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

Abstract

The present study investigates the effect of the major sudden stratospheric warming (SSW) event of 2009, on the small‐scale gravity wave (GW) activity in the ionosphere. Small‐scale fluctuations with time periods within the range of 10–90 min observed in Global Positioning System total electron content (TEC) data have been used as a proxy for GW activity in the ionosphere. TEC data from five longitudinally separated Global Positioning System stations located around 60∘N latitude have been utilized for this purpose. In the initial phase of the major warming, when the stratospheric conditions are similar to a minor warming during which the mean zonal flow starts to weaken, the ionopsheric GW activity tends to increase. However, during the peak phase of the SSW, as the zonal mean wind starts to reverse its direction, and after the peak warming, as the winds remain weak, conditions are less favorable for upward propagation of a spectrum of GWs, and thus the ionospheric GW activity is reduced, as seen from the behavior of the small‐scale TEC fluctuations during the latter period of the SSW. Similar reduction in GW activity is also observed in the middle atmosphere (65–100 km) as seen from GWs derived from SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) temperature profiles. The reductions in GW activity is more prominent during local daytime as compared to nighttime period. The reduction in GW activity shows a longitudinal variation with some locations showing relatively more reduction in the GW activity as compared to others.

Impact of gravity wave drag on the thermospheric circulation: implementation of a nonlinear gravity wave parameterization in a whole-atmosphere model

“…Using the SABER measurement aboard the TIMED satellite, Pancheva and Mukhtarov (2011) investigated the behavior of the SW2 in the MLT. There, the typical observed peak values for the SW2 amplitudes are situated at low latitudes during the June solstice: 25-28 K at 15-30 • N and 15-20 K at 15-25 • S. In our study, GCM simulations based on two different GW parameterizations yield different results for the SW2 tide.…”

“…The amplitude maximizes at around a 125 km height. The maxima are 41 K at 15 • S and 38 K at 20 • N. The peak of the SW2 amplitude above a 200 km height (34 K) appears at 15-25 • S, and the secondary peak (10 K) is found around 45 • N. Using the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) measurement aboard the TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics) satellite, Pancheva and Mukhtarov (2011) Forbes et al, 2011). The simulated SW2 in the SH (NH) is larger (smaller) than the observed SW2.…”

Impact of Gravity wave drag on the thermospheric circulation: Implementation of a nonlinear gravity wave parameterization in a whole atmosphere model

“…During minor warming, thermospheric GWs activity can be enhanced significantly (e.g., Yiğit et al, 2014;Yiğit and Medvedev, 2016), while during major warmings it may encounter a decrease (Nayak and Yiğit, 2019). Here, we used a whole atmosphere GCM incorporating a whole atmosphere GW parameterization in order to the study the mean dynamical effects of GWs and their impact on the semidiurnal tides in the thermosphere.…”

September 2019 Antarctic Sudden Stratospheric Warming: Quasi‐6‐Day Wave Burst and Ionospheric Effects

“…In the last decade, the aeronomy community has come to the realization that SSWs can be a significant source of ionospheric variability (Chau et al, ; Pedatella et al, ). In particular, the January 2009 major Arctic SSW, which took place under extremely quiet solar and geomagnetic activity conditions, enabled many studies to attribute observed ionospheric perturbations to the SSW (e.g., Chau et al, ; Goncharenko et al, , ; Fejer et al, ; Liu et al, ; Lin et al, ; Nayak & Yiğit, ; Oyama et al, ; Pedatella & Forbes, ; Patra et al, ; Pancheva & Mukhtarov, ; Rodrigues et al, ; Yue et al, ; Yadav et al, ). Most studies concentrated on the dayside low‐latitude region, where the ionospheric response to the SSW was most pronounced.…”