the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Dust pollution in China affected by different spatial and temporal types of El Niño
- 1Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China
- 2Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington, USA
- These authors contributed equally to this work.
- 1Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China
- 2Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington, USA
- These authors contributed equally to this work.
Abstract. Dust is an important aerosol affecting air quality in China in winter and spring that is potentially influenced by the interannual climate variability associated with El Niño. In this study, the effects of different temporal and spatial types of El Niño on dust pollution in winter and spring in China and the potential mechanisms are investigated using the Energy Exascale Earth System Model version 1 (E3SMv1). We find that the Eastern Pacific (EP) and Central Pacific (CP) El Niño both increase wintertime dust concentrations by 5–50 µg m-3 over central-eastern China. Due to a stronger wind and lower relative humidity, which favor dust emissions near sources, and a strengthened northwesterly and reduced precipitation, which are conducive to dust transport, dust concentrations during the CP El Niño are 5–20 µg m-3 higher in northern China than during the EP El Niño. El Niño with a short duration (SD) increases winter dust concentrations by 20–100 µg m-3 over northern China relative to the climatological mean, while there is a decrease of 5–50 µg m-3 during the long duration (LD) El Niño, which are also related to the El Niño-induced changes in atmospheric circulation, precipitation, and relative humidity. In the following spring season, all types of El Niño events lead to an increase in dust over the northern China, but only the increase during the LD El Niño is statistically significant, suggesting that the weaker intensity but longer duration of the LD El Niño events can significantly affect spring dust in China. Our results contribute a better understanding of the influence of different types of El Niño events on dust pollution in China, which have profound implications for air pollution control and dust storm prediction.
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Yang Yang et al.
Status: final response (author comments only)
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RC1: 'Comment on acp-2022-355', Anonymous Referee #1, 29 Jun 2022
General comments
This study analyzed the impacts of different types of El Niño on dust activities over China using E3SMv1 model simulation. The authors showed that El Niño causes changes in boreal winter (DJF) dust concentrations over China by modulating wind speed and relative humidity near the dust sources (e.g., Gobi desert). The impacts on boreal spring (MAM) dust concentrations are statistically unclear. The influences of different types of El Niño are dicussed. Overall, the paper is well organized, helpful and appropriate for publication in ACP. I may recommend publication of this manuscript after the following comments are addressed.
Specific comments
- The results might be sensitive to the model selected (i.e., E3SMv1). The authors pointed out that there are model biases in simulating dust emissions (Section 2.3). However, explanation on how these biases may affect the key results (e.g., as shown in Figure 2) is not clearly discussed. The discussion given in Section 4 might be too short. Further, is it possible to suggest that these biases are associated with the model biases in simulating humidity or near surface wind?
- I am wondering if the current model can provide the output of dust deposition and if the analysis of El Niño impacts on dust deposition is necessary.
- Line 185: It is unclear about the period of the sensitivity experiments. Why did the authors chose 13 years only? I supposed that the period of the sensitivity experiment for SD El Niño should be longer than LD El Niño, as there are more SD El Niño events (Lines 159-160).
Technical corrections
- Lines 23-24: This sentence needs to be rephrased.
- Line 26 and others: Do you mean ‘boreal winter’?
- Line 26: ‘an’ → ‘a’
- Lines 79-80: This reference (https://doi.org/10.5194/acp-22-5253-2022) might be helpful to reinforce the statement of El Niño impacts on dust actitivities. For example, the El Niño–Southern Oscillation (ENSO) shows causal impacts on dust emission over the northwestern China and wetdust deposition over the eastern China. In addition, there is ENSO impacts on dust concentrations over the southern and western China.
- Line 183: If the results are based on the ensemble mean, it should be stated clearly.
- Line 592: 98% or 90%? It is more common to use 99% or 95% significance level, instead of 98%.
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AC1: 'Reply on RC1', Yang Yang, 08 Aug 2022
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-355/acp-2022-355-AC1-supplement.pdf
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RC2: 'Comment on acp-2022-355', Anonymous Referee #2, 30 Jun 2022
Comments and suggestions
This study examines the impacts of different types of El Nino events on dust pollution in China based on an earth system model. According to the model simulation, the authors suggested that dust concentrations during the CP El Nino are much higher in northern China than during the EP El Nino. The short duration (SD) El Nino increases winter dust concentration over northern China, while there is a decrease in dust concentration during the long duration (LD) El Nino. In general, the topic of this study is interesting. However, current version of the manuscript at least needs a major revision. My comments are shown as follows.
This study examines the impacts of different types of El Nino events (EP, CP, SD, LD) on the dust concentration over China only based on one model simulation. Can the different impacts of the four types of El Nino event on the dust concentration over China can be obtained in the observations?
The obtained results of this study are only based on one model simulation. Many studies have demonstrated that impact of ENSO on extratropical atmospheric circulation and climate variation over East Asia are strongly model-dependent. It cannot confirm the robustness of the results obtained in this study only based on one model simulation.
Lines 183-184: 3 ensemble and the last 10 years are used to analysis. It should be mentioned that there exist a large internal variability over extratropics. Thus, 3 ensemble and 10 years mean cannot well remove the internal atmospheric variability.
From. Fig. 4, it shows that there exist large differences in the atmospheric anomalies over East Asia related to the four types of El Nino. First, what are the mechanisms for the formations of the atmospheric anomalies induced by the different types of El Nino. Second, what are the factors for the differences of atmospheric anomalies generated by EP and CP El Nino (SD and LD El Nino)?
Lines 218-222: From Fig. 2c, the difference of dust concentrations over central-eastern China are weak and statistically insignificant. Hence, you cannot conclude that dust concentrations increase more significantly over central-eastern China. In addition, actually, from Fig. 2, differences in the dust concentrations between CP and EP are mostly insignificant in China. The related conclusions you mentioned are incorrect.
Lines 276-285: A comparison of Fig. 5 and Fig. 4 indicate that the simulated atmospheric circulation anomalies over East Asia show notably different with those in the observations. How can you say they are similar? In addition, the variables shown in Fig. 5 should be similar to those shown in Fig. 4. For example, SLP anomalies should be shown. In addition, the composites for the SD and LD El Nino events should also be shown in Fig. 5.
Minors:
Line 81: the under-->delete the
Lines 139-140: Nino3.4 SST index is defined as area-mean SST anomalies in the Nino3.4 region.
Definition of the EP and CP events: You should note that there also exist mixed El Nino event.
The years of CP, EP, SD and LD El Nino events should be shown in a Table.
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AC2: 'Reply on RC2', Yang Yang, 08 Aug 2022
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-355/acp-2022-355-AC2-supplement.pdf
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AC2: 'Reply on RC2', Yang Yang, 08 Aug 2022
Yang Yang et al.
Yang Yang et al.
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