Review of “The third Met Office Unified Model-JULES Regional Atmosphere and Land Configuration, RAL3”

By Bush et al. 2024

The manuscript provides a thorough and well-organized overview of the third version of the Regional Atmosphere and Land (RAL3) model developed at the UK Met Office (with partners). It highlights significant advancements from RAL2, including the incorporation of a double-moment microphysics scheme and a bi-modal cloud scheme. Additionally, the manuscript details updates to the boundary layer scheme and its integration with the land model, marking a notable improvement over previous versions.

The paper is exceptionally well-written and achieves its goal of informing the community about the advancements in RAL3 and its configurations. It is highly comprehensive, including detailed documentation of the system and its performance evaluations. However, certain details, such as repository ticket numbers, might be overly specific and could be reconsidered for brevity.

Overall, I believe the manuscript is an excellent contribution to the field and recommend its publication in its current form.

“The third Met Office Unified Model-JULES Regional Atmosphere and Land Configuration, RAL3” by Mike Bush et al. 

In this manuscript, the authors describe the release configuration and updates of the third version of the Met Office Unified Model-JULES Regional Atmosphere and Land Configuration (RAL3). One of the major advantages of RAL3 is its unified configuration over both tropical and mid-latitude domains, with significant updates in double-moment microphysics, a bi-modal cloud scheme, as well as improvements in boundary layer mixing and land surface parameterizations. The authors evaluate the performance of RAL3 across tropical and mid-latitude domains, at different spatial resolutions and temporal scales, ranging from short-range weather forecasting to numerical weather prediction (NWP) and climate simulations. The results demonstrate a major improvement in model performance and suggest that RAL3 is suitable for use in research, operational NWP, and climate applications. Readers will benefit from a deeper understanding of convection-permitting modeling for various applications. I recommend accepting this manuscript with minor revisions.

Minor Suggestions:

1. On line 6, page 4, change "inform inform" to "inform."
2. The authors claim that cloud bases and fractions have been improved across RAL3.0 and 3.3. It would be useful to add a cloud verification in Figure 9 to support this.
3. It would be helpful to include composite radar reflectivity observations in either Figure 15 or S4.