| 16 Feb 2026
Remote sensing of local-dust across the Canadian Arctic
Abstract. We investigated the optical and microphysical characterization of High- and sub-Arctic dust events across the Canadian Arctic Archipelago (CAA). Events from local sources (local dust) were first identified and characterized using a combination of ground-based lidar, two AERONET instruments, and passive (MODIS, Sentinel-2, MISR) imagery in the neighbourhood of the High-Arctic Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Nunavut (on Ellesmere Island in the northernmost part of the CAA).
The PEARL findings informed the identification and characterization of local dust events over other parts of the CAA using a suite of satellite instruments whose remote sensing (RS) capabilities were complementary to or an extension of the ground- and satellite-based techniques employed at Eureka. The events included plumes emanating from Axel Heiberg Island, just west of Ellesmere Island, Banks Island in the southwest corner of the CAA, Ellef Ringnes Island in the eastern part of the central CAA and Prince of Wales Island / Victoria Island in the central southern CAA. Plume identification, plume source and CM (coarse mode) aerosol optical depth (AOD) retrievals were investigated using a combination of low to high spatial resolution (MODIS to Sentinel-2) color imagery and the MODIS dark target AOD product over water. Plume thickness, height and speed for most of the events were obtained (depending on orbit availability and lack of cloud contamination) from MISR (Multi-angle Imaging Spectro Radiometer) stereoscopic products.
These RS results support an argument for the ubiquitous presence of pan-Arctic, low altitude dust that is typically (away from any strong sources such as mountainous drainage basins) at the lower levels of detectability offered by ground- and satellite-based RS techniques. The ability to RS airborne, near-source, local dust events and characterize dust properties and dynamics of important regions such as the CAA is critical to understanding local dust impacts such as early snow/ice melt and the nucleation role of local dust in the formation of low-altitude clouds.
I recommend publication after minor revisions -- specifically, the addition of certain caveats. Here is my full review:
This paper applies a collection of in situ and remote sensing observations to characterize the properties of seven dust events in the Canadian Arctic Archipelago. Surface data focuses on instruments at Eureka: the CIMEL, from which AERONET retrieval products were obtained, the Arctic HSRL, and an APS. Satellite remote sensing data include MODIS, MISR, and Sentinel-2 imagery, aerosol optical depth mapping, and from MISR, also plume heights. Wind data are obtained from MISR and from Reanalysis. The authors have built a cottage industry in studying dust in the Arctic, which is an important topic, as summarized in the paper’s introduction section; this paper aims to provide a useful addition to that literature.
A lot of careful work has gone into analyzing the seven cases presented. The value in this work is that it demonstrates techniques that could to some extent be applied more widely around the Arctic based on remote sensing data alone. Such wider application would be part of follow-on work, which is why the current paper is appropriate for AMT, as the authors indicate. The authors make a considerable effort to justify the interpretation of satellite remote-sensing signals in the seven cases as due to local dust events, and they are each quite convincing, despite very low AOD values. I note that most passive satellite remote-sensing observations in the Arctic remain extremely difficult to interpret. My primary recommendation is that in the Abstract and especially in the Conclusions, caveats might be provided that make clear the seven cases presented here are all distinct, narrow plumes, at least partly over dark water, downwind of likely dust sources, under contemporaneous high-wind conditions, and that interpreting MODIS and MISR data as indicating local dust plumes more generally must be done with similar care. Some further notes are included below.
Notes
Lines 182-184. As this study uses primarily MODIS DT over water, in interpreting the FMF product, one needs to consider that sea spray can also be a “coarse mode” aerosol, especially in the vicinity of the high-wind events that can also be effective in mobilizing local dust. This is not a concern in the seven cases highlighted in the current paper, but caution would be needed when applying the approach more generally.
Figure 2. In itself, this is a tough measurement. All the AODs are below 0.01. I understand that the authors have done a convincing job assembling other indications that this is a dust event. However, I have to ask whether variability in the background AOD produces similar fluctuations in general, especially if the intent is to subsequently apply this technique more widely, specifically in cases lacking the distinct, narrow plumes over dark water surfaces, downwind of regions with the characteristics of likely dust sources represented by the seven cases studied in detail here.
Lines 285-288. I know it is given in the publication cited in the footnote, but this estimate of MOIDS sensitivity to AOD seems *extremely* optimistic, especially when applied in the Arctic. Consider the further, extenuating conditions at high latitudes – low sun angle, very bright snow or ice-covered surfaces that can affect the recorded signal in nearby dark-water areas due to latency, internal reflections, or other instrumental effects, and possible thin cirrus contamination. I guess, for wider application of the approach, it would strengthen the case to show that, in non-dust circumstances (based on verifiable surface measurements where available), such remote-sensing signals are unlikely to occur. I.e., characterize as much as possible the likelihood of false positives.
Figure 4. Another thought, given the challenges involved in applying this technique more widely. Conditions for mobilizing dust would include sufficiently high wind (which is considered for the cases included in the paper), the availability upwind of loose surface dust that is not snow-, ice-, or vegetation-covered (also considered in the paper for the case studies), and usually some surface roughness to mix momentum downward. At least some locations of surface dust deposits have already been mapped across the Arctic, based on the identification of dry river deposits, mountain talus accumulations, etc. in seasons when those surfaces are snow- and ice-free. The exposure of such upwind surfaces at the specific time of dust-plume observation could be verified with contemporaneous satellite imagery. These considerations would be especially important when interpreting possible remote-sensing local dust-plume detections in general, in the absence of ground-truth data. (I agree that the seven specific cases presented in the current paper are convincing.)
Page 18, footnote 34. I’m not sure what “…neither the plume height nor the plume speed sampling trajectories are subject to any objective sampling protocol…” means. As I understand, the MISR MINX retrievals are done on all 1 km pixels within a user-defined aerosol plume region where the spatial contrast relative to surrounding pixels in the multi-angle images is sufficiently above the noise to produce a geometric height retrieval.
Generally, it would be helpful to have a more complete list of Symbols and Abbreviations. I know there is a list in Appendix B, but many are missing, such as, tco, tcp, tcl, VDR, etc. It is a long article, and there are many non-standard abbreviations; searching for the meaning of some abbreviation becomes tedious.