How New Mini-Satellites Could Impact Hurricane Forecasts

A convoy of mini-satellites will use GPS to measure wind speeds at the warm surface core of tropical cyclones — where ocean meets air.

by Kimberly Miller, The Palm Beach Post, Fla. / December 5, 2016

(TNS) -- A fleet of eight micro-satellites launch this month from Cape Canaveral to investigate an atmospheric mystery as old as the sea and sky.

With core technologies the size of a loaf of bread and weighing just 64 pounds each, the innovative Cyclone Global Navigation Satellite System will belt the Earth between the Tropic of Cancer and Tropic of Capricorn to monitor hurricane hot spots.

The convoy of mini-satellites uses GPS to measure wind speeds at the warm surface core of tropical cyclones — where ocean meets air. It’s a region shrouded from even the most advanced radar technologies by rain drops, but believed to be critical in predicting cyclone intensity, girth and potential storm surge.

 

And unlike the 6,280-pound behemoth GOES-R weather spacecraft that was successfully launched Nov. 19 from the Cape, the minis will spread out around the globe providing full-time coverage of all the tropics all the time.

“This isn’t the first set of micro-satellites, but this is the vanguard of new satellites, it’s the beginning,” said Christine Bonniksen, NASA’s program executive for the system, dubbed CYGNSS. “These smaller satellites, with all the advances in technology, are becoming much more capable and can provide more frequent readings.”

The project is the first space-based system selected for funding by NASA’s Earth Venture Program, which focuses on lower-cost, science-driven missions that can be rapidly developed.

About $155 million was awarded for CYGNSS, which includes $102 million to principal investigator Chris Ruf, a professor in the University of Michigan’s Department of Climate and Space Sciences, and $53 million for the Pegasus rocket. Because the satellites are so light, they can all launch on one rocket.

The launch is scheduled for Dec. 12 at 8:05 a.m.

 

“This has not been done before on a satellite,” said Chris Landsea, science and operations officer at the National Hurricane Center. “It’s experimental and very intriguing with the promise that it may help us quite a bit.”

While forecasting the path of a hurricane has improved 50 percent over the past 15 years, forecasting storm intensity has lagged.

James Franklin, chief of the National Hurricane Center’s hurricane specialist unit, said the error rates for intensity were basically flat between 1990 and 2010. They’ve since fallen, and Franklin said there appears to have been about a 20 percent improvement in intensity errors the past 5 to 7 years.

Still, October’s Hurricane Matthew caught forecasters off guard when it intensified by 80 mph in 24 hours to become a dangerous Category 5 hurricane with 160 mph winds.

Part of the challenge in forecasting intensity is penetrating the hurricane eyewall to gather information about a storm’s inner core and the critical interactions happening in a slice of atmosphere just above the surface of the sea where the strongest winds are found.

Frank Marsik, an associate research scientist with University of Michigan’s Department of Climate and Space Sciences, said wind speeds are currently measured by satellites with radar scatterometers that emit microwave pulses toward the ocean’s surface and measure the subsequent backscattered signals.

The idea is a calm ocean will reflect very little microwave emissions back to the satellite, while wind-whipped waves will reflect more, helping forecasters determine wind strength.

But the signals break apart in the intense rainfall typically found at the eye of a hurricane.

CYGNSS will use already available GPS signals from existing satellites that are transmitted all day all over the globe and at a lower frequency than the scatterometers.

“As a result, the GPS signals can penetrate through the intense tropical rainfall associated with a hurricane eyewall, allowing the CYGNSS team to probe the inner core of hurricanes for the first time,” Marsik said. “This is critical, as improved forecasts of hurricane intensity (wind speed) will also lead to improvements in the forecast of the storm surge associated with land-falling hurricanes.”

Between 1963 and 2012, 49 percent of tropical cyclone deaths were storm surge related.

Data from the micro-satellites should be streaming in by the beginning of the 2017 hurricane season, but it may be another year before hurricane center meteorologists decide how to incorporate it into their forecasts.

“This will allow us to get the same readings the (hurricane hunter) planes get but all the way down to the surface of the ocean,” Bonniksen said. “And we will gather that information from the minute that the storm starts gathering all the way until it dissipates.”

©2016 The Palm Beach Post (West Palm Beach, Fla.) Distributed by Tribune Content Agency, LLC.

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