Regional, Seasonal and Diurnal Variations of Convection in the Asian Monsoon Region

1. Regional, Seasonal and Diurnal Variations of Convection in the Asian Monsoon Region Ulrike Romatschke, Robert Houze, Socorro Medina Clouds and Precipitation Seminar, University of Washington, 15 November 2007

2. Region of Study

3. Outline • Introduction Dataset • Regonal Variations Comparison with Houze et al. • Seasonal Variations Premonsoon – Monsoon • Diurnal Variations Dependence on topography • Conclusion and future Work

4. Dataset • TRMM Precipitation Radar (PR), Version 6 • Products 2A23: Radar Rain Characteristics 2A25: Radar Rainfall Rate and Profile • Monsoon Season: June - September 1999-2001 2004-2006 • Premonsoon Season: May 1999-2006

5. Data Processing • Interpolation on Cartesian Grid Gridspacing horizontal: ~5 km vertical: 250 m • Search for individual systems contiguous pixels define system characteristic parameters (e.g. time, location, size,…)

6. 20 16 12 8 4 0 Definitions Height [km] • Deep Intense Convective Cores 40 dBZ echo > 10 km in hight • Wide Intense Convective Cores 40 dBZ echo area > 1,000 km² • Broad Stratiform Echos area > 50,000 km² 0 42.5 85 Distance [km] 24 22 20 Latitude 84 86 88 90 Longitude 15 20 Latitude 90 95 [dBZ] Longitude

7. Objectives • Compare with Houze et al. (2007) • Extend dataset geographical region Premonsoon Season • Diurnal Cycle • Find especially active regions

8. Outline • Introduction Dataset • Regonal Variations Comparison with Houze et al. • Seasonal Variations Premonsoon – Monsoon • Diurnal Variations Dependence on topography • Conclusion and future Work

9. Comparison Deep Intense Convective Cores 1999-2001/2004-2006 2002-2003

10. Large Scale Flow Patterns during Monsoon 700 mb 1000 mb 40 30 20 10 60 70 80 90 100/60 70 80 90 100 Terrain [km]

11. Comparison Wide Intense Convective Cores 1999-2001/2004-2006 2002-2003

12. Comparison Broad Stratiform Systems 1999-2001/2004-2006 2002-2003

13. Outline • Introduction Dataset • Regonal Variations Comparison with Houze et al. • Seasonal Variations Premonsoon – Monsoon • Diurnal Variations Dependence on topography • Conclusion and future Work

14. Premonsoon Monsoon Deep Intense Convective Cores

15. The Indian Dry-Line Weston (1971) 1000 mb 700 mb Surface p [mb] and v 500 mb v

16. The Indian Dry-Line 200 mb 700 mb 1000 mb Monsoon Premonsoon

17. Premonsoon Monsoon Wide Intense Convective Cores

18. Premonsoon Premonsoon Wide vs. Deep Intense Convective Cores

19. Monsoon Monsoon Wide vs. Deep Intense Convective Cores

20. Monsoon Ganges Delta Wide vs. Deep Intense Convective Cores

21. Premonsoon Monsoon Broad Stratiform Systems

22. Rain Climatology Monsoon Broad Stratiform Systems Xie et al. (2006)

23. Outline • Introduction Dataset • Regonal Variations Comparison with Houze et al. • Seasonal Variations Premonsoon – Monsoon • Diurnal Variations Dependence on topography • Conclusion and future Work

24. Diurnal Cycle, Monsoon

25. Diurnal Cycle

26. Diurnal Cycle

27. Diurnal Cycle, Monsoon

28. Diurnal CycleDeep Intense Convective CoresMonsoon

29. Diurnal CycleDeep Intense Convective CoresMonsoon

30. Diurnal CycleDeep Intense Convective CoresMonsoon

31. Diurnal CycleDeep Intense Convective CoresMonsoon

32. Diurnal CycleDeep Intense Convective CoresPremonsoon

33. Diurnal CycleDeep Intense Convective CoresPremonsoon Surface p [mb] and v Weston (1971) Xie et al. (2006)

34. Diurnal Cycle, Deep Intense Convective Cores, Premonsoon Zuidema (2002) Mean percent high cloudiness Cloud Top < 210 K May – September 1999

35. Diurnal Cycle, Monsoon

36. Diurnal Cycle, MonsoonWide Intense Convective Cores1999-2001 vs. 2004-2006 1999-2001 2004-2006

37. Diurnal CycleWide Intense Convective CoresMonsoon

38. Diurnal CycleWide Intense Convective CoresMonsoon Xie et al. (2006)

39. Diurnal CycleWide Intense Convective CoresPremonsoon - Monsoon

40. Diurnal CycleWide Intense Convective CoresPremonsoon

41. Diurnal Cycle, Monsoon

42. Diurnal Cycle, Monsoon

43. Diurnal CycleBroad Stratiform SystemsMonsoon

44. Diurnal CycleBroad Stratiform SystemsMonsoon

45. Diurnal CycleBroad Stratiform SystemsMonsoon

46. Diurnal CycleBroad Stratiform SystemsMonsoon Williams and Houze (1987)

47. Outline • Introduction Dataset • Regonal Variations Comparison with Houze et al. • Seasonal Variations Premonsoon – Monsoon • Diurnal Variations Dependence on topography • Conclusion and future Work

48. Conclusions • Larger independent dataset seems to confirm Houze et al. (2007) • Premonsoon – Monsoon •Shift in places of occurrence of Deep and Wide Intense Convective Cores. • More Wide Intense Convective Cores and Broad Stratiform Systems over the ocean during Monsoon. • Diurnal Cycles • Strong afternoon peak in Deep Intense Convective Cores. • Afternoon and night peaks in Wide Intense Convective Cores. • Evening minimum in Broad Stratiform Systems. • Rain climatology compares • with Broad Stratiform Systems over the ocean. • with Wide Intense Convective Cores at the Himalayan Foothills. • not with Deep Intense Convective Cores.

49. Conclusions • Larger independent dataset seems to confirm Houze et al. (2007) • Premonsoon – Monsoon •Shift in places of occurrence of Deep and Wide Intense Convective Cores. • More Wide Intense Convective Cores and Broad Stratiform Systems over the ocean during Monsoon. • Diurnal Cycles • Strong afternoon peak in Deep Intense Convective Cores. • Afternoon and night peaks in Wide Intense Convective Cores. • Evening minimum in Broad Stratiform Systems. • Rain climatology compares • with Broad Stratiform Systems over the ocean. • with Wide Intense Convective Cores at the Himalayan Foothills. • not with Deep Intense Convective Cores. This is just the beginning!

50. Future Work • Get 2002/2003 Version 6 data. • Statistics for other variables. • Look at specific regions • physical background • different variable fields (e.g. wind) • satellite data