Impacts of dust on regional tropospheric chemistry during the ACE-Asia experiment: A model study with observations
Impacts of dust on regional tropospheric chemistry during the ACE-Asia experiment: A model study with observations
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DOI：
10.1029/2003jd003806
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发表时间：
2004-08-04
影响因子：
4.4
通讯作者：
Anderson, TL
中科院分区：
文献类型：
--
作者：
Tang, YH;Carmichael, GR;Anderson, TL
利用一个综合性的区域尺度化学输送模式STEM-2K 1（Sulfur Transport and Emissions Model 2001），研究了2001年4月4-14日亚洲-太平洋区域气溶胶特征试验（ACE-Asia）期间沙尘的外流及其对区域化学的影响。在这一时期，沙尘暴在塔克拉玛干沙漠和戈壁沙漠由于冷空气爆发而初始化，并向东输送，并且随着锋面离开大陆，暴露的土壤中释放的灰尘往往会加剧沙尘暴。模拟的沙尘与地面天气观测、卫星图像和C-130飞机的测量结果吻合良好。分析了C-130飞机对富尘期和低尘期气溶胶化学成分的观测结果。在亚微米气溶胶中，富含灰尘的空气质量具有升高的Δ Ca/Δ Mg、Δ NH（4）（+）/Δ SO（4）（2-）和Δ NO（3）（-）/Δ CO的比率（Δ表示观测浓度和背景浓度之间的差异）。通过将这些反应纳入分析中，研究了涉及O-3，NO2，SO2和HNO 3的非均相反应对粉尘的影响。这些反应对区域化学有重要影响。例如，C-130飞行6中的低O-3浓度只能用非均相反应的影响来解释。在近地层中，模拟的非均相反应表明，O-3，SO2，NO2和HNO 3分别减少了20%，55%，20%和95%，平均在此期间。此外，NO，HONO和白天OH分别增加了20%，30%和4%，在污染区域。当灰尘遇到新鲜污染物时，这些非均相反应可导致光化学系统的一系列复杂响应。此外，这些反应可以改变气溶胶的化学尺寸分布。在重粉尘负载下，这些反应可导致>20%的硫酸盐和>70%的硝酸盐与粗粒级分结合。尘埃的辐射影响也会影响光化学系统。例如，OH水平可以在表面附近降低20%。尘埃辐射的影响被证明是弱于大多数物种的异质性的影响。
A comprehensive regional-scale chemical transport model, Sulfur Transport and Emissions Model 2001 (STEM-2K1), is employed to study dust outflows and their influence on regional chemistry in the high-dust Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) period, from 4-14 April 2001. In this period, dust storms are initialized in the Taklamagan and Gobi deserts because of cold air outbreaks, are transported eastward, and are often intensified by dust emitted from exposed soils as the front moves off the continent. Simulated dust agrees well with surface weather observations, satellite images, and the measurements of the C-130 aircraft. The C-130 aircraft observations of chemical constituents of the aerosol are analyzed for dust-rich and low-dust periods. In the submicron aerosol, dust-rich air masses have elevated ratios of DeltaCa/DeltaMg, DeltaNH(4)(+)/DeltaSO(4)(2-), and DeltaNO(3)(-)/DeltaCO (Delta represents the difference between observed and background concentrations). The impacts of heterogeneous reactions on dust involving O-3, NO2, SO2, and HNO3 are studied by incorporating these reactions into the analysis. These reactions have significant influence on regional chemistry. For example, the low O-3 concentrations in C-130 flight 6 can be explained only by the influence of heterogeneous reactions. In the near-surface layer, the modeled heterogeneous reactions indicated that O-3, SO2, NO2, and HNO3 are decreased by up to 20%, 55%, 20%, and 95%, respectively, when averaged over this period. In addition, NO, HONO, and daytime OH can increase by 20%, 30%, and 4%, respectively, over polluted regions. When dust encounters fresh pollutants, these heterogeneous reactions can lead to a series of complex responses of the photochemical system. In addition, these reactions can alter the chemical-size distribution of the aerosol. Under heavy dust loadings, these reactions can lead to >20% of the sulfate and >70% of the nitrate being associated with the coarse fraction. The radiative influence of dust can also affect the photochemical system. For example, OH levels can decrease by 20% near surface. The dust radiative influence is shown to be weaker than the heterogeneous influence for most species.