30 50 90 South Latitude North Absorbed solar flux Emitted infrared flux energy gain energy loss +  

10. Mean annual precipitation Mean annual precipitation as a function of latitude. (after Sellers, 1965) 2000 1500 1000 500 mm 0 90 60 40 30 20 10 0 10 20 30 40 60 90 North Latitude South

11. mean meridional circulation The mean meridional circulation and main surface wind regimes. after Defant, 1958 Hadley circulation 

12. ITCZ

14.  A satpix tour of the tropics  The zonal mean circulation (Hadley circulation), Inter- Tropical Convergence Zone (ITCZ)  Field experiments  Macroscale circulations, The Walker circulation, Monsoons  Synoptic scale weather systems, tropical waves  Moist convection and convective systems  The Madden-Julian Oscillation, Westerly wind bursts  Concluding remarks Next topic

15. Field Experiments in the Tropics 1969 - 1979  Bermuda Oceanographic and Meteorological EXperiment (BOMEX) 1969  Holland & Rasmusson, (1973), MWR, 101, 44-55.  Global Atmospheric Research Programme (GARP) Atlantic Tropical Experiment (GATE) July 1974  GARP: Fleming et al., (1979), BAMS, 60, 649-659.  GATE: Kuettner et al. (1974) BAMS, 55, 711-744.  The MONsoon EXperiment (WMONEX December 1978, SMONEX May – August, 1979)  WMONEX: Greenfield & Krishnamurti (1979), BAMS, 60, 649- 659.SMONEX: Fein & Kuettner (1980) BAMS, 61, 461-474.

16. Field Experiments in the Tropics 1987 -  Australian Monsoon EXperiment & Equatorial Mesoscale EXperiment (AMEX, EMEX) January – February 1987  AMEX Holland et al. (1986), BAMS, 67, 1466-1486.  EMEX Webster & Houze (1991), BAMS, 72, 1481-1505.  Tropical Oceans Global Atmosphere Couple Ocean Atmosphere Response Experiment (TOGA COARE) November 1992 – February 1993  Webster & Lucas (1992), BAMS, 73, 1377-1416.

17.  A satpix tour of the tropics  The zonal mean circulation (Hadley circulation), Inter- Tropical Convergence Zone (ITCZ)  Field experiments  Macroscale circulations, The Walker circulation, Monsoons  Synoptic scale weather systems, tropical waves  Moist convection and convective systems  The Madden-Julian Oscillation, Westerly wind bursts  Concluding remarks Next topic

18. 850 mb 200 mb JJA

19. 200 mb 850 mb DJF

20. Velocity potential We can separate the three-dimensional velocity field into a rotational part and a divergent part (see e.g. Holton, 1972, Appendix C.) rotational nondivergent irrotational divergent

21. Upper tropospheric (200 mb) mean seasonal velocity potential indicating the divergent part of the mean seasonal wind which is proportional to . (Adapted from Krishnamurti et al., 1973).

22. OLR < 225 W m  2 month From Lau & Chan, 1983

24. Walker circulation

25.  A satpix tour of the tropics  The zonal mean circulation (Hadley circulation), Inter- Tropical Convergence Zone (ITCZ)  Field experiments  Macroscale circulations, The Walker circulation, Monsoons  Synoptic scale weather systems, tropical waves  Moist convection and convective systems  The Madden-Julian Oscillation, Westerly wind bursts  Concluding remarks Next topic

26. Monsoons July

27. SE Asian Monsoon

28. January

29. Australasian Monsoon

30. South America: January climatology 200 mb wind850 mb wind

31. (From Webster, 1983) An example of monsoon variability 1963 1971 West coast of India

32.  A satpix tour of the tropics  The zonal mean circulation (Hadley circulation), Inter- Tropical Convergence Zone (ITCZ)  Field experiments  Macroscale circulations, The Walker circulation, Monsoons  Synoptic scale weather systems, tropical waves  Moist convection and convective systems  The Madden-Julian Oscillation, Westerly wind bursts  Concluding remarks Next topic

33. Time-longitude section of vis imagery - latitude band 10 -15 N From Wallace, 1970 July August June 0107 01/06 0108 time

34. Fig. 1.23 GMS – IR 25 Dec 1978 MSLP 25 Dec 1978 Winter MONEX A B C From Webster, 1983

35. Fig. 1.24 250 mb 25 Dec 1978 850 mb 25 Dec 1978 Winter MONEX A B C A BC shaded horizontal wind divergence From Webster, 1983

36. The variation of surface pressure at Darwin for the period 23 - 28 Dec. 1978.

37. Easterly waves over Africa WV Imagery 17 June 1997 00Z

38. Tropical cyclones TC tracks (1979-1988) Super typhoon Wynnie 11 Aug 1997

39.  A satpix tour of the tropics  The zonal mean circulation (Hadley circulation), Inter- Tropical Convergence Zone (ITCZ)  Field experiments  Macroscale circulations, The Walker circulation, Monsoons  Synoptic scale weather systems, tropical waves  Moist convection and convective systems  The Madden-Julian Oscillation, Westerly wind bursts  Concluding remarks Next topic

40. Moist Convection Trade Cumuli

41. The tropical troposphere  z km 29 o C -73 o C 15 -121 o C observed -150 o C+150 o C 77 o C Conclusion: Deep tropical circulations cannot be dry adiabatic

42. The role of diabatic processes z km 15 Conclusion: Deep convection occupies a small fractional area Latent heat release opposes adiabatic cooling Radiative cooling opposes adiabatic warming ITCZ subtropical high Fast ascent Slow descent

44. Successive locations of radar reflectivity contours in a tropical squall line. From Chang et al. (1987) Radar reflectivity contours (dBZ) of a tropical squall line observed during COPT81 (Ivory Coast, West Africa). Horizontal cross-section at low levels (0.5 – 1.5 km).

45. Radar reflectivity contours (dBZ) of a tropical squall line observed during COPT81 (Ivory Coast, West Africa). Vertical cross-section along the axis of propagation.

46. Types of convection

48.  A satpix tour of the tropics  The zonal mean circulation (Hadley circulation), Inter- Tropical Convergence Zone (ITCZ)  Field experiments  Macroscale circulations, The Walker circulation, Monsoons  Synoptic scale weather systems, tropical waves  Moist convection and convective systems  The Madden-Julian Oscillation, Westerly wind bursts  Concluding remarks Next topic

49. From JAS, Sept. 1972 Madden-Julian Oscillation

50. From Webster 1987 Madden-Julian Oscillation MJO

51. Indian Ocean Feb/Mar 2001 06/0207/0213/02 17/0224/0206/03

52. West Pacific Ocean – Feb 2001 06/0209/0213/02 21/0224/0229/02

53. http://www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/OLR/hov.last6mths.anom.S.gif

54. GOES-9 12 UTC 2 Dec 1997 10.7 micron image Westerly wind bursts

56.  Interaction between moist convection and the large-scale flow.  What are the controls on deep convection.  Models don’t get the diurnal variation correct.  No generally accepted theory of the Madden-Julian Oscillation.  Weather forecasting in the tropics is still very difficult compared with that in the middle latitudes. A few outstanding problems

57. The End Thank you for your interest Talk available at: http://www.meteo.physik.uni-muenchen.de\~roger\030514-dlr.pdf