| 15 Jan 2026
Exploring the Mechanisms of Dust Emission and Transport based on Observations and GEOS-Chem Simulations
Abstract. Dust aerosols play a significant role in climate and air quality, yet understanding of their emission and long-range transport mechanisms remains incomplete. We investigated a severe April 2025 dust event in northern China using multi-source observations and GEOS-Chem simulations, comparing it against the 30-year climatology and historical events to analyze its meteorology, emission, and transport. Results show that the dust event in April was originated in the western Inner Mongolia (WIM) source region, accompanied by wind speeds exceeding 8 m/s and hourly PM₁₀ concentrations above 1900 μg/m³, and affected the southern China including Yangtze River Basin and Hainan Province. Under the influence of the Siberian high-pressure system and the Mongolian cyclone, the WIM experienced persistent dry-cold advection. Three months preceding the dust event, the WIM exhibited high temperatures (~2 °C), reduced precipitation (~−25 mm) and low volumetric soil water (~−0.02 m³/m³). Comparison with two other severe historical dust events in year 2021 and 2023, demonstrating that long-range transport in 2025 was primarily due to strong northerly winds that effectively guided southward transport of dust aerosols. Furthermore, the dust in 2025 consistently moved southward but generally behind the rainband, which imply relatively low wet scavenging and thereby enabling stable long-range transport. The study confirms that persistent drought and strong winds triggered intense dust emission, and that airflow transport under specific synoptic conditions dominated the long-range dust transport.
General remarks:
The authors present a detailed and well-documented case study of a dust storm originating in western Inner Mongolia that affected southern regions of China, including Hainan Island. The manuscript provides a thorough analysis of the physical processes driving dust emission, wet deposition, and long-range transport, and the comparison with historical records from the past 30 years as well as two recent dust storms is informative. However, while the results are clearly presented and internally consistent, many of the findings align closely with existing understanding of dust storm behavior. As a result, the study’s broader scientific significance and novelty are somewhat limited.
The manuscript would benefit from improved conciseness. While the discussion of the physical factors controlling dust emission and transport (e.g., wind, temperature, soil moisture, and precipitation) is relevant and informative, this material is repeated in multiple sections of the paper (lines 143–154, 236–244, 247–248, 271–273, etc.). Consolidating these discussions would reduce redundancy and improve the overall flow of the manuscript.
Specific comments:
Line 87-91: Why do the authors use ERA5 instead of MERRA2 meteorological data in the analysis? It’s worth noting that the latter is the meteorological data used to drive the GEOS-Chem atmospheric chemical transport model simulations.
Figure 2: Why is the coverage of MODIS AOD so sparse in the China region? The data shown in the figure makes it difficult to distinguish between PM10 and AOD. Please change "scatter plot represents PM10 concentration" to "solid circles represent PM10 concentration".
Figures 2: Please explain that the wind speed scale is located in the upper right corner of each subplot, and explain what the small inset in the lower right corner represents.
Line 121 and Figure 3: If the PM10 and PM2.5 concentrations in the WIM region remain around 100 μg/m³ and 20 μg/m³, respectively (Figure 3), then why is the ratio of PM2.5 to PM10 0.3 instead of 0.2?
Line 122 and Figure 3: Figure 3 shows that the dust storm began in the WIM region at 10:00 on April 11th, not at 17:00 as stated in line 122. In fact, the dust storm reached its peak at 17:00 at the WIM source region.
Line 126-127: Figure 4 does not show AOD values exceeding 2 in WIM.
Line 246-249: Please delete these two sentences, as they do not provide any necessary information.
Lie 275: What does “both” refer to?
Figure 9: Please specify the geographical coverage in the caption.
Figure 10: Please specify the geographical coverage for “western Inner Mongolia” in the caption.
Line 312-314: Please rephrase this sentence.
Figure 11: Please change “scatter plots” to be “filled circles”.
Technique correction:
Figure 1: change “WIM” to “Western Inner Mongolia (WIM)” and change “western Inner Mongolia” to “WIM”.
Line 271-272: Change “to compare” to “we compare”.