Fig 1.
Map of the hubbard brook experimental forest.
The panel on the left places the HBEF within the northeastern United States, and the panel on the right shows the locations of the snow courses and weather stations used in this analysis. All map layers are published and available at https://hubbardbrook.org/data-catalog/. Specific layers are cited in the [S1 Methods].
Table 1.
Datasets and definitions of derived variables used in this study.
Fig 2.
Dates of major snowpack milestones.
In each panel the lower line is the onset date (when the snowpack reached 6 cm of snow water equivalent). The middle line is the date the snowpack reached its maximum, and the top line indicates the date of the last recorded snow. Solid lines through the data indicate significant trends at p< = 0.05. Slopes and precise p-values are found in Table 2. Panel A corresponds to snowcourse (SC)17, which faces north at 898 meters in elevation. Panel B corresponds to SC19, which faces north at 600 meters, and panel C corresponds to SC2, which faces south at 555 meters.
Fig 3.
Annual maximum snowpack size (SWE) from three snowcourses (SC) which vary by elevation and aspect.
Solid lines indicate significant trends at p< = 0.05. Slopes and precise p values are found in Table 2.
Table 2.
Median lengths (in days) and trends over time in the timing of: Snowpack duration, snowpack onset, day of maximum snow water equivalent, and day of the last recorded snow, as well as the maximum SWE for the year, at three sites that vary in aspect and elevation at Hubbard Brook from the winter of 1968 through the winter of 2023.
Fig 4.
Trends in total precipitation in the winter period, separated by volume that fell on days above freezing, or days at or below freezing.
Panels d-f show the average temperatures at each site in this period.
Table 3.
Environmental conditions in the winter timeperiod at each location, showing any changes over time and correlations between each variable and the maximum size of the snowpack (SWE).
Fig 5.
Total snowpack losses during winter (see Table 2) from three snow courses which vary in elevation and aspect.
Solid lines indicate significant trends at p<0.05, dashed line indicates trend at p<0.1. Slopes and exact p-values are found in Table 3. Panel a shows the total net loss over the entire winter period. Panel b shows the number of weeks showing a net snowpack loss, and panel c shows the average size of the loss per each weekly loss.
Table 4.
Environmental conditions in the spring timeperiod (between the median date of maximum SWE and the median date of last-recorded snow) at each site paired with correlations between each variable and the date of last recorded snow.