Low frequency gravity wave spectra generated by cosmic strings

1988 ◽  
Vol 215 (3) ◽  
pp. 477-482 ◽  
Author(s):  
Roger W. Romani
2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Guillaume Michel ◽  
Benoît Semin ◽  
Annette Cazaubiel ◽  
Florence Haudin ◽  
Thomas Humbert ◽  
...  

2008 ◽  
Vol 8 (22) ◽  
pp. 6775-6787 ◽  
Author(s):  
M. Rauthe ◽  
M. Gerding ◽  
F.-J. Lübken

Abstract. More than 230 nights of temperature measurements between 1 and 105 km have been performed at the Leibniz-Institute of Atmospheric Physics in Kühlungsborn with a combination of two different lidars, i.e. a Rayleigh-Mie-Raman lidar and a potassium lidar. About 1700 h of measurements have been collected between 2002 and 2006. Apart from some gaps due to the adverse weather conditions the measurements are well distributed throughout the year. Comprehensive information about the activity of medium- and low-frequency gravity waves was extracted from this data set. The dominating vertical wavelengths found are between 10 and 20 km and do not show any seasonal variation. In contrast the temperature fluctuations due to gravity waves experience a clear annual cycle with a maximum in winter. The most significant differences exist around 60 km where the fluctuations in winter are more than two times larger than they are in summer. Only small seasonal differences are observed above 90 km and below 35 km. Generally, the fluctuations grow from about 0.5 K up to 8 K between 20 and 100 km. Damping of waves is observed at nearly all altitudes and in all seasons. The planetary wave activity shows a similar structure in altitude and season as the gravity wave activity which indicates that similar mechanisms influencing different scales. Combining the monthly mean temperatures and the fluctuations we show that the transition between winter and summer season and vice versa seems to start in the mesopause region and to penetrate downward.


2017 ◽  
Vol 122 (16) ◽  
pp. 8517-8524 ◽  
Author(s):  
M. R. Schoeberl ◽  
E. Jensen ◽  
A. Podglajen ◽  
L. Coy ◽  
C. Lodha ◽  
...  

1994 ◽  
Vol 21 (18) ◽  
pp. 2039-2042 ◽  
Author(s):  
A. de la Torre ◽  
A. Giraldez ◽  
P. Alexander
Keyword(s):  

Atmosphere ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 81 ◽  
Author(s):  
Shaohua Gong ◽  
Guotao Yang ◽  
Jiyao Xu ◽  
Xiao Liu ◽  
Qinzeng Li

A low-frequency inertial atmospheric gravity wave (AGW) event was studied with lidar (40.5° N, 116° E), meteor radar (40.3° N, 116.2° E), and TIMED/SABER at Beijing on 30 May 2012. Lidar measurements showed that the atmospheric temperature structure was persistently perturbed by AGWs propagating upward from the stratosphere into the mesosphere (35–86 km). The dominant contribution was from the waves with vertical wavelengths λ z = 8 − 10   km and wave periods T ob = 6.6 ± 0.7   h . Simultaneous observations from a meteor radar illustrated that MLT horizontal winds were perturbed by waves propagating upward with an azimuth angle of θ = 247 ° , and the vertical wavelength ( λ z = 10   km ) and intrinsic period ( T in = 7.4   h ) of the dominant waves were inferred with the hodograph method. TIMED/SABER measurements illustrated that the vertical temperature profiles were also perturbed by waves with dominant vertical wavelength λ z = 6 − 9   km . Observations from three different instruments were compared, and it was found that signatures in the temperature perturbations and horizontal winds were induced by identical AGWs. According to these coordinated observation results, the horizontal wavelength and intrinsic phase speed were inferred to be ~560 km and ~21 m/s, respectively. Analyses of the Brunt-Väisälä frequency and potential energy illustrated that this persistent wave propagation had good static stability.


1990 ◽  
Vol 17 (10) ◽  
pp. 1581-1584 ◽  
Author(s):  
J. Lefrère ◽  
C. Sidi
Keyword(s):  

1963 ◽  
Vol 15 (3) ◽  
pp. 385-398 ◽  
Author(s):  
K. Hasselmann

The energy transfer due to non-linear interactions between the components of a gravity-wave spectrum discussed in Parts 1 and 2 of this paper is evaluated for a fully and partially developed Neumann spectrum with various spreading factors. The characteristic time scales of the energy transfer are found to be typically of the order of a few hours. In all cases the high frequencies and the low-frequency peak are found to gain energy from an intermediate range of frequencies. The transfer of energy to very low frequencies and to waves travelling at large angles to the main propagation direction of the spectrum is negligible. Computations are presented also for the rate of decay of swell interacting with local wind-generated seas (represented by a Neumann spectrum). An appreciable decay is found only for swell frequencies in the same range as those of the local sea.


1991 ◽  
Vol 43 (8) ◽  
pp. 2733-2735 ◽  
Author(s):  
David P. Bennett ◽  
François R. Bouchet
Keyword(s):  

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