Understanding meteorological influences on PM_2.5 concentrations across China: a temporal and spatial perspective

With frequent air pollution episodes in China, growing research emphasis has been put on quantifying meteorological influences on PM2.5 concentrations. However, these studies mainly focus on isolated cities, whilst meteorological influences on PM2.5 concentrations at the national scale have not yet been examined comprehensively. This research employs the CCM (convergent cross-mapping) method to understand the influence of individual meteorological factors on local PM2.5 concentrations in 188 monitoring cities across China. Results indicate that meteorological influences on PM2.5 concentrations have notable seasonal and regional variations. For the heavily polluted North China region, when PM2.5 concentrations are high, meteorological influences on PM2.5 concentrations are strong. The dominant meteorological influence for PM2.5 concentrations varies across locations and demonstrates regional similarities. For the most polluted winter, the dominant meteorological driver for local PM2.5 concentrations is mainly the wind within the North China region, whilst precipitation is the dominant meteorological influence for most coastal regions. At the national scale, the influence of temperature, humidity and wind on PM2.5 concentrations is much larger than that of other meteorological factors. Amongst eight factors, temperature exerts the strongest and most stable influence on national PM2.5 concentrations in all seasons. Due to notable temporal and spatial differences in meteorological influences on local PM2.5 concentrations, this research suggests pertinent environmental projects for air quality improvement should be designed accordingly for specific regions.

Wheat Production Simulation Based on the ALMANAC Model of North China Region

<p>Wheat (<em>Triticumaestivum</em>) is one of the world's three major food crops, whose production is related to regional food security issues. Studies have shown that technological progress and climate change have a significant impact on wheat yield. We selected North China region as the study site because it is the main producer of wheat and because it experiences active climate change. Using the Agricultural Land Management Alternatives with Numerical Assessment Criteriamodel and statistical analysis method, the following factors were considered to determine the dominant factor that affects wheat production: temperature, precipitation, sunshine, and other climatic factors, mechanical power, irrigation area, chemical fertilizer amount, reservoir total storage capacity, and other technical factors.Results showed that wheat productionis affected by both climatic and non-climatic factors in North China region. Increased temperature has a positive impact on wheat production, whereas reduceds unshine has a negative effect. Warm and dry climate trends areconducive to wheat production. Mechanical tillage and fertilization, irrigation, and water conditions are conducive to the production of wheat, among which water condition has the most significant effect onwheat yield improvement. Compared withthe effects of climaticfactors, those of technical factors are more obvious and direct. In the premise of guaranteed technical conditions, the impactof climate changeonwheat production is more evidentindeveloped areas. Underdeveloped areas of wheat production are more dependent on technological progress; in particular, they rely on the use of chemical fertilizers.</p><p> </p>