The Convective Cloud Population of the Madden-Julian Oscillation:
Early Results from DYNAMO
Int. Conf. on Opportunities and Challenges in Monsoon Prediction in a Changing ClimateGolden Jubilee of the Indian Institute of Tropical Meteorology, Pune, India, 23 February, 2012
R. Houze D. Hence, S. Brodzik, K. Rasmussen, S.Powell,
H. Barnes, B. Dolan, K. Chakravarty, C. Burleyson, Z. Li, S. Ellis, T. Weckwerth, J. Vivekanandan, J. Hubbert, W.-C. Lee
MJO Initiation area
Addu Atoll
Five radars on Addu Atoll
Radar experiment goal
Characteristics and evolution of the MJO cloud population in the region where the disturbance builds up
Addu Atoll
S
Ka
NCAR S-PolKaRadar
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Rain over area scanned by S-PolKa
Suppressed conditionechoes
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Suppressed phases:
Lines of non-precipitating
clouds
Suppressed phases: The “worm echo”
Slightly active moist layer
Clouds building at cold pool boundaries
Slightly active moist layer
Clouds building at cold pool boundaries
Cold pool boundaries seen
in differential reflectivity
(ZDR)
Birds?Dragonflies?
???
Birds caught on camera
graupel
small ice large non-melting ice
heavyrain
meltingice
Moderate cumulonimbus begin to grow upscale
Doppler velocity
Hydrometeor type
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October 16
Refl. Rain
Conv.
Strat.
October 16
5 km
10 km
Intense melting layer
melting snow
graupel
50 dBZ!
Active phase few days later
Convection feeding into a large MCS
Biggest MCS of first active phase: weak unidirectional shear
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Squall line in late active phase westerlies
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Suppressed condition clouds
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Westerly Surges
November
October
Larger than mesoscale
organization of deep
convection
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Long arc line
Long arc linesegment on
radar
Squall linein the strong westerlies
Weak stratiform in the strong westerlies
Stra
tifor
m R
ain
Frac
tion
S-PolKa S-band Stratiform Rain Fraction
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The most robust squall line in the
strong westerlies…
…has only moderate stratiform
Momentum transport
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Summary of MJO cloud population characteristics & evolution seen by the S-PolKa radarHumidity gradient layers monitored & measuredCloud lines dominate in highly suppressed periodCold pools are first stage of convective population Graupel & other ice lofted & input into stratiform regionsConvection enhanced inside stratiform regionsMCS development strongest in weak shearShear inhibits stratiform region formation Westerlies organize convection on larger than mesoscaleSquall lines form in westerlies at back of active zoneSquall lines transport momemtum downward
End
This research is supported by NSF grant ATM AGS-1059611, DOE grant DE-SC0001164/ER-64752, and NASA grants NNX10AM28G and NNX10AH70G
End
This research is supported by NSF grant ATM AGS-1059611, DOE grant DE-SC0001164/ER-64752, and NASA grants NNX10AM28G and NNX10AH70G
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