High-Altitude Imaging Wind and Rain Airborne Profiler

NASA's High-Altitude Imaging Wind and Rain Airborne Profiler - or HIWRAP - is a conically scanning Doppler radar, meaning it scans in a cone-shaped manner. Wind measurements are crucial for understanding and forecasting tropical storms since they are closely tied to the overall dynamics of the storm. The HIWRAP instrument is able to measure line-of-sight (along the radar beam) and because it scans in a cone beneath the aircraft, it gets two looks at most parts of the storm, allowing calculations of the three-dimensional wind and rain fields. In the absence of rain, it can also measure ocean surface winds.

Transcript

00:00:00 When it comes to hurricanes, research has come a long way to help predict when and where a storm will hit. Forecasting intensity is a much bigger challenge, and an instrument called HIWRAP will investigate the strength of a storm. The HIWRAP instrument will fly aboard an aircraft to study storms from the very large down to the very small scale. Braun: And because those smaller scales tend to be much chaotic and difficult to predict, and the interactions between those smaller scales and the large scales is far more complex, it makes it a huge challenge to try to improve intensity forecasts. The High-Altitude Imaging

00:00:40 Wind and Rain Airborne Profiler, or HIWRAP, is a radar designed to examine the factors of storm intensity. Braun: The HIWRAP Doppler radar is a dual-frequency radar, so it has two frequencies that measure at two different angles and as the plane is flying, it's sort of scanning in a cone. And as it's flying over a particular target--say, the eyewall of a storm--by scanning in a cone it looks first one way, and then sees the storm from a different direction. And that's what allows us then to measure the three-dimensional winds and precipitation within the storm. Because the storm and the aircraft are both moving, the HIWRAP must send out 5,000 pulses

00:01:21 a second to get an accurate read on precipitation particles, like rain or ice. The signals that bounce back reveal the type, size, and distribution of rain or ice particles, as well as how fast the particles are moving. The speed of the particles can help determine the wind and circulation in a storm. HIWRAP will provide scientists with years of unprecedented data that will allow them to decipher the formation, structure, and intensification of hurricanes.

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