Transcript 131211SanFrancisco_AGU-MJO_v11_Houze.pptx

AGU Annual Meeting, San Francisco, 11 December 2013
Indian
Ocean
West
Pacific
“Active
Period”
~1-3 weeks
The MJO
scale
~30-60
days
1
2
3
4
“Active
5
Period”
~1-3 weeks
6
7
8
TOGA
DYNAMO
COARE
Wheeler &
Hendon 2004
The convective scales
Examples from DYNAMO
~½-1 h
Shallow
isolated
Deep cores
Examples
~5-10 h
Wide cores
Broad
stratiform
From Powell and Houze 2013
TRMM radar shows how the scale of individual
convective entities vary with phase of the MJO
Shallow Isolated
Echoes
Deep Convective
Cores
Wide Convective
Cores
Broad Stratiform
Regions
Suppressed conditions
Active conditions
Barnes and Houze 2013
~50 aircraft surveys in TOGA COARE
Convective
Stratiform
x
Kingsmill and Houze 1999
~50 aircraft surveys in TOGA COARE
Convective
Stratiform
x
Kingsmill and Houze 1999
Wide convective elements and broad
stratiform regions are like Moncrieff’s
mesoscale layer model of deep tropical
convection…
100-200 km
Moncrieff 1992
…mesoscale adjustment to shear and
thermodynamic stratification
DYNAMO radar data show microphysical stratification
~constant for both convective and stratiform entities
October
November
December
Convective
Convective
Convective
Stratiform
Stratiform
Small ice
Dry snow
Graupel
Melting snow
Stratiform
Small ice
Dry snow
Graupel
Melting snow
% of observations
Rowe & Houze 2013
Intermediate scales
• Smaller than MJO
• Larger than convective entities
S-PolKa Radar Rainfall at Addu Atoll in DYNAMO
OLR
Powell and Houze 2013
October Active Period
Rain seen by the
S-PolKa radar in
DYNAMO
November Active Period
Filter and composite
Occurred in
“episodes”
separated by
~2-7 days
December Active Period
Zuluaga and Houze 2013
Composite large-scale divergence and vertical motion
during 2-day rainfall episodes
Divergence
Zuluaga and Houze 2013
Variation of the DYNAMO radar echo population
relative to a precpitation episode
Composite of all 2-day
rainfall episodes
Zuluaga and Houze 2013
The largest scale
Vertical structure of the MJO
Moncrieff 2004
Vertical structure of the MJO
Coupling
with the
changeable
convective
population
Moncrieff 2004
Vertical structure of the MJO
• Kelvin wave
• Rossby wave
• 2-7 day waves
• Cloudhumidity
feedback
• Mid-latitude
interaction
Moncrieff 2004
Summary
Convection in the MJO has multiple important scales
•
•
•
•
Shallow isolated
Deep cores
Wide cores
Broad stratiform rain areas
How does convection accommodate systematically to
• Intermediate scale waves, which account for most
of the rainfall
• Larger scale of the MJO itself
End
This research was supported by
NASA grants NNX10AH70G, NNX13AQ37G and NNX13AG71G
NSF grant AGS-1059611
DOE grant DE-SC0008452
Extra Slides
DYNAMO radar data composited relative to the
mesoscale airflow
Convective
Convective
entities
…Barnes talk & upcoming paper
DYNAMO radar data composited relative to the
mesoscale airflow
Stratiform entities
Convective
Convective
entities
0°C
…Barnes talk & upcoming paper
Stretched Building Block Hypothesis
Mapes et al. 2006
Cloud population at three different times
Large-scale wave structure at the same times
Vertical structure of the MJO
~10,000 km
Moncrieff 2004
Upper-level eastward propagating Kelvin waves?
u’ at 150 mb
DYNAMO
…Scott Powell’s poster