Temporal, spatial and meteorological variations in hourly PM2.5 concentration extremes in New York City

摘要: Abstract Variations in the extreme percentiles of empirical hourly PM 2.5 concentration distributions from a unique high-density network 20 stations within New York City are statistically analyzed. Significant diurnal, seasonal and day-of-week variations noted, with highest concentrations typically found between 7:00 9:00 a.m., during summer, on weekdays. The lowest generally early morning hours (4:00–6:00 a.m.), winter weekends. amplitudes these diurnal cycles vary percentile, less pronounced for some cases percentiles. patterns suggest that although anthropogenic factors may be primarily responsible observed cycle, meteorological conditions also have influence. There is little spatial variation across city. Highly significant between-station correlations obtained all seasons. However, lower correlation winter. Meteorologically, occur moderate southwesterly winds high temperatures humidity summer. These related to westward expansion Bermuda high-pressure system. Calm conducive particulate concentrations. Relatively strong northerly associated It appears regional-scale processes dominate day-to-day changes