Fig. 4
Annual air temperature and snow depth changes. a–d Air temperature anomaly \({\mathrm{\Delta }}\hat T_{y,b}\) relative to the 1981–2010 reference period calculated from mean annual air temperatures at 2-m height above the ground level interpolated from the ERA Interim reanalysis data set. Mean values calculated as de-clustered, indexed area-weighted averages (Eq. 4). Dark colored dashed lines indicate 4-year end-point running means. Snow depth changes \({\mathrm{\Delta }}\hat S_{y,b}\) in a and b, indicated in gray, calculated as the difference relative to the 1999–2010 reference period from the CMC reanalysis data set (eq. 5). e, f Onset of snow SO, snow insulation maximum SIM (dashed line), and the end of snow melt SE. Uncertainties are expressed as shading at 95% confidence. Sample size n indicates the number of boreholes
