the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 22 Apr 2026
Impact of large-scale atmospheric winter circulation on sea ice motion in the Arctic in 2000–2025
Abstract. This study examines the relationship between atmospheric large-scale circulation indices, twelve finer-scale circulation types, and ice drift speed at three fixed transects. The aim is to analyse the impact of atmospheric pressure patterns on ice drift. The North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Pacific-North American Pattern (PNA), and Arctic Dipole Anomaly (DA) explain about 10 % of the drift speed variations in the Beaufort Gyre (BG), Transpolar Drift Stream (TDS) and Fram Strait (FR). Self-organizing maps (SOM) analysis further reveals distinct circulation types even when large-scale circulation indices appear similar, which explains the low explanatory power of the large scale circulation indices alone. However, mean sea level pressure (MSLP) variability at optimal locations accounts for approximately 40 to 60 % of the observed drift speed variations, with sea ice thickness and thickness anomalies showing no significant improvement in explanatory power. Sea ice thickness exhibits a strong seasonal cycle and is predominantly influenced by the time of year, suggesting that its impact on drift speed may manifest over climatic timescales.
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CC1: 'Comment on egusphere-2026-1578', Lejiang Yu, 18 May 2026
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1578/egusphere-2026-1578-CC1-supplement.pdfCitation: https://doi.org/
10.5194/egusphere-2026-1578-CC1 -
RC1: 'Comment on egusphere-2026-1578', Anonymous Referee #1, 20 May 2026
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1578/egusphere-2026-1578-RC1-supplement.pdf
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RC2: 'Comment on egusphere-2026-1578', Anonymous Referee #2, 16 Jun 2026
This manuscript explores the relationship between ice motion and large circulation patterns vs regional MSLP patterns with the aim to determine which has greater influence. The findings show that the regional MSLP patterns defined through SOM analysis, accounted for more of the ice motion than the large circulation modes such as AO, NAO, PNA and DA. I found the concept of this paper interesting particularly in the finding showing that using regional MSLP patterns were more informative in ice flow studies compared to using large scale circulation indices. However, I found the message of this paper was lost. I was confused at numerous points in the paper about the inclusion of some points that I didn’t think were necessary nor added to the story and felt that the manuscript was disjointed. In particularly I feel that the main and most interesting results were not really highlighted clearly enough and that time should be taken to clean up how you describe and talk about the climate indices and regional MSLP patterns as I think that multiple terms were used for these throughout. I think these points and the ones below need to be addressed before this paper can be accepted for publication.
Wider points to be addressed:
- There are a couple of incorrect statements made I believe. Between lines 124-125 you state that Deser et al. (2000) applied rotated PA to 700 mb geopotential heights, however having checked this paper, I see no mention of this. They did apply EOF analysis to sea ice and then did a regression analysis to circulation patterns, but nowhere was 700 mb geopotential height ever mentioned. Furthermore upon checking the NOAA CPC where you got the NAO and PNA indices from, they actually apply the RPCA technique to monthly standardised 500mb heights between 20N-90N which is different to what is in this manuscript.
- The paper I find confusing at times as you move between talking about the large scale circulation patterns and MSLP patterns which I think has to do with how they are referred to, for example you mention large-scale circulation indices, then finer scale circulation types, which are also referred to as regional MSLP, Arctic atmosphere circulation types. And throughout you mention pressure patterns which further adds to confusion as the indices are related to pressure patterns. I would choose a nomenclature for each process and stick to it throughout
- I find the discussion and conclusions section confusing. It does not, in my view, follow a logical structure and feels a bit disjointed. I also feel that it does not comprehensively lay out the results and contextualise what they mean regarding using climate indices vs regional MSLP patterns to investigate ice flow.
- Proper contextualisation of where you research fills a gap is needed earlier. You place this almost at the end of the introduction when this would be much more important to state when going between the large-scale circulation indices to what you did (between lines 48-49).
- I would rethink some of the wording in the paper because I feel that you overstate that pressure gradients results in geostrophic wind that leads to ice motion as though this is a new concept, when in fact this is incredibly well known.
- As you only have ice motion data from 2000-2023 and MSLP data from 2000-2025 would it not make sense to just use the same time period for both datasets especially considering there is only two years difference. I know that you use the same time frame for the regression analysis but I would argue it would be better to stick to the same time frame throughout.
Detailed points:
L14: What do you mean by explanatory power?
L26: Changes in wind? What changes do you mean here, is this climate change related or just wind variability?
L28: In what way where the ice deformations ‘more important’ than expected, not sure why it is relevant to note this in general
L34: ‘Ice motion is essential for redistributing and exporting ice…’ I find this an odd phrasing because ice motion actually does redistribute and exports ice, the word essential here is not needed.
L49: “ the Arctic atmosphere circulation types” are these universal circulation types or what does this actually mean?
L77-78: “The results highlight the locations of ….” Not sure why you have included a result statement in your material and methods section.
L81-82: ‘and show the spatial correlation between ice motion and atmospheric pressure’ this can lead to confusion because you use ice motion data from polar pathfinder but this line makes it appear that both were from ERA5. I would remove it completely as you calculate the correlation across two different datasets.
L82: “Retrieved daily means of 1 hourly data” was this just MSLP?
L100: Where in the mid-latitudes are the centres of action for the AO?
L102: You mention the stratospheric connection of the AO but this is not talked about again anywhere in the paper so I am not sure if it is required to mention this in the paper.
L106: Do you mean you used the AO index from NOAA CPC?
L125: Do you mean you used the NAO and PNA indices from NOAA CPC, and what do you mean daily values were calculated, daily values of what?
L147: Figure X? Which figure are you referencing?
L162: What do you mean that the circulation types show increasing cyclonic activity? As this is a SOM not a temporal analysis of the circulation I am not clear what you mean by increasing?
L167: I am unclear what you mean in this following sentence “The features of the pressure fields are reflected in the average circulation index on each node”
L168: Again you referencing decreasing MSLP and I am not sure what you mean by this.
L170: “Circulation types towards the right..” Do you mean the last/right column of figure 2?
L187-188: “We observed that the ice drift speed across the transect can be over three times faster when the circulation type is favourable” is this for all three regions, do you have actual data to show this and what is meant by favourable for each of the three transects?
L223-226: This whole section currently states the ice flows faster when there is a strong pressure gradient, but this is a very obvious statement but in its current format reads as though this a surprising or new finding. I would suggest rewording.
Also left-hand side and right-hand side of what? This is used multiple times throughout the manuscript and you need to be a lot clearer about what you mean
Figure 5: How do these drift speeds compare to drift speeds under observed motion, in other words how significant is this ice motion in regards the real world, do these constitute fast ice motion speeds? Also are any of these significant?
L232-240: This section seemingly compares the figure 4a ice drift speeds to the circulations patterns in the modes in figures 1 and 2, however it is never really clear which figure (1 or 2) that I should be comparing to when you discuss the pressure patterns, please point to which specific figure you are referring to. Furthermore, I don’t see any reference to figure 5b of the MSLP gradients (in particular their actual values) and what is most interesting here is that the largest gradient in TDS doesn’t actually correlate to the largest ice flow and yet this is not really mentioned. I would either make more reference to this figure or remove.
L235-237: I was expecting more discussion about the relevance of noting the different average index values for the large-scale circulation indices either here or in the discussion, as it is interesting to note their different phases and yet fast ice motion.
L286-289: This section is confusing. You state that a pressure dipole was not necessary to drive fast flow, but what is your definition of a pressure dipole? Or are you saying that either a high or low pressure anomaly can drive fast ice flow? However, line 289 says that the pressure gradient drives the geostrophic wind which almost negates the previous point and a high/low pressure coupling is important (which is my interpretation of a pressure dipole).
L297-298: Is this line on the positive feedback loop important to note if so can you elucidate more about this statement.
L299-305: This feels more like an opening paragraph for this section especially considering you have already been discussing the nodes from the SOM.
L310: You claim that you defined the TDS as a drift pattern that brings ice towards the Fram Strait, however I am sure that this has been well defined before. Can you explain more what you mean here?
L312: You state at times the TDS was reversed and ice motion was intensive, what do you mean by intensive, have you a numeric value for this?
Citation: https://doi.org/10.5194/egusphere-2026-1578-RC2
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