Soil frost measurements have been made at Sleepers River Research Watershed starting in 1983. Measurements were made by U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory from 1983 to 1993, followed by the U.S. Geological Survey from 1993 to the present. Measurements started at 5 sites and has increased to 10 sites. Sites range in elevation from 225 to 670 meters and are in a mix of field and forest types. Soil frost measurements are made with tubes filled with methylene blue solution; on freezing, the methylene blue remains in the liquid phase, yielding clear ice that marks the depth of soil frost (Ricard and others, 1976). Soil frost measurements typically are made 2 to 4 times a month between November and May. This data release includes two tables. "Frost site description" lists elevation, latitude, longitude, tube IDs, number of tubes, vegetation type, years of record, and periods of data collection for each site. "Sleepers frost 1983-2020" includes measurements of the depth of the thawed layer above frozen ground (starting in 1993), the total depth of frozen ground, and the snow depth at frost tubes. Resources: Ricard, J.A., Tobiasson, W., Greatorex, A., 1976, The field assembled frost gage: Corps of Engineers, U.S. Army, Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire. Brown, P.J. and DeGaetano, A.T., 2011, A paradox of cooling winter soil surface temperatures in a warming northeastern United States: Agricultural and Forest Meteorology, 151(7), pp.947-956. Campbell, J.L., Ollinger, S.V., Flerchinger, G.N., Wicklein, H., Hayhoe, K. and Bailey, A.S., 2010, Past and projected future changes in snowpack and soil frost at the Hubbard Brook Experimental Forest, New Hampshire, USA: Hydrological Processes, 24(17), pp.2465-2480. Shanley, J.B., and Chalmers, A.T., 1999, The effect of frozen soil on snowmelt runoff at Sleepers River, Vermont: Hydrological Processes 13: 1843-1857. Hardy, J.P., Groffman, P.M., Fitzhugh, R.D., Henry, K.S., Welman, A.T., Demers, J.D., Fahey, T.J., Driscoll, C.T., Tierney, G.L., and Nolan, S., 2001, Snow depth manipulation and its influence on soil frost and water dynamics in a northern hardwood forest: Biogeochemistry 56:151-174.
