The Blue River measurement system consists of 32 Hobo Pendants measuring temperature and light intensity at 1.5 m above ground, four storage rain gauges measuring total precipitation, and five snow stakes measuring snow depth as recorded by cameras mounted on nearby trees. Temperature sensors are located in shaded forest understory locations and shielded from direct incoming radiation by locally designed pvc radiation shields . Rain gauges and snowstakes were located in forest openings to limit the influence of canopy interception on precipitation accumulation. All sites began measurements in 2012. About two thirds of the pendant sites began recording during late-May to late-June with the remaining sites beginning in mid-October to early-November. The rain gauges began measurement during 17–19 October and the snow stakes during 31 October – 14 November.
The pendants measure air temperature and light intensity every 15 minutes. The rain gauges report accumulated precipitation, and are read twice a year during the late-spring and the early-fall. Photographs of the snow stakes are taken once every 3 hours between 8AM and 6 PM. Currently, snow depth data is measured by manually interpreting individual snow stake photographs.
A snow stake is established at each site with a metal fence post driven into the ground to support a 2" PVC pipe that slides over the post. Survey rod decals are placed on most of the PVC pipes except at lower elevation sites where shorter stakes are adequate and stream level metal guys are used as the calibration system. Slope, aspect, and canopy closure are recorded for all sites, as well as the initial stake tare reading on the ground (not all stake readings begin at zero). A camera is established near the stake and records x number of photos per day.
