Validation of TROPOMI tropospheric NO 2 columns using dual-scan multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements in Uccle, Brussels
2020
Abstract. Ground-based multi-axis differential optical absorption spectroscopy
(MAX-DOAS) measurements of aerosols and tropospheric nitrogen dioxide
( NO2 ) were carried out in Uccle (50.8 ∘ N, 4.35 ∘ E),
Brussels, during 1 year from March 2018 until March 2019. The instrument
was operated in both the UV and visible wavelength ranges in a dual-scan
configuration consisting of two sub-modes: (1) an elevation scan in a fixed
viewing azimuthal direction (the so-called main azimuthal direction)
pointing to the northeast and (2) an azimuthal scan in a fixed low elevation
angle (2 ∘ ). By applying a vertical profile inversion algorithm in the
main azimuthal direction and a parameterization technique in the other
azimuthal directions, near-surface NO2 volume mixing ratios (VMRs) and
vertical column densities (VCDs) were retrieved in 10 different azimuthal
directions. The dual-scan MAX-DOAS dataset allows for partly resolving the
horizontal distribution of NO2 around the measurement site and studying
its seasonal variations. Furthermore, we show that measuring the
tropospheric NO2 VCDs in different azimuthal directions improves the
spatial colocation with measurements from the Sentinel-5 Precursor (S5P),
leading to a reduction of the spread in validation results. By using
NO2 vertical profile information derived from the MAX-DOAS
measurements, we also resolve a systematic underestimation in S5P NO2
data due to the use of inadequate a priori NO2 profile shape data in the satellite retrieval.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
76
References
16
Citations
NaN
KQI