Enhancing Low-Cost Ozone Spectrometers to Measure Mesospheric Winds and Tides

Abstract

Ground-based spectrometers have been developed to measure the concentration, velocity, and temperature of ozone in the mesosphere and lower thermosphere (MLT) using low-cost satellite television electronics to observe the 11.072 GHz spectral line of ozone. A two-channel spectrometer has been engineered to yield various performance improvements, including a doubling of the signal-to-noise ratio, improved data processing efficiency, and lower power consumption at 15 W. Following 2009 and 2012 observations of the seasonal and diurnal variations in ozone concentration near the mesopause, the ozone line was observed at an altitude near 95 km and latitude of 38 degrees north using three single-channel spectrometers located at the MIT Haystack Observatory (Westford, MA), Chelmsford High School (Chelmsford, MA), and Union College (Schenectady, NY) pointed south at 8 degrees. Observations from 2009 through 2014 are used to derive the nightly-averaged seasonal variation in meridional velocity, as well as the seasonally-averaged variation with local solar time. The results indicate a seasonal trend in which the winds at 95 km come from the north at about $10\,\text{m}\text{s}^{-1}$ in the summer of the northern hemisphere, and from the south at about $10\,\text{m}\text{s}^{-1}$ in the winter. Nighttime data from -5 to +5 hours local solar time show a gradual transition of the meridional wind velocity from about -$20\,\text{m}\text{s}^{-1}$ to +$20\,\text{m}\text{s}^{-1}$. These two trends correlate with nighttime wind measurements from the Millstone Hill High-Resolution Fabry-Perot Interferometer (FPI) in Westford, MA, which uses the 557.7 nm green line nightglow from atomic oxygen centered at 95 km. The results have also been compared with average meridional winds measured with meteor radar.