Ionospheric response to 2009 sudden stratospheric warming in the Northern Hemisphere

Abstract

We study the behavior of the F region ionosphere in the Northern Hemisphere during the sudden stratospheric warming period of 19-30 January 2009 by using FORMOSAT-3/Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) ionosphere data (N m F 2 , h m F 2 , and height profile). We concentrated our study in the longitude bands 30°E-30°W, as well as 150°E-150°W, where no detailed study has been reported so far. At low magnetic latitude, the N m F 2 decreases except during 09-12 LT: in the latitude zone of 20-40°N m F 2 shows an increase of 30% during 09-12 LT. At higher magnetic latitude the N m F 2 shows an increase during daytime and a reduction in the evening (21-03 LT). There is a latitude zone where N m F 2 does not change. The latitude seems to correspond to the latitude where atmospheric temperature does not change. The behavior of the N m F 2 seems to suggest a reduction of neutral density in low latitude and increase of neutral density in higher latitude. During the period of day of year (DOY) 25-31, the N m F 2 shows a drastic reduction only during 06-09 LT in low latitudes, which is slightly away from geomagnetic equator. This special feature which occurred during declining phase of the sudden stratospheric warming (SSW) might be explained as due to enhanced dynamo electric field. The study suggests global change of the thermosphere including dynamo region, in spite of the fact that SSW is a high-latitude phenomenon which occurred much below the height region of thermosphere.

Impact of the semidiurnal lunar tide on the midlatitude thermospheric wind and ionosphere during sudden stratosphere warmings

“…Polyakova et al [2014] found a reduced diurnal amplitude in the TEC at midlatitudes over Siberia during the 2009 and 2013 SSWs. Changes in the Northern Hemisphere midlatitude N m F 2 was also observed during the 2009 SSW by Oyama et al [2014]. Variability in the midlatitude ionosphere is not necessarily restricted to the Northern Hemisphere, and Fagundes et al [2015] observed variability in TEC at a Southern Hemisphere midlatitude station in Brazil (53.8 ∘ S, 67.8 ∘ W).…”

Interhemispheric Transport of the Ionospheric F Region Plasma During the 2009 Sudden Stratosphere Warming

“…It is seen that the ionospheric responses to a SSW commonly have a hemispheric difference at both low and middle latitudes (e.g., Korenkov et al, 2012; Oyama et al, 2014; Pancheva & Mukhtarov, 2011; Pedatella & Maute, 2015; Yue et al, 2010). Especially, the magnitude of the electron density perturbations around EIA regions is significantly different in both hemispheres during SSWs (e.g., Goncharenko, Coster, et al, 2010; H. Liu, Yamamoto, et al, 2011).…”

Variation of Small‐Scale Gravity Wave Activity in the Ionosphere During the Major Sudden Stratospheric Warming Event of 2009

“…It was devoid of any major geomagnetic disturbance which could help interpret the effects due to internal sources. Second, the 2009 SSW event has been studied extensively (Azeem et al, ; Chau et al, ; Conde & Nicolls, ; Fagundes et al, ; Fang et al, ; Forbes & Zhang, ; Fuller‐Rowell, Akmaev, et al, ; Fuller‐Rowell, Wang, et al ; Goncharenko, Coster, et al, ; Goncharenko, Chau, et al, ; He et al, ; Klimenko et al, ; Korenkov et al, ; Lin et al, ; Liu et al, , ; McDonald et al, ; Oyama et al, ; Patra et al, ; Pedatella et al, ), which gives us an advantage to use it as an ideal testbed. However, we must emphasize that none of the studies focused on small‐scale GWs.…”