La Cañada, weather station setup

   Juan Lacruz, La Cañada Observatory, first draft Dec. 2006, last updated 2007 Sept 10

La Cañada Astronomical Observatory, near Avila, Spain. Started operations in the summer of 2002. The main activities are the observation of near Earth objects and comets. Since December 2006 it hosts an automatic weather station, below you'll find the details about the station setup.

The weather unit is a wireless Oregon WMR918 (replaced by a wireless Davis Vantage PRO2 since 2007 Sept 7), below is a photo of the console which is connected to the Observatory's control PC by means of a USB-RS232 cable converter.

The indoor sensor, measures the barometric pressure,temperature and humidity. It has been moved into the house kitchen, about 50 meters away from the observatory, to monitor conditions inside the house. The communications between the wireless sensor and the central unit seem to be fine in spite of the walls in between and the distance.

To reduce the effects of turbulence to a minimum the wind vane and anemometer have been attached to the top of a thin metal pole kept in position with guy wires, the sensors are about 5 meters above ground level.

Below you can see the detail of the outside thermo-higrometer. The sensors have been placed inside a Davis passive radiation shield which permits the air flow and isolates from direct Sun light as well as from infrared emited by the ground and other sources of radiation. According to the standard it is positioned 1.5m above the ground level, the temperature value depends strongly on this because the cold air, being denser, tends to occupy the lower levels and when there's no wind it's prone to form layers of different temperatures.

The rain gauge has been attached to the mast with an arm 40 cm long to minimize any possible shadow effect. Guy wires attach at the same level of the gauge to prevent wind induced vibrations. To increase the resolution beyond the Oregon's nominal of 1 l/m2 it has been modified, a funnel has been adapted increasing the reception area by four, now it can appreciate 0.25 l/m2. The station is controlled by the observatory's PC running virtual weather station on windows XP.

Below follows some general views of the station, North and East views.

South and west views, the distance to the bushes to the south is about 9m, the distance to the observatory is 7m.

A satellite link to the internet for a faster connection in a rural area.

Since 2007 Sept 7, the station has been replaced by a wireless Davis vantage PRO2.