9/5/2023 0 Comments Doppler radar oahuThese elevations range from 0.5° above the horizon to as high as 19.5° above the horizon. Because it’s important to see the elevated structure in features like thunderstorms, the radars regularly cycle through different elevations. Weather radars don’t just scan along one level. In VCP12, the radar will scan 14 elevation angles in 4.2 minutes. However, because the phase only changes when an object moves along the radar beam, the radar can only measure movement toward or away from the radar.Įxample storm mode VCP. The radar measures the change in phase of the beam between two pulses, and uses the difference to estimate the object’s speed. ![]() The radar also determines the velocity of the objects it detects, which can be used to infer wind speed in the atmosphere. For each hour of operation, the radar is only actually transmitting for seven seconds. However, each radar pulse lasts less than 1/600,000 of a second, which is followed by a listening period that lasts almost 1/1,000 of a second. The radar pulses have an average power of 450,000 Watts. Larger or more numerous objects return more energy, and result in a higher reflectivity. The energy is converted into reflectivity, and the time is converted into distance from the radar. The radar measures how much energy is reflected back, and how long it took to return. (The objects could be anything, not just precipitation one common problem around Hawaii is with sea spray being detected during windy days.) A small fraction of the energy is returned to the radar. The radar transmits an electromagnetic pulse, which reflects off objects in the atmosphere. This article includes information about weather radar in general, and about the specific radar sites we have in Hawaii. Weather radars are one of the most effective tools for detecting rainfall. This storm brought large hail to Kailua and Kaneohe, including a record-setting hailstone that measured 4.25 inches long, and generated a tornado that damaged homes in Lanikai.
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