第一届未来大气科学论坛

Lakes exert strong influences on local weather and climate due to large differences in their temperature from that of the adjacent land surface. In this study, we quantify the spatial patterns and the long-term change in land-lake thermal contrast ΔTs, defined as land surface temperature minus lake surface temperature, using sub-grid data generated by an Earth system model under the SSP585 scenario. A surface energy balance framework was deployed to diagnose the contributions of long-term changes in lake and land biophysical properties (surface albedo, Bowen ratio and convection efficiency) and in radiation energy to the long-term trends of ΔTs. Results show that rising CO2 amplifies the daytime ΔTs (making it more positive) and dampens the nighttime ΔTs (making it less negative) across all climate zones. The annual mean ΔTs ranges from 1.75 K in Tropical Climate to 2.82 K in Arid Climate in 2019 to 2023. All climate zones exhibit increasing trends in the annual ΔTs. The global mean annual ΔTs shows a regime shift from being negative (0.61 K; land being cooler than lakes) in 2019-2023 to being positive (0.37 K; land being warmer than lakes) in 2096-2100. The primary driver of these long-term trends is reduction in the lake Bowen ratio. Albedo reduction has a relatively minor effect on the overall trend due to similar changes in land and lake albedo associated with shortened snow cover periods on land and ice cover periods in lakes. The role of increase in the downward longwave radiation is more complex and varies by climate zone. These results suggest that lake breezes should intensify in the future.