Review attached as supplement.

This paper is a technical documentation of the atmospheric model CanAM5 that is part of the CanESM used for its CMIP6 simulations. It documented the modifications made to the previous model version CanAM4, which are for the optical properties of cloud particles and land/ocean/snow surface in the radiative calculations, cloud microphysical scheme, and surface processes. It also contains description of the spin-up of the carbon model and tuning of the CanAM5 and CanESM5.  The paper then documented the rudimental performances of climatologies in clouds, radiation, zonally averaged winds and temperature, surface pressure and precipitation against observations and CanAM4. It provided some insight, although rather superficial, into the cause of the model biases. I think the paper is valuable for model developers and potential users of its simulations. I therefore recommend a minor revision. The paper is a straightforward documentation. I only have some minor comments.

1. For the benefit of the readers, please describe what is the second aerosol indirect aerosol effect that is included in Equation (2). Line 1 on page 5.

2. Line 24 on page 5 missed a period. This is the same in Line 14 on page 7.

3.  The sentence in line 23 on page 8 is poorly written. Please revise.

4. Line 14 on page 9: add "net downward" after 2.5 W/m2.

5. Line 24 on page 12: "..., there is a shift to more optically thin ( < 23) in CanAM5", this is inconsistent with Figure 2 which shows less optically thin clouds with tau less than 6. It is also inconsistent with Figure 3. 

6. First paragraph of Section 6.3 on zonal wind: there seems to be cherry picking.  CanAM5 shows larger bias than CanAM4 not just in the Northern Hemisphere. It is also larger in the Southern Hemesphere as indicated in Figure 8. The attribution of orographic gravity wave drag parameterization (Line 6-7 in the paragraph) is thus questionable.