Aircraft measurement of the probability distribution of

precipitation rate and liquid water content

in the hurricaneR. A. Black J. Hallett

AOML, Miami, FL DRI Reno, NV

Typical WP-3D Flight Tracks

From Marks_et_all_1992

High RR Storms

• Storm A has almost all convective precip

• All others used standard flight pattern

• Storm B was SS Cat-4 during observation

Low RR Storms

• These storms had little high RR

• Storms were sampled normally

• 90% RR < 20 mm hr-1

• Long tail shows high RR eyewall was penetrated.

Recent Storms

• 90% RR < 20• Tail at large RR

nearly flat, smaller range.

• Strong Eyewall reflectivity avoided

HotPlate Raingauge

• Max RR 70mm hr-1

• Exposure: • 10 m elevation• 300 m from sea• Clear toward SE - N• Shielded N-E by

building• Max Power 1000 W

Hotplate Raingauge

• Data from Aug. 11 - Oct. 14, 2008• Winds normally off the sea• Looks similar to small RR hurricane

Raingauge PDF - Cont.

• Humid Tropical Coastal Air• Includes 1 torrential rain event

A Torrential Rain event

• This is the extreme event of the period.• Note the rapid increase in accumulation when RR >

50 mm hr-1.• Total 24-hr rain: 161 mm

Reflectivity - High RR

• Mean high reflectivity 35 - 45 dBZ

• Shallow slope on low reflectivity side

• Cum. Dist. Doesn’t reach 100% because data < 0 dBZ are included

Low RR storms

• Mean reflectivity 30 - 35 dBZ

• Peak reflectivity < ~50 dBZ

• Storms mostly steady - state

Recent Storms

• Median reflectivity < 30 dBZ

• Peak reflectivity < 50 dBZ

• High reflectivity area avoided

MM5 H. Bonnie 1998 Sim.

Conclusions

• Choice of flight path impacts data• Low RR Hurricane rainfall is similar to

Coastal Miami, FL summer rain• PDF can be used to compare model

result to observations• Changing rainfall climatology should be

detectable