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Illustration of GPS IIF satellite.
To get ready for this year’s hurricane season, several NOAA scientists spent the last few months working to place Frisbee-sized satellite antennas high atop stationary platforms in the Gulf of Mexico. The instruments are based on Global Positioning System technology—most commonly known for making precise location measurements.
NOAA researchers are testing their ability to use a serendipitous power of GPS signals to improve weather forecasts—including forecasting hurricanes.
“We hope data from these GPS-Meteorology stations will make our tropical storm and hurricane forecasts even more accurate,” said Seth Gutman, at NOAA’s Earth System Research Laboratory in Boulder, CO.
GPS-Met station in Whitney, Nebraska.
High resolution (Credit: NOAA)
GPS radio signals—transmitted by satellite and received on the ground—are slowed down and bent by water vapor in Earth’s atmosphere. A decade ago, scientists were frustrated by this “noisy” effect of that water on their GPS positioning systems. In recent years, however, NOAA scientists and others around the world have learned to “listen to the noise” and use it to measure water vapor content, which has been notoriously difficult to understand, Gutman said.
It’s a critical variable in atmospheric science. However, moisture-rich air can make a hurricane more intense and dry air can weaken it. Water vapor also is a powerful greenhouse gas.
This winter’s Gulf installations of “GPS-Meteorology” packages are the first deployments this far away from land over open water. Being far from land makes for more accurate measurements of water vapor in an area where almost no other weather information is available.
Data from the GPS-Met packages will be pulled into forecast models this hurricane season, and Gutman and his colleagues suspect they’ll see improvements in storm forecasts. The data could even improve forecasts of weather much farther away, too.
NOAA’s observatory in Barrow, Alaska, host to a new GPS-Met system that identified problems with local water vapor measurement instruments.
High resolution (Credit: NOAA)
“If successful, the experiment could have far-reaching consequences, since most of the atmospheric moisture in the eastern two-thirds of the United States has its origins in the Gulf of Mexico,” Gutman said.
Gutman’s team is working closely with the National Weather Service Lake Charles, LA Forecast Office, for forecast improvements. The NOAA scientists also are collaborating with Louisiana State University researchers, who want to use GPS-Met data to make more accurate measurements of water height changes associated with storm surges, subsidence, and even climate change.
In addition, the NOAA team is working to install GPS-Met packages in other critical locations, including NOAA’s climate observatories. When a station was installed in Barrow, Alaska, recently, Gutman’s team found disagreement between his instrument’s measurements and observations made by balloon-borne instruments. It turned out that certain sensors on the balloon package were faulty.
“These problems were going unnoticed, because there was nothing to compare the data with,” Gutman said. “Now we have a reliable point of comparison.”
Learn more about NOAA's GPS-Meteorology stations online.