uid=HFR,o=lter,dc=ecoinformatics,dc=org all public read doi:10.6073/pasta/523532960e3b8c955b09d9bdfa0c02a6 Emery Boose https://orcid.org/0000-0003-4820-0231 Mark VanScoy 2026 English

Water storage in snowpack is a key factor in the hydrological cycle of central New England. The Harvard Forest Snow Pillow provides continuous long-term measurements of the water content of snowpack (snow water equivalent) during the winter months. The snow pillow is located in a mature mixed hardwood stand with scattered conifers about 50 m north of the Nelson Brook Big Weir. For current data, please see: https://harvardforest.fas.harvard.edu/met-hydro-stations.

climate hydrology precipitation snow snow water equivalence water balance LTER controlled vocabulary disturbance LTER core area Harvard Forest HFR LTER USA HFR default

This dataset is released to the public under Creative Commons CC0 1.0 (No Rights Reserved). Please keep the dataset creators informed of any plans to use the dataset. Consultation with the original investigators is strongly encouraged. Publications and data products that make use of the dataset should include proper acknowledgement.

Creative Commons Zero v1.0 Universal https://spdx.org/licenses/CC0-1.0.html CC0-1.0 https://harvardforest.fas.harvard.edu/exist/apps/datasets/showData.html?id=HF155 Prospect Hill Tract (Harvard Forest). Coordinates based on WGS84 datum. -72.18665 -72.18665 +42.53521 +42.53521 340 340 meter 2009 2026 ongoing. Data updated monthly Information Manager Harvard Forest

324 North Main Street Petersham MA 01366 USA

(978) 724-3302 hf-im@lists.fas.harvard.edu Harvard Forest

324 North Main Street Petersham MA 01366 USA

(978) 724-3302 (978) 724-3595 https://harvardforest.fas.harvard.edu

Trees were removed to create a small opening (15 m) in the canopy to reduce snow interception by branches. Leaf litter and the top 4 cm of organic soil were replaced with sand and graded to create a level surface 5 m in diameter. The snow pillow (rubber, 3 m diameter) was installed on this surface, enclosed in a rubber liner and hardware cloth, and filled with 150 gallons of propylene glycol (75%) and water (25%). A pressure transducer provides continuous measurements of the mass of snow on the pillow. The sensor is scanned every 10 seconds and 15-minute average values are retained. Instruments are disconnected in summer (June 1-Sep 30) to protect from lightning damage. All times are Eastern Standard Time. Each winter the start and end dates of the snowpack season are determined by field observation and images from the EMS subcanopy camera (HF158). Snow water equivalent is set to zero at other times. During the first part of 2014-2015, the snow pillow sensor failed and snow water equivalent was estimated from snowpack depth recorded at the EMS camera (snow ratio 25%). During 2025-2026, the snow pillow sensor proved to be unreliable and snow water equivalent was estimated from snowpack depth recorded at the NEON camera (snow ratio 10% to 50%) and selected manual measurements.

Harvard Forest

324 North Main Street Petersham MA 01366 USA

(978) 724-3302 (978) 724-3595 https://harvardforest.fas.harvard.edu https://ror.org/059cpzx98 pointOfContact The Harvard Forest Long-Term Ecological Research (LTER) program examines ecological dynamics in the New England region resulting from natural disturbances, environmental change, and human impacts. National Science Foundation LTER grants: DEB-8811764, DEB-9411975, DEB-0080592, DEB-0620443, DEB-1237491, DEB-1832210. hf155-01-daily.csv daily hf155-01-daily.csv 118594 62cc488283e107f91533a65e2ffacfa0 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p15/hf155/hf155-01-daily.csv date date YYYY-MM-DD jd Julian day nominalDay 1 whole swe snow water equivalent. Average of 10-second measurements. millimeter 0.001 real NA missing value f.swe flag for snow water equivalent M missing. Instrument not installed, instrument not working correctly, or measured value out of range. E estimated. Value estimated from incomplete measurements or from other sources. 5961 hf155-02-15min.csv 15-minute hf155-02-15min.csv 14815235 a94516dd2c8f048cfa70cb71d566a579 1 \r\n column , https://harvardforest.fas.harvard.edu/data/p15/hf155/hf155-02-15min.csv datetime date and time at end of sampling period YYYY-MM-DDThh:mm jd Julian day nominalDay 1 whole swe snow water equivalent. Average of 10-second measurements. millimeter 0.001 real NA missing value f.swe flag for snow water equivalent M missing. Instrument not installed, instrument not working correctly, or measured value out of range. E estimated. Value estimated from incomplete measurements or from other sources. 572256 atmosphere watershed long-term measurement 1,2 https://harvardforest.fas.harvard.edu/data-archives/data-in-real-time/met-hydro-stations/ https://harvardforest.fas.harvard.edu/exist/apps/datasets/showData.html?id=HF001 https://harvardforest.fas.harvard.edu/exist/apps/datasets/showData.html?id=HF070