LOCATION DESCRIPTION
Snow course data have been collected approximately weekly at a network of standard rain gages at the Hubbard Brook Experimental Forest from 1956 to the present when there was snow on the ground. Snow courses are located near each of the standard rain gage openings and are numbered according to the rain gage. Each snow course is a forested area of about 1/4 ha.
During the period from 1967 to 1984, the network was reduced to 2 snow courses on the north-facing slope (STA17 and STA19) and two snow courses on the south-facing slope (STA2 and STA9), along with a snow course at the headquarters location(STAHQ). Ongoing data collection occurs at these five snow courses.
Snow course locations are described in the data package entity snowcourse_info.csv. The latitude and longitude describe the location of the standard rain gage associated with each snow course.
SAMPLING DESIGN: SNOW DEPTH AND SNOW WATER EQUIVALENT
Each measurement consists of ten sample points 2 meters apart along a transect line. On the next date, a parallel line is used, 2 meters from the previous line. At each point, snow depth and water content are measured using a Mt. Rose snow tube. The ten snow depth measurements are averaged.
SAMPLING DESIGN: SOIL FROST DEPTH AND FROST OCCURRENCE
The presence or absence of frost in the ground is checked at each of the ten sample points along each snow course transect by probing with a ski pole. The percentage of total probe locations having frost is recorded for each snow course. At the first two snow points that have frost, a hole is dug into the soil and the depth of the frost is measured and recorded. The two depths are averaged to calculate frost depth. If no frost is found along a transect, the frost depth is recorded as zero.
Frost data from stations 2 and 17 have been collected from 1956 to the present. These stations have the longest continuous records and are representative of mid-elevation south-facing and high-elevation north-facing slopes. Frost data for stations 9, 19 and HQ begins in 1994. Prior to 1970 frost measurement was sporadic and the general impression was that there was none. Data for these years should be used with caution. The number of frost points sampled has also varied over the years.
RELEVANT PUBLICATIONS:
Bailey, Amey S, J. W Hornbeck, John L Campbell, and C. Eagar. 2003. Hydrometeorological Database for Hubbard Brook Experimental Forest: 1955-2000. USDA Forest Service, Northeastern Research Station.
Campbell, J. L., S. V. Ollinger, G. N. Flerchinger, H. Wicklein, K. Hayhoe, and A. S. Bailey. 2010. Past and projected future changes in snowpack and soil frost at the Hubbard Brook Experimental Forest, New Hampshire, USA. Hydrological Processes 24:2465-2480.
CALCULATIONS
Snow water content on a watershed basis can be obtained from the snow course data by weighting using the following expressions:
Through 1966:
W1 = 0.10 SC1 + 0.46 SC2 + 0.44 SC3
W2 = 0.02 SC1 + 0.41 SC2 + 0.57 SC3 (prior to cutting)
W3 = 0.08 SC2 + 0.39 SC3 + 0.19 SC4 + 0.34 SC5
W4 = 0.03 SC1 + 0.08 SC2 + 0.01 SC3 + 0.30 SC6 + 0.30 SC7 + 0.28 SC8
W5 = 0.32 SC6 + 0.30 SC7 + 0.06 SC9 + 0.11 SC10 + 0.21 SC11
W6 = 0.31 SC9 + 0.49 SC10 + 0.20 SC11
1967 – 1978:
W1 = 0.516 SC2 + 0.472 SC3
W3 = 0.151 SC2 + 0.473 SC3 + 0.370 SC5 + 0.07
W4 = 0.315 SC2 + 0.386 SC6 + 0.275 SC10 - 0.09 (prior to cutting)
W5 = 0.111 SC5 + 0.565 SC6 + 0.333 SC10 (without SC11)
W5 = 0.446 SC6 + 0.313 SC10 + 0.209 SC11 + 0.03 (with sc11)
W6 = 0.330 SC6 + 0.656 SC10 + 0.02 (without sc11)
W6 = 0.250 SC6 + 0.511 SC10 + 0.258 SC11 - 0.01 (with sc11)
Through 1973:
W8 = 0.17 SC17 + 0.16 SC19 + 0.51 SC20 + 0.16 SC21
1974-1983:
W7 = 0.497 SC14 + 0.209 SC17 + 0.200 SC19 + 0.081 SC20 + 0.21
W8 = 0.042 SC14 + 0.263 SC17 + 0.166 SC19 + 0.527 SC20
Since the network was reduced to 2 snowcourses on each side (north-facing and south-facing), regression analysis for watershed values has not been performed.
