the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 28 Jul 2025
Analysis of a saline dust storm from the Aralkum Desert – Part 2: Atmospheric flow precursors in the Euro-Atlantic region
Abstract. Wind-blown dust emissions from the man-made Aralkum Desert pose significant environment and human health risks across Central Asia. Yet, little is known about the atmospheric circulation patterns favoring dust outbreaks from the region. This study examines the role of upstream atmospheric blocking and recurrent transient Rossby wave packets (RWPs) in initiating a severe dust storm from the Aralkum Desert in May 2018. Results show that the dust event was triggered by an unusual early-summer cold air outbreak and attendant postfrontal northerly winds reaching 24–31 m/s. The compound cold air and dust outbreaks were preceded by repeated meridional flow amplification linked to recurrent RWPs across the North Atlantic, persistent blocking over Scandinavia, and the subsequent development of a pronounced ridge-trough couplet that facilitated cold intrusions into Kazakhstan. This study underscores the importance of Euro-Atlantic blocking systems in shaping surface weather hazards in the downstream Central Asia region.
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RC1: 'Comment on egusphere-2025-2808', Anonymous Referee #1, 21 Aug 2025
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This manuscript describes the synoptic evolution leading to a significant dust storm. However, it fails to provide a novel, rigorous, and causal analysis of the large-scale precursors. The study does not move beyond a plausible description of correlated events to deliver the promised insight into "dynamic teleconnections." The central issue is the lack of a demonstrable causal link between the identified Euro-Atlantic blocking/Rossby wave packets (RWPs) and the specific dust event in question. The analysis presents a plausible correlation but fails to establish a robust dynamical narrative, relying heavily on circumstantial evidence and subjective interpretation of standard reanalysis products. The methodological approach is insufficient to support the broad conclusions drawn. A fundamental revision would be required, involving a more sophisticated dynamical analysis to quantitatively link the upstream wave activity to the downstream response. However, given the scope of the required changes, my recommendation is to reject the current manuscript.
Specific Comments
1. Lack of Novelty and Incremental Insight:
The finding that Scandinavian blocking can lead to cold air outbreaks (CAOs) in Central Asia is well-established in the literature (e.g., Tyrlis and Hoskins, 2008; Tuel and Martius, 2024, both cited by the author). This manuscript merely applies this known mechanism to a specific case study without adding substantial new understanding. The analysis does not go significantly beyond a standard synoptic case study description using ERA5 data.
The claim of investigating "dynamic teleconnections" is overstated. The study describes a sequence of events but does not employ any diagnostic tools (e.g., potential vorticity tendency analysis, ray tracing, sensitivity experiments) to rigorously trace the energy propagation or causality from the North Atlantic RWPs to the downstream trough development in a quantifiable way.
2. Methodological Deficiencies in Establishing Causality:
The detection of recurrent RWPs using the Hovmöller-based R metric is interesting. However, the manuscript does not adequately demonstrate that these specific wave packets were responsible for the blocking onset or amplification. The statement that "RWPs may have served as precursors" is highly speculative and not backed by any causal analysis. The temporal sequence shown in Fig. 5a could easily be coincidental rather than causal.
The analysis of the warm conveyor belt (WCB) and its role is superficial. The authors point out its presence and potential importance but fail to quantify its diabatic contribution to downstream ridge building (e.g., through PV modification budgets or trajectory analysis), which is crucial for the claimed mechanism (Pfahl et al., 2015).
3. Inconsistent and Speculative Narrative:
The manuscript attempts to link too many phenomena (North Atlantic RWPs, Scandinavian blocking, a cyclone near Greenland, a WCB, wave breaking in the Barents Sea) into a single causal chain for one dust event. The narrative becomes speculative, especially when claiming that events in the North Pacific ("Recurrent transient RWPs are also observed over the North Pacific...") are part of the story without presenting any analysis to support a physical connection to the Euro-Atlantic sector or Central Asia. This weakens the focus and gives the impression of "hand-waving."
4. Questionable Framing as a "Companion Study":
The manuscript is presented as "Part 2" of a comprehensive investigation, with "Part 1" (Xi et al., 2025) focusing on satellite aerosol products. However, the two parts are entirely disconnected. There is no integration of the aerosol findings from Part 1 (e.g., the extreme AOD values, retrieval challenges) into the dynamical analysis presented here. The dust storm itself is treated only as a symptom of the meteorology, and the "saline" aspect mentioned in the title is never discussed in the context of the atmospheric dynamics. This represents a missed opportunity for a truly interdisciplinary study and makes the "companion" framing seem forced.
5. The definition of a "dusty day" based on SYNOP reports, which includes haze reports following dust within 48 hours, seems overly broad and could inflate the number of events used for the climatological comparison in Fig. 3b.
Citation: https://doi.org/10.5194/egusphere-2025-2808-RC1
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