Seasonal variation of gravity wave activity in the lower atmosphere observed with the MU radar

1994 ◽  
Vol 99 (D11) ◽  
pp. 23057 ◽  
Author(s):  
Y. Murayama ◽  
T. Tsuda ◽  
S. Fukao
Keyword(s):  
Seasonal Variation ◽  
Gravity Wave ◽  
Wave Activity ◽  
Lower Atmosphere ◽  
Mu Radar

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 Turbulence characteristics in the tropical mesosphere as obtained by MST radar at Gadanki (13.5° N, 79.2° E)

2001 ◽  
Vol 19 (8) ◽  
pp. 1019-1025 ◽  
Author(s):  
M. N. Sasi ◽  
L. Vijayan
Keyword(s):  
Seasonal Variation ◽  
Gravity Wave ◽  
Middle Atmosphere ◽  
Indian Subcontinent ◽  
Southwest Monsoon ◽  
Wave Activity ◽  
Tropical Meteorology ◽  
Monsoon Period ◽  
Mst Radar ◽  
Summer Maximum

Abstract. Turbulent kinetic energy dissipation rates (ε) and eddy diffusion coefficients (Kz) in the tropical mesosphere over Gadanki (13.5° N, 79.2° E), estimated from Doppler widths of MST radar echoes (vertical beam), observed over a 3-year period, show a seasonal variation with a dominant summer maximum. The observed seasonal variation of ε and Kz in the mesosphere is only partially consistent with that of gravity wave activity inferred from mesospheric winds and temperatures measured by rockets for a period of 9 years at Trivandrum (8.5° N, 77° E) (which shows two equinox and one summer maxima) lying close to Gadanki. The summer maximum of mesospheric ε and Kz values appears to be related to the enhanced gravity wave activity over the low-latitude Indian subcontinent during the southwest monsoon period (June – September). Both ε and Kz in the mesosphere over Gadanki show an increase with an increase in height during all seasons. The absolute values of observed ε and Kz in the mesosphere (above ~80 km) does not show significant differences from those reported for high latitudes. Comparison of observed Kz values during the winter above Gadanki with those over Arecibo (18.5° N, 66° W) shows that they are not significantly different from each other above the ~80 km altitude.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; tropical meteorology; wave and tides)

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 Seasonal variation of short-period (<2 h) gravity wave activity over Gadanki, India (13.5°N, 79.2°E)

2008 ◽  
Vol 113 (D14) ◽  
Author(s):  
Gopa Dutta ◽  
Toshitaka Tsuda ◽  
P. Vinay Kumar ◽  
M. C. Ajay Kumar ◽  
Simon P. Alexander ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Gravity Wave ◽  
Wave Activity ◽  
Period 2 ◽  
Short Period

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
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