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The Second Generation Optimized Fabry-Perot Doppler Imager (SOFDI), designed and built by Michigan Aerospace Corporation, arrived at the Geophysical Institute of Peru Huancayo Geophysical Observatory located at the magnetic equator in Peru. SOFDI is a portable, unmanned, remote-controlled instrument constructed to measure continuous 24-hour (i.e., nighttime and daytime) winds and temperatures from the upper mesosphere and lower thermosphere. These measurements will test a hypothesis about the stability of the F-layer which would predict disturbances in the ionosphere. Such ionospheric disturbances cause radio communication disruptions.

Dr. Andrew Gerrard of the New Jersey Institute of Technology said “Michigan Aerospace designed and built SOFDI to serve multiple roles; an incredibly difficult challenge that turned out to be an utter success. We are able to make measurements not previously possible.” Daytime measurements of winds and temperatures based on the 630 nm emission from thermospheric atomic oxygen (OI) have been difficult to obtain in the past because of the large solar background continuum which overpowers the comparatively weak emission. The novel triple-etalon Fabry-Perot interferometer in the SOFDI instrument filters out the solar background and enables the measurement of this 630nm emission during the daytime. Dr. Gerrard continues, “The quality, tuning control, and overall performance of the three etalons in SOFDI is exceptional.”

SODFI was funded by a Defense University Research Instrumentation Program (DURIP) grant from the Air Force Office of Scientific Research and by the NSF Aeronomy Program. The project was led by Dr. John Meriwether of Clemson University and Dr. Andrew Gerrard, currently at the New Jersey Institute of Technology. This project was initially funded so that the 24-hour ground-based wind measurements from SOFDI could be used to validate in-situ wind measurements from the Air Force Communications/Navigations Outage Forecasting System (C/NOFS) satellite. C/NOFS is part of an intensive space weather modeling effort that will attempt to predict the low latitude occurrence of Equatorial Spread-F (ESF). SOFDI promises to test recent theories suggesting the timing of the reversal of the zonal wind from west to east is an important predictor of ESF development.