Diurnal variation of mountain waves

Worthington, R. M.

doi:10.5194/angeo-24-2891-2006

Cited by 7 publications

(2 citation statements)

References 47 publications

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“…The influence of mountain waves on the daytime spectral gap is less clear (Worthington and Thomas, 1998) as this influence is often masked by the influence of convection gravity waves which are initiated when the CBL itself acts as an effective mountain (Worthington, 2006). Jiang et al (2006) report that the developing CBL, below a mountain wave train, acts as a sponge layer absorbing the downward propagating wave energy.…”

Section: Discussionmentioning

confidence: 99%

Spectral gap characteristics in a daytime valley boundary layer

Babić

Večenaj

Wekker

2017

Quart J Royal Meteoro Soc

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A correct estimation of turbulent variances and covariances in the atmospheric boundary layer relies on the determination of turbulent perturbations of wind speed components and scalar quantities, which requires the presence of a so‐called spectral gap. The goal of this work is to determine the range of gap scales necessary to define turbulent perturbations in a daytime valley boundary layer. To accomplish this, we analyze data from a large number of propeller‐vane and sonic anemometers using the fast Fourier transformation and the multiresolution flux decomposition. Daytime gap scales are found to range from 17 to 29 min and show large spatial variability across the valley floor and the adjacent slopes. Synoptically driven conditions that favour the occurrence of mesoscale phenomena, such as rotors and mountain waves, shift daytime gap scales toward longer periods. The low‐frequency end of the gap is also affected by the presence of slope winds that are characterized by a periodicity ranging from 80 to 200 min. Finally, we present a conceptual model of the daytime valley spectral gap which summarizes the findings of this study.

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Section: Discussionmentioning

confidence: 99%

Spectral gap characteristics in a daytime valley boundary layer

Babić

Večenaj

Wekker

2017

Quart J Royal Meteoro Soc

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“…Mountain waves also occur above convective rolls present above mountains (Bradbury, ), being launched by a process similar to convection waves, where the mountain waves modulate the strength of convection (Hosler et al ., ; Orville, ; Tang et al ., ) and the convection partly forces the waves (Worthington, , ). Worthington () suggests there are two types of mountain wave: classic ‘type 1’ mountain waves are forced directly by high ridge‐like mountains; ‘type 2’ are forced indirectly, for example above convection, rotors and turbulence in the lower boundary layer, with the flow only becoming mostly wave‐like above a mountain‐wave launching height (Shutts, ).…”

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confidence: 99%