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Aerosol variability is influenced by changes in emissions and atmospheric dynamics. The aim of this study is to identify the role of synoptic weather systems in affecting the aerosol variation over East Asia under future changes in atmospheric dynamics. First we investigate the influence of synoptic weather on aerosol optical depth (AOD) spatiotemporal variability using long-term observations from Moderate Resolution Imaging Spectroradiometer (MODIS). We demonstrate that the major synoptic weather patterns of each season are among the dominant factors that affect AOD variations. During spring and autumn, AOD variability is significantly influenced by dynamic transport under northeasterly (winter monsoon) or southwesterly (summer monsoon) conditions. In summer, the maximum anomaly of the AOD variability was associated with the occurrence of fronts and tropical cyclones near Taiwan. While in winter, cold surge was the major event controlling the AOD variability. As atmospheric dynamics are well connected with AOD interannual variability, the AOD predictability over East Asia is associated with the predictability of synoptic weather systems. We apply the high-resolution atmospheric model (HiRAM) to identify these weather systems in present climate and under future warming scenarios. Under future climate based on HiRAM, the occurrence of summer tropical cyclones decreases by 32%, and the autumn southwesterly pattern increases by 50%. Considering the frequency change in summer tropical cyclones and autumn southwestlies under future scenarios, this may lead to the accumulation of AOD over China during summer and autumn through dynamic transport. The results suggest that AOD variations in East Asia may change along with future changes in the large-scale circulation under global warming. • Transport under monsoons notably altered aerosol variability in spring and fall. • In summer, AOD variability was highly linked to fronts and cyclones near Taiwan. • Cold surge was the major event controlling the aerosol variability in winter. • The future change in event frequency may lead to aerosol accumulation over China. [ABSTRACT FROM AUTHOR]

In East Asia, rice is a key crop that is subject to significant insect driven crop damage often leading to wide scale reliance on insecticides. We assessed the effects of releasing conditions (including density, frequency and distribution points) of a parastic wasp (i.e., Trichogramma japonicum) on the control efficacy it provided against two rice pest herbivores (i.e., Chilo suppressalis and Cnaphalocrocis medinalis). Optimal control was achieved by three releases of 150,000 wasps per hectare across 75 release points within a hectare rice field. A following 2-year large-scale field experiment demonstrated that the release of parasitic wasps allowed a 60.0 % reduction in insecticide use when compared to the insecticide treatment alone. Importantly, there was also a 3.7 % increase in pest control, 2.5 % increase in rice yield, and an overall 4.5 % increase in net economic benefit when the release of parasitic wasps was combined with insecticide application. This was an improvement on the use of either parasitic wasps alone or insecticide application alone. Release of parasitic wasps had co-benefits for other invertebrate predators whose abundance was increased by 65.8 % relative to the insecticide only treatment, however, this fell to a 26.4 % increase when parasitic wasps release was combined with insecticide use. Additionally, the combined treatment group of parasitic wasps and insecticides exhibited the highest net economic benefit (40488.9±593.2 Chinese Yuan (CNY) ha−1), significantly surpassing both the parasitic wasps-only treatment by 8.9 % and the treatment of no parasitic wasps and no insecticide by 21.8 %. These findings suggest that parasitic wasps releasing is a feasible approach to ecological engineering to promote multiple ecosystem services linked to greater crop yield in agroecosystems. • Trichogramma japonicum wasps are natural enemies of rice pests. • An optimal strategy for releasing T. japonicum in eastern China is proposed. • T. japonicum and insecticide use maximizes pest control. • This increases yields leading to economic benefits. • T. japonicum without insecticide benefits other natural enemies. [ABSTRACT FROM AUTHOR]

As a highly urbanized city in East Asia, Hong Kong has faced severe photochemical ozone (O 3) pollution for years. A comprehensive understanding of pollution characteristics is crucial for effective mitigation of the O 3 problem. This study systematically investigated the multi-year trends of surface O 3 over the last decade using measurements from 11 selected Air Quality Monitoring Stations (AQMS). The analysis reveals upward trends in the annual average and daily maximum 8-h average (DMA8) O 3 from 2011 to 2022, with rates of 0.34 ppb year−1 (p < 0.05) and 0.22 ppb year−1 (p = 0.19), respectively. Though upward trends of DMA8 O 3 were observed at urban stations (0.10–0.88 ppb year−1), the significant decreases in NO 2 levels at all stations (−0.18 to −1.75 ppb year−1) led to a decline of total oxidants (O x , O 3 +NO 2). In addition to the daytime O 3 peak increase, a clear nighttime O 3 peak was present with a significant increasing trend, which was associated with the regional transport of O 3 -rich plumes and weakened NO titration effect. The relative contributions of local production and regional transport were investigated, and results indicated that local control efforts have predictably alleviated the locally produced O x , while the regional background O x still contributes significantly but appears to decline. Furthermore, an observation-based model was employed to examine the evolution of O 3 -precursors relationships. The results indicate that O 3 formation was still VOC-limited in Hong Kong, and the suppressive effect of NO x on O 3 formation has decreased in recent years. In terms of abatement strategies, apart from aromatics, we emphasize the significance of carbonyl compounds due to their high reactivity to O 3 production. • A comprehensive analysis presents the long-term upward trend of surface O 3 in Hong Kong. • Elevated nighttime O 3 peaks in Hong Kong due to the regional transport of O 3 -rich plumes with reduced NO titration effect. • Strict emission control measures have alleviated local O x production and ceased the degradation of regional background O x. • The O 3 formation regime remains VOC sensitive, with high reactivity contribution from aromatics and carbonyl compounds. [ABSTRACT FROM AUTHOR]