Satellite remote sensing of aerosols: information content of different measurement types

摘要

We present an analysis of the aerosol retrieval capabilities of different types of satellite measurements. Here, we consider single- and multiple-viewing-angle measurements of intensity and of intensity together with polarization. In particular, we investigated their information content with respect to aerosol size distribution, optical thickness, and refractive index. For our investigation we employed a newly developed linearized vector radiative transfer model. This radiative transfer model accurately simulates the intensity vector and additionally calculates the derivatives with respect to the relevant aerosol properties. The use of an accurate linearized radiative transfer model in combination with an analytical inversion approach allows a solid error analysis and quantification of the information content of the different measurement types. In order to obtain optimal aerosol information from satellite measurements, multiple-wavelength multiple-viewing-angle measurements of intensity and polarization are needed. Furthermore, multiple-wavelength multiple-viewing-angle measurements of only intensity provide better aerosol information than multiple-wavelength measurements of intensity and polarization in one viewing direction. On the other hand, for single-viewing-angle instruments the inclusion of polarization leads to an improvement in accuracy in effective radius, refractive index, and optical thickness of a factor 10-100 compared to intensity measurements alone. Here, the inclusion of polarization has an even stronger effect than for multiple-viewing-angle measurements.