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Freshwater Content Gridded Data

Estimates of liquid freshwater content (hereafter, FWC) of the Beaufort Gyre region (BGR) Figure 1)  are computed following Proshutinsky et al. (2009) using CTD, XCTD, and UCTD profiles collected each year from July through October: a total of 3309 water-column profiles in the 2000s, 2961 profiles in the 2010s, and 267 profiles in the 2020s.

Spatial maps (on a 50-km square grid) of FWC distribution were constructed in the BGR, which is defined to be between 70˚N and 80˚N, and 130˚W - 170˚W where water depths exceed 300 m, using optimal interpolation for each year from 2003 through 2022 (Figure 2). Spatially-integrated fresh water volumes for the BGR (encompassing an area of 1.023 x 106 km2) are labelled for each year on each panel in Figure 2, with uncertainties determined from combining the uncertainties in the profiles with the optimal interpolation errors shown in Figure 3.

Uncertainties for each grid cell, determined using the optimal interpolation technique previously described in Proshutinsky et al. (2009), were updated and are presented in Figure 3.

Gridded data are available in the “2003-2022” folder and more information about data and figures illustrating the data are provided in the folder entitled “Data Description.”

Figure 1 (a) Beaufort Gyre Observational System (BGOS) assets configuration with A-D mooring locations depicted as stars, and sites of “standard” CTD stations where observations of sea ice and water physical and geochemical parameters have been conducted over the period 2003-2022; (b) and (c) Time-averaged summer FWC (relative to reference salinity 34.8, m; colors and contours) in the BGR for 2000s and for 2022. The colored area of the 2022 chart shows the BGR 50x50 km grid coverage. d) Decadal (1950-2000) and annual FWC in the BGR.(thousand cubic km).
Figure 2 FWC in the BGR based on hydrographic measurements as in Figure 1c. The black dots indicate locations of observational sites. The white lines duplicate contours of FWC distribution shown in colors. Numbers at the bottom of each panel indicate total FWC in the region (10³ km³) and root‐mean‐square error of freshwater content interpolation (10³ km³).
Figure 3 FWC errors in the Beaufort Gyre region associated with the optimal interpolation method. See Proshutinsky et al., 2009 for more details.

Proshutinsky, A., R. Krishfield, M.-L. Timmermans, J. Toole, E. Carmack, F. Mclaughlin, W. J. Williams, S. Zimmermann, M. Itoh, & K. Shimada (2009), Beaufort Gyre freshwater reservoir: State and variability from observations, Journal of Geophysical Research, 114, 1–25, doi:10.1029/2008JC005104.