Abstract
The massive eruption at 40°N (planetographic latitude) in December
2010 has produced significant and long-lived changes in temperature and
species abundances in Saturn's northern hemisphere (Fletcher et al.,
2011). The northern storm region has been observed on many occasions in
between January and August of 2011 by Cassini's Composite Infrared
Spectrometer (CIRS). In this time period, temperatures in regions
referred to as "beacons" (warm regions in the stratosphere at certain
longitudes in the storm latitude) became significantly warmer than
pre-storm values of 140K. These temperatures reached a peak of 220K near
the 2-mbar region in May 2011 following the merger of two beacons. These
are the highest temperatures ever observed at this altitude on Saturn.
The temperatures in the storm region vary longitudinally by ~70K which
is the largest variation in temperature ever seen on Saturn. These warm
temperatures resulted in the detection of ethylene
(C2H4) using CIRS. Early analysis of the May data
indicates ethylene volume mixing ratios of 3x10-8 at 2 mbar.
These beacon regions have also led to the identification of rare species
such as diacetylene (C4H2), methylacetylene
(CH3C2H), and carbon dioxide (CO2) in
the stratosphere. These species were previously measured by the Infrared
Space Observatory (de Graauw et al., 1997) and CIRS (Guerlet et al.,
2010). However, mapping these species in longitude and latitude over the
storm region using CIRS provides insight into the changes in the
photochemistry induced by the storm. Ground-based observations were
performed using the high-resolution spectrometer Celeste in May and July
to confirm the CIRS detection of ethylene and to study its spectral
signatures at higher spectral resolution than available with CIRS, and
investigate the evolution of its abundance profile as the storm
progresses. The time evolution of ethylene abundance in Saturn's
northern storm region using CIRS and ground-based data from the
McMath-Pierce Telescope (May 2011) and the United Kingdom Infrared
Telescope (July 2011) will be presented. In addition, the abundance
profiles, as measured by CIRS, of C4H2,
CH3C2H, and CO2 will also be discussed
including how their abundance profiles have changed throughout the storm
period.
Original language | English |
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Journal | American Geophysical Union, Fall Meeting 2011 |
Volume | 11 |
Publication status | Published - 1 Dec 2011 |
Externally published | Yes |