The objectives of RAINEX are to use airborne observations to examine
simultaneously the dynamic and thermodynamic structures of hurricane inner core and
outer rainband regions where the positive potential vorticity associated with deep
convective cores are located. Numerical models will be used to investigate the
interactions of the rainbands and primary hurricane vortex circulation and their
role in hurricane intensity change. RAINEX is the first experiment using three-
Doppler-aircraft flying in hurricanes. Airborne Doppler radar will be used to
observe both eyewall and rainband internal vorticity structures simultaneously.
Dropsondes and smart balloon data will be used for thermodynamic environment of
hurricane rainbands and eyewall to support both analysis and modeling/forecasting.
Use model to determine how the vorticity features evolve and storm intensity changes.
Two NOAA smart balloons were launched from Puerto Rico in an effort to place the
balloons into a hurricane during the RAINEX experiment. Balloon 1 was launched at
about 0120 hours (GMT) on September 8th, 2005. It tracked to the northwest in the
direction of Hurricane Ophelia. After tracking the balloon for nearly a day and half,
the solar panel stopped working. This failure was diagnosed by monitoring the solar
radiation reading from the solar pyranometer, while the solar panel charging current
remained at zero as the battery voltage decreased over time. The balloon data were
monitored for a few hours and when it was determined beyond doubt that the batteries
were not going to charge, the balloon flight was terminated. We may have been able
to track the balloon for several hours longer, however we decided to terminate the
flight while battery power was good and so we could ensure the balloon did drop into
the ocean. The balloon position and altitude were tracked until it went into the
Balloon 2 was launched approximately 4 hours after the termination of balloon
1 at about 1838 hours (GMT) on September 9th, 2005. The balloon started heading
mostly to the west, over the Dominican Republic then over Cuba (which was not in the
direction that we wanted). After going across Cuba the balloon headed directly toward
the Yucatan Peninsula. After flying for a little over three days the elevation of the
balloon was changed from 2600 meters to around 700 meters. Balloon 2 then flew for a
few more hours, with everything working just fine, when communications to the balloon
failed and was never established again.
Map of the 2 smart balloons during RAINEX. Red dots path of balloon 1, blue dots
path of balloon 2.
The hurricane balloon effort during August and September 2005 provided important
logistical and practical experience for the smart balloon team. The significance of the
smart balloons to RAINEX is that they provided critical data in the boundary layer,
where relatively little in situ data are available from other sources.
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