On the effect of boundary conditions on the Canadian Regional Climate Model: use of process tendencies

Climate simulations results can be very different when the regional climate model used is driven by different data. In this paper, the fifth generation Canadian Regional Climate Model (CRCM5) response is assessed when driven by various boundary conditions. The latter are provided by outputs from the second-generation Canadian Earth System Model (CanESM2) and the Max Planck Institute for Meteorology’s Earth System Model (MPI-ESM-LR) and also from ERA-Interim reanalysis. Physical and dynamical tendencies are analysed when the regional model is well spun up and is sufficiently affected by the lateral forcing data. The results indicate that the model is very sensitive to those imposed lateral conditions. Compared to observations, the CRCM5 exhibits excessive heating in the lower levels and cooling above when driven by the three driving data. It is also found that the two global models contribute to these anomalies but with different effects. Temperature tendencies revealed a cooling in lower layers when CRCM5 is driven by CanESM2 while a heating is noted when the model is forced by MPI-ESM-LR. Specific humidity tendencies also showed different effects depending on the driving data used.