Sensitivity of Summer Drying to Spring Snow-Albedo Feedback Throughout the Northern Hemisphere From Satellite Observations

The spring snow-albedo feedback (SAF) has been found to be positively correlated with summer drying in the United States in climate change simulations. However, whether this relationship exists in real climate is unclear. In this letter, we explored the relationship between spring SAF and summer drying with the help of satellite observations. It was found that a positive correlation between spring SAF and summer drying existed from 1982 to 2013. There was a negative interannual correlation between spring SAF strength and summer soil moisture (SM) ( $r < -0.35$ ) and a positive interannual correlation between spring SAF and land surface temperature ( $T_{s}$ ) in summer ( $r > 0.35$ ) throughout dry regions in western North America, Europe, and central Asia. Furthermore, the strength of the snow-cover component ( $- 0.67 \,\pm \, 0.06{\%}\,\cdot \,\text {K}^{-1}$ , effect of $T_{s}$ on land surface albedo ( $a_{s}$ ) over surfaces transitioning from snow-covered to snow-free conditions) was about twice the magnitude of the metamorphosis component ( $- 0.31 \pm 0.07{\%}\cdot \text {K}^{-1}$ , effect of $T_{s}$ on $a_{s}$ over snow-covered surfaces) during the spring, which explained the majority of spring SAF strength over the Northern Hemisphere (NH) snow-covered landmass during 1982–2013. Meanwhile, the sensitivity of summer SM and $T_{s}$ to changes in the snow-cover component rather than the metamorphosis component dominated the relationship between spring SAF and summer drying over the NH. This was the first attempt to provide observational evidence for the sensitivity of summer drying to spring SAF over the NH.