scholarly journals Momentum budget of the migrating diurnal tide in the mesosphere and lower thermosphere

2010 ◽  
Vol 115 (D20) ◽  
Author(s):  
R. S. Lieberman ◽  
D. A. Ortland ◽  
D. M. Riggin ◽  
Q. Wu ◽  
C. Jacobi
Keyword(s):  
Lower Thermosphere ◽  
Diurnal Tide ◽  
Momentum Budget ◽  
Mesosphere And Lower Thermosphere

The wind regime of the mesosphere and lower thermosphere during the DYANA campaign—II. Semi-diurnal tide

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 ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Diurnal Tide ◽  
Wind Regime ◽  
Mesosphere And Lower Thermosphere

The Momentum Budget in the Stratosphere, Mesosphere, and Lower Thermosphere. Part II: The In Situ Generation of Gravity Waves

2018 ◽  
Vol 75 (10) ◽  
pp. 3635-3651 ◽  
Author(s):  
Ryosuke Yasui ◽  
Kaoru Sato ◽  
Yasunobu Miyoshi
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Lower Thermosphere ◽  
Shear Instability ◽  
Wave Forcing ◽  
Momentum Budget ◽  
Mesosphere And Lower Thermosphere ◽  
In Situ Generation ◽  
Mlt Region

The contributions of gravity waves to the momentum budget in the mesosphere and lower thermosphere (MLT) is examined using simulation data from the Ground-to-Topside Model of Atmosphere and Ionosphere for Aeronomy (GAIA) whole-atmosphere model. Regardless of the relatively coarse model resolution, gravity waves appear in the MLT region. The resolved gravity waves largely contribute to the MLT momentum budget. A pair of positive and negative Eliassen–Palm flux divergences of the resolved gravity waves are observed in the summer MLT region, suggesting that the resolved gravity waves are likely in situ generated in the MLT region. In the summer MLT region, the mean zonal winds have a strong vertical shear that is likely formed by parameterized gravity wave forcing. The Richardson number sometimes becomes less than a quarter in the strong-shear region, suggesting that the resolved gravity waves are generated by shear instability. In addition, shear instability occurs in the low (middle) latitudes of the summer (winter) MLT region and is associated with diurnal (semidiurnal) migrating tides. Resolved gravity waves are also radiated from these regions. In Part I of this paper, it was shown that Rossby waves in the MLT region are also radiated by the barotropic and/or baroclinic instability formed by parameterized gravity wave forcing. These results strongly suggest that the forcing by gravity waves originating from the lower atmosphere causes the barotropic/baroclinic and shear instabilities in the mesosphere that, respectively, generate Rossby and gravity waves and suggest that the in situ generation and dissipation of these waves play important roles in the momentum budget of the MLT region.

scholarly journals MF radar observations of the diurnal tide over Syowa, Antarctica (69° S, 40° E)

2009 ◽  
Vol 27 (7) ◽  
pp. 2653-2659 ◽  
Author(s):  
Y. Tomikawa ◽  
M. Tsutsumi
Keyword(s):  
Lower Thermosphere ◽  
Radar Data ◽  
Diurnal Tide ◽  
Syowa Station ◽  
Meridional Winds ◽  
Realistic Representation ◽  
Height Dependence ◽  
Mesosphere And Lower Thermosphere ◽  
The Antarctic ◽  
Mf Radar

Abstract. Characteristics of the diurnal tide in the Antarctic mesosphere and lower thermosphere (MLT) are investigated using 10 years of medium frequency (MF) radar data from Syowa Station (69° S, 39.6° E). Seasonal variations and height dependence of the diurnal amplitude and phase of zonal and meridional winds are mostly consistent with previous studies using the other Antarctic station data. The meridional momentum flux due to the diurnal tide shows a seasonal variation clearly different between above and below 90 km, which has never been reported in the literature. Finally, a cause of some discrepancy in the characteristics of the diurnal tide between the observation and simulation (i.e., GSWM-02) is discussed. It implies that the realistic representation of gravity waves in the simulation is crucial for realistic modeling of the diurnal tide.

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