The role of 1-D and 3-D radiative heating in the organization of shallow cumulus convection and the formation of cloud streets

Jakub, Fabian; Mayer, Bernhard

doi:https://doi.org/10.5194/acp-17-13317-2017

Articles | Volume 17, issue 21

https://doi.org/10.5194/acp-17-13317-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-17-13317-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 17, issue 21

Research article

|

09 Nov 2017

Research article |

| 09 Nov 2017

The role of 1-D and 3-D radiative heating in the organization of shallow cumulus convection and the formation of cloud streets

Fabian Jakub and Bernhard Mayer

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Final revised paper (published on 09 Nov 2017)
Preprint (discussion started on 08 May 2017)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Review of “The role of 1D and 3D radiative heating on the organization of shallow cumulus convection and the formation of cloud streets” by Jakub and Mayer', Anonymous Referee #1, 27 May 2017
- AC1: 'Author Response', Fabian Jakub, 21 Aug 2017
RC2: 'Review of Jakub and Mayer', Anonymous Referee #2, 16 Jun 2017
- AC2: 'Author Response', Fabian Jakub, 21 Aug 2017

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Fabian Jakub on behalf of the Authors (21 Aug 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (30 Aug 2017) by Philip Stier

RR by Anonymous Referee #1 (08 Sep 2017)

Suggestions for revision or reasons for rejection

I feel that the paper has been improved and it is close to be accepted. However, I still feel a couple details in the explanation of the model setup need to be corrected. I also feel that my request to include additional analysis was mostly ignored. I provide below a short list what I feel would be needed in association with Fig. 1.

Model setup 1. It is still unclear what the (revised) description of the surface layer model humidity means ["soaking wet (30% water volume mixing ratio)"], lines 195-196. Is that what is sometimes referred to as surface moisture availability (e.g., 1 if the surface corresponds to the ocean and smaller value over land)? In a simple parameterization of the surface vapor flux, the surface temperature prescribes the water vapor mixing ratio as corresponding to saturation at the surface temperature and smaller a value over land. If I want to repeat the authors experiment I need to know what to use and currently I am left guessing. 2. The explanation what C_skin is still confusing, line 203, table 1. I looked at Hues et al. GMD 2010 and there I see C_sk that is different to what the authors use in the paper under review. I think the units and values given in the table imply that C_skin is simply the depth of a uniform-temperature layer of water for which the energy balance equation is given by rho_w c_w H dT/dt = net_surface_energy_flux. That is, C_skin is the same as H in my formula. A complication is that Heus et al. also state that the surface model uses 4 layers. I think the authors need to be very specific what they use [1 layer, 4 layers? constant temp and moisture availability (or whatever variable is used)?]. Again, I would not be able to setup my own simulation following the authors' explanations.

Additional analysis. Figure 1 is quite impressive, but I wonder if the difference in cloud sizes (smaller in the lower panel to my eye) comes from difference in the boundary depth and/or radiative cooling (BTW, the radiative cooling is the "destabilization rate" in 5th bullet in specific comments section of my previous review; the authors were confused with what I meant). I feel that at least the lower-tropospheric moisture and temperature profiles, cloud fraction profiles, as well as mean radiative cooling should be shown together with the two panels. If they are really close, than please say so in the text to emphasize that other factors (like the BL depth) are practically the same in both simulations. But showing a figure would be better.

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RR by Anonymous Referee #2 (13 Sep 2017)

ED: Reconsider after minor revisions (Editor review) (20 Sep 2017) by Philip Stier

AR by Fabian Jakub on behalf of the Authors (05 Oct 2017) Author's response Manuscript

ED: Publish as is (06 Oct 2017) by Philip Stier

AR by Fabian Jakub on behalf of the Authors (06 Oct 2017)

Short summary

The formation of shallow cumulus cloud streets was historically attributed primarily to dynamics. Here, we focus on the interaction between radiatively induced surface heterogeneities and the resulting patterns in the flow. Our results suggest that solar radiative heating has the potential to organize clouds perpendicular to the sun's incidence angle.