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Solar occultation measurement geometry depicting solar rays passing through the limb of the Earth's atmosphere during spacecraft sunrise and sunset.
Source publication
The Solar Occultation For Ice Experiment (SOFIE) is scheduled for launch onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite in March 2007. SOFIE is designed to measure polar mesospheric clouds (PMCs) and the environment in which they form. SOFIE will conduct solar occultation measurements in 16 spectral bands that are used to retrieve ve...
Context in source publication
Context 1
... uses the technique of satellite solar occultation to measure vertical profiles of limb path atmospheric transmission within 16 spectral bands between 0.29 -5.32 µm wavelength. Occultation measurements are accomplished by monitoring solar intensity as the satellite enters or exits the Earth's sunlit side (spacecraft sunrise or sunset, see Figure 1). The ratio of solar intensity measured through the atmosphere to the intensity measured outside the atmosphere (exoatmospheric) yields atmospheric transmissions, which are the basis for retrieving physical properties. ...
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Citations
Space Dynamics Laboratory (SDL) recently designed, built, and delivered
the Solar Occultation for Ice Experiment (SOFIE) instrument as the
primary sensor in the NASA Aeronomy of Ice in the Mesosphere (AIM)
instrument suite. AIM's mission is to study polar mesospheric clouds
(PMCs). SOFIE will make measurements in 16 separate spectral bands,
arranged in eight pairs between 0.29 and 5.3 μm. Each band pair will
provide differential absorption limb-path transmission profiles for an
atmospheric component of interest, by observing the sun through the limb
of the atmsophere during solar occulation as AIM orbits Earth. A
pointing mirror and imaging sun sensor coaligned with the detectors are
used to track the sun during occulation events and maintain stable
alignment of the sun on the detectors. This paper outlines the mission
requirements and goals, gives an overview of the instrument design,
fabrication, testing and calibration results, and discusses lessons
learned in the process.
The Solar Occultation For Ice Experiment (SOFIE) was launched onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite on 25 April 2007, and began science observations on 14 May 2007. SOFIE conducts solar occultation measurements in 16 spectral bands that are used to retrieval vertical profiles of temperature, O3, H2O, CO2, CH4, NO, and polar mesospheric cloud (PMC) extinction at 11 wavelengths. SOFIE provides 15 sunrise and 15 sunset measurements each day at latitudes from 65°-85°S and 65°-85°N. This work describes the SOFIE experiment and shows preliminary retrieval results based on observations from the initial months on-orbit.
The Solar Occultation For Ice Experiment (SOFIE) was launched onboard the Aeronomy of Ice in the Mesosphere (AIM) spacecraft to measure polar mesospheric clouds (PMCs) and their environment. This work describes methods for identifying PMCs in SOFIE observations and determining mass density, particle shape, particle effective radius, and the parameters of a Gaussian size distribution. Results using SOFIE measurements from the northern summer of 2007 are compared with concurrent observations by the ALOMAR lidar in northern Norway. Ice particle properties determined from SOFIE are in good agreement with the lidar results, considering the differences in instrument characteristics.
The Halogen Occultation Experiment (HALOE) conducted satellite solar occultation measurements for 14 years ending on 21 November 2005. HALOE contained a calibration wheel, which included three neutral density filters that were used to examine response linearity through a combination of ground and on-orbit measurements. Although measurement uncertainties preclude a confident assessment of the true extent of nonlinearity, the on-orbit data lead to the conclusion that any existing response nonlinearity has changed by less than 2% over the mission lifetime. This conclusion eliminates a potentially significant uncertainty when using HALOE data for studies of long-term atmospheric trends.
