Retrieval of Atmospheric Parameters from Spectroscopic Observations using DOAS Instruments - RAPSODI

使用 DOAS 仪器从光谱观测中检索大气参数 - RAPSODI

• 批准号: 272342164
• 负责人: Professor Dr. Ulrich Platt
• 金额: --
• 依托单位: Institut für Umweltphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/272342164?language=en
• 关键词: Retrieval; Atmospheric; Parameters; Spectroscopic; Observations

The Earth s atmosphere is governed by complex chemical and dynamical processes, and a detailed knowledge of the vertical distribution of trace gases and aerosols is crucial for a thorough understanding of the atmospheric system. Remote sensing measurements are ideally suited for the determination of the vertical structure of the atmosphere. Ground-based, airborne and satellite borne remote sensing measurements provide a contact free method to measure the atmospheric composition from a distance. In particular, Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) represents versatile and cost effective method for the observation of the vertical distribution of a variety of trace gases and of aerosols. In the framework of the proposed project, a novel retrieval algorithm will be developed, which will allow for a thorough exploitation of the information contained in MAX-DOAS measurements of scattered and direct sunlight. In contrast to existing algorithms, DOAS analysis and profile retrieval will be performed in a single step. This simultaneous retrieval of vertical profiles of aerosols and trace gases directly from the measured spectral radiances is expected to lead to a significant increase in the overall information content. Additional information on the state of the atmosphere will be gained from a simulation of the broadband spectral structure, which has so far been ignored in traditional DOAS applications, and from an explicit modelling of rotational Raman scattering (Ring effect). A T-Matrix and/or Mie model coupled to a radiative transfer model will allow for a retrieval of aerosol microphysical properties, such as size distribution and complex refractive index, from solar almucantar measurements, similar to existing algorithms for Aeronet sun photometer measurements. This algorithm will serve as the basis for a thorough assessment of the overall information content of MAX-DOAS measurements with respect to trace gases, aerosol extinction and aerosol microphysical properties. Measurements by a novel Polarimetric MAX-DOAS (PMAX-DOAS) instrument, which will be designed and built in the scope of this project, will yield a further enhancement of the information content of scattered light measurements. Skylight measurements at different orientations of a rotatable polarising filter will allow for the reconstruction of the Stokes vector. Polarisation-dependent measurements of the intensity, trace gas column and Ring effect will significantly increase the accuracy of aerosol and trace gas retrievals. In order to fully exploit information content of the PMAX-DOAS, the retrieval algorithm will be based on a vectorised radiative transfer model, which enables the simulation of the full Stokes vector.

地球大气是由复杂的化学和动力学过程控制的，对微量气体和气溶胶垂直分布的详细了解对于彻底了解大气系统至关重要。遥感测量非常适合于确定大气的垂直结构。地面、机载和卫星遥感测量提供了一种从远处测量大气成分的无接触方法。特别是，多轴差分光学吸收光谱（MAX-DOAS）代表了多种微量气体和气溶胶垂直分布观察的通用和经济有效的方法。在拟议项目的框架内，将开发一种新的检索算法，该算法将允许彻底利用散射和直射阳光的MAX-DOAS测量中包含的信息。与现有算法相比，DOAS分析和剖面检索将在一个步骤中完成。直接从测量的光谱辐射中同时检索气溶胶和微量气体的垂直剖面，预计将导致总体信息含量的显著增加。关于大气状态的额外信息将从宽带光谱结构的模拟中获得，这在传统的DOAS应用中迄今被忽略，并从旋转拉曼散射（环效应）的明确建模中获得。t矩阵和/或Mie模型与辐射传输模型耦合，将允许从太阳almucantar测量中检索气溶胶微物理特性，如尺寸分布和复折射率，类似于Aeronet太阳光度计测量的现有算法。该算法将作为全面评估MAX-DOAS测量关于微量气体、气溶胶消光和气溶胶微物理特性的总体信息内容的基础。在本项目范围内设计和建造的新型偏振MAX-DOAS （PMAX-DOAS）仪器将进一步提高散射光测量的信息含量。在可旋转偏振过滤器的不同方向上的天窗测量将允许Stokes矢量的重建。偏振相关的测量强度、痕量气体柱和环效应将显著提高气溶胶和痕量气体检索的准确性。为了充分利用PMAX-DOAS的信息内容，检索算法将基于矢量化辐射传输模型，该模型可以模拟全Stokes矢量。