Ground-based snowfall and snowpack measurements

Abstract

Measurement of snow at time of fall Precipitation gauges Several complications arise when using precipitation gauges to measure snowfall that are not as much of a problem when measuring rainfall. Gauge catch losses are more severe for snow than rain, so that precipitation gauge shields are much more of a necessity. Additionally, subfreezing temperatures during winter, and usually during a snowfall event, dictate that an antifreeze solution be used to prevent collected water from freezing (an evaporation suppressant might be necessary to minimize evaporative losses); and, to insure that bridging of snow over the gauge orifice does not happen, the gauge is sometimes heated. The positioning of the snow-precipitation gauge on the landscape must also be considered in order to get a more representative catch of snowfall. Nonrecording gauges There are two classes of nonrecording gauges, those read on a daily or more frequent basis and storage gauges that are read only after a period of time has elapsed, like once a month or once a season. A subtype of the daily nonrecording gauge is the gauge that is only read after a snowfall event has been observed. If a gauge is to be read on a 6- or 24-hour interval, antifreeze, orifice heating, and evaporation suppressants are not as critical as for a storage gauge. For those nonrecording gauges, the funnel and collection tube, used for rainfall events, are removed from the gauge and snow falls directly into the outside container.