AUTOMATED QUALITY-CONTROL PROCEDURE FOR THE WATER EQUIVALENT OF SNOW ON THE GROUND MEASUREMENT

Snow water equivalent (SWE) has been measured daily by the United Stat es National Weather Service since 1952, whenever snow depth is 2 in. ( 5 cm) or greater, These data are used to develop design snow loads for buildings, for hydrological forecasting, and as an indicator of clima te change. To date they have not been subjected comprehensively to qua lity control. An automated quality control procedure for these data is developed here, which checks daily SWE values for common data entry e rrors, values beyond reasonable limits, and consistency with daily pre cipitation and estimated melt. Potential effects of drifting in high w inds and of the intrinsic microscale variability of SWE are also consi dered. An SWE measurement is declared suspicious if a sufficient discr epancy is found with respect to the expected SWE. Data values flagged as potential errors are checked manually. Results of applying the proc edure to available SWE data from the northeastern United States are al so summarized.