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St. Petersburg Coastal and Marine Science Center

St. Petersburg Coastal and Marine Science Center > Coastal Change Hazards: Hurricanes and Extreme Storms

Coastal Change Hazards: Hurricanes and Extreme Storms

Ground Surveys

A U.S. Geological Survey surveyor sets up a global positioning system reference station in Florida Everglades over a known benchmark
Figure 1: A USGS surveyor sets up a GPS reference station in Florida Everglades over a known benchmark. The GPS receiver (blue) is placed in a waterproof box during data collection. A Dorne-Magolin type GPS antenna is used to minimize multi-path interference from adjacent objects. A fixed height antenna tripod is used to ease setup and reduce setup error. [larger version]
The USGS uses global positioning system (GPS) differential correction techniques to improve the quality of aircraft trajectories. The underlying premise of differential GPS (DGPS) is that any two receivers, a base station or reference receiver and a rover receiver, are relatively close together and experience similar atmospheric errors. Atmospheric errors that are not accounted for may reduce the quality of the aircraft trajectories. DGPS requires that the reference GPS receiver be set up on a precisely known location (Figure 1). For a particular survey, the USGS either set up their own reference station or use National Oceanographic and Atmospheric Administration/National Geodetic Survey Continuous Operating Reference Stations (NOAA/NGS CORS) stations. The base station receiver calculates its position based on satellite signals and compares this location to the precise known location. The difference is applied to the GPS data recorded by the aircraft's GPS receiver, thus improving the overall quality or the trajectory.

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St. Petersburg Coastal and Marine Science Center > Coastal Change Hazards: Hurricanes and Extreme Storms

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