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Polar Quantifies Magnetospheric Drivers of Upper Atmospheric Chemistry Changes

SNOE high resolution global image PIXI high resolution global image

High resolution global imaging from Polar is a critical element for determining solar influenced controls of the upper atmosphere

Global variations in energetic particle precipitation and global variations in the atmospheric O/N2 ratio at 100-300 km altitude.
PIXIE: auroral X-rays quantify global >5 keV electron precipitation
UVI: auroral UV (130.4, 135.6, 140-160, 160-175, 175-190 nm)
VIS: auroral visible & UV (130.4, 391.4, 557.5, 630.0, 656.3, 732.0 nm)

Swaths of nitric oxide density in the 100-200 km altitude lower thermosphere.
UVS: auroral UV (215, 237 nm)

Polar/UVI O/N2 ratio showing atmospheric oxygen depletion following the July ³Bastille Day²

Ring current decay precipitates energetic O and H. On reaching the atmosphere, neutral O ionizes again from collisions, and then radiatively recombines yielding the O emission. Here, the O/N2 ratio is drastically reduced during strong activity. Because N2 is relatively stable, oxygen outflow into the magnetosphere probably caused most of the variation.

Interpretation and Implications:
Separation of natural and human-induced effects on the abundance of stratospheric ozone and odd nitrogen species require understanding of the natural processes leading to the formation and destruction of NOx and Ox.

POLAR, together with SAMPEX and SNOE shows how auroral and geomagnetic activity have a significant impact on Earth's atmospheric chemistry during major space weather storms.

Petrinec, S. M., W. L. Imhof, D. L. Chenette, J. Mobilia, and T. J. Rosenberg, Dayside/nightside auroral X-ray emission differences and implications for ionospheric conductance, Geophys. Res., Lett., 20, 3277, 2000.
Liou, K., P. T. Newell, C.-I. Meng, M. Brittnacher, and G. Parks, Characteristics of the solar wind controlled auroral emissions, J. Geophys. Res., 103, 17543, 1998.
Barth, C. A., Baker, D.N., Mankoff K.D., and Bailey S.M., The Northern Auroral Region as Observed in Nitric Oxide, Geophys. Res. Lett., 28, 1463, 2001.

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