AIM’s continues to function nominally. At the end of November AIM completed its 25,000 orbit of the earth! We also transitioned to our backup control mode called TMON/RTS for the solar eclipse which occurred on November 25.
The SOFIE instrument continues to operate nominally. With the Southern Hemisphere (SH) of 2011-2012, AIM is now observing its tenth PMC season. The figures below summarize the SOFIE observations of PMC occurrence frequency, vertical column ice water content (IWC), mesopause temperature, and water vapor, for the Northern Hemisphere (NH) on the left, and SH on the right. The results indicate greater variability in ice frequency and IWC in the SH compared to the NH. This difference is consistent with greater variability in SH temperatures compared to the NH. Water vapor variability is also correlated to PMCs, although water variability is lower, and similar in the NH and SH.
CIPS continues to perform well, with no health issues. The current publicly available version, which was released in December 2011, is v4.20, revision 05. The plot below shows the daily frequencies measured by CIPS for all southern hemisphere seasons thus far observed by AIM. At CIPS latitudes the SH 2011-2012 season is quite similar to the 2010-2011 season. Fewer clouds are present this season than in seasons prior to 2010. There was also a sharp decline in PMC frequency beginning in late January that is likely the result of inter-hemispheric teleconnections. That is, warming in the winter (northern) hemisphere stratosphere led to changes in atmospheric circulation that led to warming in the summer (southern) mesopause region and thus fewer clouds.