Preprints
https://doi.org/10.5194/egusphere-2025-3157
https://doi.org/10.5194/egusphere-2025-3157
10 Oct 2025
 | 10 Oct 2025
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Spatial-scale dependence of aerosol indirect effects over land in eastern China: A comparative analysis

Yuqin Liu, Tao Lin, Jiahua Zhang, Fu Wang, Meixia Lin, Yuan Chen, Yiyi Huang, Hongkai Geng, Xin Cao, and Gerrit de Leeuw

Abstract. Regulatory effects of liquid water path (LWP) on cloud droplet effective radius (CER) and the interaction between aerosol optical depth (AOD) and cloud properties were systematically investigated. MODIS and CALIOP observed aerosols and clouds over eastern China in two periods: 2008–2014 (period 1) and 2015–2022 (period 2). The results show two distinct regimes of the variation of CER with LWP: a rapid growth regime (LWP < 55/50 g/m²) and a decreasing regime (LWP = 55–135/50–100 g/m²) (thresholds vary by period). The sensitivity of CER to AOD (SCER) shows a negative correlation, and the SCER in the LWP regime 2 shows larger than that in LWP regime 1. Here, the spatial scale is described by buffer size and study area. Overall, |SCER| decreases with increasing spatial scale. The optimal buffer sizes show notable variations in the range from 6°×6° to 10°×10°: increasing as study areas increase in period 2, but decreasing in period 1 for LWP regime 2. Compared with period 1, |SCER| in period 2 exhibits significantly decreases, reflecting the weaker of aerosol-cloud interactions for declining aerosol concentrations. Additionally, the sensitivity of Nd (cloud droplet number concentration) to AOD (SNd) shows a positive correlation, with SNd decreases as spatial scale increases. The optimal buffer sizes show larger in the 8°×8° and 10°×10° regions than that in the 4°×4° and 6°×6° areas. This study reveals the scale-dependence of aerosol-cloud interactions.

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Yuqin Liu, Tao Lin, Jiahua Zhang, Fu Wang, Meixia Lin, Yuan Chen, Yiyi Huang, Hongkai Geng, Xin Cao, and Gerrit de Leeuw

Status: open (until 21 Nov 2025)

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Yuqin Liu, Tao Lin, Jiahua Zhang, Fu Wang, Meixia Lin, Yuan Chen, Yiyi Huang, Hongkai Geng, Xin Cao, and Gerrit de Leeuw
Yuqin Liu, Tao Lin, Jiahua Zhang, Fu Wang, Meixia Lin, Yuan Chen, Yiyi Huang, Hongkai Geng, Xin Cao, and Gerrit de Leeuw
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Latest update: 10 Oct 2025
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Short summary
This study reveals how air pollution affects cloud properties in eastern China using satellite data from 2008–2022. We find CER/LWP relationship exhibits three phases, modulated by aerosol concentration. The Twomey effect is confirmed, and its sensitivity shows significant spatial-scale dependence. Surprisingly, cleaner air after 2015 make clouds less sensitive to pollution's effects. The optimal buffer sizes show notable variations for the study area in the range from 6°×6° to 10°×10°.
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