SRS

The sonic ranging sensor (SRS) is a vertically mounted ranging device that sends a sonic “ping” downward toward the ground or snow surface, then records the down-and-back transit time to produce an offset distance (in meters) of the reflecting surface from the device itself. Generally, such devices are used to measure snowpack buildup as winter progresses. Because the speed of sound in air is a function of air temperature (+6% error at 20 C vs. at 0 C; -6% error at minus 20 C), the output must be corrected for the ambient temperature. The measured distance, when subtracted from the snow-free distance, results in a value equivalent to the snow depth at that time. Typically, several such devices are run in concert to produce multiple snow depth samples.

• Snow depth