During the past few months, our planet has been subjected to some of the largest geomagnetic storms on record, and the TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics) spacecraft — built and operated by The Johns Hopkins University Applied Physics Laboratory (APL) for NASA — has recorded the impact of these storms on our atmosphere.
Although the sun is on the downward slope of its 11-year cycle, it has been quite active since late October 2003, when it unleashed nearly a dozen X-class (the strongest) flares in 14 days — equaling the total number observed during the previous year, according to NASA. A flare on Nov. 4 topped the charts as the strongest on record; one on Oct. 28 ranked third.
As streams of supercharged particles were hurled toward Earth at speeds of 4—5 million mph, the TIMED spacecraft had a front-row seat for observing the effects of these space-based hurricanes on Earth's atmosphere. The data are helping scientists unravel the mysteries surrounding the overall connection and interaction between the sun and our planet's atmosphere.
TRACKING STORM EFFECTS
Strong X-class flares can trigger planet-wide radio blackouts and long-lasting geomagnetic disturbances, which in turn can interfere with satellite operations or overload power grids on Earth. The effects from the recent X-class flares, however, were not as severe as some scientists predicted. Radio blackouts disrupted communications in some areas. Solar protons penetrated Earth's atmosphere, exposing astronauts and some air travelers on flights close to the poles to radiation doses equal to a chest X-ray. And auroras were displayed in places where they're seldom seen, including Maryland, Texas and Florida.
"Our quick-look data analysis indicates something very unusual about the source of the auroras that stretched so far south," says Larry Paxton, APL project scientist for TIMED's Global Ultraviolet Imager (GUVI). "It appears that the solar coronal mass ejection associated with these massive flares thrust particles into our atmosphere that normally would have been deflected by the magnetosphere, Earth's protective magnetic shield. We need to understand this so we can continue to protect our satellites in Earth orbit and on interplanetary missions."
TIMED instruments also noted tremendous increases in incoming solar X-ray and ultraviolet radiation levels, which heat up and expand the Earth's upper atmosphere. The resulting density increase can cause low-Earth-orbiting satellites to slow down or change orbits.
"These storms are providing a great opportunity to study how our atmosphere's composition changed and how the storms affected the ionosphere — a region of our atmosphere that greatly impacts the effectiveness of many communications and navigations systems," Paxton says.
"TIMED is providing the first-ever global picture of our upper atmosphere, its composition and temperature, as well as the wind structure as a function of the sun's activity," says APL's Elsayed Talaat, of the TIMED science team. "We know many of the inputs and outputs affecting our atmosphere, but we're still trying to understand how its response changes with the magnitude or type of solar event or geomagnetic storm. TIMED is an important piece in solving this sun-Earth connection puzzle."
Note: High-resolution images of the record-setting solar flares, acquired by the APL-developed Global Ultraviolet Imager instrument onboard TIMED, are available for download at http://www.timed.jhuapl.edu/press2/120803/guvi/guvi_data.html.