Precipitation Dependence of Temperature Trends Across the Contiguous US. Issue 4 (11th February 2022) - Abatzoglou, John T.
Abstract: Temperature and precipitation covary across timescales due to thermodynamic and dynamic processes. We examine spatial patterns and trends of daily precipitation dependence of maximum and minimum temperature anomalies across the contiguous United States during 1950–2020. In the warm season, maximum temperatures are anomalously cool on wet days, while in the cool season, minimum temperatures are anomalously warm on wet days. During 1950–2020, warm‐season maximum temperatures increased 0.5°C more on wet days than on dry days, whereas minimum temperature on dry days warmed slightly more than on wet days in both the warm and cool season. By contrast, climate models show more subtle and consistent precipitation dependence of temperature trends with approximately 0.2°C more warming on dry days than on wet days. Improved understanding of precipitation‐dependent temperature trends is critical for understanding and modeling the impacts of changing climate on snowpack, drought, and heat stress. Plain Language Summary: Are wet days warmer or cooler than dry days, and have wet or dry days warmed faster? These simple questions have answers that vary spatially, seasonally, and diurnally. Here, we explore these patterns using long‐term temperature records across the contiguous United States. We find that maximum temperatures generally warmed more on wet than dry days during 1950–2020, while the opposite was seen for minimum temperatures warmed more on dry days than wet days. Global climate models show a more consistent pattern of greater warming on dry days than wet days. The extent to which wet days warm relative to dry days with continued climate change will shape impacts on critical physical, ecological, and social systems, including snowpack, agricultural and ecological drought, and heat stress. Key Points: Daily maximum temperatures are cooler, and minimum temperatures are warmer, on wet days relative to dry days for most of the contiguous United States Observed maximum temperatures have warmed more on wet than dry days, while minimum temperatures have warmed more on dry than wet days Climate models depict slightly enhanced warming trends on dry days compared with wet days