|Second review of “The sensitivity of atmospheric blocking to upstream latent heating - numerical experiments” by Daniel Steinfeld, Maxi Boettcher, Richard Forbes, and Stephan Pfahl|
The authors have responded to and accounted for most of my previous concerns. In particular, the structure is now well balanced between detailed and additional case studies, which are compared carefully, the scope is clearly introduced, the discussion of figures is easier to follow, and the paper has improved overall. However, my earlier concern on the assessment of the control simulations has not been considered appropriately. This point is detailed below, along with a few specific comments, but should not require much additional work before the paper can be considered for publication in Weather and Climate Dynamics.
I fully understand that the predictability of blocking situations is beyond the scope of the paper. The authors justify that “the reference simulations capture large-scale blocking conditions”, which is true, but how close are these to the actual large-scale blocking conditions? If the model completely diverged from reality—which does not appear to be the case here—there would be no point at investigating real case studies. In their response figure AR1 the authors show that the control simulation is very close to the analysis after 3 days, which is good and strengthens the results, and deviates after 6 days, which is okay but deserves some discussion. This must be mentioned at least, and showed in any case, otherwise it may be interpreted as trying to hide some findings. As I suggested in my previous review, the analysis could be included by adding panels (or simply the 2-pvu contour) in Figs. 3–4 and S1–3 (or alternatively 7–8) and/or intensity and spatial extent in Figs. 2 and 10.
l. 34 “concepts”: studies?
l. 83–99 specify the boxes are fixed during each run
l. 105–107 this is not convincing…
l. 116–117 emphasize this terminology is used for all variable throughout the paper
l. 229–232 avoid referring to Fig. 1b as it does not show the features mentioned here
l. 352 day 2 or 3?
l. 356 “underestimated”: weaker?
l. 366–368 “demonstrates” is too strong, as uncertainty can arise from low-level moisture in the initial conditions, phasing between lower and upper-level flows, etc.
l. 438–547 (4.2.2) Fig. 9 is (1) very similar to Fig. 7, (2) only once referred to, and (3) implies returning to day 3 after discussing day 6 in Fig. 8. I thus recommend merging Fig. 9 with Fig. 7 (or alternatively with Figs. 3–4 and S1–S3) by simply adding a contour of strong PV advection by the divergent wind (see e.g. Fig. 7 in https://doi.org/10.1002/qj.2419) and merging contents of 4.2.2 with 4.2.1.
l. 501–503 The definition of intensity and spatial extent indices is unclear: relative or normalized differences? Better express as percentage?
Figure 1 “2 days lead time”: rather 42h in (a) and 36h in (b)?
Figure 11 use different symbols or annotate reduced and enhanced LH.