Land-Atmosphere interaction over North America in the current and future climates using Canadian Regional Climate Model (CRCM5)

Abstract:

In this study, we investigate how land-atmosphere coupling and interaction may affect future extreme temperature events, particularly the role of soil moisture in modulating the frequency and duration of extreme hot events using the fifth generation of Canadian Regional Climate Model (CRCM5). With this objective, two sets of simulations were carried out: the soil moisture is coupled with the atmosphere for both current and future periods in the first set of simulations, while climatological values of soil moisture (obtained from the first set) are prescribed for current (1981-2010) and future (2071-2100) periods for the second set of simulations. Each set consists of 4 simulations, driven by two different GCMs (MPI and CanESM2) for two representative concentration pathways (RCP4.5 and RCP8.5). Associated with the decrease of soil moisture in the future climate, the projected soil moisture-temperature coupling regions extend beyond the Great Plains in to the Canadian Prairies. Results also indicate that the land surface plays a significant role in the projected change of extreme temperature events (e.g. number of hot days) over parts of North America. It is noted that the impact of land-atmosphere coupling is stronger on the changes in the variability than on the mean and these changes are co-located with areas where the reduction of soil moisture is intense.