9:00 AM - 10:30 AM
[AAS07-P10] Improving MAX-DOAS tropospheric NO2 profile retrievals using ground-based in-situ and direct-sun observations
Keywords:nitrogen dioxide, NO2, remote sensing
Here, we revisit the retrieval of NO2 vertical profiles with the ground-based MAX-DOAS observations. Observations of MAX-DOAS installed at JAMSTEC Yokosuka Headquarters in an urban area (Yokosuka, Kanagawa) indicate that the retrieved NO2 vertical column density depends significantly (up to ~18%) on the ‘a priori’ vertical profile required for the MAX-DOAS retrieval. When a priori vertical profiles assuming higher fractions of NO2 present in the lower atmosphere (0–1 km altitude range) are used, the NO2 column densities tend to be small, implying that the aforementioned bias between satellite and ground-based observations may be partly remedied. The shifts in the NO2 vertical column densities and the NO2 surface concentrations retrieved with such an improved MAX-DOAS algorithm were supported by the independent direct-sun Pandora spectrometer observations, and in-situ measurements of cavity attenuated phase shift spectroscopy (CAPS), respectively. These comparisons result in more plausible a priori vertical profiles and, finally, the NO2 vertical profile retrievals with MAX-DOAS measurements are to be improved.
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