Browsing by Author "Gordley, Larry L."

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    High Precision Refraction Measurements By Solar Imaging During Occultation: Results From Sofie
    Gordley, Larry L.; Burton, J.; Marshall, B. T.; McHugh, M.; Deaver, L.; Nelsen, J.; Russell, James M. III; Bailey, Scott M. (Optical Society of America, 2009-09-01)
    A new method for measuring atmospheric refraction angles is presented, with in-orbit measurements demonstrating a precision of +/-0.02 arcsec (+/-0.1 mu rad). Key advantages of the method are the following: (1) Simultaneous observation of two celestial points during occultation (i.e., top and bottom edges of the solar image) eliminates error from instrument attitude uncertainty. (2) The refraction angle is primarily a normalized difference measurement, causing only scale error, not absolute error. (3) A large number of detector pixels are used in the edge location by fitting to a known edge shape. The resulting refraction angle measurements allow temperature sounding up to the lower mesosphere. (C) 2009 Optical Society of America
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    Trends in the polar summer mesosphere temperature and pressure altitude from satellite observations
    Bailey, Scott M.; Thurairajah, Brentha; Hervig, Mark E.; Siskind, David E.; Russell, James M. III; Gordley, Larry L. (2021-09-01)
    Time series of mesospheric temperature and pressure altitude are produced through combining observations by the Halogen Occultation Experiment (HALOE), Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER), and Solar Occultation for Ice Experiment (SOFIE) instruments. Time series of both temperature and pressure altitude are produced through the combination of HALOE/SABER providing 29 years in length and HALOE/SOFIE providing 22 years in length. The different sampling of the three instruments constrains the time series to June in the northern hemisphere and December in the southern hemisphere and 6470 degrees in both hemispheres. We interpret the time series by fitting them to simple descriptions of the variations including solar, intra-hemispheric, inter-hemispheric, and linear trend terms. The inferred intra- and inter-hemispheric terms show that dynamical influences rival solar variability in the mesosphere. We find a robust result that the mesosphere is in general cooling at most altitudes at approximately 1-2 K per decade in response to greenhouse gas increases. That cooling leads to a shrinking of the atmosphere on the order of 100-200 m per decade. The shrinking leads to a reduction in cooling and eventually a warming near 0.005 hPa due to hydrostatic contraction.