Joint assembly AGU-GAC-MAC-CGU
Year of publication:
High-resolution regional climate model outputs, including surface hydrologic variables such as streamflows, are increasingly being used directly in many impact and adaptation studies. The realism of these RCM simulated surface variables for the high-latitude regions is dependent to a large extent on the representation of surface types and processes important for these regions and their atmosphere interactions. This will be demonstrated by comparing simulations performed with the fifth generation of the Canadian Regional Climate Model (CRCM5), with and without organic soil, near-surface permafrost, lakes and interactive phenology, for the Canadian high-latitude and Arctic regions. The comparison of simulations with and without organic soil, for example, indicates significant differences in the energy and water partitioning at the surface, leading to differences in both the regional climate and hydrology. The runoff and therefore streamflows are higher for the summer and fall seasons in the simulation with organic soil compared to the one without organic soil, while the inverse is noted for the spring season. The relatively higher value of runoff in summer and fall in the simulation with organic soil is mostly due to increased drainage contribution. Similarly, the differences in the surface climate, particularly the 2-m minimum temperatures, lead to differences in the hot spell characteristics in the two simulations. This talk will discuss the mechanisms leading to these differences as well as the comparisons between the other simulations performed to identify the impact of lakes and interactive vegetation on the surface hydrology/climate. Projected changes to selected hydrometeorological variables over Canada from the improved model simulations will also be presented.