【摘要】 利用新一代大气化学在线耦合模式WRF-Chem研究城市扩张对珠三角地区春季气象条件的改变及其对地面O3浓度的影响。研究结果表明:受城市扩张的影响,珠三角城区的月平均气温上升0.35℃;城区夜间相对湿度下降幅度为4%～6%,影响程度大于白天;风速在白天和夜间都有不同程度的下降,城市月平均风速下降1.89 m/s;边界层高度在白天和夜间均升高,城市月平均边界层高度上升39.82 m。城市扩张后,城市月平均O3浓度增加0.89 ppbv,增幅大于1.5 ppbv的区域主要在佛山和东莞,白天O3浓度增幅为0.6～1.5 ppbv,夜间增幅及影响范围都大于白天,O3浓度增加区域与主要气象要素变化的区域相一致;白天14:00城区混合层内总臭氧柱浓度增加了80 ppbv;O3浓度对气象要素的敏感程度表现为:温度>边界层高度>风速>相对湿度;白天O3浓度增幅呈U型,其中14:00的O3增幅最小,为0.2 ppbv;夜间O3增幅呈倒V型,其中20:00的增幅最大(>1.5 ppbv)。更多还原

【Abstract】 In this study,a new generation of fully-coupled meteorology and atmospheric chemistry(Weather Research and Forecasting-Chemistry model,WRF-Chem) model is used to simulate the impacts of urban expansion on major meteorological variables and ozone concentration in spring over the Pearl River Delta(PRD).Results showed that urban expansion increases monthly-averaged 2 m air temperature in urban areas by 0.35 ℃.In urban areas,the relative humidity decreases by 4%~6%,especially during nighttime.Higher roughness elements in urban areas reduce daytime and nighttime wind speed,leading to a decrease of 1.89 m/s in monthly urban-averaged 10-m wind speed.The same dynamic effect generates more vigorous daytime and nighttime planetary boundary layer(PBL) and results in an increase of 39.82 m in monthly urban-averaged PBL height.These subtle changes due to urban expansion result in decernable increases in ozone concentration.Ozone concentration increases mainly in Foshan,Dongguan and south Guangzhou(around 1.5 ppbv),and the increase is larger in daytime than that of nighttime.Monthly ozone concentrations increased by 0.89 ppbv for the whole urban areas in PRD,and the areas of ozone concentration increase coincide with areas of meteorological parameters variation.At 14:00 LST,total ozone concentrations within the mixed layer in urban areas increased 80ppbv.The ozone-concentration change is mostly sensitive to changes in temperature,followed by those in PBL height and wind speed,and least to changes in the relative humidity.During the daytime(08:00—18:00 local time) the ozone concentrations increase is a U-type,in which the fewest increase is 0.2 ppbv at 14:00 LST,while at nighttime the ozone concentration increase is a V-type,and the largest increase is at 20:00 LST(more than 1.5ppbv).更多还原