By leveraging spatial and temporal analogs, we established a statistical relationship between the S/P ratio and temperature. We present the global climatological map of T50%—the temperature at which the S/P ratio reaches 50% as well as the maximum and current sensitivity of the S/P ratio to warming. These results are provided at a 1° × 1° resolution, covering latitudes up to 65°.
T50% stays between 1°C and 2°C including ocean grids, exceeds 5°C in high elevation regions, and is colder than 2°C in the eastern North America and west to mid Asia. The T50% is related to relative humidity (RH), elevation and temperature regimes. Additionally, the elevation variation within each 1° grid contributes to its spatial variability. In contrast, the maximum sensitivity remains relatively homogeneous over midlatitude continents and exhibits strong land-ocean contrast, where the average value is around -10%/°C over land and exceeds -25%/°C over ocean. Besides RH and elevation, both the annual temperature standard deviation and the snowfall season length affect maximum sensitivity.
A closer examination of temperature sensitivity reveals that latitudes between 40°N–60°N and around 60°S experience relatively high sensitivity (<-8%/°C and <-15%/°C, respectively) under current climatological conditions. If climatological temperatures continue to rise, regions north of 50°N, south of 60°S, and the Tibetan Plateau will see an accelerated decline in the S/P ratio per 1°C of warming, exhibiting a stronger sensitivity.
Our results provide the climatology of the S/P ratio and highlight the spatial variability of the phase transition temperature and S/P ratio temperature sensitivity, providing valuable insights for improving model parameterizations and enhancing the representation of precipitation phase partitioning in large-scale applications.
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