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Neutral density measurement from simultaneous radar observation of meteors
  • Nicolas Lee,
  • Sigrid Close
Nicolas Lee
Stanford University

Corresponding Author:nnlee@stanford.edu

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Sigrid Close
Stanford University
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Abstract

Observations of atmospheric neutral density and associated dynamics within the lower thermosphere has been a challenge to the atmospheric science and space community due to its inaccessibility to balloon-borne or orbital in situ instruments. We present a methodology to study the latitudinal and temporal variation of neutral density in this region through a simultaneous campaign at geographically distinct high-power large-aperture (HPLA) radar facilities to observe meteor trajectories. These meteors are formed by meteoroids entering the Earth’s atmosphere; the deceleration they undergo due to atmospheric drag provides a source of information to determine the neutral density of the atmosphere at altitudes of 80 to 140 km. Through the measurement of meteor head echo trajectories using specialized radar waveforms and signal processing to enhance the range resolution, combined with novel statistical techniques to account for the distribution of meteoroid properties, the temporal evolution of atmospheric neutral density from 70 to 140 km can be characterized with sub-km altitude resolution. Initial results will be presented from the first of four observation campaigns planned during the 2019-2021 period using the HPLA radar sites at Jicamarca, Millstone Hill, and Resolute Bay, which span equatorial to polar latitudes at similar longitude. The simultaneous measurements across facilities complements other measurements of atmospheric composition and structure at similar altitudes to provide improved identification of latitudinal coupling and forcing from lower altitudes into the magnetosphere-ionosphere-thermosphere (MIT) system.