Propagation of the solar semidiurnal tide in the mesosphere and lower thermosphere at mid latitudes

1991 ◽  
Vol 96 (A2) ◽  
pp. 1129-1133 ◽  
Author(s):  
R. R. Clark ◽  
J. E. Salah
Keyword(s):  
Lower Thermosphere ◽  
Semidiurnal Tide ◽  
Mesosphere And Lower Thermosphere

Height-latitude structure of the vertical component of the migrating semidiurnal tide in the upper mesosphere and lower thermosphere region (80–100 km)

2011 ◽  
Vol 47 (1) ◽  
pp. 108-118 ◽  
Author(s):  
Yu. I. Portnyagin ◽  
E. G. Merzlyakov ◽  
T. V. Solov’eva ◽  
A. I. Pogorel’tsev ◽  
E. V. Suvorova ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Vertical Component ◽  
Semidiurnal Tide ◽  
Mesosphere And Lower Thermosphere

Radar observations of the semidiurnal tide in the mesosphere and lower thermosphere at midlatitudes

1994 ◽  
Vol 56 (10) ◽  
pp. 1251-1261 ◽  
Author(s):  
J.E. Salah ◽  
R.R. Clark ◽  
J.M. Forbes ◽  
A.H. Manson ◽  
S.K. Avery ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Semidiurnal Tide ◽  
Radar Observations ◽  
Mesosphere And Lower Thermosphere

Influence of geomagnetic disturbances on midlatitude mesosphere/lower thermosphere mean winds and tides 

2021 ◽  
Author(s):  
Christoph Jacobi ◽  
Friederike Lilienthal ◽  
Dmitry Korotyshkin ◽  
Evgeny Merzlyakov ◽  
Gunter Stober
Keyword(s):  
Lower Thermosphere ◽  
Meridional Wind ◽  
Vertical Profiles ◽  
Semidiurnal Tide ◽  
Geomagnetic Disturbances ◽  
Noticeable Effect ◽  
Zonal Winds ◽  
The Mean ◽  
Mesosphere And Lower Thermosphere ◽  
Midlatitude Mesosphere

<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>

scholarly journals Gravity wave propagation through a large semidiurnal tide and instabilities in the mesosphere and lower thermosphere during the winter 2003 MaCWAVE rocket campaign

2006 ◽  
Vol 24 (4) ◽  
pp. 1199-1208 ◽  
Author(s):  
B. P. Williams ◽  
D. C. Fritts ◽  
C. Y. She ◽  
R. A. Goldberg
Keyword(s):  
Wave Propagation ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Lower Thermosphere ◽  
Semidiurnal Tide ◽  
Frequency Spectra ◽  
Mesosphere And Lower Thermosphere ◽  
Using Data ◽  
Wind Profiles ◽  
Full Temperature

Abstract. The winter MaCWAVE (Mountain and convective waves ascending vertically) rocket campaign took place in January 2003 at Esrange, Sweden and the ALOMAR observatory in Andenes, Norway. The campaign combined balloon, lidar, radar, and rocket measurements to produce full temperature and wind profiles from the ground to 105 km. This paper will investigate gravity wave propagation in the mesosphere and lower thermosphere using data from the Weber sodium lidar on 28–29 January 2003. A very large semidiurnal tide was present in the zonal wind above 80 km that grew to a 90 m/s amplitude at 100 km. The superposition of smaller-scale gravity waves and the tide caused small regions of possible convective or shear instabilities to form along the downward progressing phase fronts of the tide. The gravity waves had periods ranging from the Nyquist period of 30 min up to 4 h, vertical wavelengths ranging from 7 km to more than 20 km, and the frequency spectra had the expected –5/3 slope. The dominant gravity waves had long vertical wavelengths and experienced rapid downward phase progression. The gravity wave variance grew exponentially with height up from 86 to 94 km, consistent with the measured scale height, suggesting that the waves were not dissipated strongly by the tidal gradients and resulting unstable regions in this altitude range.

scholarly journals Influence of geomagnetic disturbances on mean winds and tides in the mesosphere/lower thermosphere at midlatitudes

2021 ◽  
Vol 19 ◽  
pp. 185-193
Author(s):  
Christoph Jacobi ◽  
Friederike Lilienthal ◽  
Dmitry Korotyshkin ◽  
Evgeny Merzlyakov ◽  
Gunter Stober
Keyword(s):  
Lower Thermosphere ◽  
Meridional Wind ◽  
Vertical Profiles ◽  
Semidiurnal Tide ◽  
Geomagnetic Disturbances ◽  
Noticeable Effect ◽  
Clear Tendency ◽  
Zonal Winds ◽  
The Mean ◽  
Mesosphere And Lower Thermosphere

Abstract. Observations of upper mesosphere/lower thermosphere (MLT) wind have been performed at Collm (51.3∘ N, 13.0∘ 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 analyse 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 for geomagnetic effects on mean winds over Collm and Kazan qualitatively agree during most of the year. For the diurnal tide, amplitudes in summer are smaller in the mesosphere and 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.

Dynamics of the Antarctic and Arctic mesosphere and lower thermosphere regions—II. The semidiurnal tide

1993 ◽  
Vol 55 (6) ◽  
pp. 843-855 ◽  
Author(s):  
Yu.I Portnyagin ◽  
J.M Forbes ◽  
G.J Fraser ◽  
R.A Vlncent ◽  
S.K Avery ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Semidiurnal Tide ◽  
Mesosphere And Lower Thermosphere ◽  
The Antarctic

scholarly journals The 8-h tide in the mesosphere and lower thermosphere over Collm (51.3° N; 13.0° E), 2004–2011

2012 ◽  
Vol 10 ◽  
pp. 265-270 ◽  
Author(s):  
Ch. Jacobi ◽  
T. Fytterer
Keyword(s):  
Negative Correlation ◽  
Lower Thermosphere ◽  
Solar Heating ◽  
Monthly Means ◽  
Semidiurnal Tide ◽  
Meteor Radar ◽  
Seasonal Behaviour ◽  
Solar Tide ◽  
Mesosphere And Lower Thermosphere ◽  
Spring Maximum

Abstract. The horizontal winds in the mesosphere and lower thermosphere (MLT) at heights of about 80–100 km have been measured continuously since summer 2004 using an all-sky 36.2 MHz VHF meteor radar at Collm, Germany (51.3° N, 13° E). A climatology of the 8-h solar tide has been constructed from these data. The amplitude shows a seasonal behaviour with maximum values during the equinoxes, and it is generally increasing with altitude. The largest amplitudes are measured in autumn, partly reaching values up to 15 m s−1. The phase, defined as the time of maximum eastward or northward wind, respectively, has earlier values in winter and later ones in summer. Except for summer, the phase difference between the zonal and meridional components is close to +2 h, indicating circular polarization of the tidal components. The vertical wavelengths are short in summer (~20 km) but significantly longer during the rest of the year. The terdiurnal tide is generally assumed to originate from either a terdiurnal component of solar heating or nonlinear interaction between the diurnal and semidiurnal tide. Analysing monthly means reveals positive correlation during the spring maximum, but negative correlation in autumn.

scholarly journals Large-Scale Waves in the Mesosphere and Lower Thermosphere Observed by SABER

2005 ◽  
Vol 62 (12) ◽  
pp. 4384-4399 ◽  
Author(s):  
Rolando R. Garcia ◽  
Ruth Lieberman ◽  
James M. Russell ◽  
Martin G. Mlynczak
Keyword(s):  
Large Scale ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Normal Modes ◽  
Zonal Winds ◽  
Broadband Emission ◽  
Summer Hemisphere ◽  
Mean Structure ◽  
Mesosphere And Lower Thermosphere ◽  
The Tropics

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.

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