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The mesoscale convection life cycle: building block or prototype for larger-scale tropical waves?

The mesoscale convection life cycle: building block or prototype for larger-scale tropical waves? . Brian Mapes @ U. of Miami Stefan Tulich, Jialin Lin @ NOAA ESRL/PSD (formerly CDC) Paquita Zuidema @ U. of Miami paper in press at Dynamics of Atmospheres and Oceans contact mapes@miami.edu.

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The mesoscale convection life cycle: building block or prototype for larger-scale tropical waves?

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  1. The mesoscale convection life cycle:building block or prototype for larger-scale tropical waves? Brian Mapes @ U. of Miami Stefan Tulich, Jialin Lin @ NOAA ESRL/PSD (formerly CDC) Paquita Zuidema @ U. of Miami paper in press at Dynamics of Atmospheres and Oceans contact mapes@miami.edu

  2. Resemblances MCS: Zipser 1969 MCS: Zipser et al. 1981 2-day: Takayabu et al. 1996 Kelvin: Straub & Kiladis 2004 MJO: Lin and Johnson 1996

  3. Outline • Multiscale resemblance illustrated from obs • Samples and regression composites • Smallest scale (building block): mesoscale (10’s km, h’s) • but with convective cell substructure • On up to intraseasonal • Null hyp: LS structure inherited from MCS ‘block’ • rejected • Instead: zones of (cu, cg, cb, ns) cloud type enhancements • Why and how? • How to interpret humidity, divergence: proxies or causes of ‘convection’?

  4. TOGA-COARE data sources at various scales Sounding array data: CSU grids VAD: ship radar (48km radius)

  5. Doppler radar VAD results: 48km radiuslag-p regressions of divergence vs. Z-R rainratemean of 7 field programs (~104 h data) (pattern similar in each of the 7) Only slight mass-balance adjustment needed Mass flux (- 10-6 s-1 per mm/h Mapes and Lin 2005 MWR Multi-hour time scale: artifact of spatial scale?

  6. Pointdata (5’ vertically pointing cloud radar coverage vs. gauge rain, EPIC 2001): irreducible multi-hour time scales? cu dynamics (multi- cellular) anvil micro- physics… …including stratiform rain

  7. Evolution (tilt) similar across timescales with fixed spatial scale(OSA divergence) total = 30d LP +BP +HP

  8. dawn visible pix at those 4 times a) b) c) d)

  9. Building block null hypothesis: that multiscale tilt is reproducibleby superpositionof fixed-structure (VAD derived) divergence building blockshmmm… No.

  10. Rather, the MCS life cycle appears to be a prototype for larger-scale waves. zonesof differentcloud types Zipser et al. 1981

  11. LS zone favors cu… … or cb … or ns anvils How is multiscale structure resemblance achieved?

  12. What variables modulate cloud types in these LS zones?Hypothesis: T, q (via parcel buoyancy): emphasis on leading edge Rain autocorrelation

  13. Entraining plume buoyancy, and its parts Pure parcel effect “Explains” “convection”? capping effect Moistness of entrained air

  14. Wrapup • Multiscale resemblance illustrated from obs • Smallest scale (building block): mesoscale • with convective substructure • COARE sounding array: ~2 day, ~2 week, ~40d periods • Slow evolution is not just a convective cloud life cycle, aliased upscale: rather, there are zones of cloud type (cu, cg, cb, ns) enhancements • On both MCS and larger scales • Why and how? • Leading edge: perhaps governed via plume buoyancy? • Circularity: is q proxy or cause? “moisture-convection feedback” • Trailing edge: more subtle? - Shear? Wave ascent? • Careful!Filtering can introduce spurious congestus stage - stratiform stage antisymmetry! Or is it a “vertical mode?”

  15. Extra slides

  16. OSA specific humidity daily means 6 hourly data 4d means 6d 24d 40d

  17. COARE divergence: OSA, IFA, VAD div OSA conv rain 48h IFA VAD

  18. Smallest scale: mesoscale (hours) even in “point” data Regressions vs. gauge rain 5 minute data Gauge rain Composites wrt +1 stdev excursions

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