1. Evaluation of MAX-DOAS aerosol retrievals by coincident observations using CRDS, lidar, and sky radiometer in Tsukuba, Japan.
- Author
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Irie, H., Nakayama, T., Shimizu, A., Yamazaki, A., Nagai, T., Uchiyama, A., Zaizen, Y., Kagamitani, S., and Matsumi, Y.
- Subjects
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ATMOSPHERIC aerosol analysis , *CAVITY-ringdown spectroscopy , *ABSORPTION spectra , *ASTRONOMICAL spectroscopy , *CORRECTION factors , *RADIOMETERS - Abstract
Coincident aerosol observations of Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS), Cavity Ring Down Spectroscopy (CRDS), lidar, and sky radiometer were conducted in Tsukuba, Japan on 5-18 October 2010. MAX-DOAS aerosol retrieval (for aerosol extinction coefficient and aerosol optical depth at 476 nm) was evaluated from the viewpoint of the need for a correction factor for oxygen collision complexes (O4 or O2-O2) absorption. The present study strongly supports this need, as systematic residuals at relatively high elevation angles (20 and 30°) were evident in MAX-DOAS profile retrievals conducted without the correction. However, adopting a single number for the correction factor (fO4 = 1.25) for all of the elevation angles led to systematic overestimation of near-surface aerosol extinction coefficients, as reported in the literature. To achieve agreement with all three observations, we limited the set of elevation angles to ⩽10° and adopted an elevation-angle-dependent correction factor for practical profile retrievals with scattered light observations by a ground-based MAX-DOAS. With these modifications, we expect to minimize the possible effects of temperature-dependent O4 absorption cross section and uncertainty in DOAS fit on an aerosol profile retrieval, although more efforts are encouraged to quantitatively identify a physical explanation for the need of a correction factor. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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