| 20 May 2026
Isolating the influence of aerosols on Arctic cloud radiative effects during a polluted warm air mass intrusion
Abstract. Arctic warm air mass intrusions are key to the region's energy balance because they transport large amounts of heat and moisture from lower latitudes. The resulting changes in heat and moisture content influences cloud properties, the thermodynamic structure of the boundary layer, and surface radiation. Warm air mass intrusions can also carry significant amounts of aerosols into the Arctic, including aerosols from anthropogenic sources at lower latitudes, which could influence the radiative impacts of such events. In this study, we examine the role of aerosol transport during a warm air mass intrusion that occurred in the central Arctic in April 2020. We use a version of the regional chemistry-climate model WRF-Chem adapted for Arctic conditions (WRF-Chem-Polar), to investigate the radiative impact of aerosol-cloud interactions associated with the event. We isolate the effects of the high aerosol burden by running the model with and without anthropogenic emissions. Anthropogenic emissions increase cloud droplet number concentration by 117% and liquid water content by 52%. However, the net surface radiative impact of these aerosol-cloud interactions is limited over sea ice. The high albedo of the underlying sea ice limits shortwave cloud cooling, while the longwave effects of cloud perturbations are small. Over open ocean regions, the surface radiative impacts of the aerosols are stronger. Overall, these results show that the net effect of an extreme aerosol transport event is sensitive to the season in which the event takes place, due to strong dependence on the surface state and the background Arctic haze conditions.
Review for: ‘Isolating the influence of aerosols on Arctic cloud radiative effects during a polluted warm air mass intrusion’ by Price et al. 2026
Price et al. have presented a modelling case study of a warm air mass intrusion observed in the Arctic by the MOSAiC campaign. They have performed simulations with and without anthropogenic pollution to investigate the role of aerosol transport within these warm air mass intrusions into the Arctic. They find that the aerosol do have an impact on the cloud droplet number and liquid water, but the effects on the radiative balance are limited, in part due to the sea ice state. The article is well written and provides an interesting insight into how human activity further impacts the Arctic, which provides important context for the region in a changing climate. All my comments are minor, and once addressed I recommend publication of this article.
Minor comments:
Line 12: I fully appreciate that the seasonality of the sea ice state makes this a reasonable conclusion, but I would rephrase this as a ‘suggestion’ or ‘implication’ rather than a proven result.
Line 24: Add ‘WAI’ between ‘Arctic events’ to be specific.
Line 25: Every year has a sea ice minima, so I would rephrase this to say ‘years in which the sea ice is below average’ or something along those lines.
Figure 1 Caption: Could you make the domain boundary lines a different colour/style to the inset boundary line, as when I first looked at the plot (and read the caption) I thought there might have been a nested model domain shown by the inset. Also could you make the inset smaller in area, as it is pretty hard to see the ship track/time because it is very small within the domain.
Line 94: Is it necessary to take the 9 nearest grid points when your resolution is 100km? I guess you are doing it to provide a level of uncertainty, but at that resolution you could easily be taking in other unrelated airmasses? Could this by why you did not see much impact from your aerosol changes? Did you compare the 9 grid mean to the nearest grid, or an interpolated point location?
Figure 2: Could you overlay the MSLP to give an idea of the synoptic settings that transported the pollution?
Line 105: Did Dada et al. do back trajectory analysis? Could you show it too? (adding the MSLP would give similar info though – so I understand if not).
Line 114: Do you have any ideas as to why the model overestimated in the earlier period? Is it a different airmass with different aerosol sources?
Line 167: I would clarify that only the Thompson results are described above/in Figure 4. I first read this to assume that the differences between the Thompson/Morrison were described above/in Figure 4.
Section 3.3: I was a little bit confused here. My understanding of the Morrison microphysics (and I assume the Thompson) is that it just handles the cloud microphysics and not aerosol microphysics (e.g. sources, growth, which is handled by MOSAIC). So why are there differences in the aerosol between the two microphysical schemes? Is it because of wet deposition? Do these schemes handle detrainment of aerosol when clouds evaporate? Or is the Morrison microphys not coupled to an aerosol scheme (if so you should state as that would not really be a fair comparison)?
Section 3.3/Figure 4/Figure A1: Could you not just put the Morrison results onto the same Figure so we can directly compare? I would make it a lot easier to see/reduce your figure count.
Line 219: add ‘during the warm air intrusion event’ at the end of sentence here to be specific.
Line 249: Where you say the ‘surface radiative impacts…. strongly dictated by seasonal conditions…’ I think you need to need to say ‘are likely’ as your study does not show that exactly. You also say ‘and background aerosols’. Do you mean the seasonality of background aerosol here too? I was thinking about that – if there is no sea ice, then there might be more sea spray/sulfate aerosol - so that would also change the background state and might also change your results?
My other thought here: Do warm air intrusions occur though the warmer months too (sorry – I am a bit ignorant about Arctic meteorology!)? If they don’t then the seasonality of sea ice doesn’t matter as much?
Figure A2: it seems the violin plots for the CDN background conditions are missing.