Intercomparison of MAX-DOAS vertical profile retrieval algorithms: studies using synthetic data
<p>Multi-axis differential optical absorption spectroscopy (MAX-DOAS) is a widely used measurement technique for the detection of a variety of atmospheric trace gases. Using inverse modelling, the observation of trace gas column densities along different lines of sight enables the retrieval of...
| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-04-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/12/2155/2019/amt-12-2155-2019.pdf |
| Summary: | <p>Multi-axis differential optical absorption spectroscopy
(MAX-DOAS) is a widely used measurement technique for the detection of a
variety of atmospheric trace gases. Using inverse modelling, the observation
of trace gas column densities along different lines of sight enables the
retrieval of aerosol and trace gas vertical profiles in the atmospheric
boundary layer using appropriate retrieval algorithms. In this study, the
ability of eight profile retrieval algorithms to reconstruct vertical
profiles is assessed on the basis of synthetic measurements. Five of the
algorithms are based on the optimal estimation method, two on parametrised
approaches, and one using an analytical approach without involving any
radiative transfer modelling. The synthetic measurements consist of the
median of simulated slant column densities of <span class="inline-formula">O<sub>4</sub></span> at 360 and
477 <span class="inline-formula">nm</span>, as well as of HCHO at 343 <span class="inline-formula">nm</span> and <span class="inline-formula">NO<sub>2</sub></span> at 477 <span class="inline-formula">nm</span>, from seven datasets simulated by five different radiative transfer
models. Simulations are performed for a combination of 10 trace gas and 11
aerosol profiles, as well as 11 elevation angles, three solar zenith, and
three
relative azimuth angles. Overall, the results from the different algorithms
show moderate to good performance for the retrieval of vertical profiles,
surface concentrations, and total columns. Except for some outliers, the root-mean-square difference between the true and retrieved state ranges between
(0.05–0.1) km<span class="inline-formula"><sup>−1</sup></span> for aerosol extinction and (2.5–5.0) <span class="inline-formula">×10<sup>10</sup></span> molec cm<span class="inline-formula"><sup>−3</sup></span> for HCHO and <span class="inline-formula">NO<sub>2</sub></span> concentrations.</p> |
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| ISSN: | 1867-1381 1867-8548 |