基于TUV模式的对流层光解速率影响因子的研究

应用TUV辐射传输模式进行了一系列的敏感性试验，以期确定影响对流层O₃和NO₂光解速率的关键性因子.结果表明，气溶胶的光学性质对光解速率的影响存在明显差异.在气溶胶光学厚度（AOD）一定的情况下，散射性越强，近地面光解速率越大；当AOD从0.5增加至2.5，J[O¹D]和J[NO₂]极大值分别下降30.3%和13.1%.光解速率对较小的云光学厚度的变化比较敏感.云对J[NO₂]的影响存在明显的时间差异，在早晨和傍晚，J[NO₂]的衰减可以达到12%，而午时，J[NO₂]的衰减不足4%；在垂直方向上，云层的存在能够减小通过云层的光化辐射通量，有效降低云下光解速率，而云滴的后向散射特性能增大云上的光解速率.臭氧能够吸收300nm左右的紫外辐射，因而臭氧柱浓度变化对J[O¹D]有显著的影响，臭氧柱浓度从200DU增加至400DU，J[O¹D]极大值下降了53.1%，J[NO₂]极大值仅降低了1.0%.同时发现，气溶胶和云相对位置的改变对光解速率的垂直分布有较大的影响，气溶胶在云上时，高层的光解速率明显增大，且气溶胶的散射性越强，光解速率的增幅越大；当吸收性气溶胶位于云上时，使得高层光化辐射通量大量衰减，此时云层对于光解速率的影响比较微弱.

A study on the influencing factors of tropospheric photolysis rate based on TUV model

In this paper, a series of sensitivity tests were carried out using radiation transfer model (TUV) to determine the key factors affecting the photolysis rate of tropospheric O₃ and NO₂. The results showed that the optical properties of aerosols could have a significant impact on the photolysis rate. When the aerosol optical depth (AOD) was constant, the stronger the scattering was, the higher the near-surface photolysis rates were. When AOD increases from 0.5 to 2.5, the maximum values of J[O¹D] and J[NO₂] decreased by 30.3% and 13.1%, respectively. The photolysis rates were more sensitive to the change of smaller cloud optical depth. The effect of cloud on J[NO₂] varied with time significantly. In the morning and evening, the attenuation of J[NO₂] could reach 12%, while the attenuation of J[NO₂] in the noon was less than 4%. In the vertical direction, the presence of the cloud layer could reduce the photolysis rate under the cloud effectively via reducing the actinic flux through the cloud layer. The backscattering properties of cloud droplets increased the photolysis rate above the cloud. Ozone could absorb ultraviolet radiation around 300nm, so total ozone content had a considerable effect on J[O¹D]. The ozone column concentration increased from 200DU to 400DU, the maximum value of J[O¹D] decreased by 53.1%, while the maximum value of J[NO₂] was only reduced by 1.0%. At the same time, the relative position of aerosols and clouds was found having a great influence on the vertical distribution of the photolysis rate. When the aerosol was located above the cloud, the photolysis rate of the upper layer was significantly increased, and the stronger the scattering of the aerosol, the greater the increase of the photolysis rate; When the absorbing aerosol was located above the cloud, the actinic flux in the upper layer was greatly attenuated. The influence of the cloud on the photolysis rate was weak in this situation.