The effects of Doppler shift on gravity wave spectra observed by MST radar

Scheffler, A. O.; Liu, C.H

doi:10.1016/0021-9169(86)90041-3

Cited by 44 publications

(21 citation statements)

References 9 publications

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“…Further, the comparison between both spectra indicate no clear cutoff beyond τ B observed under active conditions. This is consistent with the fact that the frequency spectra of vertical velocity are highly sensitive to Doppler-shifting effects (Scheffler and Liu, 1986;Fritts and VanZandt, 1987).…”

Section: Resultssupporting

confidence: 71%

High-resolution vertical velocities and their power spectrum observed with the MAARSY radar – Part 1: frequency spectrum

Rapp

Stober

et al. 2018

Ann. Geophys.

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Abstract. The Middle Atmosphere Alomar Radar System (MAARSY) installed at the island of Andøya has been run for continuous probing of atmospheric winds in the upper troposphere and lower stratosphere (UTLS) region. In the current study, we present high-resolution wind measurements during the period between 2010 and 2013 with MAARSY. The spectral analysis applying the Lomb-Scargle periodogram method has been carried out to determine the frequency spectra of vertical wind velocity. From a total of 522 days of observations, the statistics of the spectral slope have been derived and show a dependence on the background wind conditions. It is a general feature that the observed spectra of vertical velocity during active periods (with wind velocity > 10 m s −1 ) are much steeper than during quiet periods (with wind velocity < 10 m s −1 ). The distribution of spectral slopes is roughly symmetric with a maximum at −5/3 during active periods, whereas a very asymmetric distribution with a maximum at around −1 is observed during quiet periods. The slope profiles along altitudes reveal a significant height dependence for both conditions, i.e., the spectra become shallower with increasing altitudes in the upper troposphere and maintain roughly a constant slope in the lower stratosphere. With both wind conditions considered together the general spectra are obtained and their slopes are compared with the background horizontal winds. The comparisons show that the observed spectra become steeper with increasing wind velocities under quiet conditions, approach a spectral slope of −5/3 at a wind velocity of 10 m s −1 and then roughly maintain this slope (−5/3) for even stronger winds. Our findings show an overall agreement with previous studies; furthermore, they provide a more complete climatology of frequency spectra of vertical wind velocities under different wind conditions.

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Section: Resultssupporting

confidence: 71%

High-resolution vertical velocities and their power spectrum observed with the MAARSY radar – Part 1: frequency spectrum

Rapp

Stober

et al. 2018

Ann. Geophys.

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“…A more serious limitation of this technique is that a clear spectral peak might not be apparent under conditions of large horizontal wind speeds . Scheffler and Liu (1986) showed that this was consistent with the effects of Doppler shifting by the horizontal winds. The technique is therefore probably of limited use at mid-latitude locations where upper-tropospheric wind speeds are typically several tens of m s −1 .…”

Section: Introductionsupporting

confidence: 74%

Retrieval of atmospheric static stability from MST radar return signal power

2004

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Abstract. An empirical technique for retrieving profiles of the square of the Brunt-Väisälä frequency, ω 2 B , from MST radar return signal power is presented. The validity of the technique, which is applied over the altitude range 1.0-15.7 km, is limited to those altitudes at which the humidity contributions to the mean vertical gradient of generalised potential refractive index, M, can be ignored. Although this is commonly assumed to be the case above the first few kilometres of the atmosphere, it is shown that humidity contributions can be significant right up to the tropopause level. In specific circumstances, however, the technique is valid over large sections of the troposphere. Comparisons of radarand (balloon-borne) radiosonde-derived ω 2 B profiles are typically quantitatively and qualitatively well matched. However, the horizontal separation between the radar and the radiosondes (which were launched at the radar site) increases with increasing altitude. Under conditions of mountain wave activity, which can be highly localised, large discrepancies can occur at lower-stratospheric altitudes. This demonstrates the fact that radiosonde observations cannot necessarily be assumed to be representative of the atmosphere above the launch site.

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“…The requirement of a long data length may restrict the availability of useful data as the atmospheric conditions like stability may change during the period of the data. Further, doppler shift due to background wind can transfer energy to lower and higher frequencies (than B-V frequency) and this would tend to flatten or stretch the spectra making identification of B-V frequency difficult (Rottger, 1980b;Scheffler andLiu, 1985, 1986). Apparently, the present data corresponds to small background wind velocity conditions as the B-V frequencies could be identified unambiguously.…”

Section: At 1730 Ist Onmentioning

confidence: 99%