Impacts of CME‐induced geomagnetic storms on the midlatitude mesosphere and lower thermosphere observed by a sodium lidar and TIMED/GUVI

2015 ◽  
Vol 42 (18) ◽  
pp. 7295-7302 ◽  
Author(s):  
T. Yuan ◽  
Y. Zhang ◽  
X. Cai ◽  
C.‐Y. She ◽  
L. J. Paxton
2021 ◽  
Author(s):  
Christoph Jacobi ◽  
Friederike Lilienthal ◽  
Dmitry Korotyshkin ◽  
Evgeny Merzlyakov ◽  
Gunter Stober

<p>Observations of upper mesosphere/lower thermosphere (MLT) wind have been performed at Collm (51°N, 13°E) and Kazan (56°N, 49°E), using two SKiYMET all-sky meteor radars with similar configuration. Daily vertical profiles of mean winds and tidal amplitudes have been constructed from hourly horizontal winds. We analyze the response of mean winds and tidal amplitudes to geomagnetic disturbances. To this end we compare winds and amplitudes for very quiet (Ap ≤ 5) and unsettled/disturbed (Ap ≥ 20) geomagnetic conditions. Zonal winds in both the mesosphere and lower thermosphere are weaker during disturbed conditions for both summer and winter. The summer equatorward meridional wind jet is weaker for disturbed geomagnetic conditions. Tendencies over Collm and Kazan for geomagnetic effects on mean winds qualitatively agree during most of the year. For the diurnal tide, amplitudes in summer are smaller in the mesosphere but greater in the lower thermosphere, but no clear tendency is seen for winter. Semidiurnal tidal amplitudes increase during geomagnetic active days in summer and winter. Terdiurnal amplitudes are slightly reduced in the mesosphere during disturbed days, but no clear effect is visible for the lower thermosphere. Overall, while there is a noticeable effect of geomagnetic variability on the mean wind, the effect on tidal amplitudes, except for the semidiurnal tide, is relatively small and partly different over Collm and Kazan.</p>


2018 ◽  
Vol 45 (19) ◽  
pp. 10,128-10,137 ◽  
Author(s):  
Jingyuan Li ◽  
Wenbin Wang ◽  
Jianyong Lu ◽  
Tao Yuan ◽  
Jia Yue ◽  
...  

2005 ◽  
Vol 62 (12) ◽  
pp. 4384-4399 ◽  
Author(s):  
Rolando R. Garcia ◽  
Ruth Lieberman ◽  
James M. Russell ◽  
Martin G. Mlynczak

Abstract Observations made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board NASA’s Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics (TIMED) satellite have been processed using Salby’s fast Fourier synoptic mapping (FFSM) algorithm. The mapped data provide a first synoptic look at the mean structure and traveling waves of the mesosphere and lower thermosphere (MLT) since the launch of the TIMED satellite in December 2001. The results show the presence of various wave modes in the MLT, which reach largest amplitude above the mesopause and include Kelvin and Rossby–gravity waves, eastward-propagating diurnal oscillations (“non-sun-synchronous tides”), and a set of quasi-normal modes associated with the so-called 2-day wave. The latter exhibits marked seasonal variability, attaining large amplitudes during the solstices and all but disappearing at the equinoxes. SABER data also show a strong quasi-stationary Rossby wave signal throughout the middle atmosphere of the winter hemisphere; the signal extends into the Tropics and even into the summer hemisphere in the MLT, suggesting ducting by westerly background zonal winds. At certain times of the year, the 5-day Rossby normal mode and the 4-day wave associated with instability of the polar night jet are also prominent in SABER data.


2015 ◽  
Vol 56 (7) ◽  
pp. 1354-1365 ◽  
Author(s):  
Xin Yao ◽  
Tao Yu ◽  
Biqiang Zhao ◽  
You Yu ◽  
Libo Liu ◽  
...  

1994 ◽  
Vol 56 (13-14) ◽  
pp. 1731-1752 ◽  
Author(s):  
Yu.I. Portnyagin ◽  
N.A. Makarov ◽  
R.P. Chebotarev ◽  
A.M. Nikonov ◽  
E.S. Kazimirovsky ◽  
...  

1999 ◽  
Vol 24 (11) ◽  
pp. 1571-1576 ◽  
Author(s):  
P.J.S. Williams ◽  
N.J. Mitchell ◽  
A.G. Beard ◽  
V.St.C. Howells ◽  
H.G. Muller

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