The direct fitting approach for total ozone column retrievals: a sensitivity study on GOME-2/MetOp-A measurements

Wassmann, A.; Borsdorff, Tobias; Brugh, J. M. J. Aan de; Hasekamp, Otto; Aben, I.; Landgraf, Jochen

doi:10.5194/amt-8-4429-2015

Cited by 11 publications

(16 citation statements)

References 66 publications

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“…Most, if not all, total O 3 algorithms (e.g., Mateer et al, 1971;Klenk et al, 1982;Bhartia and Wellemeyer, 2002;Coldewey-Egbers et al, 2005;Eskes et al, 2005;Veefkind et al, 2006;Lerot et al, 2010Lerot et al, , 2014Loyola et al, 2011;Van Roozendael et al, 2006Wassmann et al, 2015) rely on an O 3 profile climatology to uniquely and completely specify the vertical distribution of a retrieved total column. Profile O 3 algorithms (e.g., Hoogen et al, 1999;Liu et al, 2005;Wei et al, 2010;Bhartia et al, 2013;Miles et al, 2015) based on the widely adopted optimal estimation (OE) inversion technique (Rodgers, 2000) require the a priori O 3 profiles and their covariances to constrain the retrievals from deviating too far from the a priori O 3 distributions. An OEretrieved O 3 profile is a combination, i.e., weighted average, of the real and the a priori profiles.…”

Section: Profile Climatologymentioning

confidence: 99%

Ozone profile climatology for remote sensing retrieval algorithms

Yang

Liu

2019

Atmos. Meas. Tech.

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Abstract. New ozone (O3) profile climatologies are created from the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) O3 record between 2005 and 2016, within the period of Aura Microwave Limb Sounder (MLS) and Aura Ozone Monitoring Instrument (OMI) assimilation. These two climatologies consist of monthly mean O3 profiles and the corresponding covariances dependent on the local solar time, longitude (15∘), and latitude (10∘), which are parameterized by tropopause pressure and total O3 column. They are validated through comparisons, which show good agreements with previous O3 profile climatologies. Compared to a monthly zonal mean climatology, both tropopause- and column-dependent climatologies provide improved a priori information for profile and total O3 retrievals from remote sensing measurements. Furthermore, parameterization of the O3 profile with total column O3 usually reduces the natural variability of the resulting climatological profile in the upper stratosphere further than the tropopause parameterization, which usually performs better in the upper troposphere and lower stratosphere (UTLS). Therefore tropopause-dependent climatology is more appropriate for profile O3 retrieval for complementing the vertical resolution of backscattered ultraviolet (UV) spectra, while the column-dependent climatology is more suited for use in total O3 retrieval algorithms, with an advantage of complete profile specification without requiring ancillary information. Compared to previous column-dependent climatologies, the new MERRA-2 column-dependent climatology better captures the diurnal, seasonal, and spatial variations and dynamical changes in O3 profiles with higher resolutions in O3, latitude, longitude, and season. The new MERRA-2 climatologies contain the first quantitative characterization of O3 profile covariances, which facilitate a new approach to improve O3 profiles using the most probable patterns of profile adjustments represented by the empirical orthogonal functions (EOFs) of the covariance matrices. The MERRA-2 daytime column-dependent climatology is used in the combo O3 and SO2 algorithm for retrieval from the Earth Polychromatic Imaging Camera (EPIC) on board the Deep Space Climate Observatory (DSCOVR) satellite, the Ozone Mapping and Profiler Suite Nadir Mapper (OMPS-NM) on the Suomi National Polar Partnership (SNPP), and the Ozone Monitoring Instrument (OMI) on the Aura spacecraft.

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Section: Profile Climatologymentioning

confidence: 99%

Ozone profile climatology for remote sensing retrieval algorithms

Yang

Liu

2019

Atmos. Meas. Tech.

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“…This error can be interpreted as the effect of the chosen reference profile on the retrieved CO column density (Borsdorff et al, 2014;Wassmann et al, 2015). If the reference profile to be scaled by the inversion has the correct shape, the null space error vanishes and the retrieved column represents an estimate of the true column.…”

Section: Inversionmentioning

confidence: 99%

“…This model requires a solar irradiance spectrum on the internal spectral grid as input, which is inferred from the daily solar measurements of TROPOMI using the deconvolution approach by van Deelen et al (2007) and Wassmann et al (2015). State-of-the-art radiative transfer models account for multiple scattering in multiple propagation directions (streams) including the polarization of light.…”

Section: Forward Modelmentioning

confidence: 99%

Carbon monoxide total column retrievals from TROPOMI shortwave infrared measurements

et al. 2016

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Abstract. The Tropospheric Monitoring Instrument (TROPOMI) spectrometer is the single payload of the Copernicus Sentinel 5 Precursor (S5P) mission. It measures Earth radiance spectra in the shortwave infrared spectral range around 2.3 µm with a dedicated instrument module. These measurements provide carbon monoxide (CO) total column densities over land, which for clear sky conditions are highly sensitive to the tropospheric boundary layer. For cloudy atmospheres over land and ocean, the column sensitivity changes according to the light path through the atmosphere. In this study, we present the physics-based operational S5P algorithm to infer atmospheric CO columns satisfying the envisaged accuracy (< 15 %) and precision (< 10 %) both for clear sky and cloudy observations with low cloud height. Here, methane absorption in the 2.3 µm range is combined with methane abundances from a global chemical transport model to infer information on atmospheric scattering. For efficient processing, we deploy a linearized two-stream radiative transfer model as forward model and a profile scaling approach to adjust the CO abundance in the inversion. Based on generic measurement ensembles, including clear sky and cloudy observations, we estimated the CO retrieval precision to be ≤ 11 % for surface albedo ≥ 0.03 and solar zenith angle ≤ 70 • . CO biases of ≤ 3 % are introduced by inaccuracies in the methane a priori knowledge. For strongly enhanced CO concentrations in the tropospheric boundary layer and for cloudy conditions, CO errors in the order of 8 % can be introduced by the retrieval of cloud parameters of our algorithm. Moreover, we estimated the effect of a distorted spectral instrument response due to the inhomogeneous illumination of the instrument entrance slit in the flight direction to be < 2 % with pseudo-random characteristics when averaging over space and time. Finally, the CO data exploitation is demonstrated for a TROPOMI orbit of simulated shortwave infrared measurements. Overall, the study demonstrates that for an instrument that performs in compliance with the pre-flight specifications, the CO product will meet the required product performance well.

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“…In the case of a single trace gas retrieval the interference terms A k,k do not exist. In such case, the meaning of the remaining column averaging kernel A k is related to the proper choice of the reference profile and the effective null space of the regularization (see the discussion in Borsdorff et al, 2014 andWassmann et al, 2015). If the chosen reference profile is correct, the equation is equal to a geometrical integration of ρ k .…”

Section: Inversionmentioning

confidence: 99%

HDO and H<sub>2</sub>O total column retrievals from TROPOMI shortwave infrared measurements

Scheepmaker

Brugh

et al. 2016

Atmos. Meas. Tech.

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Abstract. The TROPOspheric Monitoring Instrument (TROPOMI) on board the European Space Agency Sentinel-5 Precursor mission is scheduled for launch in the last quarter of 2016. As part of its operational processing the mission will provide CH 4 and CO total columns using backscattered sunlight in the shortwave infrared band (2.3 µm). By adapting the CO retrieval algorithm, we have developed a non-scattering algorithm to retrieve total column HDO and H 2 O from the same measurements under clear-sky conditions. The isotopologue ratio HDO / H 2 O is a powerful diagnostic in the efforts to improve our understanding of the hydrological cycle and its role in climate change, as it provides an insight into the source and transport history of water vapour, nature's strongest greenhouse gas. Due to the weak reflectivity over water surfaces, we need to restrict the retrieval to cloud-free scenes over land. We exploit a novel 2-band filter technique, using strong vs. weak water or methane absorption bands, to prefilter scenes with medium-to-high-level clouds, cirrus or aerosol and to significantly reduce processing time. Scenes with cloud top heights 1 km, very low fractions of high-level clouds or an aerosol layer above a high surface albedo are not filtered out. We use an ensemble of realistic measurement simulations for various conditions to show the efficiency of the cloud filter and to quantify the performance of the retrieval. The single-measurement precision in terms of δD is better than 15-25 ‰ for even the lowest surface albedo (2-4 ‰ for high albedos), while a small bias remains possible of up to ∼ 20 ‰ due to remaining aerosol or up to ∼ 70 ‰ due to remaining cloud contamination. We also present an analysis of the sensitivity towards prior assumptions, which shows that the retrieval has a small but significant sensitivity to the a priori assumption of the atmospheric trace gas profiles. Averaging multiple measurements over time and space, however, will reduce these errors, due to the quasi-random nature of the profile uncertainties. The sensitivity of the retrieval with respect to instrumental parameters within the expected instrument performance is < 3 ‰, which represents only a small contribution to the overall error budget. Spectroscopic uncertainties of the water lines, however, can have a larger and more systematic impact on the performance of the retrieval and warrant further reassessment of the water line parameters. With TROPOMI's high radiometric sensitivity, wide swath (resulting in daily global coverage) and efficient cloud filtering, in combination with a spatial resolution of 7 × 7 km 2 , we will greatly increase the amount of useful data on HDO, H 2 O and their ratio HDO / H 2 O. We showcase the overall performance of the retrieval algorithm and cloud filter with an accurate simulation of TROPOMI measurements from a single overpass over parts of the USA and Mexico, based on MODIS satellite data and realistic conditions for the surface, atmosphere and chemistry (including isotopologues). This shows th...

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The direct fitting approach for total ozone column retrievals: a sensitivity study on GOME-2/MetOp-A measurements

Cited by 11 publications

References 66 publications

Ozone profile climatology for remote sensing retrieval algorithms

Ozone profile climatology for remote sensing retrieval algorithms

Carbon monoxide total column retrievals from TROPOMI shortwave infrared measurements

HDO and H<sub>2</sub>O total column retrievals from TROPOMI shortwave infrared measurements

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The direct fitting approach for total ozone column retrievals: a sensitivity study on GOME-2/MetOp-A measurements

Cited by 11 publications

References 66 publications

Ozone profile climatology for remote sensing retrieval algorithms

Ozone profile climatology for remote sensing retrieval algorithms

Carbon monoxide total column retrievals from TROPOMI shortwave infrared measurements

HDO and H&lt;sub&gt;2&lt;/sub&gt;O total column retrievals from TROPOMI shortwave infrared measurements

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HDO and H<sub>2</sub>O total column retrievals from TROPOMI shortwave infrared measurements