IRt/c data examples

Data of one month of nice weather

Ta is the ambient air temperature, TSS the snow surface temperature measured with the IRt/c, RSSWR short wave solar radiation, and HSS snow height. In the thermal infrared snow is almost black. So at clear sky the snow surface always cools down far below air temperature because of radiation loss toward the cold clear sky. On the 18^th of May the sky was covered by clouds, resulting in reduced incoming short wave and almost no net long wave radiation loss (air temp. = surface temp.). During all other days we had melting at the snow surface bringing the surface temperature to the melting temperature.

Similar plot for February

The surface temp may be as much as 20°C below air temp.

We calibrate the IR for case temperature of +5 to –25°C and surface temperature of 0°C to –30°C. During this period you may see 4 periods with cloud cover and one even with a small snowfall.

The surface temp is one of the most important parameters in the evaluation of the surface structure of the snow cover and for snow stability evaluation.

Typical layout of a remote station with optional sensors.

The IR sensor mounted in a radiation shield in front. The other sensors are snow depth (ultra sonic), air temp and humidity, short wave radiation reflected by snow cover.

View from below. The sensor is mounted about 5m above ground.

Complete station with the famous Matterhorn in the back.

The highest stations are at 3500m. The have to work under very rough environmental conditions. Most of the installations are only accessible by helicopter.