Ionospheric signatures of sudden stratospheric warming: Ion temperature at middle latitude

Abstract

Sudden stratospheric warming (SSW) is a large‐scale meteorological process in the winter hemisphere lasting several days or weeks. The Incoherent Scatter World Day campaign conducted on January 17–February 1, 2008 was arranged during a minor SSW event and focuses on studies of thermospheric and ionospheric response to stratospheric changes. We analyze ion temperature observations at 100–300 km height obtained by the Millstone Hill incoherent scatter radar (42.6°N, 288.5°E). Alternating regions of warming in the lower thermosphere and cooling above 150km altitude were observed by the radar. We use National Center for Environmental Prediction (NCEP) temperature data at 10hPa (∼30km) level and the F10.7 and Ap indices to identify any cause‐effect relationship between observed variations in the temperature and stratospheric warming event. We conclude that the seasonal trend, solar flux and geomagnetic activity cannot account for the observed warming and cooling temperature variation and suggest that this variation is associated with stratospheric warming. This study demonstrates a link between the lower atmosphere and the ionosphere which has not been considered before and indicates that ionospheric variability as part of space weather should be considered in conjunction with stratospheric changes.

Variabilities of mesospheric tides and equatorial electrojet strength during major stratospheric warming events

“…Using E-P flux calculations, Yamashita et al (2002) suggested cross equatorial propagation of semi-diurnal tide, which was excited in the winter hemisphere, up to MLT heights. Goncharenko and Zhang (2008) noted significant afternoon changes in ion temperature in the altitude range of ∼120-140 km and above over Millstone Hill (42.6 • N, 71.5 • W) prior to the minor SSW event that occurred during January 2008. As the year 2008 corresponds to low solar activity, the authors attributed the increase of ion temperature to be associated with the SSW event and from the temporal and altitudinal variations in the temperature anomaly, they inferred that it might be related to semi-diurnal tide modulation.…”

“…Hoffmann et al (2007) observed enhanced semi-diurnal tidal amplitudes over a high-latitude station, Andenes (69 • N, 16 • E), in February 2006, when a major warming event occurred. Goncharenko and Zhang (2008) observed that ion temperatures at a mid-latitude site during the stratospheric warming of January 2008 revealed alternating regions of cooling in a large altitude range (150-300 km) and warming in a narrow altitude band (120-140 km). Earlier, Vineeth et al (2007a) observed a cooling in the daytime mesopause temperature over Trivandrum at the time of CEJ events.…”

Stratospheric warming influence on the mesosphere/lower thermosphere as seen by the extended CMAM

“…A number of experimental results during the winter of 2008/2009 have shown perturbations in the neutral and ion temperature and winds (e.g. Goncharenko and Zhang, 2008;Conde and Nicholls, 2010;Funke et al, 2010;Kurihara et al, 2010), coinciding with the onset of the major stratospheric warming event of January and February 2009. Therefore the modelling efforts have been extended into the upper atmosphere to examine the dynamical coupling between middle and upper atmosphere.…”

Satellite observations of middle atmosphere gravity wave absolute momentum flux and of its vertical gradient during recent stratospheric warmings

“…Also the mesosphere (e.g., Labitzke, 1972;Jacobi et al, 2003;Siskind et al, 2005Siskind et al, , 2010Hoffmann et al, 2007;Yamashita et al, 2013;Zülicke and Becker, 2013), and even the thermosphere/ionosphere are affected (e.g., Goncharenko and Zhang, 2008;Fuller-Rowell et al, 2010;Yigit et al, 2014). The selective filtering of gravity waves by the anomalous winds during (major) SSWs is an important mechanism in these vertical influences.…”