Solar storm dumps gigawatts into Earth's upper atmosphere
A recent flurry of eruptions on the sun did more than spark pretty auroras around the poles. NASA-funded researchers say the solar storms of March 8th through 10th dumped enough energy in Earth鈥檚 upper atmosphere to power every residence in New York City for two years.
鈥淭his was the biggest dose of heat we鈥檝e received from a solar storm since 2005,鈥� says Martin Mlynczak of NASA Langley Research Center. 鈥淚t was a big event, and shows how solar activity can directly affect our planet.鈥�
Mlynczak is the associate principal investigator for the SABER instrument onboard NASA鈥檚 TIMED satellite. SABER monitors infrared emissions from Earth鈥檚 upper atmosphere, in particular from carbon dioxide (CO2) and nitric oxide (NO), two substances that play a key role in the energy balance of air hundreds of km above our planet鈥檚 surface.
鈥淐arbon dioxide and nitric oxide are natural thermostats,鈥� explains James Russell of Hampton University, SABER鈥檚 principal investigator. 鈥淲hen the upper atmosphere (or 鈥榯hermosphere鈥�) heats up, these molecules try as hard as they can to shed that heat back into space.鈥�
That鈥檚 what happened on March 8th when a coronal mass ejection (CME) propelled in our direction by an X5-class solar flare hit Earth鈥檚 magnetic field. (On the 鈥淩ichter Scale of Solar Flares,鈥� X-class flares are the most powerful kind.) Energetic particles rained down on the upper atmosphere, depositing their energy where they hit. The action produced spectacular auroras around the poles and significant1 upper atmospheric heating all around the globe.
鈥淭he thermosphere lit up like a Christmas tree,鈥� says Russell. 鈥淚t began to glow intensely at infrared wavelengths as the thermostat effect kicked in.鈥�
For the three day period, March 8th through 10th, the thermosphere absorbed 26 billion kWh of energy. Infrared radiation from CO2 and NO, the two most efficient coolants in the thermosphere, re-radiated 95% of that total back into space.
In human terms, this is a lot of energy. According to the New York City mayor鈥檚 office, an average NY household consumes just under 4700 kWh annually. This means the geomagnetic storm dumped enough energy into the atmosphere to power every home in the Big Apple for two years.
鈥淯nfortunately, there鈥檚 no practical way to harness this kind of energy,鈥� says Mlynczak. 鈥淚t鈥檚 so diffuse and out of reach high above Earth鈥檚 surface. Plus, the majority of it has been sent back into space by the action of CO2 and NO.鈥�
During the heating impulse, the thermosphere puffed up like a marshmallow held over a campfire, temporarily increasing the drag on low-orbiting satellites. This is both good and bad. On the one hand, extra drag helps clear space junk out of Earth orbit. On the other hand, it decreases the lifetime of useful satellites by bringing them closer to the day of re-entry.
The storm is over now, but Russell and Mlynczak expect more to come.
鈥淲e鈥檙e just emerging from a deep solar minimum,鈥� says Russell. 鈥淭he solar cycle is gaining strength with a maximum expected in 2013.鈥�
More sunspots flinging more CMEs toward Earth adds up to more opportunities for SABER to study the heating effect of solar storms.
鈥淭his is a new frontier in the sun-Earth connection,鈥� says Mlynczak, and the data we鈥檙e collecting are unprecedented.鈥�
Stay tuned for updates from the top of the atmosphere.
Source: Science@NASA
