A 3‐D empirical model of F region Medium‐Scale Traveling Ionospheric Disturbance bands using incoherent scatter radar and all‐sky imaging at Arecibo

Abstract

[1] Perhaps the most persistent and prominent of the midlatitude nighttime F region phenomena observed with all-sky imagers is the Medium-Scale Traveling Ionospheric Disturbances (MSTID) that occur when the geomagnetic activity is low. We introduce a simple empirical 3-D model of these bands, which was developed on the basis of an extension of results given by Seker et al. (2008). Seker et al. (2008) reported observational results on the 3-D geometry of MSTID structures found using combined incoherent scatter radar (ISR) and all-sky imager observations over the Arecibo Observatory in Puerto Rico. To confirm and further investigate these findings, a simple empirical 3-D model of nighttime MSTID bands is constructed. We show ISR and all-sky imager results derived from the model, compare them with the actual observations, and highlight the important findings. This model is intended to replicate both the azimuth-scanning ISR and the all-sky imager results and is especially useful in explaining how these complex structures appear in azimuth-scanning ISR results. In addition, confidence in the empirical model allows us to know what to expect from the theory (of MSTID) and to assess how well geomagnetically quiet, nighttime, midlatitude, F region electrodynamics models succeed. Furthermore, the technique described in the paper is not limited to F region or midlatitudes only; it could be applied to any other phenomenon which can be observed by both radar and imager.

Horizontal parameters of daytime thermospheric gravity waves and E region neutral winds over Puerto Rico

“…Various techniques exist to measure the horizontal propagation parameters of the waves, with many recent studies making use of broad arrays of dual-frequency GPS receivers to study the propagation of total electron content perturbations [e.g., Afraimovich et al, 1998Afraimovich et al, , 2000Afraimovich et al, , 2003Saito et al, 1998Saito et al, , 2001Hernández-Pajares et al, 2006;Kotake et al, 2006;Nicolls et al, 2004;Tsugawa et al, 2007;Ishida et al, 2008;Ogawa et al, 2009]. All-sky airglow imaging (in particular of the 630 nm OI thermospheric emission) can be used to study the propagation of nighttime MSTIDs [e.g., Mendillo et al, 1997;Garcia et al, 2000;Shiokawa et al, 2003aShiokawa et al, , 2003bShiokawa et al, , 2006Candido et al, 2008;Seker et al, 2009Seker et al, , 2011Martinis et al, 2010]. HF Doppler sounders are also used to study the horizontal parameters and propagation directions of daytime and nighttime TIDs [e.g., Crowley et al, 1987;Crowley and Rodrigues, 2012].…”

The collapse of the midnight ionosphere and behavior of meridional neutral winds at Townsville over a full solar cycle

“…Their results showed that the midnight h m F 2 descended by 50 to 100 km in 85% of the events. The midnight collapse has been investigated by many other researchers, using incoherent scatter radar (ISR) [Behnke and Harper, 1973;Harper, 1979;MacPherson et al, 1998;Seker et al, 2009], airglow techniques [Nelson and Cogger, 1971;Vlasov et al, 2005], and theoretical models [Crary and Forbes, 1986]. Behnke and Harper [1973], MacPherson et al [1998], andVlasov et al [2005] reported the reduction and reversal of the equatorward neutral wind as the basis for the midnight collapse in their observations.…”

Midnight ionosphere collapse at Arecibo and its relationship to the neutral wind, electric field, and ambipolar diffusion

“…Their results show that HmF 2 descends 50 to 100 km in 85 percent of the nights near midnight. This conspicuous phenomenon has been extensively studied using ISR [ Behnke and Harper , 1973; Harper , 1979; MacPherson et al , 1998; Seker et al , 2009], airglow techniques [ Nelson and Cogger , 1971; Vlasov et al , 2005], and theoretical models [ Crary and Forbes , 1986]. Behnke and Harper [1973], MacPherson et al [1998], and Vlasov et al [2005] reported the reduction and reversal of the prevailing equatorward neutral wind being the cause of the midnight collapses they observed.…”

“… Behnke and Harper [1973], MacPherson et al [1998], and Vlasov et al [2005] reported the reduction and reversal of the prevailing equatorward neutral wind being the cause of the midnight collapses they observed. The reversal of meridional winds is thought to be due to the pressure bulge associated with the midnight temperature maximum [ Colerico et al , 1996; Seker et al , 2009]. Crary and Forbes [1986], using numerical simulations, and Harper [1979], using two nights of ISR observation, attributed the collapse to the shear in the meridional wind associated with upward propagating semidiurnal tide.…”