the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 18 Jun 2025
Assessment and prediction of dust emissions, deposition and radiation forcing in Central Asia
Abstract. Dust aerosols regulate Earth's climate through radiative and cloud interactions. This study combines MERRA-2 reanalysis with CMIP6 models to quantify Central Asian dust-climate interactions (1980–2100). Four SSP scenarios reveal: 1) Three emission hotspots (Tarim Basin, Aral Sea, Gobi Desert; >15 μg·m⁻²·s⁻¹) with expanding deposition zones (>8 μg·m⁻²·s⁻¹); 2) Strong climate policy sensitivity, with SSP5-8.5 driving 94.9 % emission increases by 2100 versus 4.5 % fluctuations under SSP1-2.6; 3) SBDART-modeled vertical radiative dichotomy: top-of-atmosphere cooling (Caspian TOA < −10 W/m²) contrasts with spring atmospheric heating (+10.02 W/m²), inducing surface shortwave loss (−20 W/m²); 4) Site-specific heating extremes – Kashgar's spring radiative forcing peaks at 92.99 W/m² with 2.61 K/day heating, while Issyk-Kul shows autumn dominance (0.34 vs 0.08 K/day spring). The "three-source high-emission-sedimentation-expansion" pattern demonstrates dust transport dynamics, where 83 % of emitted particulates undergo trans-regional redistribution. Policy-driven emission variances highlight decarbonization's dust suppression potential (R²=0.89 between CO2 forcing and dust flux). Radiative forcing vertical gradients explain 76 % of observed surface cooling variance through atmospheric energy reallocation. Seasonal heating asymmetries (4.25× inter-site differences) are mechanistically linked to terrain-circulation coupling, particularly the Pamir-Tian Shan vortex modulation. This multi-scale analysis establishes new constraints for arid-region aerosol-climate modeling, emphasizing the necessity of incorporating policy-sensitive dust parametrizations in next-generation Earth system models.
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2025-965', Anonymous Referee #1, 15 Sep 2025
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RC2: 'Comment on egusphere-2025-965', Anonymous Referee #2, 15 Sep 2025
General Comments
This manuscript addresses the evolution of dust emissions, deposition, and radiative forcing in Central Asia using MERRA-2 reanalysis, CMIP6 multi-model ensembles, ground-based observations. The region is a globally significant dust source, and the authors’ attempt to analyze its emission-deposition-radiation chain provides a valuable regional perspective on the dust life cycle. The manuscript is generally well-structured and provides useful regional insights, but the analysis and discussion should be deepened to meet ACP’s standards of scientific rigor and novelty.
Major Comments
- The claim of presenting the first “closed-loop emission-deposition-radiation analysis” should be moderated. Several previous studies (e.g., Kok et al., 2023; Zhao et al., 2022, 2023, 2024) have examined the dust life cycle, particularly at the global scale. While the proposed “closed-loop” framework is conceptually interesting, its interpretation and scientific depth remain somewhat superficial. A more detailed discussion of how this framework advances understanding beyond prior studies would strengthen the contribution of the manuscript.
- The manuscript presents ensemble mean maps and time series for future projections, but the inter-model spread is not shown or sufficiently discussed. Given the known diversity in dust emission schemes and particle size assumptions across CMIP6 models, the robustness of the results cannot be fully assessed from the ensemble mean alone. For example, the large differences in emission trajectories between the Aral Sea and Tarim Basin under SSP585 may depend heavily on the dust emission parameterizations of specific models. To strengthen confidence in the findings, it would be helpful to include an explicit representation of the inter-model spread and a more thorough discussion of how much weight should be placed on the ensemble mean versus the range of individual model outcomes.
- The SARIMA analysis is an interesting addition, but its role in the manuscript is unclear. The projected period (2024-2029) is short compared to the centennial-scale projections in CMIP6, and it is unclear how these two approaches complement each other. The authors should clarify the purpose: Is SARIMA intended as an operational tool (e.g. for regional dust risk management) or as a methodological complement to CMIP6? Without clearer framing, this analysis risks looking tangential.
Minor comments
- Please specify the units for all figures.
- Be cautious when using the term “significant” throughout the manuscript. If you intend to use it in a statistical sense, please provide the corresponding statistical values.
- It appears that the authors presented absolute dust emissions and deposition under the SSP scenarios rather than changes relative to the historical period, even though the figure captions describe them as showing changes (Figures 3,5, and Supplementary Figures 7-8). To better highlight the increasing or decreasing trends, I recommend revising these figures to show relative changes compared to the historical baseline.
- Figure 1: Abbreviations such as Kaz, Uzb, etc. should be written in full or explained in the figure caption. In addition, since you refer to multiple sites later in the manuscript, I also suggest specifying their names here (e.g., Dushanbe, Issyk-Kul, Jinghe). This will help readers clearly understand where the stations are located.
- Line 233: “The reanalysis data agrees with the MME simulations, with the Taylor skill score (SS) close to 1.” I recommend clarifying the exact value of the Taylor skill score rather than the qualitative description. Providing the precise number will improve the rigor and transparency of the results.
- Line 268: “In contrast, the Tarim Basin experienced a long-term decrease in emissions…”. The decreasing trend is not clearly visible.
- Line 274: “a gradual decreasing trend” — same comment as above.
- Line 286: I don’t think they are “in good agreement”. The maps appear different both spatially and in magnitude. Could you provide a quantitative measure of similarity (e.g., Taylor skill score) to support this?
- Line 312-317: In my view, the Supplementary Figures 7-8 do not clearly support your argument. Regardless of the future scenario and time ranges, they appear very similar. Since they present absolute values rather than changes relative to the historical period, I recommend revising them to show relative differences so that the trends are more clearly visible.
- Line357-360: A more detailed explanation of the seasonal characteristics of dust would be helpful.
- Line 381: The radiative forcing you used is ATM. Please specify this clearly so readers understand that it is not TOA or SFC. In addition, it would be helpful to briefly explain why ATM was chosen here, so readers can better understand the rationale behind this choice.
Technical corrections
- Line 86: “long-term trend of the shortwave radiation forcing (ADRF)”. The meaning of ADRF is not clearly conveyed here. I suggest writing out the full name of ADRF explicitly.
- Line 151: “The selection criteria include key variables of the dust cycle: monthly mean dust emission fields and dry/wet deposition fluxes”. Since you have used variable names in your figures (e.g., Figures. 2, 4, 6…), I recommend also specifying the variable names here for consistency and clarity.
- Line 305: Do you mean Supplementary Figures 7-8? Supplementary Figure 5-6 only shows the historical period, not the future.
- Line345: Do you mean northern (a-c) and southern (d-f) Xinjiang? Please clarify.
- Figure 9: Panels (a) through (j) should be clearly explained in the caption.
- Line 439: The wording is contradictory. “increased”, a negative rate (-0.3), and “declining trend” conflict with one another. If the flux is decreasing, it should be described as a decrease at that rate.
Citation: https://doi.org/10.5194/egusphere-2025-965-RC2 -
CC1: 'Comment on egusphere-2025-965', Dipesh Rupakheti, 21 Sep 2025
As a researcher who has studied aerosol properties and modification in aerosol optical and physical properties (during heavy aerosol events) based on the AERONET dataset in central Asia (please see the paper list at the end), this paper attracted my attention. I read the paper with full consideration. I have provided some general suggestions to consider.
- I support the comments/suggestions provided by two esteemed reviewers. Addressing those will definitely enhance the quality of this manuscript.
- The graphical abstract reads crowded. Needs revision.
- First-time used abbreviations must be expanded.
- L71: This sentence reads incomplete; revise.
- L109: heliometers or sun-photometers?
- Section 2.2.1: Here, the authors need to mention the station from where the AERONET/SONET data were used. Include the data access link.
- Figure 6 is difficult to understand (overcrowded). Same for Figure 9.
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Some of our works based on aerosol loading in Central Asia:
- Rupakheti, , Rupakheti, M., Rai, M., Yu, X., Yin, X., Kang, S., Orozaliev, M. D., Sinyakov, V. P., Abdullaev, S. F., Sulaymon, I. D., Hu, J.: Characterization of columnar aerosol over a background site in Central Asia. Environmental Pollution, 316 (120501): 1-10, 2023.
- Rupakheti, D., Rupakheti, M., Yin, X., Hofer, J., Rai, M., Hu, Y., Abdullaev, S. F., Kang, S.: Modifications in aerosol physical, optical and radiative properties during heavy aerosol events over Dushanbe, Central Asia. Geoscience Frontiers, 12 (101251): 1-14, 2021
- Rupakheti, , Rupakheti, M., Abdullaev, S. F., Yin, X., Kang, S.: Columnar aerosol properties and radiative effects over Dushanbe, Tajikistan in Central Asia. Environmental Pollution, 265 B (114872): 1-12, 2020.
- Rupakheti, , S. Kang, M. Bilal, J. Gong, X. Xia, Z. Cong.: Aerosol optical depth climatology over Central Asian countries based on Aqua-MODIS Collection 6.1 data: Aerosol variations and sources. Atmospheric Environment, 207: 205-214, 2019.
- Rupakheti, D., Yin, X., Rupakheti, M., Zhang, Q., Li, P., Rai, M., & Kang, S.: Spatio-temporal characteristics of air pollutants over Xinjiang, northwestern China. Environmental Pollution, 268 A (115907): 1-11, 2021.
Citation: https://doi.org/10.5194/egusphere-2025-965-CC1
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- 1
This manuscript addresses an important topic, the dust emission, deposition, and radiative forcing over Central Asia, using MERRA-2 reanalysis, CMIP6 multi-model ensemble simulations, and radiative transfer/statistical modeling. This manuscript provides long-term historical analysis and future projections under different SSP scenarios, as well as an integration with ground-based observations. This study contributes to understanding dust-climate interactions in a data-scarce but climatically important region. While the study is potentially valuable, several issues need to be addressed before publication.
Major comments:
1. Figures and readability:
Some figures are difficult to interpret without clear legends and labels. For instance the unit in figure 6 caption: μg-m-2-s-1, the superscripts should be typeset properly. I recommend change the font size for figures.
Please proofread the whole manuscript. There are occasional grammar issues and awkward phrasing. Most of them do not substantially impede understanding, though some do affect the clarity.
2. Clarity in presentation of novelty:
This study uses a combination of MERRA-2, CMIP6, and SBDART, but it is not very clear what is genuinely new compared to previous dust studies over Central Asia. The authors should clarify what exactly is new in this work and how this advances beyond previous studies.
3. Interpretation of radiative effects:
The results show strong vertical gradients in radiative forcing and surface cooling. However, the physical interpretation in the manuscript is limited. For instance, what are the implications for regional climate? More discussion regarding the broader implication would be beneficial.
Technical comments: