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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

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

slide2

Resemblances

MCS: Zipser 1969

MCS: Zipser et al. 1981

2-day: Takayabu et al. 1996

Kelvin: Straub & Kiladis 2004

MJO: Lin and Johnson 1996

outline
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’?
toga coare data sources at various scales
TOGA-COARE data sources at various scales

Sounding array data: CSU grids

VAD: ship radar (48km radius)

slide5

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?

slide6
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

evolution tilt similar across timescales with fixed spatial scale osa divergence
Evolution (tilt) similar across timescales with fixed spatial scale(OSA divergence)

total

=

30d

LP

+BP

+HP

slide9

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

rather the mcs life cycle appears to be a prototype for larger scale waves
Rather, the MCS life cycle appears to be a prototype for larger-scale waves.

zonesof differentcloud types

Zipser et al. 1981

slide11

LS zone favors cu…

… or cb

… or ns anvils

How is multiscale structure resemblance achieved?

slide13
What variables modulate cloud types in these LS zones?Hypothesis: T, q (via parcel buoyancy): emphasis on leading edge

Rain autocorrelation

entraining plume buoyancy and its parts
Entraining plume buoyancy, and its parts

Pure parcel effect

“Explains” “convection”?

capping effect

Moistness of entrained air

wrapup
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?”
osa specific humidity
OSA specific humidity

daily means

6 hourly data

4d means

6d

24d

40d

coare divergence osa ifa vad
COARE divergence: OSA, IFA, VAD

div

OSA

conv

rain

48h

IFA

VAD

smallest scale mesoscale hours even in point data
Smallest scale: mesoscale (hours) even in “point” data

Regressions vs. gauge rain

5 minute data

Gauge rain

Composites wrt +1 stdev excursions