All‐sky imaging observations of mesospheric fronts in OI 557.7 nm and broadband OH airglow emissions: Analysis of frontal structure, atmospheric background conditions, and potential sourcing mechanisms

Abstract

[1] All-sky imaging observations of distinct, large horizontal transient mesospheric structures with a spatial scale of $100 km detected in images of broadband OH and OI 557.7 nm airglow emissions were made over Clemson, South Carolina, on the night of 14-15 October 2001. We designate these structures as mesospheric fronts and present a detailed summary of this night series of observations, paying particular attention to the details of the different frontal structures, the wave-like activity seen throughout the night, and the background atmospheric conditions. These data are compared to other observations of similar mesospheric fronts found in the literature, and we seek to understand them in relation to mesospheric bores, ducted gravity waves, mesospheric wall events, and nonlinear gravity wave interactions. We find that the observed frontal characteristics and the atmospheric background structure exhibit a close resemblance to previous observations of mesospheric bores. Owing to this similarity, and supported by gravity wave ray-tracing experiments, we propose a sequence of events that generated the mesospheric fronts observed in the airglow emission. Furthermore, we note this similarity in atmospheric structure suggests a potential means of predicting the occurrence of such mesospheric phenomena.

Observation of a mesospheric front in a thermal-doppler duct over King George Island, Antarctica

“…The report of only two wave front events (wall event reported by Bageston et al (2011) and the present study), among a large number of gravity wave events, confirms the low occurrence rate of bores at high southern latitudes compared to lower latitudes (Fechine et al, , 2009). The event reported here could not be classified as a mesospheric bore according to the criteria used in the literature (Dewan and Picard, 1998;Smith et al, 2003;Brown et al, 2004;Smith et al, 2005). The present observation is comprised by a mesospheric front having a sharp "front" that extended across the entire all-sky image, with a series of crests following the front and an observed phase speed of 92 m s −1 .…”

“…These kind of frontal events are subclassified mainly between wall and bore. However, fronts that do not satisfy all the criteria of a bore or wall (Brown et al, 2004), but present analogous characteristics to these fronts -including a extended frontal pattern and ducting conditions -still can be classified as a mesospheric front, following the criteria listed by Brown et al (2004).…”

“…According to the definitions currently accepted by the scientific community, mesospheric front is a type of gravity wave which presents a frontal airglow emission enhancement or depletion that can be followed by a series of wave crests phase-locked to the leading front (Brown et al, 2004;Smith et al, 2005). These kind of frontal events are subclassified mainly between wall and bore.…”

Climatology of medium‐scale traveling ionospheric disturbances observed by the midlatitude Blackstone SuperDARN radar

“…HINDGRATS is based on the gravity wave regional or global ray tracing model, run in a reverse ray tracing mode Brown et al, 2004]. The model results are shown in Figure 16 and utilized a 2.5 • × 2.5…”

First Ground Observations of OI5577 Green Line Emission over the Taiwan Area

“…There have been many studies (e.g., Colerico et al 1996; Angelats i Coll and Forbes 1998; Balan et al 2004;Brown et al 2004;Smith et al 2006) that utilize the information of OI5577 airglow to deduce the dynamics and structure of the E region or F region of the iono-sphere (upper mesosphere or thermosphere). Weinberg and Mann (1967) of the University of Hawaii conducted the first systematic sky-scanning measurements of OI5577 airglow and other wavelength bands at Mt.…”