Global Variability of Intense Convection

Robert A. Houze, Jr.University of Washington

ISSCP at 30, New York, 22 April 2013

Radars in Space

CloudSat2006-

TRMM1997-

Epic Floods in Pakistan2010, 2011, 2012

25N

30N

65E 75E65E 75E 65E 75E

2010 2011 2012

16

0

Hei

ght (

km)

8

Distance (km) 287 0 232 0 241 0

Sindh

TRMM data showing storms producing the floods

These storms are

Mesoscale Convective Systems

“MCSs”

Large areasof cold top

Example outbreak of MCSs

1458GMT 13 May 2004

ConvectivePrecipitation

StratiformPrecipitation

Radar echoes showing the precipitation in the 3 MCSs

TRMM and CloudSat radars & other data have helped us map

MCS occurrence globally

Identify each contiguous 3D echo objectseen on radar

Convective component Stratiform component

Extreme characteristicContiguous 3D volume ofconvective echo > 40 dBZ

Top height > 10 km

“Deep convective core” Horizontal area > 1 000 km2

“Wide convective core”

Extreme characteristicContiguous stratiform echo

with horizontal area > 50 000 km2

“Broad stratiform region”

TRMM Radar Distinguishes Convective and Stratiform Components of MCSs

Continents

Deep Convective

Cores

BroadStratiform

Regions

JJAS DJF

Wide Convective

Cores

South Asia&SouthAmerica

Deep Convective

Cores

BroadStratiform

Regions

Wide Convective

CoresAfrica

Oceans

TRMM Radar Observations of the MJO over the Indian Ocean

Phase 7

Active Phase Suppressed Phase

Deep Convective

Cores

Broad Stratiform

Rain Areas

The A-Train Era

Details learned from field projects

Basic components

Houze et al. 1989

Anvil Anvil

Raining core

Cold top

Str

atifor

m

Conve

ctiv

e

A-Train sees all of this!

How A-Train sees the whole MCS

12

3

The Anvil Problem

Extensively studied

Need to understand how anvil is related to the

raining region

Mesoscale Convective System

Statistics of anvil width & thickness seen by CloudSat

Yuan and Houze 2010

Africa Indian Ocean

Yuan, Houze, and Heymsfield 2011

Africa Indian Ocean

Internal structure of MCS anvils

Combining cloud top and raining cores

260KClosedcontour Rain

Heavy rain

Identify High Cloud Systems (HCSs)

ConnectedHCSs

SeparatedHCS

Which HCSs are MCSs?

Yuan and Houze 2010

PDF of rain amount as a function of raining core properties

Size of raining core

Min

TB

11 o

ver

rain

ing

co

re

2000 km2

220°K

56% all tropical rain

Using these values for “MCS” criteria

Yuan and Houze 2010

MCSs Over the Whole TropicsSmallest 25% (<12,000 km2)

Largest 25% (>40,000 km2)

“Superclusters”

Yuan and Houze 2010

Indian Ocean MCSs Contribution to Rainfall by phase of the Madden-Julian Oscillation

Yuan and Houze 2012

Connected MCSs

Separated MCSs

Other high cloud systems

Active Suppressed

Composite MCS Lightning

Determined from WWLLN

Separated

West PacificEq. Africa Eq. AtlanticArgentina

Connected

Composite MCS Lightning in the MJO

Separated

SeparatedSUPPRESSED

ACTIVE

Conclusions• TRMM radar data:

• Deep convection takes on various forms

• Forms controlled by mountain ranges & flow regimes such as the MJO & monsoon

• A-Train data • Show anvils of MCSs• Identifies MCSs globally• Lightning data related to MCSs, e. g.

in MJO• To come: relate to aerosol

observations

EndThis research was supported by NASA grant NNX10AH70G, NASA

grant NNX10AM28G, and NSF grant AGS-1144105

CloudSat applied to MCS anvils

Internal structure of MCS anvils

CVCV

CVCV

Indian Ocean Anvils

MODIS/AMSR-E identifies cold top

locates the raining coreremainder is anvil

Anvil Anvil

Raining core

Cold top

Frequency of MCS anvils over tropics

Yuan and Houze 2010