Trade-offs and synergistic evolution between PM2.5 concentration shrinkage and light rain events in the Loess Plateau
Based on the trade-offs and synergistic relationship perspective,the relationships,spatial and tem-poral evolution,and geographic variations of PM2 5 concentration and light rain events in the Loess Plateau were investigated from a long time series and a multi-level spatial scale from 1998 to 2017.The results show that:1)The PM2.5 concentration and light rain events in the Loess Plateau show a slight upward trend in the fluctuation of'three peaks and three valleys'with a circle of 5 or 4 years;2)The relationship between PM2.5 concentration and light rain events is characterised by"process synergy+incremental trade-off".In terms of process evolution,synergy is the dominant relationship between PM2.5 concentration and light rain events in the Loess Plateau dur-ing the study period,but in terms of incremental changes based on tilt rate,the two are dominated by an aniso-tropic trade-off,indicating that the light rain events have been increasing in anisotropic direction.Trade-off re-lationship is dominant,suggesting that the enhancement of light rain events is important in the future haze man-agement in the Loess Plateau;3)The spatial relationships and evolutionary trends of different indicators of light rain events and PM2.5 concentration are significantly different;the role of light rain events in winter and spring seasons,especially the number of light rain days in winter and spring,in relation to PM2.5 concentration is significantly stronger than that on an annual scale;4)The trade-offs and synergistic relationship between PM2.5 concentration and light rain events and their evolutionary characteristics show significant spatial and tem-poral heterogeneity in different management zones,and the river valley plains and the soil and rocky mountain-ous areas with higher levels of urbanisation and industrialisation are the areas with the most significant changes in the trade-off-synergistic relationship between PM2.5 concentration and light rain events in the Loess Plateau,and are the sensitive areas for the relationship between the two.
PM2.5 concentrationlight rain eventtrade-offs and synergistichazethe Loess Plateau
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