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The Convective Cloud Population during the Buildup of the Madden-Julian Oscillation

This study analyzes convective cloud behavior during Madden-Julian Oscillation with TRMM data, radar echoes, and A-Train observations. Different phases of MJO impact cloud formation and organization, revealing insights into mesoscale convective systems.

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The Convective Cloud Population during the Buildup of the Madden-Julian Oscillation

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  1. The Convective Cloud Population during the Buildup of the Madden-Julian Oscillation R. Houze, S. Brodzik, J. YuanUniversity of Washington AGU Fall Meeting, San Francisco, 7 December 2011

  2. The Convective Cloud Population during the Buildup of the Madden-Julian Oscillation Three perspectives: TRMM Still going on! A-Train DYNAMO

  3. The MJO

  4. Indian Ocean 1 Phases of the MJO 2 3 Wheeler and Hendon 2004 4 5 6 7 8 DYNAMO

  5. TRMM

  6. Frequency of radar echo in “broad stratiform regions” of MCSs Phase 1 Phase 5 Phase 3 Phase 7

  7. Frequency of radar echo in “deep convective cores” Phase 1 Phase 5 Phase 3 Phase 7

  8. Frequency of “shallow isolated” radar echoes (anomaly) Phase 1 Phase 5 Phase 3 Phase 7

  9. Variation of Echo Category with MJO Phase

  10. A-Train

  11. Mesoscale Convective Systems (MCSs) have cold tops and large intense raining cores Both raining and anvil components are identified using A-Train instruments

  12. a) Cloud coverage b) Contribution to precipitation “Connected MCSs” “Separated MCSs” CMCSs SMCSs HCSs excl.MCSs non-HCSs Percentage % Other High CloudSystems Non-high-cloudSystems

  13. DYNAMO

  14. Cloud Structures (NCAR S-PolKa radar)

  15. Suppressed phase: Lines of non-precipitating clouds

  16. Suppressed phase: Clouds at cold pool boundaries

  17. Suppressed phase: Clouds at cold pool boundaries

  18. Small cumulonimbus small ice large non-melting ice graupel 8 km melting snow 4 km heavy rain

  19. Small, weakstratiform area

  20. Active phase: Large mesoscale system Stratiform Convective

  21. Robust melting layerinLarge MCS 10 km 5 km

  22. Convection feeding into a large MCS

  23. Shear

  24. Low-level westerly component, upper-level easterly component NE SW NE SW

  25. Biggest MCS of first active phase: weak unidirectional shear

  26. Larger-than-mesoscale Organization

  27. Giant Rings of Convection

  28. Westerly Surges

  29. Conclusions • Shallow isolated clouds present all the time • Stratiform regions have the biggest variation from suppressed to active phases • SF regions are associated with the largest MCSs • SF regions can be extremely robust with strong melting layers with melting graupel as well as snow • Shear seems to inhibit stratiform region formation • Convection has larger-than-mesoscale organization: rings, westerly bursts,….

  30. End This research is supported by NSF grant ATM AGS-1059611, DOE grant DE-SC0001164/ER-64752, and NASA grants NNX10AM28G and NNX10AH70G

  31. Extras

  32. Identify each contiguous 3D echo objectseen by TRMM PR Convective component Stratiform component Extreme characteristic Contiguous 3D volume ofconvective echo > 30 dBZ Extreme characteristic Contiguous stratiform echowith horizontal area > 50 000 km2 “Broad stratiform region” Top height > 8 km “Deep convective core” Horizontal area > 800 km2 “Wide convective core” Categories of radar echoes seen by TRMM

  33. MODIS TB11 + AMSR-E (Yuan and Houze 2010) combined to find“cold centers” & “raining areas” Locate 1st closed contour Use 260 K threshold Associate pixels with nearest cold center Use 1 mm/h threshold for rain rate Use 6 mm/h threshold for heavy rain

  34. 1 2 3 4 5 6 7 8 Phase

  35. 200 600 Mixing ratio anomaly 1000 Pressure (hPa) Phases 1,8 Phases 2,3 Phases 4,5 Phases 6,7 200 600 1000 DYNAMO 50 E 100 E 150 E 200 E

  36. Descent of easterlies

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