城市群區大氣污染物的輻射強迫及其對能量平衡的影響

內容摘要

利用發展的氣溶膠-氣候耦合模式重點研究了中國地區沙塵暴頻發的春季氣溶膠對大氣輻射、邊界層氣象和天氣的影響。持續4天的特大沙塵暴期間我國戈壁地區平均地面短波、長波輻射強迫可達到-90 W/m2和+40 W/m2。中國東部沙塵、人為氣溶膠和總氣溶膠在地表的平均淨輻射強迫分別為-8.4 W/m2，-10.2 W/m2，-18.0 W/m2，在大氣頂的輻射強迫分別為+1.2 W/m2，-4.3 W/m2，-3.1 W/m2，表明春季沙塵對大氣的增暖作用和總體氣溶膠的製冷作用。研究發現沙塵對總體氣溶膠地面輻射強迫的貢獻可達42%，反映了我國春季沙塵氣溶膠對輻射的影響具有與人為氣溶膠相當的貢獻。研究還發現總氣溶膠使感熱和潛熱通量都減少，在中蒙邊境附近的沙漠地區，感熱最大減少達到-40Wm-2,在黃河中下游地區，潛熱最大減少為-30Wm-2，地表總通量在長江以北的廣大地區明顯減少，其中戈壁和黃河中下游地區減少～-40 m-2，長三角和中國南方大部分地區通量減少分別為～-25Wm-2和-20Wm-2。氣溶膠還導致邊界層高度明顯降低，在上述通量變化較大的北方地區，日均邊界層高度最大減少200米，在長江流域和中國南方，邊界層高度減少約～100米。氣溶膠可以使中國東部大部分地區近地面氣溫降低~1°C, 降水減少~0.8mm/天。 An online coupled regional climate-chemistry-aerosol model (RIEMS-Chemaero) has been developed and applied to investigate the aerosol effects on atmospheric radiation, boundary layer meteorology and weather in spring, when dust storm often occur. Dust aerosols exerted a significant impact on radiation energy budget during the dust storm period, with the 4-day mean values of shortwave and longwave radiative forcings at the surface up to -90 Wm-2 and +40 Wm-2, respectively, over the Gobi desert. In east China, the domain average net radiative forcings due to dust, non-dust aerosols and all aerosols at the surface are estimated to be -8.4 Wm-2, -10.2 Wm-2 and -18.0 Wm-2 , respectively at the surface, and +1.2 W/m2，-4.3 W/m2，-3.1 W/m2 at TOA，indicating the dust warming and total aerosols cooling effects. The dust forcing accounts for about 42% of the total aerosol forcing at the surface in the domain, indicating the dust impact on radiation is comparable to that of anthropogenic aerosols. It is also found that aerosols cause decreases in both surface sensible (SH) and latent heat (LH) fluxes, with maximum decrease of SH flux up to -40Wm-2, in the deserts around the China-Mongolia border, and maximum LH flux decrease of -30Wm-2, in the lower reaches of the Yellow River. The total flux decreased apparently in large areas north of the Yangtze River, with maximum decrease up to -40Wm-2, in the Gobi and the middle and lower reaches of the Yellow River. In the Yangtze Delta region and large areas of south China, the decreases in the total fluxes were about ～-25Wm-2 and -20Wm-2, respectively. Aerosol radiative forcing induced a decrease in PBL height, with maximum decrease of 200 meter in most parts of north China where large flux variation occurred, and of ~100 meter in the regions along the Yangtze River and south China. The total aerosols induced a decrease of ~1.0 °C in the near surface air temperature and a decrease of ~0.8mm/day in precipitation in most areas of east China.

城市群區大氣污染物的輻射強迫及其對能量平衡的影響

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