What is NEXRAD?
NEXRAD, or NEXt generation RADar, is a Doppler radar system designed for weather surveillance. It functions mainly as an early warning system for meteorological events such as hurricanes and thunderstorms. NEXRAD stations provide almost complete radar coverage of the United States. Each station has a range of about 124 nautical miles.

How does NEXRAD work?
NEXRAD stations continuously send radar, or microwave, signals into the Earth's atmopshere. If the signal encounters an object, such as a raindrop or a bird, most of the energy will dissipate, but some of it will bounce back to the radar receiver. The amount of energy that's ultimately returned depends on the number or density of objects in the atmosphere. This amount is called "reflectivity." NEXRAD can also track the velocity and direction of objects in the atmosphere in this way.

Why Study Birds with NEXRAD?
Though NEXRAD was designed and built to detect weather, it also captures fingerprints of migrating birds. In fact, it is perhaps the single most important method of tracking bird migrations on a large scale in the United States. NEXRAD allows scientists to keep track of when birds are migrating, what routes they are following, how weather affects their migration, how many are migrating at any given time, etc. Not only does this data help increase our knowledge about migratory birds, it is also leading to important conservation efforts, such as the protection of critical migratory routes and stopover areas.

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