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STATUS:
10.27.2017
Instrument Status:
The spacecraft continues to perform nominally.
SOFIE
SOFIE will resume measurements the first week of November, 2017, when the AIM orbit beta angle becomes low enough (below ~67 degrees) to enable solar occultation to be viewed from orbit. The upcoming winter will feature nearly co-located sunrise and sunset measurements at polar latitudes, that will be used in investigations of the mesospheric vortex. SOFIE science and housekeeping parameters all indicate a stable and healthy instrument. SOFIE V1.3 data are available online through February 2017.
Thurairajah et al. [2017] recently investigated the response of PMCs to the 27-day solar rotation using SOFIE and CIPS observations. The PMC response was quantified in terms of the sensitivity to changing solar Lyman- intensity. Analysis of PMC data from 14 seasons indicates a large seasonal variability in sensitivity with both correlation and anti- correlation between PMC properties and Lyman- irradiance for individual seasons. However, a superposed epoch analysis reveals the expected anti-correlation between variations in solar Lyman- and variations in PMC ice water content (IWC), albedo, and frequency of occurrence. An example of these results is shown in the figure below (Figure 8 from Thurairajah et al., 2017). The PMC height is found to significantly correlate with 27-day variations in solar Lyman- in the Southern Hemisphere (SH), but not in the Northern hemisphere (NH). Depending on instrument and property, the time lag between variations in PMC properties and solar Lyman-alpha ranges from 0 to 3 days in the NH and from 6 to 7 days in the SH. These hemispheric differences in PMC height and time lag are not understood, but it is speculated that they result from dynamical forcing that is controlled by the 27-day solar cycle.
Thurairajah, B., G. E. Thomas, C. von Savigny, M. Snow, M. E. Hervig, S. M. Bailey, C. E. Randall (2017), Solar-induced 27-day variations of polar mesospheric clouds from the AIM SOFIE and CIPS experiments, J. Atmos. Solar-Terr. Phys., http://dx.doi.org/10.1016/j.jastp.2016.09.008.
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