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The Role of Neutral Atmospheric Dynamics in Cusp Density - 2nd Campaign

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Final rept. 1 Dec 2012-30 Nov 2013

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This report covers research undertaken to verify and improve models of atmospheric density fluctuations in the regions of the magnetic cusp, where increased electromagnetic activity can correspond to a cusp upwelling which can double the atmospheric density at altitudes of up to 400km, relevant to satellite drag orbits.. The grant funded a field trip in January 2013 to Svalbard for a joint opticalradar experiment to augment the first case study from January 2012. Two Fabry-Perot interferometers measured the non-ionized component of the upper atmosphere, and independent measurements of the ionosphere were made using the European Incoherent Scatter Svalbard Radar. These observations were used to partially verify a mechanism proposed by Carlson et al in 2012 which proposed that depositing energy at high altitudes would require less energy to lift a shorter column of air to higher altitude thus increasing the atmospheric density. Observations showed that large vertical winds in the cusp area did correspond to large ion temperatures 2000K, and low vertical winds with low ion temperatures 1000K unable to measure horizontal plasma velocities due to an equipment constraint, the team inferred horizontal plasma flows of greater than 2000 ms using these ion temperatures. Measurements on 12 Jan 2013 showed no cusp upswelling, while those on 14 Jan 2013 showed significant strong sustained upwelling winds, giving a useful contrast. Preliminary results from the first campaign appear to confirm the Carlson et al mechanism, while findings from the second campaign this grant confirm that it is necessary to have both soft particle precipitation and simultaneously fast plasma flow in order to provide frictional heating at a high enough altitude to lift the atmosphere at satellite altitudes.

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  • Atmospheric Physics

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