Nocturnal boundary layer turbulence regimes analysis during the BLLAST campaign

Yus-Díez, Jesús; Udina, Mireia; Soler, M. R.; Lothon, Marie; Nilsson, Erik; Bech, Joan; Sun, Jielun

doi:10.5194/acp-2018-1300

Cited by 4 publications

(4 citation statements)

References 27 publications

(67 reference statements)

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“…When the wind speed is lower than the threshold, V TKE does not change significantly with the wind speed. The relationships between turbulence intensity and V produce a similar hockey‐stick shape as that obtained by Yus‐Díez et al (2019) for April 18–24. Different wind speed thresholds ( V T ) were observed at each level during the period April 18–24: V T _0.5 m = 1.6 m s −1 , V T _1 m = 2.0 m s −1 , V T _2 m = 2.4 m s −1 , V T _4 m = 3.2 m s −1 , V T _10 m = 4.0 m s −1 , V T _20 m = 4.8 m s −1 and V T _32 m = 5.2 m s −1 .…”

Section: Resultssupporting

confidence: 83%

Characteristics of turbulence over the semi‐fixed desert area north of Xinjiang, China

Mamtimin

Wang

Sayit³

et al. 2021

Earth Surf Processes Landf

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As the largest fixed and semi-fixed desert in China, the Gurbantünggüt Desert undergoes a long period of snow cover in the winter and the rapid growth of ephemeral plants in the spring, presenting obvious seasonal changes in the underlying desert surface type, which can lead to variation in the turbulence of the nearsurface boundary layer turbulence over the desert. In this study, gradient tower data and eddy covariance data from 2017 were analysed to investigate the turbulence characteristics of the different surface boundary layers in the hinterland of the Gurbantünggüt Desert. The results indicate that stable atmospheric conditions in

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Section: Resultssupporting

confidence: 83%

Characteristics of turbulence over the semi‐fixed desert area north of Xinjiang, China

Mamtimin

Wang

Sayit³

et al. 2021

Earth Surf Processes Landf

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“…The interaction leads to the transition of local and global shear, which has been described by the hockey-stick transition (HOST) pattern (Sun et al, 2012(Sun et al, , 2016. Many field observations such as the BLLAST campaign (Yus-Díez et al, 2019), the LABLE (Bonin et al, 2015), the PREF (Russell et al, 2016), the LBA (Dias-Júnior et al, 2017), and the FLOSSII (Acevedo et al, 2016) have proved the HOST pattern. Some simplified model simulations have also captured the incident (Costa et al, 2020;Maroneze et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Revealing the Dynamical Transition of Anisotropy behind the HOST by Koopman Analysis

Zuo

Chen

et al. 2020

Preprint

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The hockey-stick transition (HOST), which is depicted by the "local and global shear" assumption, about the turbulence kinetic energy with the averaged flow intensity is noticed widely. However, the intrinsic mechanism of averaged flow influences turbulence kinetic energy via shear and buoyancy is missing. In this research, we deploy the Koopman operator to expose invariant subspaces of the Ri series to identify the quasiperiodic coherent structures from the single tower observation. Analysis of turbulence fluxes and anisotropy demonstrates the mechanism, that is, horizontal kinetic energy coupled with vertical downward flux, whereby anisotropy evolution is changed. Examining the anisotropy invariants changing with kinetic energy reveals a dynamical transition that determines the threshold of HOST. Moreover, the mechanism about how the shear and vertical momentum influences the transition point of HOST is at first given by a group of a quadratic relationship when the anisotropy crossed over the transition point. Plain Language SummaryThe turbulence intensity is always influenced by submesoscale motions in a nocturnal stable boundary layer. This multiscale interaction can be displayed by the hockey-stick transition, which is depicted by the "local and global shear" assumption. Although this pattern is noticed widely in many different field observations, the intrinsic mechanism of averaged flow influences turbulence kinetic energy via shear and buoyancy is unclear. Because during the interaction, turbulent eddies in the nocturnal stable boundary layer are embedded in the coherent structures, leading to the difficulty in the estimation of the time length of the interaction. In this research, we deploy the Koopman operator to expose invariant subspaces of the Ri series to identify the quasiperiodic coherent structures from the single tower observation. Anisotropy analysis based on the time length-averaged result from the subspaces reveals the existence of the mechanism, that is, horizontal kinetic energy transport coupled with a vertical downward flux, which causes the unique evolution of turbulence anisotropy. Moreover, a dynamical transition is discovered when the anisotropy invariants change with kinetic energy which determines the threshold of HOST by a group of quadratic curves about the shear and vertical momentum when the anisotropy crossed over the transition point.

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“…The interaction leads to the transition of local and global shear, which has been described by the hockey‐stick transition (HOST) pattern (Sun et al, 2012, 2016). Many field observations such as the BLLAST campaign (Yus‐Díez et al, 2019), the LABLE (Bonin et al, 2015), the PREF (Russell et al, 2016), the LBA (Dias‐Júnior et al, 2017), and the FLOSSII (Acevedo et al, 2016) have proved the HOST pattern. Some simplified model simulations have also captured the incident (Costa et al, 2020; Maroneze et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Revealing the Dynamical Transition of Anisotropy Behind the HOST by Koopman Analysis

Zuo

Chen

et al. 2020

Geophysical Research Letters

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The hockey-stick transition (HOST), which is depicted by the "local and global shear" assumption, about the turbulence kinetic energy with the averaged flow intensity is noticed widely. However, the intrinsic mechanism of averaged flow influences turbulence kinetic energy via shear and buoyancy is missing. In this research, we deploy the Koopman operator to expose invariant subspaces of the Ri series to identify the quasiperiodic coherent structures from the single tower observation. Analysis of turbulence fluxes and anisotropy demonstrates the mechanism, that is, horizontal kinetic energy coupled with vertical downward flux, whereby anisotropy evolution is changed. Examining the anisotropy invariants changing with kinetic energy reveals a dynamical transition that determines the threshold of HOST. Moreover, the mechanism about how the shear and vertical momentum influences the transition point of HOST is at first given by a group of a quadratic relationship when the anisotropy crossed over the transition point. Plain Language Summary The turbulence intensity is always influenced by submesoscale motions in a nocturnal stable boundary layer. This multiscale interaction can be displayed by the hockey-stick transition, which is depicted by the "local and global shear" assumption. Although this pattern is noticed widely in many different field observations, the intrinsic mechanism of averaged flow influences turbulence kinetic energy via shear and buoyancy is unclear. Because during the interaction, turbulent eddies in the nocturnal stable boundary layer are embedded in the coherent structures, leading to the difficulty in the estimation of the time length of the interaction. In this research, we deploy the Koopman operator to expose invariant subspaces of the Ri series to identify the quasiperiodic coherent structures from the single tower observation. Anisotropy analysis based on the time length-averaged result from the subspaces reveals the existence of the mechanism, that is, horizontal kinetic energy transport coupled with a vertical downward flux, which causes the unique evolution of turbulence anisotropy. Moreover, a dynamical transition is discovered when the anisotropy invariants change with kinetic energy which determines the threshold of HOST by a group of quadratic curves about the shear and vertical momentum when the anisotropy crossed over the transition point.

show abstract

Nocturnal boundary layer turbulence regimes analysis during the BLLAST campaign

Cited by 4 publications

References 27 publications

Characteristics of turbulence over the semi‐fixed desert area north of Xinjiang, China

Characteristics of turbulence over the semi‐fixed desert area north of Xinjiang, China

Revealing the Dynamical Transition of Anisotropy behind the HOST by Koopman Analysis

Revealing the Dynamical Transition of Anisotropy Behind the HOST by Koopman Analysis

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