11 Nov 2022
11 Nov 2022
Status: this preprint is currently under review for the journal AMT.

Stratospheric Temperature Measurements from NanoSatellite Observations of Stellar Occultation Bending

Dana L. McGuffin1, Philip J. Cameron-Smith1, Matthew A. Horsley1, Brian J. Bauman1, Wim De Vries1, Denis Healy2, Alex Pertica1, Chris Shaffer2, and Lance M. Simms1 Dana L. McGuffin et al.
  • 1Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, CA, United States
  • 2Terran Orbital, Irvine, CA, United States

Abstract. Stellar occultation observations from space can probe the stratosphere and mesosphere at a fine vertical scale around the globe unlike other measurement techniques like radiosondes, aircraft, and radio occultation. We imaged the refractive bending angle of a star centroid for a series of occultations by the atmosphere. Atmospheric refractivity, density, and then temperature are retrieved from the bending observations with the Abel transformation and Edlén's law, the hydrostatic equation, and the ideal gas law. The retrieval technique is applied to data collected by two nanosatellites operated by Terran Orbital. Measurements were primarily taken by the GEOStare SV2 mission, with a dedicated imaging telescope, supplemented with images captured by spacecraft bus sensors, namely the star trackers on other Terran Orbital missions. The bending angle noise floor is 10 arcseconds and 30 arcseconds for the star tracker and GEOStare SV2 data, respectively. The most significant sources of uncertainty are due to centroiding errors due to the fairly low-resolution stellar images and telescope pointing knowledge derived from noisy satellite attitude sensors. The former mainly affects the star tracker data, while the latter limits the GEOStare SV2 accuracy with both providing low vertical resolution. This translates to a temperature profile retrieval up to roughly 20 km for both star tracker and GEOStare SV2 datasets. In preparation of an upcoming 2023 mission designed to correct these deficiencies, SOHIP, we simulated bending angle measurements with varying magnitudes of error. The expected maximum altitude of retrieved temperature is 41 km on average for these simulated measurements with a noise floor of 0.39 arcseconds. Our work highlights the capabilities of stellar occultation observations from nanosatellites for atmospheric sounding. Future work will investigate high frequency observations of atmospheric gravity waves and turbulence, mitigating the major uncertainties observed in these datasets.

Dana L. McGuffin et al.

Status: open (until 02 Jan 2023)

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Dana L. McGuffin et al.

Dana L. McGuffin et al.


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Short summary
This work demonstrates the viability of a remote sensing technique using nanosatellites to measure stratospheric temperature. This measurement technique can probe the stratosphere and mesosphere at a fine vertical scale around the globe unlike other high altitude measurement techniques, which would provide an opportunity to observe atmospheric gravity waves and turbulence. We analyze observations from two satellite platforms to provide a proof-of-concept and characterize measurement uncertainty.