the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
The crucial representation of deep convection for the cyclogenesis of medicane Ianos
Abstract. The paper presents a model intercomparison study to improve the prediction and understanding of Mediterranean cyclone dynamics. It is based on a collective effort with five mesoscale models to look for a robust response among ten numerical frameworks used in the community involved in the networking activity of the EU COST Action "MedCyclones". The obtained multi-model, multi-physics ensemble is applied to the high-impact medicane Ianos of September 2020 with focus on the cyclogenesis phase, which was poorly forecast by numerical weather prediction systems. Models systematically perform better when initialised from operational IFS analysis data compared to the widely used ERA5 reanalysis. Reducing horizontal grid spacing from 10 km with parameterised convection to convection-permitting 2 km further improves the cyclone track and intensity. This highlights the critical role of deep convection during the early development stage. Higher resolution enhances convective activity, which improves the phasing of the cyclone with an upper-level jet and its subsequent intensification and evolution. This upscale impact of convection matches a conceptual model of upscale error growth in the midlatitudes, while it emphasises the crucial interplay between convective and baroclinic processes during medicane cyclogenesis. The ten numerical frameworks show robust agreement but also reveal model specifics that should be taken into consideration, such as the need for a parameterization of deep convection even at 2 km horizontal grid spacing in some models. While they require generalisation to other cases of Mediterranean cyclones, the results provide guidance for the next generation of global convection-permitting models in weather and climate.
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Status: open (until 18 Jun 2024)
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RC1: 'Comment on egusphere-2024-1105', Anonymous Referee #1, 25 May 2024
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The present manuscript provides a comprehensive overview of the intensification and convection formation of Medicane Ianos using different limited area models. While there are many articles related to Medicane Ianos, the reviewer recognizes that this manuscript represents a thorough investigation of the most important factors that could affect the formation and intensification of the medicane, including initial data, resolution, and initial time, with significant scientific collaboration.
The manuscript is very well written. Despite the complexity of the research, which involves numerous models and sensitivity experiments, the authors have managed to condense the information in the figures and text in a way that flows smoothly and is easy for readers to follow.
I believe the document should be published, with only a few minor comments that the authors should review or clarify. Otherwise, the document is excellent in its current state.
MINOR COMMENTS:
- Line 190 (page 7): In the sentence "Additional simulations were initialized at 00 UTC on 14 September but are not shown, because they generally did not develop a cyclone," you use the word "generally," which does not imply "all." Does this mean that at least one model configuration developed a cyclone at 00 UTC on the 14th? If so, it would be good to be more specific, because if at least one model did develop a cyclone at that time, it would be worth describing here, as I don´t know any previous scientific paper that showed that in the past.
- Line 200 (page 7): Is there any database with estimated intensity based on different types of observations?
- Lines 323 - 325 (page 11): Here, you might consider discussing that explicit convection with deep convection parametrization switched OFF may result in overly strong cyclones and excessive precipitation in some cases. Additionally, you could mention that the ocean-atmosphere interaction in the model could help mitigate this negative effect.
- Figure 4: The legends in the figure captions should be described more thoroughly. While they are clear when reading the article, they are not immediately clear just from the figure caption.
Citation: https://doi.org/10.5194/egusphere-2024-1105-RC1
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