Altitude dependence of vertical velocity spectra observed by VHF radar

Kuo, F. S.; Shen, Hung-Wen; Fu, I. J.; Chao, J. K.; Röttger, J.; Liu, Chao-Han

doi:10.1029/rs020i006p01349

Cited by 16 publications

(17 citation statements)

References 7 publications

(1 reference statement)

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“…These "break points" are at ∼ 9 km for active conditions and ∼ 10.5 km for quiet conditions, which are close to the tropopause heights. A similar height dependence of spectral slopes was also reported by previous studies (e.g., Kuo et al, 1985;Larsen et al, 1987). When active and quiet periods are considered together (i.e., the whole data set is analyzed despite the background wind conditions), the so-called "general" spectra of vertical velocity are derived and reveal intermediate slopes compared with those under active or quiet conditions.…”

Section: Resultssupporting

confidence: 56%

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: 56%

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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“…Because horizontal velocities can approach and even exceed 100 m/s, pointing accuracies of a few tenths of a degree or a few mrad are required to insure that horizontal contamination does not exceed a few tenths of m/s. Among the few reported measurements of vertical wind profiles and their spectra are the papers of Kuo et al [ 1985], Larsen et al [ 1986 Copyright 1995 by the American Geophysical Union.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous lidar observations of vertical wind, temperature, and density profiles in the upper mesophere: Evidence for nonseparability of atmospheric perturbation spectra

Gardner¹,

Tao²,

Papen³

1995

Geophysical Research Letters

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A Na Wind/Temperature lidar was used to measure Na density, atmospheric temperature, and vertical wind profiles between 84 and 100 km altitude on September 27, 1993 at Haleakala, Maui during the 1993 Airborne Lidar and Observations of the Hawaiian Airglow (ALOHA‐93) Campaign. The data were used to compute the vertical wave number (m) and observed temporal frequency spectra (ω) of relative atmospheric density, relative temperature, and vertical winds perturbations. The shapes and magnitudes of the relative density and temperature spectra are consistent with the large body of previously published observations. The spectral indices are near −3 for the m‐spectra and near −2 for the ω‐spectra. The spectral index of the vertical wind ω‐spectrum is near 0. The spectral index of the vertical wind m‐spectrum is very small (−1.4). This result is inconsistent with the concept of separable (m, ω) joint spectra for wave induced perturbations. The measured rms perturbations during the observation period are, respectively, 4.9%, 4.5%, and 3.9 m/s for relative atmospheric density, relative temperature, and vertical winds.

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“…The ST-radar studies of Kuo et al (1985) measured the slopes of vertical-velocity spectra to be near A1.7 in the middle troposphere and near A0.34 in the lower stratosphere. Larsen et al (1987) reported slopes near A1.3 for troposphere/lower-stratosphere data and Sidi et al (1988) reported a spectral slope of A1.8 for the lower stratosphere based on a high-resolution balloon measurement.…”

Section: Vertical-wave Number Spectramentioning

confidence: 99%

Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar

Mitchell¹,

Howells²

1998

Ann. Geophys.

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Abstract. The EISCAT VHF radar (69. 4°N, 19.1°E) has been used to record vertical winds at mesopause heights on a total of 31 days between June 1990 and January 1993. The data reveal a motion ®eld dominated by quasi-monochromatic gravity waves with representative apparent periods of $30±40 min, amplitudes of up to $2.5 m s A1 and large vertical wavelength. In some instances waves appear to be ducted. Vertical pro®les of the vertical-velocity variance display a variety of forms, with little indication of systematic wave growth with height. Daily mean variance pro®les evaluated for consecutive days of recording show that the general shape of the variance pro®les persists over several days. The mean variance evaluated over a 10 km height range has values from 1.2 m 2 s A2 to 6.5 m 2 s A2 and suggests a semi-annual seasonal cycle with equinoctial minima and solsticial maxima. The mean vertical wavenumber spectrum evaluated at heights up to 86 km has a slope (spectral index) of A1.36 0.2, consistent with observations at lower heights but disagreeing with the predictions of a number of saturation theories advanced to explain gravity-wave spectra. The spectral slopes evaluated for individual days have a range of values, and steeper slopes are observed in summer than in winter. The spectra also appear to be generally steeper on days with lower mean vertical-velocity variance.

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Altitude dependence of vertical velocity spectra observed by VHF radar

Cited by 16 publications

References 7 publications

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

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

Simultaneous lidar observations of vertical wind, temperature, and density profiles in the upper mesophere: Evidence for nonseparability of atmospheric perturbation spectra

Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar

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