Vertical structure of the stable boundary layer detected by RASS-SODAR and in-situ measurements in SABLES 2006 field campaign

Viana, Samuel; Yagüe, Carlos; Maqueda, Gregorio

doi:10.2478/s11600-010-0072-7

Cited by 4 publications

(9 citation statements)

References 44 publications

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“…Observed waves in geophysical flows especially in the SABL are far more complex than theoretically investigated waves. Signatures that are sinusoidal for just a couple of cycles are often referred to as "waves" due to lack of observations to estimate the special characteristics of waves discussed in the previous section [Caughey and Readings, 1975;de Baas and Driedonks, 1985;Einaudi and Finnigan, 1993;Lee et al, 1997;Cuxart et al, 2002;Anderson, 2003;Meillier et al, 2008;Viana et al, 2010Viana et al, , 2012. Waves with a number of cycles of approximately constant amplitude and period are referred to as clean waves here and have been observed mainly in the middle and upper troposphere [e.g., Hicks and Angell, 1968;Gage and Gossard, 2003;Alexander et al, 2010], and z ≥ O(10 m) in the SABL, where turbulent mixing is often weak and the mean wind varies less compared to the flow near the surface [e.g., Gossard et al, 1970;Einaudi and Finnigan, 1993;Eaton et al, 1995].…”

Section: Observations Of Waves and Wave-turbulence Interactionsmentioning

confidence: 99%

“…Wave activities associated with fronts have been observed to contain intermittent turbulence [e.g., Tjernström and Mauritsen, 2009]. Wave-turbulence interactions are also evident from direct observations of wind speed and indirect observations such as sensible heat fluxes, which is revealed by the observed nonorthogonal phase difference between vertical velocity and temperature oscillations [e.g., Viana et al, 2012]. In contrast to the zero sensible heat transport by a monochromatic buoyancy wave of infinitely small amplitude in an inviscid medium over a wave period based on linear wave theory, the observed sensible heat transport is often not zero.…”

Section: 1002/2015rg000487mentioning

confidence: 99%

“…Although wave pressure signals are clearly identifiable in the SABL, waves are also identifiable by monitoring time series of temperature oscillations [e.g., Lee and Barr, 1998;Viana et al, 2012] and horizontal or vertical wind oscillations from towers [e.g., Rees and Mobbs, 1988]. Sun et al [2015] found that the percentage of observed wind speeds that exceed the wind speed required for generation of strong turbulent mixing near the surface decreases with height.…”

Section: Fixed-point Measurementsmentioning

confidence: 99%

“…Radio acoustic sounding system (RASS), which utilizes radio and acoustic sounding systems together, can measure air temperature profiles [May et al, 1990]. With the combination of a sodar system and a Doppler RASS, both temperature and wind can be measured simultaneously at a vertical resolution of 5 m and a minimum height of 10 to 20 m, which may be suitable for SABL [e.g., Engelbart and Bange, 2002;Viana et al, 2012].…”

Section: Remote Sensingmentioning

confidence: 99%

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Review of wave‐turbulence interactions in the stable atmospheric boundary layer

Sun

Nappo²,

Mahrt

et al. 2015

Reviews of Geophysics

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Flow in a stably stratified environment is characterized by anisotropic and intermittent turbulence and wavelike motions of varying amplitudes and periods. Understanding turbulence intermittency and wave-turbulence interactions in a stably stratified flow remains a challenging issue in geosciences including planetary atmospheres and oceans. The stable atmospheric boundary layer (SABL) commonly occurs when the ground surface is cooled by longwave radiation emission such as at night over land surfaces, or even daytime over snow and ice surfaces, and when warm air is advected over cold surfaces. Intermittent turbulence intensification in the SABL impacts human activities and weather variability, yet it cannot be generated in state-of-the-art numerical forecast models. This failure is mainly due to a lack of understanding of the physical mechanisms for seemingly random turbulence generation in a stably stratified flow, in which wave-turbulence interaction is a potential mechanism for turbulence intermittency. A workshop on wave-turbulence interactions in the SABL addressed the current understanding and challenges of wave-turbulence interactions and the role of wavelike motions in contributing to anisotropic and intermittent turbulence from the perspectives of theory, observations, and numerical parameterization. There have been a number of reviews on waves, and a few on turbulence in stably stratified flows, but not much on wave-turbulence interactions. This review focuses on the nocturnal SABL; however, the discussions here on intermittent turbulence and wave-turbulence interactions in stably stratified flows underscore important issues in stably stratified geophysical dynamics in general.

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Section: Observations Of Waves and Wave-turbulence Interactionsmentioning

confidence: 99%

Section: 1002/2015rg000487mentioning

confidence: 99%

Section: Fixed-point Measurementsmentioning

confidence: 99%

Section: Remote Sensingmentioning

confidence: 99%

See 2 more Smart Citations

Review of wave‐turbulence interactions in the stable atmospheric boundary layer

Sun

Nappo²,

Mahrt

et al. 2015

Reviews of Geophysics

Self Cite

134

124

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show abstract

“…Terrain slope and inhomogeneity may also significantly affect the flow in this regime (e.g. Shapiro and Fedorovich 2007;Stoll and Porté-Agel 2009;Viana et al 2012;Mahrt et al 2013). As a result, modelling the VSBL remains a challenge since classical scaling laws may be inapplicable (e.g.…”

Section: Introductionmentioning

confidence: 99%

Early Warning Signals for Regime Transition in the Stable Boundary Layer: A Model Study

Hooijdonk

Moene

Scheffer

et al. 2016

Boundary-Layer Meteorol

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The evening transition is investigated in an idealized model for the nocturnal boundary layer. From earlier studies it is known that the nocturnal boundary layer may manifest itself in two distinct regimes, depending on the ambient synoptic conditions: strongwind or overcast conditions typically lead to weakly stable, turbulent nights; clear-sky and weak-wind conditions, on the other hand, lead to very stable, weakly turbulent conditions. Previously, the dynamical behaviour near the transition between these regimes was investigated in an idealized setting, relying on Monin-Obukhov (MO) similarity to describe turbulent transport. Here, we investigate a similar set-up, using direct numerical simulation; in contrast to MO-based models, this type of simulation does not need to rely on turbulence closure assumptions. We show that previous predictions are verified, but now independent of turbulence parametrizations. Also, it appears that a regime shift to the very stable state is signaled in advance by specific changes in the dynamics of the turbulent boundary layer. Here, we show how these changes may be used to infer a quantitative estimate of the transition point from the weakly stable boundary layer to the very stable boundary layer. In addition, it is shown that the idealized, nocturnal boundary-layer system shares important similarities with generic non-linear dynamical systems that exhibit critical transitions. Therefore, the presence of other, generic early warning signals is tested as well. Indeed, indications are found that such signals are present in stably stratified turbulent flows.

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Model simulation of gravity waves triggered by a density current

Udina

Soler

Viana

et al. 2012

Quart J Royal Meteoro Soc

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In this study, starting from an observational case of internal gravity waves (IGWs) generated at the top of a drainage flow during the SABLES2006 field campaign, we aim to reproduce the IGWs and their origin through mesoscale meteorological modelling. We used the Weather Research and Forecast (WRF) model with fine horizontal resolution (1 km), testing the model capabilities to simulate the IGWs through a WRF fixed physics package option but two different planetary boundary layer schemes, the Mellor-Yamada-Janjić (MYJ) and the Yonsei University (YSU). The comparison between model simulations and measurements from a 100 m meteorological tower reveals that the MYJ scheme simulation gives much better results, as it better represents the main features of the density current measured by the tower instruments, although the event is predicted to occur sooner than it is observed to occur. The study has also shown the capacity of this scheme to detect the oscillations in temperature and specific humidity generated by the arrival of the density current. In contrast, the YSU scheme captures the arrival of the current on time but it fails to correctly track its properties and therefore it does not reproduce the gravity waves with the current arrival. In addition, wave parameters calculated from model outputs (MYJ) using the wavelet method reveal waves with longer periods and longer wavelengths (T = 20-22 min and λ = 8-10 km) than those calculated from measurements (T = 9.2 min and λ = 3.

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Vertical structure of the stable boundary layer detected by RASS-SODAR and in-situ measurements in SABLES 2006 field campaign

Cited by 4 publications

References 44 publications

Review of wave‐turbulence interactions in the stable atmospheric boundary layer

Review of wave‐turbulence interactions in the stable atmospheric boundary layer

Early Warning Signals for Regime Transition in the Stable Boundary Layer: A Model Study

Model simulation of gravity waves triggered by a density current

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