Polar Quantifies Magnetospheric Drivers of Upper Atmospheric Chemistry Changes

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Polar Quantifies Magnetospheric Drivers of Upper
Atmospheric Chemistry Changes
Precipitating electrons
High resolution global imaging from Polar is a
critical element for determining solar influenced
controls of the upper atmosphere

• The importance of magnetospheric dynamics on the
  aeronomy of the upper atmosphere is known but it
  has never been clear how important, how
  extensive, how often, and how extreme the effect
  can be.
• Polar imaging provides a global view of the
  location and allows the intensity of the
  energetic processes to be inferred.
• Polar investigators have shown that catalytic
  atmospheric species can vary by as much as a
  factor of ten during extreme storm conditions.

Nitric oxide abundance
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Polar Quantifies Magnetospheric Drivers of Upper
Atmospheric Chemistry Changes
Measurements
POLAR 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
gt5 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)
SNOE Swaths of nitric oxide density in the
100-200 km altitude lower thermosphere. UVS
auroral UV (215, 237 nm)
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Polar Quantifies Magnetospheric Drivers of Upper
Atmospheric Chemistry Changes
Observations
greater than five-fold variation
measure of atmospheric nitric oxide
measure of precipitating keV electrons
measure of magnetospheric storm activity
NO(and NO2) enhancements are often confined to
the region of production which can reach into the
upper stratosphere. Downward transport can
extend perturbations in O3 chemistry to lower
regions of the stratosphere.
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Polar Quantifies Magnetospheric Drivers of Upper
Atmospheric Chemistry Changes
Observations
Energetic electron precipitation dissociates N2
to produce N(2D) and N(4S) that in turn produce
enhanced NO and NO2. The precipitation will also
dissociate water vapor enhancing HOx.
Enhancements within the mesosphere-thermosphere
system, and their consequences on the
stratosphere, can persist for many hours and
sometimes days.
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Polar Quantifies Magnetospheric Drivers of Upper
Atmospheric Chemistry Changes
Observations
Polar/UVI O/N2 ratio showing atmospheric oxygen
depletion following the July Bastille Day
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.
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Polar Quantifies Magnetospheric Drivers of Upper
Atmospheric Chemistry Changes
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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Backup Slides
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Polar Orbit 2001-2005
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Solar Max vs the Declining Phase
Strength of the Solar Cycle
Strength of Geomagnetic Activity
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Energetic Particles and the Solar Cycle
Phases of the solar cycle bring very different
solar input conditions which in turn, result in
very different magnetospheric responses