Review of Dynamics of stratospheric wave reflection over the North Pacific, by M. K. Schutte, A. Portal, S. H. Lee, and G. Messori.

The authors present an evaluation of the composite evolution of wave reflection events in the North Pacific, which previous studies had connected with cold spells in North America. The identification of reflection events is based on an regional index of eddy heat flux, and the dynamics of these events are characterized using geopotential height, eddy heat flux, three-dimensional wave activity flux, and the wavenumber - phase speed spectra. The main results show a westward propagating ridge and the development of a trough downstream during the evolution of reflection events, which is associated with a change of sign in the meridional eddy heat flux. In turn these eddy heat fluxes can explain the meridional transport of colder air from the pole to lower latitudes, leading to a decrease of temperature over North America.

The paper is well-written and the presentation of the results is clear. I appreciate the level of detail given in the description and interpretation of each figure. I recommend publication after consideration of the comments given below.

Comments:

- The three-dimensional wave activity flux (WAF) used in this study (Plumb 1985) is a diagnostic for the stationary component of the wave field. However, the results presented reveal the presence of migrating eddies during the evolution of reflection events, especially at the end of their life cycle. Therefore, I would suggest to use a diagnostic of the WAF suitable to the problem at hand, for example the one proposed by Takaya and Nakamura (2001). On the other hand, the authors may reconsider the need of including a WAF analysis in the paper, given the detailed analysis of the geopotential and eddy heat fluxes.

- lines 41-43 and 48-50. The eddy heat flux is part of the vertical component of different 3D wave activity flux diagnostics (e.g. Plumb 1985, 1986, Takaya and Nakamura 2001), but strictly speaking it is proportional to the vertical group velocity only in a zonal mean framework, where the EP flux represents the wave activity flux in the meridional-vertical plane.

- Lines 77-78. Why is the meridional wind component not deseasonalized?

- Eq. 1. Please specify the pressure level at which RI is defined (is it 100 hPa?).

- Line 92. Are the weather regimes computed using year-round data? Why not only winter data? Is there any sensitivity there?

- The arrows in Fig. 3 are confusing. The vertical component represents the vertical component of the WAF(?), but the vertical axis in the figure represent time. If the authors decide to keep the analysis of the WAF (after switching to Takaya and Nakamura 2001), then I would suggest to plot it on a map like Fig. 4.

- Lines 297-298. How many reflective events are also regime transitions? Are the composites of Figs. 7-8 dominated by the signal of those transitions that are also reflective events? Does the composites of transitions that are NOT reflective events show a similar qualitative evolution to those that are?

- I find section 3.3 unnecessary for the goals of the study. The summary at the end of the section would be a sufficient remark to make in the text without the need of showing the figures.

Takaya, K., and H. Nakamura, 2001: A Formulation of a Phase-Independent Wave-Activity Flux for Stationary and Migratory Quasigeostrophic Eddies on a Zonally Varying Basic Flow. J. Atmos. Sci., 58, 608–627