Improved WRF‐Chem Simulations of Dust Deposition and Its Association With Observed Chlorophyll‐a Concentration During the 2021 East Asian Super Dust Storm

Abstract Frequent dust storms in spring not only affect air quality and climate change, but also influence marine productivity through dust transport and deposition in High‐Nutrient, Low‐Chlorophyll (HNLC) regions. However, there is still considerable uncertainty regarding how dust quantitatively affects the growth of phytoplankton. This study refined the surface erodibility factor in the WRF‐Chem (Weather Research and Forecasting model coupled with Chemistry) model, improving the simulation accuracy of dust emission, transport and deposition. Using this improved model and satellite observations, we investigated the relationship between dust deposition and chlorophyll‐a (Chl‐a) concentration in the Northwest Pacific following the 2021 East Asian super dust storm. Results showed that the super dust storm increased dust deposition flux in the ROI (Region of Interest) by 66.67% (0.15 μg m −2 s −1 ) compared with the historical average for 11 March–9 April during 2011–2020. Correspondingly, Chl‐a concentration increased by 25.71% (0.88 mg m −3 ) and exhibited a clear temporal lag after dust deposition. Variations in the FLH/Chl‐a (fluorescence line height per unit Chl‐a) ratio suggested enhanced phytoplankton physiological activity after the dust deposition. Meanwhile, relatively high SST (sea surface temperature) and PAR (photosynthetically active radiation), together with shallower MLD (mixed layer depth) conditions, may also have provided favorable environmental conditions for phytoplankton growth. These results suggest that the Chl‐a concentration enhancement was likely associated with the combined effects of dust deposition and marine environmental factors. This study provides an effective approach for improving dust simulations and advances the understanding of how atmospheric dust deposition affects marine ecosystems.