scholarly journals Aspects of Convective Boundary Layer Turbulence Measured by a Dual-Doppler Lidar System

2013 ◽  
Vol 30 (9) ◽  
pp. 2132-2142 ◽  
Author(s):  
Luisa Röhner ◽  
Katja Träumner
Keyword(s):  
Boundary Layer ◽  
Convective Boundary Layer ◽  
Horizontal Wind ◽  
High Temporal Resolution ◽  
Wind Component ◽  
Rain Event ◽  
Convective Boundary ◽  
Light Rain ◽  
Boundary Layer Height ◽  
Boundary Layer Turbulence

Abstract Special designed dual-Doppler setups can be used to retrieve simultaneous measurements of two wind components with high temporal resolution in several heights throughout the atmospheric boundary layer. During a field campaign in summer 2011, different scan strategies were performed to demonstrate the opportunities of obtaining variance profiles of the vertical and horizontal wind components in complex terrain. A simplified error analysis reveals the effects of the error propagation of the uncorrelated noise of the single lidar systems. A comparison shows that the course of the derived horizontal wind component is in accordance to in situ measurements. The dual-Doppler vertical wind velocity reflects the up- and downdrafts in a convective boundary layer and is even able to reflect a light rain event. The normalized profiles of the vertical velocity variances reproduce the well-known decrease from about one-third of the boundary layer height to its top. The horizontal velocity variance did not reveal a systematic behavior on the considered days.

scholarly journals A Method for Estimating the Turbulent Kinetic Energy Dissipation Rate from a Vertically Pointing Doppler Lidar, and Independent Evaluation from Balloon-Borne In Situ Measurements

2010 ◽  
Vol 27 (10) ◽  
pp. 1652-1664 ◽  
Author(s):  
Ewan J. O’Connor ◽  
Anthony J. Illingworth ◽  
Ian M. Brooks ◽  
Christopher D. Westbrook ◽  
Robin J. Hogan ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Convective Boundary Layer ◽  
Sonic Anemometer ◽  
Horizontal Wind ◽  
Inertial Subrange ◽  
Doppler Velocity ◽  
Doppler Lidar ◽  
Convective Boundary ◽  
Dissipation Rates

Abstract A method of estimating dissipation rates from a vertically pointing Doppler lidar with high temporal and spatial resolution has been evaluated by comparison with independent measurements derived from a balloon-borne sonic anemometer. This method utilizes the variance of the mean Doppler velocity from a number of sequential samples and requires an estimate of the horizontal wind speed. The noise contribution to the variance can be estimated from the observed signal-to-noise ratio and removed where appropriate. The relative size of the noise variance to the observed variance provides a measure of the confidence in the retrieval. Comparison with in situ dissipation rates derived from the balloon-borne sonic anemometer reveal that this particular Doppler lidar is capable of retrieving dissipation rates over a range of at least three orders of magnitude. This method is most suitable for retrieval of dissipation rates within the convective well-mixed boundary layer where the scales of motion that the Doppler lidar probes remain well within the inertial subrange. Caution must be applied when estimating dissipation rates in more quiescent conditions. For the particular Doppler lidar described here, the selection of suitably short integration times will permit this method to be applicable in such situations but at the expense of accuracy in the Doppler velocity estimates. The two case studies presented here suggest that, with profiles every 4 s, reliable estimates of ε can be derived to within at least an order of magnitude throughout almost all of the lowest 2 km and, in the convective boundary layer, to within 50%. Increasing the integration time for individual profiles to 30 s can improve the accuracy substantially but potentially confines retrievals to within the convective boundary layer. Therefore, optimization of certain instrument parameters may be required for specific implementations.

scholarly journals Conceptual study on nucleation burst evolution in the convective boundary layer – Part I: Modelling approach

2005 ◽  
Vol 5 (6) ◽  
pp. 11413-11487 ◽  
Author(s):  
O. Hellmuth
Keyword(s):  
Boundary Layer ◽  
Convective Boundary Layer ◽  
Ultrafine Particle ◽  
Particle Formation ◽  
Convective Boundary ◽  
Aerosol Dynamics ◽  
Boundary Layer Turbulence ◽  
Model Setup ◽  
Conceptual Study ◽  
Modelling Approach

Abstract. A high-order modelling approach to interprete 'continental-type' particle formation bursts in the anthropogenically influenced convective boundary layer (CBL) is proposed. The model considers third-order closure for planetary boundary layer turbulence, sulfur and ammonia chemistry and aerosol dynamics. In part I of the present paper, previous observations of ultrafine particle evolution are reviewed, model equations are derived, the model setup for a conceptual study on binary and ternary homogeneous nucleation is defined, and shortcomings of process parameterization are discussed. In subsequent parts of the paper simulation results obtained within the framework of a conceptual study on the CBL evolution and new particle formation (NPF) will be presented and compared with observational findings.

scholarly journals Application of Convective Condensation Level Limiter in Convective Boundary Layer Height Retrieval Based on Lidar Data

Atmosphere ◽  
2017 ◽  
Vol 8 (12) ◽  
pp. 79 ◽  
Author(s):  
Hong Li ◽  
Yi Yang ◽  
Xiao-Ming Hu ◽  
Zhongwei Huang ◽  
Guoyin Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Convective Boundary Layer ◽  
Lidar Data ◽  
Convective Boundary ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Convective Condensation

scholarly journals Structures of Bragg Scatter Observed with the Polarimetric WSR-88D

2013 ◽  
Vol 30 (7) ◽  
pp. 1253-1258 ◽  
Author(s):  
Valery M. Melnikov ◽  
Richard J. Doviak ◽  
Dusan S. Zrnić ◽  
David J. Stensrud
Keyword(s):  
Boundary Layer ◽  
Signal Processing ◽  
Data Collection ◽  
Convective Boundary Layer ◽  
Dual Polarization ◽  
Detection Capability ◽  
Convective Boundary ◽  
Boundary Layer Turbulence ◽  
Fine Structures

Abstract Enhancements to signal processing and data collection in the dual-polarization Weather Surveillance Radar-1988 Doppler (WSR-88D) to increase its detection capability yield observations of “fine” structures from Bragg scatterers. Several types of the fine structures observed in and above the boundary layer are discussed. These Bragg scatter structures include the top of the convective boundary layer, nonprecipitating clouds, strong convective plumes above the boundary layer, and a layer of weak reflections associated with decaying boundary layer turbulence. A conclusion that data from polarimetric WSR-88Ds can be used to obtain the depth of the convective boundary layer is made.

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