AGU: Geophysical Research Letters

 

Editors' Highlight

Modeling atmospheric effects of the September 1859 solar flare

In 1989, energetic protons ejected from the Sun hurtled toward Earth, creating magnetic storms that damaged satellite systems. Some of these protons penetrated the stratosphere where they ionized and dissociated nitrogen and oxygen molecules, which then formed ozone-depleting nitrogen oxides. Though the 1989 solar flare was the strongest seen using satellite monitoring, Thomas et al. (2007) noted that a solar flare recorded in 1859 was likely far more energetic. To study this, the authors developed a scale factor between known nitrate enhancements from recent solar proton events (SPEs). By using data on nitrate enhancements in Greenland ice cores following the 1859 SPE, they used the scale factor to determine that the total energy released by the 1859 SPE was 6.5 times larger than that released in 1989. Models using this energy total showed that 3.5 times more ozone was destroyed in the 1859 SPE than in the 1989 SPE. Because ozone regulates the amount of harmful ultraviolet radiation reaching Earth, the authors stressed that understanding intense SPEs will be important to predicting potential damage to the biosphere.

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