Channel Description
Measurement Coverage
Sun Sensor
PMC Measurements
Cosmic Dust
Refraction Angle Temperatures Trade Studies

Temperature Retrievals Using Solar Refraction Angles

During an occultation event, solar rays are refracted by the Earth's atmosphere towards higher densities (see Figure 1). Because the refraction angle is directly related to the atmospheric density profile, measured refraction angles can be used to retrieve temperature profiles. Profiles of atmospheric refraction angle will be determined from the SOFIE sun sensor with sub-arcsec precision, and subsequently used to retrieve temperature versus altitude with a high degree of accuracy and vertical resolution. This basic approach was pioneered using Global Positioning Satellite (GPS) data.  A retrieval based on simulated SOFIE refraction angle measurements is shown in Figure 2.  These results suggest that SOFIE refraction angle temperatures will have better than 2 K accuracy at altitudes below 50 km.

Figure 1.  Bending of solar rays during an occultation.

Figure 2.  Temperature retrieval using simulated refraction angle measurements from the SOFIE sun sensor.