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 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 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.