Environment Canada (EC) vertical wind profiler output

Contact: Michael Earle (michael.earle@ec.gc.ca)

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Notes:

Data plots represent 30-minute consensus averages from the Halifax boundary layer wind profiler, located at Fergusons Cove, approximately 6.5 km SSE from the Dalhousie Ground Station. The averaged data have been subject to cursory QC using the profiler software. Vertical profiles of wind speed and direction ('winds' folder) and image plots of profiler signal-to-noise ratio used to characterize the marine boundary layer turbulence('turb' folder) are provided, specific details of which are given below.

Winds: determined from the backscattering of radio waves by atmospheric turbulence. Barbs indicate the direction and speed of winds in knots. The power of the backscattered signal is small, and is often too small to detect in drier, more quiescent conditions, resulting in gaps in the output. These gaps can also arise due to noise/interference.

Boundary layer turbulence: the profiler signal-to-noise ratio (SNR) is dictated by atmospheric turbulence. Hence, gradients in the SNR can be used qualitatitively to identify regions of disparate turbulence, which lends itself to the characterization of boundary layer development and height. The colour scale in SNR image plots is determined dynamically from the range of SNR values over a given time interval, and so may differ from plot to plot. An example SNR plot, which clearly shows the development of the marine boundary layer on July 10 2011, is provided for reference (Boundary_Layer_Development_EXAMPLE_110710.pdf).