Impact of IGW on the spectra of turbulent fluctuations of vertical velocity measured by a Doppler lidar

2021 ◽  
Author(s):  
Viktor A. Banakh ◽  
Igor N. Smalikho ◽  
Artem A. Sukharev
Keyword(s):  
Vertical Velocity ◽  
Doppler Lidar ◽  
Turbulent Fluctuations

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 

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

<p>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.</p>

scholarly journals Combined vertical-velocity observations with Doppler lidar, cloud radar and wind profiler

2015 ◽  
Vol 8 (8) ◽  
pp. 3527-3536 ◽  
Author(s):  
J. Bühl ◽  
R. Leinweber ◽  
U. Görsdorf ◽  
M. Radenz ◽  
A. Ansmann ◽  
...  
Keyword(s):  
Vertical Velocity ◽  
Wind Profiler ◽  
Doppler Lidar ◽  
Velocity Measurements ◽  
Fall Velocity ◽  
Cloud Radar ◽  
Meteorological Observatory ◽  
Comprehensive Classification ◽  
Single Instrument ◽  
Simultaneous Sensing

Abstract. Case studies of combined vertical-velocity measurements of Doppler lidar, cloud radar and wind profiler are presented. The measurements were taken at the Meteorological Observatory, Lindenberg, Germany. Synergistic products are presented that are derived from the vertical-velocity measurements of the three instruments: a comprehensive classification mask of vertically moving atmospheric targets and the terminal fall velocity of water droplets and ice crystals corrected for vertical air motion. It is shown that this combination of instruments can up-value the measurement values of each single instrument and may allow the simultaneous sensing of atmospheric targets and the motion of clear air.

scholarly journals Year-Long Vertical Velocity Statistics Derived from Doppler Lidar Data for the Continental Convective Boundary Layer

2017 ◽  
Vol 56 (9) ◽  
pp. 2441-2454 ◽  
Author(s):  
Larry K. Berg ◽  
Rob K. Newsom ◽  
David D. Turner
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Vertical Velocity ◽  
Wind Shear ◽  
Time Of Day ◽  
Lidar Data ◽  
Surface Shear Stress ◽  
Doppler Lidar ◽  
Convective Boundary ◽  
Degree Of Instability

AbstractOne year of coherent Doppler lidar data collected at the U.S. Department of Energy’s Atmospheric Radiation Measurement site in Oklahoma was analyzed to provide profiles of vertical velocity variance, skewness, and kurtosis for cases of cloud-free convective boundary layers. The variance was normalized by the Deardorff convective velocity scale, which was successful when the boundary layer depth was stationary but failed in situations in which the layer was changing rapidly. In this study, the data are sorted according to time of day, season, wind direction, surface shear stress, degree of instability, and wind shear across the boundary layer top. The normalized variance was found to have its peak value near a normalized height of 0.25. The magnitude of the variance changes with season, shear stress, degree of instability, and wind shear across the boundary layer top. The skewness was largest in the top half of the boundary layer (with the exception of wintertime conditions). The skewness was also found to be a function of the season, shear stress, and wind shear across the boundary layer top. Like skewness, the vertical profile of kurtosis followed a consistent pattern, with peak values near the boundary layer top. The normalized altitude of the peak values of kurtosis was found to be higher when there was a large amount of wind shear at the boundary layer top.

scholarly journals Combined vertical-velocity observations with Doppler lidar, cloud radar and wind profiler

2015 ◽  
Vol 8 (1) ◽  
pp. 353-373
Author(s):  
J. Bühl ◽  
R. Leinweber ◽  
U. Görsdorf ◽  
M. Radenz ◽  
A. Ansmann ◽  
...  
Keyword(s):  
Vertical Velocity ◽  
Ice Crystals ◽  
Wind Profiler ◽  
Doppler Lidar ◽  
Velocity Measurements ◽  
Fall Velocity ◽  
Cloud Radar ◽  
Meteorological Observatory ◽  
Abstract Case ◽  
Comprehensive Classification

Abstract. Case studies of combined vertical-velocity measurements of Doppler lidar, cloud radar and wind profiler are presented. The measurements were taken at the Meteorological Observatory Lindenberg, Germany. Synergistic products are presented that are derived from the vertical-velocity measurements of the three instruments: A comprehensive classification mask of vertically moving atmospheric targets and the terminal fall velocity of water droplets and ice crystals corrected for vertical air motion. It is shown that the measurements of the Doppler lidar can extent the view of the cloud radar and the wind profiler, especially when observing clouds.

scholarly journals Updraft and downdraft characterization with Doppler lidar: cloud-free versus cumuli-topped mixed-layer

2010 ◽  
Vol 10 (4) ◽  
pp. 9219-9252 ◽  
Author(s):  
A. Ansmann ◽  
J. Fruntke ◽  
R. Engelmann
Keyword(s):  
Boundary Layer ◽  
Vertical Velocity ◽  
Unit Length ◽  
Mixing Layer ◽  
Average Frequency ◽  
Cloud Base ◽  
Doppler Lidar ◽  
Fair Weather ◽  
Pronounced Increase ◽  
Horizontal Extent

Abstract. For the first time, a comprehensive, height-resolved Doppler lidar study of updrafts and downdrafts in the mixing layer is presented. The Doppler lidar measurements were performed at Leipzig, Germany, in the summer half year of 2006. The conditional sampling method is applied to the measured vertical velocities to identify, count, and analyze significant updraft and downdraft events. Three cases of boundary layer evolution with and without fair weather cumuli formation are discussed. Updrafts occur with an average frequency of 1–2 per unit length zi (boundary layer depth zi), downdrafts 20%–30% more frequently. In the case with cumuli formation, the draft occurrence frequency is enhanced by about 50% at cloud level or near cloud base. The counted updraft events cover 30%–34%, downdrafts 53%–57% of the velocity time series during the main period of convective activity. By considering all drafts with horizontal extent >36 m in the analysis, the updraft mean horizontal extent ranges from 200–350 m and is about 0.15zi in all three cases. Downdrafts are a factor of 1.3–1.5 larger. The average value of the updraft mean vertical velocities is 0.5–0.7 m/s or 0.4w∗ (convective velocity scale w∗), and the negative downdraft mean vertical velocities are weaker by roughly 10%–20%. The analysis of the relationship between the size (horizontal extent) of the updrafts and downdrafts and their mean vertical velocity reveals a pronounced increase of the average vertical velocity in updrafts from 0.4–0.5 m/s for small thermals (100–200 m) to about 1.5 m/s for large updrafts (>600 m) in the case with fair weather cumuli. At cloudless conditions, the updraft velocities were found to be 20% smaller for the large thermals.

scholarly journals Reconciling Differences Between Large‐Eddy Simulations and Doppler Lidar Observations of Continental Shallow Cumulus Cloud‐Base Vertical Velocity

2019 ◽  
Vol 46 (20) ◽  
pp. 11539-11547 ◽  
Author(s):  
Satoshi Endo ◽  
Damao Zhang ◽  
Andrew M. Vogelmann ◽  
Pavlos Kollias ◽  
Katia Lamer ◽  
...  
Keyword(s):  
Vertical Velocity ◽  
Large Eddy Simulations ◽  
Cloud Base ◽  
Doppler Lidar ◽  
Cumulus Cloud ◽  
Shallow Cumulus ◽  
Large Eddy ◽  
Lidar Observations

scholarly journals Improvement of vertical velocity statistics measured by a Doppler lidar through comparison with sonic anemometer observations

2016 ◽  
Vol 9 (12) ◽  
pp. 5833-5852 ◽  
Author(s):  
Timothy A. Bonin ◽  
Jennifer F. Newman ◽  
Petra M. Klein ◽  
Phillip B. Chilson ◽  
Sonia Wharton
Keyword(s):  
Vertical Velocity ◽  
Close Agreement ◽  
Sonic Anemometer ◽  
Lag Time ◽  
Volume Averaging ◽  
Doppler Lidar ◽  
Established Method ◽  
Velocity Statistics ◽  
Sonic Anemometers ◽  
Velocity Variance

Abstract. Since turbulence measurements from Doppler lidars are being increasingly used within wind energy and boundary-layer meteorology, it is important to assess and improve the accuracy of these observations. While turbulent quantities are measured by Doppler lidars in several different ways, the simplest and most frequently used statistic is vertical velocity variance (w′2) from zenith stares. However, the competing effects of signal noise and resolution volume limitations, which respectively increase and decrease w′2, reduce the accuracy of these measurements. Herein, an established method that utilises the autocovariance of the signal to remove noise is evaluated and its skill in correcting for volume-averaging effects in the calculation of w′2 is also assessed. Additionally, this autocovariance technique is further refined by defining the amount of lag time to use for the most accurate estimates of w′2. Through comparison of observations from two Doppler lidars and sonic anemometers on a 300 m tower, the autocovariance technique is shown to generally improve estimates of w′2. After the autocovariance technique is applied, values of w′2 from the Doppler lidars are generally in close agreement (R2 ≈ 0.95 − 0.98) with those calculated from sonic anemometer measurements.

scholarly journals Turbulent structure and scaling of the inertial subrange in a stratocumulus-topped boundary layer observed by a Doppler lidar

2015 ◽  
Vol 15 (10) ◽  
pp. 5873-5885 ◽  
Author(s):  
J. Tonttila ◽  
E. J. O'Connor ◽  
A. Hellsten ◽  
A. Hirsikko ◽  
C. O'Dowd ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Velocity ◽  
Marine Boundary Layer ◽  
Turbulent Structure ◽  
Inertial Subrange ◽  
Doppler Lidar ◽  
Turbulent Dissipation ◽  
Additional Information ◽  
Velocity Statistics ◽  
Velocity Skewness

Abstract. The turbulent structure of a stratocumulus-topped marine boundary layer over a 2-day period is observed with a Doppler lidar at Mace Head in Ireland. Using profiles of vertical velocity statistics, the bulk of the mixing is identified as cloud driven. This is supported by the pertinent feature of negative vertical velocity skewness in the sub-cloud layer which extends, on occasion, almost to the surface. Both coupled and decoupled turbulence characteristics are observed. The length and timescales related to the cloud-driven mixing are investigated and shown to provide additional information about the structure and the source of the mixing inside the boundary layer. They are also shown to place constraints on the length of the sampling periods used to derive products, such as the turbulent dissipation rate, from lidar measurements. For this, the maximum wavelengths that belong to the inertial subrange are studied through spectral analysis of the vertical velocity. The maximum wavelength of the inertial subrange in the cloud-driven layer scales relatively well with the corresponding layer depth during pronounced decoupled structure identified from the vertical velocity skewness. However, on many occasions, combining the analysis of the inertial subrange and vertical velocity statistics suggests higher decoupling height than expected from the skewness profiles. Our results show that investigation of the length scales related to the inertial subrange significantly complements the analysis of the vertical velocity statistics and enables a more confident interpretation of complex boundary layer structures using measurements from a Doppler lidar.

scholarly journals Improvement of Vertical Velocity Statistics Measured by a Doppler Lidar through Comparison with Sonic Anemometer Observations

2016 ◽  
Author(s):  
Timothy A. Bonin ◽  
Jennifer F. Newman ◽  
Petra M. Klein ◽  
Phillip B. Chilson ◽  
Sonia Wharton
Keyword(s):  
Vertical Velocity ◽  
Sonic Anemometer ◽  
Lag Time ◽  
Volume Averaging ◽  
Doppler Lidar ◽  
Atmospheric Conditions ◽  
Established Method ◽  
Velocity Statistics ◽  
Sonic Anemometers ◽  
Velocity Variance

Abstract. Since turbulence measurements from Doppler lidars are being increasingly used within wind energy and boundary-layer meteorology, it is important to assess and improve the accuracy of these observations. While turbulent quantities are measured by Doppler lidars in several different ways, the simplest and most frequently used statistic is vertical velocity variance (σ2ω) from zenith stares. However, the competing effects of signal noise and resolution volume limitations, which respectively increase and decrease σ2ω, reduce the accuracy of these measurements. Herein, an established method that utilizes the autocovariance of the signal to remove noise is evaluated and its skill in also correcting for volume-averaging effects in the calculation of σ2ω is assessed. Additionally, this autocovariance technique is further refined by defining the amount of lag time to use for the most accurate estimates of σ2ω. Through comparison of observations from two Doppler lidars and sonic anemometers on a 300-m tower, the autocovariance technique is shown to improve estimates of σ2ω over a variety of atmospheric conditions. After the autocoviance technique is applied, values of σ2ω from the Doppler lidars are generally in close agreement (R2 ≈ 0.95–0.98) with those calculated from sonic anemometer measurements.

scholarly journals Doppler Lidar Vertical Velocity Statistics Value-Added Product

2015 ◽  
Author(s):  
R. K. Newsom ◽  
◽  
C. Sivaraman ◽  
T. R. Shippert ◽  
L. D. Riihimaki
Keyword(s):  
Vertical Velocity ◽  
Value Added ◽  
Doppler Lidar ◽  
Velocity Statistics
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