The role of land-atmosphere feedbacks in heatwave and drought development

Heatwaves often co-occur with droughts and can lead to grave consequences for human health, resource economies, and the environment. In southern Canada, heatwaves are expected to become more frequent over the course of the 21st century. However, projections of heatwave and drought frequency and intensity are still subject to large uncertainties. Their development depends on complex land-atmosphere feedbacks, which are often insufficiently represented in Earth system models. Field observations across the soil-plant-atmosphere continuum are scarce, contributing to uncertain projections of heatwave and drought frequency and intensity in a warming climate. Integrated observations are urgently needed for comprehensive diagnosis of land-atmosphere feedback mechanisms and for the evaluation of coupled land-atmosphere models. Improved heatwave and drought projections provide a crucial tool for guiding climate mitigation and adaptation efforts in the forestry, agriculture, and hydro-electricity sectors, which are vital components of the Canadian economy. The overall objective of this research program is to improve the understanding of how heatwaves and droughts develop to better support climate mitigation and adaptation efforts. Four linked short-term objectives (2021-2026) will be achieved by combining cross-scale observations of land-atmosphere interactions across the soil-plant-atmosphere continuum covering 5 major Canadian ecosystem types with coupled land-atmosphere modelling, satellite-based remote sensing, and balloon sounding observations. Plant physiology and surface heat and moisture flux measurements will be used to analyse vegetation responses to atmospheric and soil water stress and to parameterise a land-atmosphere model, atmospheric observations will be used to validate model simulations, and remote sensing and balloon sounding data will be used to expand spatial coverage beyond the field sites. The research program will elucidate how land-atmosphere interactions contribute to heatwave and drought development with a particular focus on southern Canada. Over the next 5 years, 4 graduate and 5 undergraduate students will be trained. They will profit from an interdisciplinary research approach and will acquire data management and analysis, programming, and communication skills preparing them for academic and non-academic job markets in the fields of climate science, weather forecasting, and natural resource management. A core component of this research program is the establishment of a long-term land-atmosphere observatory at the Acadia Research Forest managed by the Canadian Forest Service (Natural Resources Canada [NRCan]). Students will benefit from collaborations with NRCan and knowledge transfer to government agencies will be facilitated through close interactions with collaborators at NRCan. Knowledge developed in this research program will also be transferred to other academics through journal publications and conference presentations.