Chief space weather forecasters Yihua Zheng and Antti Pulkkinen are helping to implement a computer technique—ensemble forecasting—that will improve NASA’s ability to predict the path and impact of severe solar storms, which can disrupt power grids on Earth, knock out satellites, and threaten the health and safety of astronauts. Credit: NASA/Chris Gunn |
After
years of relative somnolence, the sun is beginning to stir. By the time
it’s fully awake in about 20 months, the team at NASA’s Goddard Space
Flight Center in Greenbelt, Md., charged with researching and tracking
solar activity, will have at their disposal a greatly enhanced
forecasting capability.
Goddard’s
Space Weather Laboratory recently received support under NASA’s Space
Technology Program Game Changing Program to implement “ensemble
forecasting,” a computer technique already used by meteorologists to
track potential paths and impacts of hurricanes and other severe weather
events.
Instead
of analyzing one set of solar-storm conditions, as is the case now,
Goddard forecasters will be able to simultaneously produce as many as
100 computerized forecasts by calculating multiple possible conditions
or, in the parlance of Heliophysicists, parameters. Just as important,
they will be able to do this quickly and use the information to provide
alerts of space weather storms that could potentially be harmful to
astronauts and NASA spacecraft.
“Space
weather alerts are available now, but we want to make them better,”
said Michael Hesse, chief of Goddard’s Space Weather Laboratory and the
recently named director of the Center’s Heliophysics Science Division.
“Ensemble forecasting will provide a distribution of arrival times,
which will improve the reliability of forecasts. This is important.
Society is relying more so than ever on space. Communications,
navigation, electrical-power generation, all are all susceptible to
space weather.” Once it’s implemented, “there will be nothing like this
in the world. No one has done ensemble forecasting for space weather.”
The
state-of-the-art capability, which Hesse’s group is implementing now
and expects to complete within three years, couldn’t come too soon,
either.
Sun growing restless
Since
the sun reached its solar minimum in 2008—the period when the number of
sunspots is lowest—it has begun to awaken from its slumber. On Aug. 4,
the sun unleashed a near X-class solar flare that erupted near an
Earth-facing sunspot. Although flares don’t always produce coronal mass
ejections (CMEs)—gigantic bubbles of charged particles that can carry up
to ten billion tons of matter and accelerate to several million miles
per hour as they erupt from the sun’s atmosphere and stream through
interplanetary space—this one did.
The
CME overtook two previous CMEs—all occurring within 48 hours—and
combined into a triple threat. Luckily for Earthlings, the CMEs produced
only a moderate geomagnetic storm when solar particles streamed down
the field lines toward Earth’s poles and collided with atoms of nitrogen
and oxygen in the atmosphere. Even so, “it was the strongest storm in
many years,” said Antti Pulkkinen, one of the laboratory’s chief
forecasters.
However,
the repercussions could be far worse in the future. As part of its
11-year cycle, the sun is entering solar maximum, the period of greatest
activity. It is expected to peak in 2013. During this time, more
powerful CMEs, often associated with M- and X-class flare events, become
more numerous and can affect any planet or spacecraft in its path. In
the past, solar storms have disrupted power grids on Earth and damaged
instrumentation on satellites. They can also be harmful to astronauts if
they are not warned to take protective cover.
“No
one knows exactly what the sun will do, Pulkkinen said. “We can’t even
tell in a week, let alone a year or two, what the sun will do. All we
know is that the sun will be more active.”
Given
the expected uptick in activity, Hesse, Pulkkinen, and Yihua Zheng,
another chief forecaster, were anxious to enhance their forecasting
acumen. They partnered with the Space Radiation Analysis Group at NASA’s
Johnson Space Center in Houston, which is responsible for ensuring that
astronauts’ exposure to deadly radiation remains below established
safety levels, and won NASA funding to develop the Integrated Advanced
Alert/Warning Systems for Solar Proton Events.
Weaknesses in current system
“Ensemble forecasting holds the key” to an enhanced alert system,” Hesse said. “We agreed that this was the way to go.”
Currently,
the laboratory is running one CME model—calculating one set of
parameters—at a time. The parameters are derived from near real-time
data gathered by NASA’s Solar Dynamics Observatory, the Solar
Terrestrial Relations Observatory, and the Solar and Heliospheric
Observatory, among others. “But since all of these are scientific
research missions, we have no guarantee of a continuous real-time data
stream,” Zheng said.
Furthermore,
imperfections exist in the data. These imperfections grow over time,
leading to forecasts that don’t agree with the evolution of actual
conditions. For NASA, the Air Force, and other organizations, which use
Goddard’s forecasts to decide whether steps are needed to protect space
assets and astronauts, uncertainty is as unwelcome as the storm itself.
Ensemble
forecasting, however, overcomes the weaknesses by allowing forecasters
to tweak the conditions. “Generating different parameters is easy—just
varying a little bit of all parameters involved in characterizing a CME,
such as its speed, propagation direction, and angular extent,” Zheng
explained. In essence, the multiple forecasts provide information on the
different ways the CME can evolve over the next few hours. “We’ll be
able to characterize the uncertainties in our forecasts, which is almost
as important as the forecast itself,” Pulkkinen added.
The
team has already installed new computer systems to run the varying
calculations and hopes to develop the ability to generate more
specialized forecasts.
“We
recognize there is a huge gap in our current capability,” Pulkkinen
continued. “We certainly don’t want to miss the solar maximum with this
capability. We’re really pushing the envelope to have it done. When we
do, we’ll be the first in the world to have it.”
When
this forecasting technique is verified and validated by NASA’s Space
Weather Laboratory, the capability will be made available to NOAA’s
Space Weather Prediction Center, which is responsible for issuing
national space weather alerts. NASA’s goal to understand and track space
weather activity will enable a greatly enhanced forecasting capability
for U.S. interests.
For more information about Goddard’s space weather efforts and access to its space weather analysis system, visit:
http://ccmc.gsfc.nasa.gov/about.php
