The Convective Cloud Population of the Madden-Julian Oscillation: Early Results from DYNAMO

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

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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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This research is supported by NSF grant ATM AGS-1059611, DOE grant DE-SC0001164/ER-64752, and NASA grants NNX10AM28G and NNX10AH70G