About the time that TOTO's deployment was winding down, other technologies that built upon TOTO's concept were gearing up. The first technology to take over the hazardous duty of being placed in the path of an oncoming twister was the turtle. These small, round devices look like hubcaps and were first sent into the field in 1986 [source: Tornado Project]. Instrumentation similar to that installed in TOTO was tucked inside turtles to record atmospheric pressure, humidity and temperature. What's more, the turtle made the jump to digital, allowing smaller instruments to produce more accurate readings.
Since turtles are small, they can be deployed throughout an area, increasing the chances one may be passed over by a twister. In May 1988, a turtle was impacted by a tornado in Oklahoma, but by the time the researchers retrieved it, the device had been tampered with, ostensibly by a curious human [source: Tornado Project].
Other devices also followed in the footsteps of TOTO. Dillocams and OZ (Observation Zero) were both designed to be placed in the path of a tornado. Both are outfitted with video cameras to capture visible data of the conditions within a twister. Snails, similar in appearance to turtles, are outfitted with seismic sensors to determine if tornadoes produce vibrations that can be felt in the ground when they pass. Researchers hoped an early warning system could be produced using seismic sensors already in use for earthquake detection, a system that's still in development [source: MSFC].
All of these devices, like TOTO, have a failing, however. Each is a one-shot deal. The optimal tornado measuring equipment would be a marriage of TOTO's portability a weather bureau's sophisticated instruments.
With the advent of Doppler radar, this became possible. Doppler radar uses radio waves to determine the density, direction and precipitation of a storm. A storm moving toward the radar sends back higher frequency radio waves to the antennae that originates and accepts waves. A storm moving away from an antenna returns in lower frequency [source: USA Today]. Doppler radar can pick up such large amounts of information about a storm that this data can be rendered into a 3-D representation of it. Meteorologists can now look into a storm to examine its characteristics, such as if it's producing hail or possesses a mesocyclone.
The Doppler On Wheels (DOW) project from the Center for Severe Weather Research and the Electra Doppler Radar (ELDORA) project from the National Center for Atmospheric Research were the first to take Doppler on the go. DOW is a Doppler antenna mounted the back of trucks, and ELDORA is a prop plane outfitted with an antenna. Both were used in the VORTEX project, arguably the first mobile tornado project to produce significant data. In June 1995, VORTEX tracked storms in Texas by plane and truck, compiling data from above and around the storm and providing meteorologists new raw information to be used for predicting when and where tornadoes will occur [source: UCAR].
While TOTO may have never taken a single accurate measurement of a tornado, the one-of-a-kind device helped pave the way to a thorough understanding of tornadoes, those steeples of fire in the sky.
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