Details

Autor(en) / Beteiligte

• Irie, H
• Nakayama, T
• Shimizu, A
• Yamazaki, A
• Nagai, T
• Uchiyama, A
• Zaizen, Y
• Kagamitani, S
• Matsumi, Y

Titel

Evaluation of MAX-DOAS aerosol retrievals by coincident observations using CRDS, lidar, and sky radiometer inTsukuba, Japan

Ist Teil von

• Atmospheric measurement techniques, 2015-07, Vol.8 (7), p.2775-2788

Ort / Verlag

Katlenburg-Lindau: Copernicus GmbH

Erscheinungsjahr

2015

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• 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.