April 12, 2005

A Short Case Study of HPWREN-Connected Anemometers in Hostile Weather Conditions

Exceeding 100 miles per hour, the wind gusts atop Mount Laguna peaks in San Diego county are not to be taken lightly. In addition to the high winds, very significant ice buildup makes sensors very heavy, and even more susceptible to wind load. "I have used RM Young and Met One mechanical wind sensors in the Arctic and never have seen the type of destruction that we are witnessing on Mount Laguna," explains Pablo Bryant of the San Diego State University Field Station Programs, and principal architect behind the HPWREN-connected weather sensors on Mount Laguna. "The erratic wind patterns accompanied by high gusts and ice create harsh environmental conditions that one would not normally associate with sunny and mild San Diego."

The following series of photos show anemometers which did not make it through the wind and ice conditions on Mount Laguna.

anemometer anemometer

Left: An initial mechanical anemometer after its installation

Above: Harsh weather conditions destroyed the propeller and the body of the anemometer

anemometer anemometer

Left: 10Hz 3D sonic anemometer in good working condition, following its installation

Above: The anemometer was seriously smashed during high winds. It was afterwards repaired by the manufacturer and put back into service.

anemometer anemometer

Left: Mechanical anemometer after the installation

Above: The head with the wind vane has disintegrated. After a previous high-wind condition, the tail of the anemometer broke off and was replaced at that time; the manufacturer offered to provide a stainless-steel alternative to the aluminum tail.

The hostility of the wind was best seen with the 10Hz data of the 3D sonic anemometer. While most days on Mount Laguna are rather pleasant, the wind can be extremely harsh, and, while hot in summer, in winter it can be combined with very low temperatures.

10Hz anemometer data Wind speed at Mount Laguna, as seen by the previously used 10Hz 3D sonic anemometer. The upper left graph shows the 10Hz horizontal speed data over the cause of a windy day. The upper right graph, showing a subset of the day, continues to be noisy on a sample-by-sample basis. The lower graph averages into once-per-second samples, and also shows the minima and maxima per second. It is obvious that the high winds do not just push the anemometer, but that the instrument receives quite serious beating.

A new all-metal and heated anemometer was recently installed to create a more survivable scenario.

The fully installed 2D sonic anemometer at a mountaintop on Mount Laguna overlooks the Anza Borrego Desert. The location is above 6200 feet altitude, and looks down towards Salton Sea below sea level. The solid metal instrument automatically heats during cold weather periods.

The new instrument simultaneously delivers data via both analog and digital channels. The analog outputs connect to the data logger, just like previous instruments, while the 1Hz digital output connects to a serial-to-Ethernet converter, which allows for a direct connection to the Internet. A server connects to the converter and receives the digital data, while then sending it out again via multicast to HPWREN, so many users can pick up the data without an extra load on the network.

Pablo Bryant Following the anemometer installation, Pablo Bryant connects the new anemometer to the datalogger for its analog output, and to a serial-to-Ethernet converter for its digital output.

While the HPWREN team has high hopes for the weather-survival of the new anemometer, it was just recently installed, and it remains to be seen how this instrument will perform in the long term. Bryant adds "I am optimistic that this newly installed all-metal, solid state, heated wind sensor will do well up there."

weather data
Display of the real-time data, available at the http://hpwren.ucsd.edu/Sensors web site.

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