The Cloud Population of the Madden-Julian Oscillation

Atmos. Sci. Colloquium, Seattle, 6 April 2012

R. Houze

and 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

Early Results from DYNAMO

IndianOcean 1

2

3

4

5

6

7

8

Wheeler and Hendon 2004

The MJO

DYNAMO

7N

Equator

S

Ka

NCAR S-PolKaRadar

Satellite

Global models

Soundings

Other island radars

Ship data

Ship radars

Aircraft data

S-PolKaradar

NCARradarprocessor

UW server UW workstations

Daily Science Summaries

NCAR field catalog

Project Data Flow

LIghtning

Radar experiment goal

Characteristics and evolution of the MJO cloud population in the region where the disturbance builds up

Addu Atoll

Supp. Supp. Supp.ActiveActive ActiveLull

Rain over area scanned by S-PolKa

Suppressed conditionechoes

Supp. Supp. Supp.ActiveActive ActiveLull

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

Supp. Supp. Supp.ActiveActive ActiveLull

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

Supp. Supp. Supp.ActiveActive ActiveLull

Giant Rings of Convection

Larger than mesoscale

organization of deep

convection

Squall line in late active phase westerlies

Doppler velocity

Hydrometeor type

Supp. Supp. Supp.ActiveActive ActiveLull

Suppressed condition clouds

Supp. Supp. Supp.ActiveActive ActiveLull

Supp. Supp. Supp.ActiveActive ActiveLull

Westerly Surges

November

October

Larger than mesoscale

organization of deep

convection

Supp. Supp. Supp.ActiveActive ActiveLull

Long arc line

Long arc linesegment on

radar

Squall linein the strong westerlies

Weak stratiform in the strong westerlies

Str

atifo

rm R

ain

Fra

ctio

nS-PolKa S-band Stratiform Rain Fraction

Supp. Supp. Supp.ActiveActive ActiveLull

The most robust squall line in the

strong westerlies…

…only moderate stratiform

…robust momentum transport

Supp. Supp. Supp.ActiveActive ActiveLull

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