scholarly journals Gravity wave activity in the lower atmosphere: Seasonal and latitudinal variations

1995 ◽  
Vol 100 (D1) ◽  
pp. 1327-1350 ◽  
Author(s):  
Simon J. Allen ◽  
Robert A. Vincent
Keyword(s):  
Gravity Wave ◽  
Wave Activity ◽  
Lower Atmosphere ◽  
Latitudinal Variations

scholarly journals Enhanced gravity-wave activity and interhemispheric coupling during the MaCWAVE/MIDAS northern summer program 2002

2006 ◽  
Vol 24 (4) ◽  
pp. 1175-1188 ◽  
Author(s):  
E. Becker ◽  
D. C. Fritts
Keyword(s):  
Gravity Wave ◽  
Rossby Wave ◽  
Lower Thermosphere ◽  
Wave Activity ◽  
Lower Atmosphere ◽  
Summer Program ◽  
Latent Heating ◽  
Austral Winter ◽  
Northern Summer ◽  
Mesosphere And Lower Thermosphere

Abstract. We present new sensitivity experiments that link observed anomalies of the mesosphere and lower thermosphere at high latitudes during the MaCWAVE/MIDAS summer program 2002 to enhanced planetary Rossby-wave activity in the austral winter troposphere. We employ the same general concept of a GCM having simplified representations of radiative and latent heating as in a previous study by Becker et al. (2004). In the present version, however, the model includes no gravity wave (GW) parameterization. Instead we employ a high vertical and a moderate horizontal resolution in order to describe GW effects explicitly. This is supported by advanced, nonlinear momentum diffusion schemes that allow for a self-consistent generation of inertia and mid-frequency GWs in the lower atmosphere, their vertical propagation into the mesosphere and lower thermosphere, and their subsequent dissipation which is induced by prescribed horizontal and vertical mixing lengths as functions of height. The main anomalies in northern summer 2002 consist of higher temperatures than usual above 82 km, an anomalous eastward mean zonal wind between 70 and 90 km, an altered meridional flow, enhanced turbulent dissipation below 80 km, and enhanced temperature variations associated with GWs. These signals are all reasonably described by differences between two long-integration perpetual model runs, one with normal July conditions, and another run with modified latent heating in the tropics and Southern Hemisphere to mimic conditions that correspond to the unusual austral winter 2002. The model response to the enhanced winter hemisphere Rossby-wave activity has resulted in both an interhemispheric coupling through a downward shift of the GW-driven branch of the residual circulation and an increased GW activity at high summer latitudes. Thus a quantitative explanation of the dynamical state of the northern mesosphere and lower thermosphere during June-August 2002 requires an enhanced Lorenz energy cycle and correspondingly enhanced GW sources in the troposphere, which in the model show up in both hemispheres.

scholarly journals Studies on atmospheric gravity wave activity in the troposphere and lower stratosphere over a tropical station at Gadanki

2005 ◽  
Vol 23 (10) ◽  
pp. 3237-3260 ◽  
Author(s):  
I. V. Subba Reddy ◽  
D. Narayana Rao ◽  
A. Narendra Babu ◽  
M. Venkat Ratnam ◽  
P. Kishore ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Lower Stratosphere ◽  
Wave Length ◽  
Wave Activity ◽  
Lower Atmosphere ◽  
Wind Fields ◽  
Atmospheric Gravity Wave ◽  
Short Period ◽  
Atmospheric Gravity

Abstract. MST radars are powerful tools to study the mesosphere, stratosphere and troposphere and have made considerable contributions to the studies of the dynamics of the upper, middle and lower atmosphere. Atmospheric gravity waves play a significant role in controlling middle and upper atmospheric dynamics. To date, frontal systems, convection, wind shear and topography have been thought to be the sources of gravity waves in the troposphere. All these studies pointed out that it is very essential to understand the generation, propagation and climatology of gravity waves. In this regard, several campaigns using Indian MST Radar observations have been carried out to explore the gravity wave activity over Gadanki in the troposphere and the lower stratosphere. The signatures of the gravity waves in the wind fields have been studied in four seasons viz., summer, monsoon, post-monsoon and winter. The large wind fluctuations were more prominent above 10 km during the summer and monsoon seasons. The wave periods are ranging from 10 min-175 min. The power spectral densities of gravity waves are found to be maximum in the stratospheric region. The vertical wavelength and the propagation direction of gravity waves were determined using hodograph analysis. The results show both down ward and upward propagating waves with a maximum vertical wave length of 3.3 km. The gravity wave associated momentum fluxes show that long period gravity waves carry more momentum flux than the short period waves and this is presented.

scholarly journals A multiannual record of gravity wave activity in Mars’s lower atmosphere from on-planet observations by the Mars Climate Sounder

Icarus ◽  
2020 ◽  
Vol 341 ◽  
pp. 113630 ◽  
Author(s):  
Nicholas G. Heavens ◽  
David M. Kass ◽  
Armin Kleinböhl ◽  
John T. Schofield
Keyword(s):  
Gravity Wave ◽  
Wave Activity ◽  
Lower Atmosphere

scholarly journals Influence of the cloud-level neutral layer on the vertical propagation of topographically generated gravity waves on Venus

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Takeru Yamada ◽  
Takeshi Imamura ◽  
Tetsuya Fukuhara ◽  
Makoto Taguchi
Keyword(s):  
Layer Thickness ◽  
Gravity Wave ◽  
Local Time ◽  
Gravity Waves ◽  
Analytical Approach ◽  
Wave Activity ◽  
Neutral Layer ◽  
Low Latitudes ◽  
Vertical Propagation ◽  
The Waves

AbstractThe reason for stationary gravity waves at Venus’ cloud top to appear mostly at low latitudes in the afternoon is not understood. Since a neutral layer exists in the lower part of the cloud layer, the waves should be affected by the neutral layer before reaching the cloud top. To what extent gravity waves can propagate vertically through the neutral layer has been unclear. To examine the possibility that the variation of the neutral layer thickness is responsible for the dependence of the gravity wave activity on the latitude and the local time, we investigated the sensitivity of the vertical propagation of gravity waves on the neutral layer thickness using a numerical model. The results showed that stationary gravity waves with zonal wavelengths longer than 1000 km can propagate to the cloud-top level without notable attenuation in the neutral layer with realistic thicknesses of 5–15 km. This suggests that the observed latitudinal and local time variation of the gravity wave activity should be attributed to processes below the cloud. An analytical approach also showed that gravity waves with horizontal wavelengths shorter than tens of kilometers would be strongly attenuated in the neutral layer; such waves should originate in the altitude region above the neutral layer.

scholarly journals 11 Years of Rayleigh Lidar Observations of Gravity Wave Activity Above the Southern Tip of South America

2019 ◽  
Vol 124 (2) ◽  
pp. 451-467 ◽  
Author(s):  
P. Llamedo ◽  
J. Salvador ◽  
A. Torre ◽  
J. Quiroga ◽  
P. Alexander ◽  
...  
Keyword(s):  
South America ◽  
Gravity Wave ◽  
Wave Activity ◽  
Rayleigh Lidar ◽  
Lidar Observations
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