Satellite Radar Studies of Extreme Convective

Storms

?Himalayas

Andes

Rockies

New Fellows Presentation, AGU, San Francisco, 5 December 2012

Robert A. Houze, Jr.University of Washington

Radars in Space

TRMM1997-

CloudSat

2006-

Typical Tropical Convective Cloud Population

TRMM

2 cm wavelength

CloudSat

3 mm wavelength

JJAS DJF

Locations of the deepest and most intense convective cores seen by TRMM over ~14 years in South Asia and South America warm seasons

Near the large mountain ranges

Romatschke et al. 2010 Romatschke and Houze 2010

Relationship to Mountain Ranges and Moisture Sources

?

Andes

HimalayasRockies

How similar are the storms in these three regimes?

The North American Case

Carlson et al. 1983

moist

Texas

dry,hot

MexicanPlateau

Gulf ofMexico

Something similar happens to extreme convective cores in the

western region of South Asia

Sawyer 1947

A case observed by TRMM

TRMM PR Observations WRF Simulation

Medina et al. 2010

Consistent with Sawyer 1947

Consistent with Sawyer

1947

Backward trajectories (HYSPLIT/NCEP)

2.5 km

1.0 km

Medina et al. 2010

Consistent with Sawyer 1947

WRF Model Simulation

Mixing ratio CAPE

Medina et al. 2010

Surface wind

Medina et al. 2010

WRF Simulation

Cloud just after convection formed in the model

Triggering is over foothills—consistent with satellite data

A similarregime occurs near the Andes

Convective Regimes in South AmericaIdentified by TRMM

Romatschke and Houze 2010

Example of triggering over

the Sierra Cordóba range

Rasmussen & Houze 2011

What the storm looked

like on the TRMM radar

Rasmussen and Houze 2011

Vertical air motions

Low-level winds

COMPOSITEof average

conditions for storms with

intense convection

seen by the TRMM radar

downup

moistunstable

Rasmussen and Houze 2011

Recap

SIMILARITIES

• Channeling of moisture

• Downwind capping

• Explosive triggeringDIFFERENCES

• Capping may be downslope from a plateau or response to flow over a ridge

• Triggering may be meteorological or orographic

?Himalayas

Andes

Rockies

LARGE MOUNTAIN RANGES NEAR WARM MOIST ZONES

• Pakistan flood cases• Convection in the Madden-

Julian Oscillation• Storm systems over land and

ocean• Other…

Similar studies

The future

?Himalayas

Andes

Rockies

This research was supported by NASA grants NNX10AH70G, NNX10AM28G,

and NSF grant AGS1144105

TRMM

GPM

Next generation:

Radars need to be in the same orbit!

CloudSat EarthCare

End

?Himalayas

Andes

Rockies

This research was supported by NASA grants NNX10AH70G, NNX10AM28G,

and NSF grant AGS1144105

End

?Himalayas

Andes

Rockies

This research was supported by NASA grants NNX10AH70G, NNX10AM28G,

and NSF grant AGS1144105

Global Pattern of Deep Convection seen by TRMM

Zipser et al. 2006

Maximum height of TRMM’s most intense radar echoes