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

• Main Author: Aruliah, Anasuya
• Other Authors: UNIVERSITY COLL LONDON (UNITED KINGDOM)
• Format: Text
• Language: English
• Published: 2013
• Subjects: Atmospheric Physics; *ATMOSPHERIC DENSITY; ARTIFICIAL SATELLITES; ELECTROMAGNETISM; FABRY PEROT INTERFEROMETERS; OPTICAL RADAR; CHAMP SATELLITE; FOREIGN REPORTS; PE61102F; Svalbard
• Online Access: http://www.dtic.mil/docs/citations/ADA602467; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA602467

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 optical/radar 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 m/s) 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. The original document contains color images.