Impacts of aerosols and clouds on photolysis frequencies and photochemistry during TRACE-P: 2. Three-dimensional study using a regional chemical transport model
Impacts of aerosols and clouds on photolysis frequencies and photochemistry during TRACE-P: 2. Three-dimensional study using a regional chemical transport model
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DOI：
10.1029/2002jd003100
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发表时间：
2003-11
影响因子：
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通讯作者：
Youhua Tang;G. Carmichael;I. Uno;Jung-Hun Woo;G. Kurata;B. Lefer;Richard E. Shelter;Hao Huang
中科院分区：
文献类型：
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作者：
Youhua Tang;G. Carmichael;I. Uno;Jung-Hun Woo;G. Kurata;B. Lefer;Richard E. Shelter;Hao Huang
[1]利用三维区域化学输送模式STEM 2K1和详细的辐射模式研究了TRACE-P期间东亚-西太平洋地区气溶胶和云对光解速率和光化学过程的影响。测量的J值进行比较，使用三维建模领域的云和气溶胶计算。该模型被证明是准确地代表在广泛的条件下观察到的J值。有和没有气溶胶和云的模式研究进行了比较，与晴朗的天空条件下，隔离的各种影响。在TRACE-P的观测期间，云对光解速率有很大的影响，云下J [NO2]降低了20%，从1公里到8公里增加了约30%。云也对短寿命的自由基（如OH和HO2）产生主要影响。在3月，云层在1公里以下的高度使OH减少23%，在1公里以上的高度使OH增加25%。亚洲的气溶胶含有大量的含碳物质、无机成分（如硫酸盐）和矿物氧化物。这些气溶胶显着影响J值和光化学过程。当对所有TRACE-P DC-8和P-3飞行进行平均时，通过影响J值，气溶胶的影响使OH在1 km以下降低了1.40%，在1 km以上降低了1.24%。气溶胶对寿命较长的化学物质的影响比云更大，因为气溶胶往往与前体共同排放，与污染的空气团接触的时间更长。累积的气溶胶影响一般是减少O3浓度约6 ppbv的生物质燃烧的羽流从东南亚排放。在特大城市烟羽中，气溶胶可以通过减少其光解损失使NOx浓度增加40%，并使NOx浓度降低相似的量。3月27日DC-8和P-3飞行的详细案例研究被用来比较云和气溶胶的影响。在这些飞行中，云对J值的影响比气溶胶的影响更强，但气溶胶显示出对O3产生更强的累积影响。
[1] A three-dimensional regional chemical transport model, STEM 2K1, coupled with a detailed radiation model is used to study the influences of aerosols and clouds on photolysis rates and photochemical processes over East Asia-Western Pacific during the TRACE-P period. Measured J-values are compared with those calculated using three-dimensional modeled fields of clouds and aerosols. The model is shown to accurately represent observed J-values over a broad range of conditions. Model studies with and without aerosols and clouds are performed and compared with clear-sky conditions to isolate the various influences. Clouds are shown to have a large impact on photolysis rates during the observation periods of TRACE-P, with J[NO2] decreased by 20% below clouds and enhanced by ∼30% from 1 km to 8 km. Clouds also exert a dominant influence on short-lived radicals, like OH and HO2. For March, clouds reduce OH by 23% at altitudes below 1 km and increase OH by ∼25% above 1 km. Asian aerosols contain large amounts of carbonaceous material, inorganic components such as sulfates, and mineral oxides. These aerosols significantly influence J-values and photochemical processes. When averaged over all TRACE-P DC-8 and P-3 flights, the aerosol influence via affecting J-values reduces OH by ∼40% below 1 km, and by ∼24% above 1 km. Aerosols have a stronger impact on longer-lived chemical species than clouds do because aerosols tend to be coemitted with precursors and have a longer contact time with the polluted air masses. The accumulated aerosol impact generally is to reduce O3 concentrations by about 6 ppbv in the biomass burning plumes emitted from Southeast Asia. In megacity plumes, aerosols can increase NOx concentration by 40% via reducing its photolytic loss and reduce NOz concentration by a similar amount. A detailed case study of the DC-8 and P-3 flights on 27 March is used to make comparisons for cloud and aerosol influences. During these flights, the cloud impact on J-values is stronger than the aerosol impact, but aerosols are shown to exert a much stronger accumulated influence on O3 production.