Combined UV and IR ozone profile retrieval from TROPOMI and CrIS measurements
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Author/Creator ORCID
Date
2022-05-12
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Citation of Original Publication
Mettig, N., Weber, M., Rozanov, A., Burrows, J. P., Veefkind, P., Thompson, A. M., Stauffer, R. M., Leblanc, T., Ancellet, G., Newchurch, M. J., Kuang, S., Kivi, R., Tully, M. B., Van Malderen, R., Piters, A., Kois, B., Stübi, R., and Skrivankova, P.: Combined UV and IR ozone profile retrieval from TROPOMI and CrIS measurements, Atmos. Meas. Tech., 15, 2955–2978, https://doi.org/10.5194/amt-15-2955-2022, 2022.
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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract
Vertical ozone profiles from combined spectral measurements in the ultraviolet and infrared spectral range were retrieved by using data from the TROPOspheric Monitoring Instrument on the Sentinel-5 Precursor
(TROPOMI/S5P) and the Cross-track Infrared Sounder on
the Suomi National Polar-orbiting Partnership (CrIS/SuomiNPP), which are flying in loose formation 3 min apart in the
same orbit. A previous study of ozone profiles retrieved exclusively from TROPOMI UV spectra showed that the vertical resolution in the troposphere is clearly limited (Mettig
et al., 2021). The vertical resolution and the vertical extent
of the ozone profiles is improved by combining both wavelength ranges compared to retrievals limited to UV or IR
spectral data only. The combined retrieval particularly improves the accuracy of the retrieved tropospheric ozone and
to a lesser degree stratospheric ozone up to 30 km. An increase in the degrees of freedom (DOF) by 1 DOF was found
in the UV + IR retrieval compared to the UV-only retrieval.
Compared to previous publications, which investigated combinations of UV and IR observations from the Ozone Monitoring Instrument and Tropospheric Emission Spectrometer
(OMI and TES) and Global Ozone Monitoring Experiment
version 2 and Infrared Atmospheric Sounding Interferometer
(GOME-2 and IASI) pairs, the degree of freedom is lower,
which is attributed to the reduced spectral resolution of CrIS
compared to TES or IASI. Tropospheric lidar and ozonesondes were used to validate the ozone profiles and tropospheric
ozone content (TOC). In their comparison with tropospheric
lidars, both ozone profiles and TOCs show smaller biases for
the retrieved data from the combined UV + IR observation
than from the UV observations alone. For the ozone profiles
below 10 km, the mean differences are around ±10 % and
the mean TOC varies around ±3 DU. We show that TOCs
from the combined retrieval agree better with ozonesonde results at northern latitudes than the UV-only and IR-only
retrievals and also have lower scatter. In the tropics, the IRonly retrieval shows the best agrement with TOCs derived
from ozonesondes. While in general the TOCs show good
agreement with ozonesonde data, the profiles have a positive
bias of around 30 % between 10 and 15 km. The reason is
probably a positive stratospheric bias from the IR retrieval.
The comparison of the UV + IR and UV ozone profiles up
to 30 km with the Microwave Limb Sounder (MLS) demonstrates the improvement of the UV + IR profile in the stratosphere above 18 km. In comparison to the UV-only approach
the retrieval shows improvements of up to 10 % depending
on latitude but can also show worse results in some regions
and latitudes.