Decomposition of wind velocity and temperature fluctuations into wave and turbulent signals, using wavelet transform

In the stable stratified atmospheric boundary layer, spectra might be affected by several kinds of waves. Since the problem of turbulent diffusion is closely related to the spectra of wind velocity fluctuations, it is necessary to separate the contributions of those waves from that of turbulence. Discrete wavelet packets transform was applied to temperature and vertical velocity fluctuations measured in Candiota, RS (31°28´ S, 53°40´ W), sampled with a frequency of 10 Hz and 1 Hz. In these datasets, waves have been detected through cospectral techniques. Wavelet transform was used to decompose the series. It allowed identification of those contributions that are related to the detected waves, which were then removed from the original signals. Therefore, this method may be used to decompose the series in two signals, one containing waves and other corresponding to random turbulence of the flow.

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Frequency Spectra of Wind Velocity Fluctuations between 1 hour and 1 month in the Atmospheric Boundary Layer over Equatorial Indonesia

Journal of geomagnetism and geoelectricity ◽

10.5636/jgg.49.supplement_s187 ◽

1997 ◽

Vol 49 (Supplement) ◽

pp. S187-S195 ◽

Cited By ~ 6

Author(s):

Hiroyuki Hashiguchi ◽

Shoichiro Fukao ◽

Manabu D. Yamanaka ◽

Toshitaka Tsuda

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Wind Velocity ◽

Frequency Spectra ◽

Velocity Fluctuations

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Study of Thermal Activity in The Mixing Layer During First Generated Single Cloud by Using Combined Observation From Boundary Layer Radar, Doppler Lidar and Time Lapse Camera

10.5194/egusphere-egu21-14016 ◽

2021 ◽

Author(s):

Ginaldi Ari Nugroho ◽

Kosei Yamaguchi ◽

Eiichi Nakakita ◽

Masayuki K. Yamamoto ◽

Seiji Kawamura ◽

...

Keyword(s):

Boundary Layer ◽

Time Series ◽

Atmospheric Boundary Layer ◽

Vertical Velocity ◽

Time Lapse ◽

Small Scale ◽

Thermal Activity ◽

Doppler Lidar ◽

Cumulus Cloud ◽

Scale Perturbation

Detailed observation of small scale perturbation in the atmospheric boundary layer during the first generated cumulus cloud are conducted. Our target is to study this small scale perturbation, especially related to the thermal activity at the first generated cumulus cloud. The observation is performed during the daytime on August 17, 2018, and September 03, 2018. Location is focused in the urban area of Kobe, Japan. High-resolution instruments such as Boundary Layer Radar, Doppler Lidar, and Time Lapse camera are used in this observation. Boundary Layer Radar, and Doppler Lidar are used for clear air observation. Meanwhile Time Lapse Camera are used for cloud existence observation. The atmospheric boundary layer structure is analyzed based on vertical velocity profile, variance, skewness, and estimated atmospheric boundary layer height. Wavelet are used to observe more of the period of the thermal activity. Furthermore, time correlation between vertical velocity time series from height 0.3 to 2 km and image pixel of generated cloud time series are also discussed in this study.

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Effect of short–time variations of wind velocity on mass transfer rate between street canyons and the atmospheric boundary layer

Atmospheric Pollution Research ◽

10.5094/apr.2014.057 ◽

2014 ◽

Vol 5 (3) ◽

pp. 484-490 ◽

Cited By ~ 14

Author(s):

Fabio Murena ◽

Benedetto Mele

Keyword(s):

Boundary Layer ◽

Mass Transfer ◽

Atmospheric Boundary Layer ◽

Wind Velocity ◽

Transfer Rate ◽

Mass Transfer Rate ◽

Street Canyons ◽

Time Variations ◽

Short Time

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How is the marine atmospheric boundary layer turbulence organized in the trades ?

10.5194/egusphere-egu21-12339 ◽

2021 ◽

Author(s):

Pierre-Etienne Brilouet ◽

Marie Lothon ◽

Sandrine Bony

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Vertical Velocity ◽

Large Scale ◽

Layer Structure ◽

Potential Temperature ◽

Surface Wind ◽

Cloud Amount ◽

Velocity Spectrum ◽

Marine Atmospheric Boundary Layer

Tradewind clouds can exhibit a wide diversity of mesoscale organizations, and the turbulence of marine atmospheric boundary layer (MABL) can exhibit coherent structures and mesoscale circulations. One of the objectives of the EUREC4A (Elucidating the role of cloud-circulation coupling in climate) field experiment was to better understand the tight interplay between the mesoscale organization of clouds, boundary-layer processes, and the large-scale environment.During the experiment, that took place East of Barbados over the Western Tropical Atlantic Ocean in Jan-Feb 2020, the French ATR-42 research aircraft was devoted to the characterization of the cloud amount and of the subcoud layer structure. During its 17 research flights, it sampled a large diversity of large scale conditions and cloud patterns. Multiple sensors onboard the aircraft measured high-frequency fluctuations of potential temperature, water vapour mixing ratio and wind , allowing for an extensive characterization of the turbulence within the subcloud layer. A quality-controled and calibrated turbulence dataset was produced on the basis of these measurements, which is now available on the EUREC4A AERIS data portal.The MABL turbulent structure is studied using this dataset, through a spectral analysis of the vertical velocity. Vertical profiles of characteristic length scales reveal a non-isotropic structure with a stretching of the eddies along the mean wind. The organization strength of the turbulent field is also explored by defining a diagnostic based on the shape of the vertical velocity spectrum. The structure and the degree of organization of the subcloud layer are characterized for different types of mesoscale convective pattern and as a function of the large-scale environment, including near-surface wind and lower-tropospheric stability conditions.&#160;

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