Explanation of charts

Data are being received on a real-time basis from many of the profilers shown on the CWINDE map. Plots are generated and updated every 30 minutes for each of the CWINDE Wind Profilers and VAD/VVP weather radar winds.

Wind barb plot

This plot is available for all wind profilers.
The wind barb plot shows the wind speed to the nearest 5 knots and the direction to the nearest degree for a given wind profiler over the last 12 hours.

The winds are plotted with the latest values on the RHS and made up of the following combinations.

Half barb = 5 knots
Full barb = 10 knots
Arrow head = 50 knots

The colour is set to change every 10 knots with the sequence repeating itself in very strong winds.

Reverse wind barb plot

As the wind barb plot described above except that the latest values are on the LHS. This is more favourable when looking at westerly winds.

Power plots

Many of the profilers in the CWINDE network also send info on the Signal to Noise Power. This can be used in conjunction with the vertical velocity plots to check the profilers performance in different weather conditions, e.g. high signal powers are often associated with low vertical velocities and heavy precipitation in 1 GHz profilers.

The signal will naturally decrease with height so a technique known as range correction is applied to the data allowing signals to be compared at all levels. A block of colour is plotted for each observation, the scales used vary and are dependent on the type of profiler and mode that the profiler is operating in. Typically grey and brown depict low signal power and purple and black high signal power.

Vertical velocity plots

The vertical velocity in metres per second can be used to show a variety of elements. In # 1 GHz profilers it can be used to determine areas of precipitation and gauge its intensity, whilst in MST profilers gravity waves can be tracked.

A block of colour is plotted for each observation. The values will range between +3 and -3 m/s in MST radar whilst the 1 GHz range profilers will tend to range between +1 and -7 m/s hence the scales used vary a great deal. A greater range of colours is used to pick out changes in precipitation intensity in the 1 GHz profilers.

Latest observation

The latest wind speed (in m/s) and direction in degrees is plotted on two line plots. This will instantly pick out areas of wind shear or a jet stream above the profiler site. The plots tend to be used in conjunction with the 12-hour wind plots.

Two-day quality evaluation plots

The quality of the data from a profiler can be determined by looking at the r.m.s. averages over the past two days for each height over four set time periods, typically 30 minutes, one hour, two hours and four hours. An estimated average (the 4-hour value divided by 3.5 is calculated and plotted alongside the time period averages. Zero is plotted where no sufficient data are available.

These plots are updated once a day.

Last updated: 17 April 2012