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Diurnal Variation in Gravity Wave Activity at Low and Middle Latitudes
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External Online Source: doi:10.5194/angeo-31-2123-2013
Author and Affiliation:
Andrioli, V. F.(Instituto de Pesquisas Espaciais, Sao Jose dos Campos, Brazil);
Fritts, D. C.(Colorado Research Associates, Inc., Boulder, CO, United States);
Batista, P. P.(Instituto de Pesquisas Espaciais, Sao Jose dos Campos, Brazil);
Clemesha, B. R.(Instituto de Pesquisas Espaciais, Sao Jose dos Campos, Brazil);
Janches, Diego(NASA Goddard Space Flight Center, Greenbelt, MD United States)
Abstract: We employ a modified composite day extension of the Hocking (2005) analysis method to study gravity wave (GW) activity in the mesosphere and lower thermosphere using 4 meteor radars spanning latitudes from 7deg S to 53.6deg S. Diurnal and semidiurnal modulations were observed in GW variances over all sites. Semidiurnal modulation with downward phase propagation was observed at lower latitudes mainly near the equinoxes. Diurnal modulations occur mainly near solstice and, except for the zonal component at Cariri (7deg S), do not exhibit downward phase propagation. At a higher latitude (SAAMER, 53.6deg S) these modulations are only observed in the meridional component where we can observe diurnal variation from March to May, and semidiurnal, during January, February, October (above 88 km) and November. Some of these modulations with downward phase progression correlate well with wind shear. When the wind shear is well correlated with the maximum of the variances the diurnal tide has its largest amplitudes, i.e., near equinox. Correlations exhibiting variations with tidal phases suggest significant GW-tidal interactions that have different characters depending on the tidal components and possible mean wind shears. Modulations that do not exhibit phase variations could be indicative of diurnal variations in GW sources.
Publication Date: Nov 29, 2013
Document ID:
20140005694
(Acquired May 16, 2014)
Subject Category: SPACE SCIENCES (GENERAL)
Report/Patent Number: GSFC-E-DAA-TN13253
Document Type: Journal Article
Publication Information: Annales Geophysicae; No. 31; 2123-2135
Publisher Information: Copernicus
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD United States
Description: 13p; In English; Original contains color and black and white illustrations
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: GRAVITY WAVES; MESOSPHERE; DIURNAL VARIATIONS; THERMOSPHERE; TIDES; RADAR; LATITUDE
Other Descriptors: METEOROLOGY; ATMOSPHERIC DYNAMICS; WAVES
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