Modeling CMAQ dry deposition treatment over Western Pacific: A distinct characteristic of mineral dust and anthropogenic aerosol

Abstract. Dry deposition plays a vital role in the aerosol removal process from the atmosphere. However, the chemical transport model (CTM) is sensitive to the dry deposition parameterization and yet remains to be determined due to the limited particle deposition measurement. By utilizing the CMAQv5.4 with the refined dust emission treatment (Kong et al., 2024), the East Asian dust (EAD) simulation during January 2023 was constructed to evaluate the performance of dry deposition parameterizations developed by PR11 (Pleim and Ran, 2011), E20 (Emerson et al., 2020), S22 (Shu et al., 2022) and P20 (Pleim et al., 2022), respectively. The result showed that the dry deposition parameterization could significantly improve the CMAQ dust emission treatment. By implementing the E20 dry deposition scheme, the CMAQ simulation performance of the surface PM₁₀ has been considerably improved with the NMB of -41.9 %, as compared to the dry deposition proposed by PR11 (54.05 %), S22 (-47.01 %) and P22 (-53.90 %). The modeled PM₁₀ pattern by E20 at the upper level (700 hPa) was mostly consistent with the observed PM₁₀ at the Lulin Atmospheric Background Station (LABS; 23.47° N, 120.87° E; 2862 m a.s.l.) where is a typical background site at Western Pacific, particularly in capturing the peak value. The high-altitude correlations (R) were well performed for E20 by 0.55, as compared to PR11 (0.47), S22 (0.54) and P22 (0.46). Moreover, E20 improved the simulated aerosol optical depth (AOD) value during the multiple dust storm in spring 2021. The noticeable reduction of the coarse mode particle's deposition velocity (V_d­) was responsible for resolving the PM₁₀ simulation underestimation. Moreover, the significant improvement of PM₁₀ was also shown by the modeled PM_2.5 On 22–31 January 2023, the in-situ measurement of the upper level observed the possibility of natural dust and anthropogenic aerosol. This is consistent with the CMAQ, which shows that both aerosol types displayed a clear "long dust-black carbon belt" along the 15°N. We proposed implementing the E20 dry deposition approach, resolving the uncertainty of the CMAQ dust emission treatment.