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Bimodality in the Vertical Structure of Tropical Diabatic Heating

Bimodality in the Vertical Structure of Tropical Diabatic Heating. Chidong Zhang RSMAS, University of Miami In collaboration with Samson Hagos, Wei-Kuo Tao, Steve Lang , Yukari Takayabu, Shoichi Shige, and Masaki Katsumata BIRS Conference on Multiscale Processes in the Tropics

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Bimodality in the Vertical Structure of Tropical Diabatic Heating

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  1. Bimodality in the Vertical Structure of Tropical Diabatic Heating Chidong Zhang RSMAS, University of Miami In collaboration with Samson Hagos, Wei-Kuo Tao, Steve Lang , Yukari Takayabu, Shoichi Shige, and Masaki Katsumata BIRS Conference on Multiscale Processes in the Tropics April, 27- May 1, 2009 Banff, Alberta Canada

  2. Derive Q1 from in situ Observations From sounding data (Yanai et al. 1973): From radar data (Houze 1983):

  3. Idealized Tropical Meso-Scale Latent Heating Profiles Schumacker et al. (2008) Premise: Diabatic heating profiles directly relevant to the tropical large-scale circulation are aggregates of heating profiles associated with different types of cloud systems. Hartmann et al (1984); Mapes and Houze (1995); Schumacher et al. (2004)

  4. Questions: • What are the structure and evolution of prevailing diabatic heating profiles directly relevant to the tropical large-scale circulation? • How do the tropical large-scale atmospheric circulations respond to the prevailing heating profiles? • What are the roles of heating profiles in the MJO?

  5. Sounding Data Sources TOGA COARE KWAJEX NAME SCSMEX LBA GATE MISMO TWP-ICE with help from Paul Ciesielski, Steve Esbensen, Richard Johnson, Masaki Katsumata, Yasu-Masa Kodama, Steve Kruger, Wei-kuo Tao, Wen-wen Tung, Xiaoqing Wu, Michel Yanai, Xiping Zeng, and Minghua Zhang Marshal Islands (Yanai et al 1973) Winter MONEX (Johnson and Young 1983) AMEX (Frank and McBride 1989) BOMEX (Nitta and Esbensen 1974) TAMEX (Johnson and Bresch 1991)

  6. TOGA COARE Q1 mean mean+std dev EOF2 REOF1 REOF2 EOF1

  7. TOGA COARE Q1 Time Series Original Reconstructed from the first two REOF modes

  8. 2 3 4 1 5 8 6 7

  9. original REOF1&2 REOF1 REOF2

  10. TOGA COARE KWAJEX NAME SCSMEX LBA GATE MISMO TWP-ICE

  11. Combined REOF Analysis REOF Mode Field Experiment

  12. A (BH) B (MH) D (RC) C (TH) 6-hourly and daily data

  13. A (shallow) B (deep) (a) D (clear) C (stratiform) 6-hourly (b) daily Dq 6-hourly and daily data

  14. Phase A: stratiform deep shallow/congestus (BH) 15% 45% 40% Phase B: stratiform deep shallow/congestus (MH) 37% 43% 20% Phase C: stratiform deep shallow/congestus (TH) 56% 38% 6%

  15. Latent Heating Profiles 15˚S – 15˚N

  16. Latent Heating Profiles (mean ± standard deviation) 15˚S – 15˚N

  17. Probability Distribution Function as a Function of Height TRMM Storm Height (30˚S-30˚N) Maximum Q1 from the soundings Short and Naramura 2000 CSH Max

  18. A linear, steady-state model (nondimensionalized):

  19. -∇·(qV) mean A B C

  20. A B C A B C Phase A: stratiform deep shallow/congestus (BH) 15% 45% 40% Phase B: stratiform deep shallow/congestus (MH) 37% 43% 20% Phase C: stratiform deep shallow/congestus (TH) 56% 38% 6%

  21. Spectra of REOF PCs for TRMM Latent Heating

  22. Composite heating for eight phases defined by the two leading HSVD modes for CSH based on its two leading REOF modes combined (left) and overlaid (right).

  23. Composite heating for eight phases defined by the two leading HSVD modes for CSH using (left) its two leading REOF modes plus the time mean and (right) the original data.

  24. 90˚E 120˚E 150˚E Lin et al (2004)

  25. (Wu 2003)

  26. Zhang and Mu (2005)

  27. Zhang and Mu (2005)

  28. A GCM experiment (Li et al. 2009): R42L9 Radiation scheme: Slingo et al (1996) Cumulus scheme: Manabe et al. (1965) Boundary layer: Holtslag and Boville (1993) Land surface: Xue et al. (1991)

  29. Summary • Tropical large-scale diabatic (and latent) heat profiles are ubiquitously dominated by two modes: deep and shallow, independent of location and data sources (soundings, TRMM retrievals, global reanalyses); • These two modes define three prevailing large-scale diabatic heating profiles that evolve in a sequence of bottom, middle, and top heavy structures; • The large-scale vertical overturning circulations responding to the three prevailing heating profiles are of multi-cell structures; • Low-level, bottom-heavy heating appears to be essential to the MJO.

  30. Questions • What are the physical/dynamical reasons for the two dominant heating modes? Or are they simply statistical artifacts? • Are the two dominant modes of heating profiles related in any way to the bimodal distributions of heating peaks and precipitation echo height? • Which one is more fundamental to the MJO, low-level moistening or low-level heating? • Is the multi-scale interaction in horizontal (synoptic vs. planetary) or vertical (shallow vs. deep) more fundamental to the MJO?

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