Hurricane-forecast satellites will keep close eyes on the tropics

A set of eight hurricane-forecast satellites being developed at the University of Michigan is expected to give deep insights into how and where storms suddenly intensify--a little-understood process that's becoming more crucial to figure out as the climate changes, U-M researchers say.

The Cyclone Global Navigation Satellite System is scheduled to launch in fall 2016. At the American Geophysical Union Meeting in San Francisco this week, U-M researchers released estimates of how significantly CYGNSS could improve wind speed and storm intensity forecasts.

CYGNSS--said like the swan constellation--is a $173-million NASA mission that U-M is leading with Texas-based Southwest Research Institute. Each of its eight observatories is about the size of a microwave oven. That's much smaller than a typical weather satellite, which is about the size of a van.

The artificial CYGNSS "constellation," as researchers refer to it, will orbit at tropical, hurricane-belt latitudes. Its coverage will stretch from the 38th parallel north near Delaware's latitude to its counterpart in the south just below Buenos Aires.

Because of their arrangement and number, the observatories will be able to measure the same spot on the globe much more often than the weather satellites flying today can. CYGNSS's revisit time will average between four and six hours, and at times, it can be as fast as 12 minutes.

Conventional weather satellites only cross over the same point once or twice a day. Meteorologists can use ground-based Doppler radar to help them make predictions about storms near land, but hurricanes, which form over the open ocean, present a tougher problem.

"The rapid refresh CYGNSS will offer is a key element of how we'll be able to improve hurricane forecasts," said CYGNSS lead investigator Christopher Ruf, director of the U-M Space Physics Research Lab and professor of atmospheric, oceanic and space sciences.

"CYGNSS gets us the ability to measure things that change fast, like extreme weather. Those are the hardest systems to measure with today's satellites. And because the world is warmer and there's more energy to feed storm systems, there's more likelihood of extreme weather."

Through simulations, the researchers quantified the improvement CYGNSS could have on storm intensity predictions. They found that for a wind speed forecast that is off by 33 knots, or 38 miles per hour--the average error with current capabilities--CYGNSS could reduce that by 9 knots, or about 10 mph.

Considering that the categories of hurricane strength ratchet up, on average, every 20 mph, the accuracy boost is "a very significant number," Ruf said.

"I'd describe the feeling about it as guarded excitement," he said. "It's preliminary and it's all based on models. People will be really excited when we get up there and it works."

The numbers could also improve as scientists update weather prediction tools to better use the new kind of information that CYGNSS will provide.

For people who live in common hurricane or typhoon paths, closer wind speed predictions could translate into more accurate estimates of the storm surge at landfall, Ruf said. That's the main way these systems harm people and property.

"The whole ocean gets higher because the wind pushes the water. That's really hard to forecast now and it's an area we hope to make big improvements in," Ruf said.

Researchers expect the satellite system to give them new insights into storm processes. Hurricanes evolve slowly at first, but then they reach a tipping point, says Aaron Ridley, a professor of atmospheric, oceanic and space sciences.

"The hurricane could be meandering across the Atlantic Ocean and then something happens." Ridley said. "It kicks up a notch and people aren't exactly sure why. A lot of scientists would like to study this rapid intensification in more detail. With a normal mission, you might not be able to see it, but with CYGNSS, you have a better chance."

The satellites will operate in a fundamentally different way than their counterparts do. Rather than transmit a signal and read what reflects back, they'll measure how GPS signals from other satellites bounce off the ocean surface. Each of the eight CYGNSS nodes will measure signals from four of the 32 Global Positioning System satellites.

They'll also be able to take measurements through heavy rain--something other weather satellites are, surprisingly, not very good at.

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New Forecast: Sun's 'Superstorms' Could Doom Satellites (SPACE.com)

Magnetic storms set off by the sun could pose a bigger threat than thought to weather, communication, military and other satellites close to Earth, with a potentially devastating economic impact, scientists suggest.

In the new study, researchers found that solar radiation can energize a belt of high-energy particles that surrounds Earth more dramatically than previously believed.

The study focused on the possible effects of a particularly strong magnetic storm on the Van Allen radiation belts, the dangerous rings of high-energy particles that girdle the Earth. The belts are split into two distinct zones. The outer belt, which is made up of electrons, reaches from about 15,800 to 31,600 miles (25,500 to 51,000 kilometers) above the surface, while the inner belt, which consists of a mix of electrons and protons, reaches from about 4,000 to 8,000 miles (6,400 to 12,800 km) above. [Stunning Photos of Solar Flares & Sun Storms]

Scientists had known the outer belt could become far more intense during geomagnetic storms caused by high-energy particles spewed by the sun, such as the storm that supercharged Earth's northern lights display Monday night (Sept. 26). However, they have long thought such storms do not affect the inner belt.

Now computer simulations suggest that during a "superstorm" — which has occurred in the past and is likely to recur in the future ? the electrons in the inner belt, too, could become energized. Near-Earth radiation could then remain dramatically more intense for several years afterward.

"The increase in radiation in the inner zone may last for up to a decade and continue damaging satellites for years after a very strong storm," study lead author Yuri Shprits, a space physicist at the University of California, Los Angeles, told SPACE.com.

This radiation would damage satellites in that zone and potentially cut their lifetimes by five-sixths or more. [Related: Space Radiation to Rise for Astronauts, Airline Passengers]

"It would not destroy all satellites at once," Shprits said. "However, at least according to our calculations, a very strong storm can increase the radiation dose in the inner zone by a factor of 10, and within a few years we may lose a significant portion of the satellites that traverse the inner zone."

In terms of new strategies that might be needed to protect satellite systems, "it's hard to say," Shprits said. "First of all, we need to estimate risks and estimate cost. If cost is too high, we may want to accept the risks and start getting ready to replenish the fleet in the case of such event."

"There are a number of rather expensive strategies that can be used to mitigate the risk, including redundancy in electronics and increased shielding," he added. "Zero risk means infinite cost."

Two missions to study the radiation belts are planned for 2012, Shprits noted: NASA's Radiation Belt Storm Probe will observe radiation belts in the equatorial plane, while Moscow State University's LOMONOSOV mission, with UCLA-built instruments on board, will observe radiation belts at low altitudes.

The scientists detailed their findings online in the Aug. 25 issue of the journal Space Weather.

Follow SPACE.com contributor Charles Q. Choi on Twitter @cqchoi. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

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Weather Satellites Vital to NASA's Future (ContributorNetwork)

As the space shuttle program comes to a close, NASA will look to the future with robotic probes of other planets. Another major part of the space agency's mission will be to launch weather satellites to observe the Earth's always-changing weather patterns.

There are several satellites in orbit now that help scientists determine how and when weather will change on our planet.

GOES/POES

The Geostationary Operational Environmental Satellite (GOES) program has satellites that stay in one particular spot in orbit over the Earth. This system uses infrared and visual photographs of the Earth's atmosphere to help scientists spot incoming weather from over the oceans.

Another system of satellites is called the Polar Operational Environmental Satellites (POES) and are in polar orbits over the Earth. As such, satellites go over both the North and South Poles on a regular basis and take pictures and measurements.

Both satellite systems are run by the National Atmospheric and Oceanic Administration. Weather photos are downloaded to the NASA website on a regular basis for anyone to observe. Dozens of satellites are in orbit to help monitor weather from above the planet and give a bird's-eye view of atmospheric conditions.

NPP

A set of polar-orbiting satellites are preparing for launch in the near future. As a transition from older satellites to ones with newer sensing equipment, NASA will launch the NPOESS Preparatory Project (NPP) to get ready for the next generation of climate-observing vehicles.

A series of environmental satellites will be used to detect climatological changes in the Earth. Earlier models involved two satellites called Terra and Aqua. The launch of the NPP satellite in late 2011 will provide a bridge until the launch of the Joint Polar Satellite System in 2015.

At 512 miles above the Earth , these satellites with also have polar orbits. Their main goal is to take pictures and measurements of the Earth's atmosphere in order to better understand climate change. The Earth Observing System (EOS) will also be able to measure ocean temperatures and will be able to view changes to land and ocean with more sensitive equipment and better technology than ever before.

Observing the Earth is one mission NASA has been developing since the mid-1960s with the launch of the Tiros and Nimbus series. When NASA focuses more on robotic and Earth science with the completion of the space shuttle program, weather satellites will be more important to the future of mankind on Earth.

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