scholarly journals Evaluation of turbulence measurement techniques from a single Doppler lidar

2017 ◽  
Vol 10 (8) ◽  
pp. 3021-3039 ◽  
Author(s):  
Timothy A. Bonin ◽  
Aditya Choukulkar ◽  
W. Alan Brewer ◽  
Scott P. Sandberg ◽  
Ann M. Weickmann ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Planetary Boundary Layer ◽  
Turbulence Intensity ◽  
Measurement Techniques ◽  
Sonic Anemometer ◽  
Shear Velocity ◽  
Turbulence Kinetic Energy ◽  
Doppler Lidar ◽  
Turbulence Measurement

Abstract. Measurements of turbulence are essential to understand and quantify the transport and dispersal of heat, moisture, momentum, and trace gases within the planetary boundary layer (PBL). Through the years, various techniques to measure turbulence using Doppler lidar observations have been proposed. However, the accuracy of these measurements has rarely been validated against trusted in situ instrumentation. Herein, data from the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) are used to verify Doppler lidar turbulence profiles through comparison with sonic anemometer measurements. For 17 days at the end of the experiment, a single scanning Doppler lidar continuously cycled through different turbulence measurement strategies: velocity–azimuth display (VAD), six-beam scans, and range–height indicators (RHIs) with a vertical stare.Measurements of turbulence kinetic energy (TKE), turbulence intensity, and stress velocity from these techniques are compared with sonic anemometer measurements at six heights on a 300 m tower. The six-beam technique is found to generally measure turbulence kinetic energy and turbulence intensity the most accurately at all heights (r2  ≈  0.78), showing little bias in its observations (slope of  ≈  0. 95). Turbulence measurements from the velocity–azimuth display method tended to be biased low near the surface, as large eddies were not captured by the scan. None of the methods evaluated were able to consistently accurately measure the shear velocity (r2 =  0.15–0.17). Each of the scanning strategies assessed had its own strengths and limitations that need to be considered when selecting the method used in future experiments.

scholarly journals Evaluation of Turbulence Measurement Techniques from a Single Doppler Lidar

2017 ◽  
Author(s):  
Timothy A. Bonin ◽  
Aditya Choukulkar ◽  
W. Alan Brewer ◽  
Scott P. Sandberg ◽  
Ann M. Weickmann ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Planetary Boundary Layer ◽  
Turbulence Intensity ◽  
Measurement Techniques ◽  
Sonic Anemometer ◽  
Shear Velocity ◽  
Turbulence Kinetic Energy ◽  
Doppler Lidar ◽  
Turbulence Measurement

Abstract. Measurements of turbulence are essential to understand and quantify the transport and dispersal of heat, moisture, momentum, and trace gases within the planetary boundary layer. Through the years, various techniques to measure turbulence using Doppler lidar observations have been proposed. However, the accuracy of these measurements has rarely been validated against trusted in situ instrumentation. Herein, data from the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) are used to verify Doppler lidar turbulence profiles through comparison with sonic anemometer measurements. For 17 days at the end of the experiment, a single scanning Doppler lidar continuously cycled through different turbulence measurement strategies: velocity azimuth display, six-beam, and range height indicators with a vertical stare. Measurements of turbulence kinetic energy, turbulence intensity, and shear velocity from these techniques are compared with sonic anemometer measurements at six heights on a 300-m tower. The six-beam technique is found to generally measure turbulence kinetic energy and turbulence intensity the most accurately at all heights, showing little bias in its observations. Turbulence measurements from the velocity azimuth display method tended to biased low near the surface, as large eddies were not captured by the scan. None of the methods evaluated were able to consistently accurately measure the shear velocity. Each of the scanning strategies assessed had its own strengths and limitations that need to be considered when selecting the method used in future experiments.

scholarly journals Improved Length Scales for Turbulence Kinetic Energy–Based Planetary Boundary Layer Scheme for the Convective Atmospheric Boundary Layer

2020 ◽  
Vol 77 (7) ◽  
pp. 2605-2626 ◽  
Author(s):  
Bowen Zhou ◽  
Yuhuan Li ◽  
Kefeng Zhu
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Atmospheric Boundary Layer ◽  
Planetary Boundary Layer ◽  
Turbulent Mixing ◽  
Turbulence Kinetic Energy ◽  
Convective Boundary ◽  
Stability Range ◽  
Length Scales ◽  
Pbl Scheme

AbstractBased on a priori analysis of large-eddy simulations (LESs) of the convective atmospheric boundary layer, improved turbulent mixing and dissipation length scales are proposed for a turbulence kinetic energy (TKE)-based planetary boundary layer (PBL) scheme. The turbulent mixing length incorporates surface similarity and TKE constraints in the surface layer, and makes adjustments for lateral entrainment effects in the mixed layer. The dissipation length is constructed based on balanced TKE budgets accounting for shear, buoyancy, and turbulent mixing. A nongradient term is added to the TKE flux to correct for nonlocal turbulent mixing of TKE. The improved length scales are implemented into a PBL scheme, and are tested with idealized single-column convective boundary layer (CBL) cases. Results exhibit robust applicability across a broad CBL stability range, and are in good agreement with LES benchmark simulations. It is then implemented into a community atmospheric model and further evaluated with 3D real-case simulations. Results of the new scheme are of comparable quality to three other well-established PBL schemes. Comparisons between simulated and radiosonde-observed profiles show favorable performance of the new scheme on a clear day.

scholarly journals HUBUNGAN VARIASI HARIAN NILAI TURBULENCE KINETIC ENERGY DAN FLUKS PANAS DI WILAYAH KOTA BANDUNG

2015 ◽  
Vol 10 (2) ◽  
Author(s):  
Fani Setyawan
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Kinetic Energy ◽  
Sonic Anemometer ◽  
Turbulence Kinetic Energy ◽  
Major Influence ◽  
The West ◽  
Daily Cycle ◽  
Boundary Layer Turbulence

Abstrak : Lapisan Batas Meteorologi merupakan suatu lapisan yang berada di bagian terbawah dari Troposfer. Salah satu fenomena yang terjadi di lapisan batas ini adalah Turbulensi yang memiliki durasi singkat namun memiliki pengaruh yang besar terhadap pembentukan cuaca di Troposfer. Dalam aktifitas Turbulensi terdapat nilai Turbulence Kinetic Energy (TKE) dan mempengaruhi transfer panas atau Fluks Panas di atmosfer. Observasi meteorologi menggunakan Sonic Anemometer dapat digunakan untuk menghitung nilai-nilai tersebut. Komponen pengamatan yang dihasilkan merupakan variabel-variabel yang digunakan untuk menghitung nilai TKE dan Fluks Panas, yaitu komponen u, v, w, dan T. Dari hasil pengamatan yang dilakukan di wilayah kota Bandung (studi kasus tanggal 26 september 2014), didapatkan variasi angin harian yang berhembus dari arah Barat hingga Utara dengan kecepatan rata-rata 4 knots. Namun pada siang hari, angin berhembus secara bergantian dari arah Barat dan dari arah Timur. Siklus harian dari nilai TKE menunjukkan adanya variasi dengan nilai yang besar saat matahari mulai muncul dan berakhir sebelum tengah hari. Sedangkan untuk siklus harian dari Fluks Panas menunjukkan fluktuasi yang signifikan saat tengah hari hingga matahari terbenam. Hal ini menunjukkan bahwa proses konveksi saat pagi hari dipengaruhi oleh Turbulence Kinetic Energy dan nilai Fluks Panas mempengaruhi proses konveksi setelah nilai TKE turun hingga matahari terbenam.Kata Kunci : Lapisan batas, Turbulence Kinetic Energy (TKE), Fluks PanasAbstrack : Meteorological Boundary Layer is a layer at lowest part of troposphere. One of phenomena at this layer is Turbulence which has a short duration but has a major influence in the weather at the Troposphere. Turbulence activities consists of a Turbulence Kinetic Energy (TKE) value and affect heat flux at the atmosphere. Meteorological observation using Sonic Anemometer can be used to calculate these values. The variables used to calculate TKE value and Heat Flux, the variable u, v, w, and T, obtained from these observation. From the observations at Bandung region (case study was september, 26, 2014), found variations in the daily wind blows from the West and North with an average speed of 4 knots. But during the day, wind blows alternately from the West and from the East. The daily cycle from TKE value indicate a variation with a great value when the sun began and endeed before noon. As for the daily cycle of heat flux show significant fluctuations at noon to sunset. This suggests that the process of convection during the morning influenced by Turbulence Kinetic Energy and value of Heat Flux affects the convection process after TKE value decline until the sunset.Keywords : Boundary layer, Turbulence Kinetic Energy (TKE), Heat Flux

scholarly journals Nocturnal Low-Level-Jet-Dominated Atmospheric Boundary Layer Observed by a Doppler Lidar over Oklahoma City during JU2003

2007 ◽  
Vol 46 (12) ◽  
pp. 2098-2109 ◽  
Author(s):  
Yansen Wang ◽  
Cheryl L. Klipp ◽  
Dennis M. Garvey ◽  
David A. Ligon ◽  
Chatt C. Williamson ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Atmospheric Boundary Layer ◽  
Urban Area ◽  
Oklahoma City ◽  
Suburban Area ◽  
Turbulence Kinetic Energy ◽  
Doppler Lidar ◽  
The Mean ◽  
Low Level Jet

Abstract Boundary layer wind data observed by a Doppler lidar and sonic anemometers during the mornings of three intensive observational periods (IOP2, IOP3, and IOP7) of the Joint Urban 2003 (JU2003) field experiment are analyzed to extract the mean and turbulent characteristics of airflow over Oklahoma City, Oklahoma. A strong nocturnal low-level jet (LLJ) dominated the flow in the boundary layer over the measurement domain from midnight to the morning hours. Lidar scans through the LLJ taken after sunrise indicate that the LLJ elevation shows a gradual increase of 25–100 m over the urban area relative to that over the upstream suburban area. The mean wind speed beneath the jet over the urban area is about 10%–15% slower than that over the suburban area. Sonic anemometer observations combined with Doppler lidar observations in the urban and suburban areas are also analyzed to investigate the boundary layer turbulence production in the LLJ-dominated atmospheric boundary layer. The turbulence kinetic energy was higher over the urban domain mainly because of the shear production of building surfaces and building wakes. Direct transport of turbulent momentum flux from the LLJ to the urban street level was very small because of the relatively high elevation of the jet. However, since the LLJ dominated the mean wind in the boundary layer, the turbulence kinetic energy in the urban domain is correlated directly with the LLJ maximum speed and inversely with its height. The results indicate that the jet Richardson number is a reasonably good indicator for turbulent kinetic energy over the urban domain in the LLJ-dominated atmospheric boundary layer.

The Martian Planetary Boundary Layer: Turbulent kinetic energy and fundamental similarity scales

2013 ◽  
Vol 47 (6) ◽  
pp. 446-453 ◽  
Author(s):  
G. M. Martínez ◽  
F. Valero ◽  
L. Vázquez ◽  
H. M. Elliott
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Planetary Boundary Layer

scholarly journals Variation of diurnal Turbulence Kinetic Energy using sonic anemometer observation: a case study Ledeng, Bandung

2018 ◽  
Author(s):  
Sandy Hardian Susanto Herho ◽  
Dasapta Erwin Irawan
Keyword(s):  
Kinetic Energy ◽  
Diurnal Variation ◽  
Wind Velocity ◽  
Sonic Anemometer ◽  
Diurnal Variations ◽  
Turbulence Kinetic Energy ◽  
Atmospheric Conditions

Sonic anemometer observation was performed on 29 - 30 September 2014 in Ledeng, Bandung to see diurnal variations of Turbulence Kinetic Energy (TKE) that occurred in this area. The measured sonic anemometer was the wind velocity components u, v, and w. From the observation result, it can be seen that the diurnal variation that happened was quite significant. The maximum TKE occurs during the daytime when atmospheric conditions tend to be unstable. TKE values were small at night when atmospheric conditions are more stable than during the daytime.

scholarly journals Turbulence Adjustment and Scaling in an Offshore Convective Internal Boundary Layer: A CASPER Case Study

2020 ◽  
Vol 77 (5) ◽  
pp. 1661-1681
Author(s):  
Qingfang Jiang ◽  
Qing Wang ◽  
Shouping Wang ◽  
Saša Gaberšek
Keyword(s):  
Boundary Layer ◽  
Surface Layer ◽  
Kinetic Energy ◽  
Wind Shear ◽  
Vertical Wind Shear ◽  
Internal Boundary Layer ◽  
Turbulence Kinetic Energy ◽  
Internal Boundary ◽  
Field Observations ◽  
The Mean

Abstract The characteristics of a convective internal boundary layer (CIBL) documented offshore during the East Coast phase of the Coupled Air–Sea Processes and Electromagnetic Ducting Research (CASPER-EAST) field campaign has been examined using field observations, a coupled mesoscale model (i.e., Navy’s COAMPS) simulation, and a couple of surface-layer-resolving large-eddy simulations (LESs). The Lagrangian modeling approach has been adopted with the LES domain being advected from a cool and rough land surface to a warmer and smoother sea surface by the mean offshore winds in the CIBL. The surface fluxes from the LES control run are in reasonable agreement with field observations, and the general CIBL characteristics are consistent with previous studies. According to the LESs, in the nearshore adjustment zone (i.e., fetch < 8 km), the low-level winds and surface friction velocity increase rapidly, and the mean wind profile and vertical velocity skewness in the surface layer deviate substantially from the Monin–Obukhov similarity theory (MOST) scaling. Farther offshore, the nondimensional vertical wind shear and scalar gradients and higher-order moments are consistent with the MOST scaling. An elevated turbulent layer is present immediately below the CIBL top, associated with the vertical wind shear across the CIBL top inversion. Episodic shear instability events occur with a time scale between 10 and 30 min, leading to the formation of elevated maxima in turbulence kinetic energy and momentum fluxes. During these events, the turbulence kinetic energy production exceeds the dissipation, suggesting that the CIBL remains in nonequilibrium.

Derivation of Turbulent Kinetic Energy from a First-Order Nonlocal Planetary Boundary Layer Parameterization

2013 ◽  
Vol 70 (6) ◽  
pp. 1795-1805 ◽  
Author(s):  
Hyeyum Hailey Shin ◽  
Song-You Hong ◽  
Yign Noh ◽  
Jimy Dudhia
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Planetary Boundary Layer ◽  
Water Cycle ◽  
Convective Boundary ◽  
First Order ◽  
Eddy Simulation ◽  
Pbl Parameterization ◽  
Planetary Boundary Layer Parameterization

Abstract Turbulent kinetic energy (TKE) is derived from a first-order planetary boundary layer (PBL) parameterization for convective boundary layers: the nonlocal K-profile Yonsei University (YSU) PBL. A parameterization for the TKE equation is developed to calculate TKE based on meteorological profiles given by the YSU PBL model. For this purpose buoyancy- and shear-generation terms are formulated consistently with the YSU scheme—that is, the combination of local, nonlocal, and explicit entrainment fluxes. The vertical transport term is also formulated in a similar fashion. A length scale consistent with the K profile is suggested for parameterization of dissipation. Single-column model (SCM) simulations are conducted for a period in the second Global Energy and Water Cycle Experiment (GEWEX) Atmospheric Boundary Layer Study (GABLS2) intercomparison case. Results from the SCM simulations are compared with large-eddy simulation (LES) results. The daytime evolution of the vertical structure of TKE matches well with mixed-layer development. The TKE profile is shaped like a typical vertical velocity (w) variance, and its maximum is comparable to that from the LES. By varying the dissipation length from −23% to +13% the TKE maximum is changed from about −15% to +7%. After normalization, the change does not exceed the variability among previous studies. The location of TKE maximum is too low without the effects of the nonlocal TKE transport.

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