Basic considerations for selection of an observing site include the following criteria:
That it be representative of prevailing weather throughout the region or locality;
Chosen to avoid: steep slopes, ridges, cliffs, hollows, buildings or large obstructions, wind effects, localised heating or cooling, shading or shielding. Tolerance to obstructions is dependent on the type of observation being made, and is described in the exposure guidelines.
Generally have all-weather access for maintenance and calibration, together with access to power and communications;
Natural vegetation kept to a few centimetres in height within the instrument enclosure. Maintenance of a buffer zone around the enclosure where natural vegetation is no higher than 0.5m.
Some localities, for which observations are essential, may not have potential sites that fully conform to the siting and exposure guidelines for a variety of reasons. Under these circumstances it will be necessary to balance scientific acceptability against practical and financial considerations.
In addition to the above guidelines, specific requirements for a Bureau solar monitoring site include the following:
The sky dome should be relatively free of obstructions, particularly in the region of the sun's path across the sky during the year. More specific details are provided in Section 3.17, Observation Specification No. 2013.
The site should be chosen so that the incidence of fog, smoke, suspended or blowing dust and airborne pollution is typical of the surrounding area.
There should be no vibration present which will adversely affect the measurement of direct normal irradiance.
Sites near areas of high albedo (i.e. surfaces with moderately or highly reflective surface) should be avoided.
A skyline diagram, as illustrated in Figures Skyline-cartesian and Skyline-polar, should be prepared as part of the site metadata.
Figure Skyline-cartesian. Cartesian skyline diagram for the Alice Springs Airport site (015590). Obstructions at this site are the anemometer tower at about 190 °, and a radome (housing the radar) at the station office due north of the equipment.Figure Skyline-polar. Polar skyline diagram for the Alice Springs Airport site. The diagram includes information about the sun-path during the year.
