利用多波段光谱反演对流层臭氧的建模研究

Observation of tropospheric ozone from space has important role in quantifying the tropospheric budget of O3, and assess its participation in tropospheric chemistry and climate forcing. In this proposal, we aimed to conduct a retrieval simulation system that includes forward model, instrument model and retrieval model to explore the feasibility of using multi-spectra measurements in the UV, polarization, visible, infrared, to improve tropospheric ozone retrievals and instrument design. The radiative transfer calculation is performed using the fully linearized vector radiative transfer model VLIDORT, which could simulate upwelling radiance from the top of atmosphere and associate weighting functions in multi-spectral, simultaneously. A retrieval algorithm needs a functional forward modeling system encapsulating all the physics and the accuracy of the ozone retrieval depends critically on representation of the physical processes in the forward model. We aim to improve the understanding of the spectral properties and the effects of surfaces, aerosol, cloud and other trace gases in the ozone absorption bands. For this purpose, a forward modeling system including the scattering, absorption and polarization properties for air, trace gases, surfaces, and several aerosol types: Dust, OC, BC, Sulfate etc. and optical thin/thick cloud (ice, water and mixture) will be set up. Forward simulation studies will be carried out for a series of spectra for a range of geophysical scenarios. .The retrieval model simultaneously retrieves several properties of the atmospheric and surface state e.g., trace gases, albedo, aerosol and other parameters. We will conduct retrieval characterization and error analysis and conduct a series of end-to-end retrieval sensitivity studies. Sensitivity study will be set over Lambertian Surfaces to understand the effect of wavelength-dependent surface albedo variations. In order to investigate the aerosol contamination, sensitive studies over high aerosol content region will be set. .There are rooms to improve current instruments design. We aim to discuss instrument design and possible improvements base on scientific requirement for space-based measurements of tropospheric ozone with the precision, resolution, and coverage. The retrieval algorithm will be physics based, which could be applied to hyper-spectral instruments like GOME-2 and IASI.

对流层臭氧廓线和边界层臭氧的卫星监测对于气候研究和监测污染物的源和输送有重要的意义。为了讨论卫星反演对流层臭氧廓线在算法设计和仪器设计上的可行性，本项目计划采用模拟反演试验的方法利用最优估计反演技术分析多个波段联合反演对流层臭氧廓线的潜力和可行性。首先利用矢量离散化纵坐标辐射传输模式VLIDORT建立能够同时模拟紫外，紫外偏振，可见，中红外，热红外大气辐射及相应权重函数的正演模型。以最优估计反演方法为基础建立多个波段联合反演对流层臭氧的反演模拟系统。以现有光谱仪参数为基础分析多波段组合对对流层臭氧反演结果的影响，同时分析云，气溶胶的不确定度对反演结果的影响。最后以模拟反演试验为基础，探讨在一定精度上以反演对流层底层臭氧为目标的光谱仪波段选择及仪器基本科学指标方案。

项目基于LBLRTM和VLIDORT建立了适用于紫外、紫外偏振、可见光和红外波段（臭氧红外吸收波段，4.7μm 和9.6μm）卫星观测模拟的正演辐射传输模型，发展了一套基于最优估计方法的反演算法模型。模拟研究了偏振和可见光光谱在对流层臭氧反演中的作用，并分析了结合紫外、偏振和可见光波段的多波段方法对对流层臭氧反演结果的影响。研究结果表明，增加紫外偏振通道可以有效提高反演结果在对流层中上层的敏感性，但是对卫星观测角度有依赖性；增加可见光波段可以显著提高反演结果在边界层内的敏感性，部分改善了对流层中、上层臭氧的敏感性。地表反照率随波长的变化同对流层臭氧有显著的相关性，但是从光谱中同时反演这些参数将降低反演结果对对流层下层臭氧的敏感性。项目执行期间同国际合作者开展了基于卫星实测资料的紫外-热红外联合反演对流层臭氧合作研究。结果表明，通过结合GOME-2紫外波段和IASI红外波段可以提高对流层中层臭氧的反演敏感性和反演精度；利用GOME-2紫外波段反演东亚地区对流层臭氧，分析了GOME-2对流层臭氧反演产品的误差和信息量等参量及其特征，并对比分析了紫外光谱仪GOME-2与热红外光谱仪TES 的对流层臭氧柱总量及其敏感性。