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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.\ud \ud 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.

The Convective and Orographically-Induced Precipitation Study, COPS, was conducted in the Black Forest region of Germany during the summer of 2007. Its aim was to advance the quality of forecasts of orographically induced convective precipitation by 4D observations and modelling. From the 13th June to the 16th August 2007, the Universities' Facility for Atmospheric Measurement (UFAM) 1.5 micron scanning Doppler lidar, operated by the University of Salford, was deployed at Achern, Baden-Württemberg, Germany, in order to take part in the extensive COPS observation campaign. The University of Salford lidar system measures radial wind and aerosol backscatter from 105 m above the surface to the top of the boundary layer. Profiles of horizontal wind velocity are shown; these being derived from performing azimuth scans of 5 minute duration, approximately every 30 minutes. Between azimuth scans, the lidar pointed vertically. Profiles of vertical velocity, its variance and skewness are also shown. Knowledge of vertical velocity skewness is important as it can help understand the structure and origin of turbulent convection in the boundary layer. The skewness of vertical velocity can provide a measure of the asymmetry in the distribution of vertical velocity perturbations within the atmospheric boundary layer (ABL). In previous studies, under fair-weather conditions, when the ABL is heated from below, skewness profile tends to be positive throughout the ABL, while under cloudy conditions, the skewness profile can be affected by cloud processes and therefore predominantly negative. The behaviour of the boundary layer is investigated using data from the Salford University Doppler lidar, microwave radiometer and automatic weather station. In this paper, selected cases are compared and the similarities and differences are noted. Investigations of possible causes of layers of positive and negative skewness are presented, along with intercomparisons with radiosonde ascents from the Achern site., Previously curated at: http://cedadocs.ceda.ac.uk/341/ Event type: conference. The publish date on this item was its original published date. This work was funded by: NERC. This item was not refereed before the publication Associated projects: UK Convective and Orographic Precipitation Study Main files in this record: rms09.pdf Item originally deposited with Centre for Environmental Data Analysis (CEDA) document repository by Dr Jenny Davis. Transferred to CEDA document repository community on Zenodo on 2022-11-24