Observational evidence of regional increasing hot extreme accelerated by surface energy partitioning

Abstract

Land-atmosphere interactions play an important role in the changes of extreme climates, especially in hot spots of land-atmosphere coupling. One of the linkages in land-atmosphere interactions is the coupling between air temperature and surface energy fluxes associated with soil moisture variability, vegetation change, and human water/land management. However, existing studies on the coupling between hot extreme and surface energy fluxes are mainly based on the parameterized solution of climate model, which might not dynamically reflect all changes in the surface energy partitioning due to the effects of vegetation physiological control and human water/land management. In this study, for the first time, we used daily weather observations to identify hot spots where the daily hot extreme (i.e., the 99th percentile of maximum temperature, Tq99th) rises faster than local mean temperature (Tmean) during 1975–2017. Furthermore, we analyzed the relationship between the trends in temperature hot extreme relative to local average (ΔTq99th/ΔTmean) and the trends in evaporative fraction (ΔEF), i.e., the ratio of latent heat flux to surface available energy, using long-term latent and sensible heat fluxes which are informed by atmospheric boundary layer theory, machine learning, and ground-based observations of flux towers and weather stations. Hot spots of increase in ΔTq99th/ΔTmean are identified to be Europe, southwestern North America, Northeast Asia, and Southern Africa. The detected significant negative correlations between ΔEF and ΔTq99th/ΔTmean suggested that the hotspot regions are typically affected by annual/summer surface dryness. Our observation-driven findings have great implications in providing realistic observational evidences for the extreme climate change accelerated by surface energy partitioning.

Continental heat storage: Contributions from ground, inland waters, and permafrost thawing

“…As part of the land surface energy balance, and despite being the smallest term in most situations (e.g., Bonan, 2002;Purdy et al, 2016), ground heat flux needs to be determined in order to close the energy balance at the surface and minimise uncertainties in the rest of components. A complete knowledge of the surface energy balance, together with soil conditions, is fundamental to understand the evolution of land-atmosphere interactions affecting important climate and meteorological phenomena, such as surface temperature increase, surface temperature variability, and extreme temperature events (Seneviratne et al, 2006;Fischer et al, 2007;Seneviratne et al, 2013;Thiery et al, 2017;Vogel et al, 2017;Ma et al, 2018;Wang et al, 2022;Parmesan et al, 2022).…”

Impacts of water surge from mountain railroad tunnels on ecological environments based on the RSEI model

“…Like the tunnel structure and maintenance, high tunnel water flows will also continuously impact the ecological environment of the surrounding area, including the water environment, vegetation environment, and biological habitat environment (Taylor and Dykstra, 2005;Wang et al, 2022). In terms of the water environment, tunnel excavation will disturb the original hydrological balance, destroy parts of the groundwater recharge, runoff, and drainage systems, and lower the local groundwater level in both the short and long terms.…”