Fig. 1: Long-term Snow Storage Index (SSI) across Western North America.
From: Recent decreases in snow water storage in western North America
a Long-term average SSI across the mountainous western cordillera, constrained to areas within each EPA Level III ecoregion where \(\overline{{{{{{\rm{SSI}}}}}}}\) ≥ 0 for 1950-2013. Black points represent SNOTEL stations in the USA, and black diamonds represent CanSWE stations in Canada. Spatially distributed VIC modeled \(\overline{{{{{{\rm{SSI}}}}}}}\) data are shown in color, with darker blue shades indicating greater \(\overline{{{{{{\rm{SSI}}}}}}}\) values and darker orange shades lower values. The twelve EPA Level III ecoregions of the western cordillera are outlined in black and are labeled as: (i) North Cascades, (ii) Cascades, (iii) Eastern Cascade Slopes and Foothills, (iv) Klamath Mountains, (v) Sierra Nevada, (vi) Blue Mountains, (vii) Columbia Mountains/Northern Rockies, (viii) Idaho Batholith, (ix) Wasatch and Uinta Mountains, (x) Canadian Rockies, (xi) Middle Rockies, (xii) Southern Rockies. Panels b and c show exemplar grid cell daily average precipitation (P) and surface water inputs (SWI) data used to calculate \(\overline{{{{{{\rm{SSI}}}}}}}\) in the Sierra Nevada, and Southern Rockies, respectively. Sine curves fit to the data are shown with black lines and the vertical yellow dashed lines indicate the peak of each sine curve. The horizontal dashed arrows notate the temporal difference in the peak precipitation and peak surface water inputs. The vertical dotted arrows notate the amplitude of each select curve.
