Validation of Aura-OMI QA4ECV NO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; climate data records with ground-based DOAS networks: the role of measurement and comparison uncertainties

Compernolle, Steven; Verhoelst, Tijl; Pinardi, Gaia; Granville, J.; Hubert, D.; Keppens, Arno; Niemeijer, Sander; Rino, Bruno; Bais, A. F.; Beirle, Steffen; Boersma, F.; Burrows, J. P.; Smedt, Isabelle De; Eskes, Henk; Goutail, Florence; Hendrick, F.; Lorente, Alba; Pazmiño, Andréa; Piters, Ankie; Peters, Enno; Pommereau, J.-P.; Remmers, Julia; Richter, Andreas; Geffen, Jos van; Roozendaël, Michel Van; Wagner, Thomas; Lambert, J. C.

doi:10.5194/acp-20-8017-2020

Cited by 40 publications

(24 citation statements)

References 75 publications

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“…L3_NO 2 products were aggregated into decadal composites by averaging pixels with a cloud fraction lower than 40%, as suggested by Bauwens et al [7] Other studies by Boersma et al [23] and van Geffen et al [32] revealed that a threshold lower than 40% leads to more accurate NO 2 retrievals. However, Copernolle et al [33] claimed that low thresholds lead to the exclusion of aerosol and NO 2 -polluted Sentinel-5P scenes, which are essential from the perspective of the present study. Based on the decadal product, the following statistics were computed:…”

Section: Analysis Of the Sentinel-5 Tropospheric No 2 Column Densitymentioning

confidence: 79%

Reduction of Air Pollution in Poland in Spring 2020 during the Lockdown Caused by the COVID-19 Pandemic

2021

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The COVID-19 pandemic has affected many aspects of human well-being including air quality. The present study aims at quantifying this effect by means of ground-level concentrations of NO2, PM2.5, as well as aerosol optical depth (AOD) measurements and tropospheric NO2 column number density (NO2 TVCD), during the imposed governmental restrictions in spring 2020. The analyses were performed for both urban and non-built-up areas across the whole of Poland accompanied by Warsaw (urban site) and Strzyzow (a background site). The results revealed that mean PM2.5 concentrations in spring 2020 for urban and non-built-up areas across Poland and for Warsaw were 20%, 23%, 15% lower than the 10-year average, respectively. Analogous mean NO2 concentrations were lower by 20%, 18%, 30% and NO2 TVCD revealed 9%, 4%, 9% reductions in 2020 as compared to 2019. Regarding mean AOD, retrieved from MERRA-2 reanalysis, it was found that for the whole of Poland during spring 2020 the reduction in AOD as compared to the 10-year average was 15%. The contribution of the lockdown within total air pollution reduction is not easily assessable due to anomalous weather conditions in 2020 which resulted in advection of clean air masses identified from MERRA-2 reanalysis and Strzyzow observatory.

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Section: Analysis Of the Sentinel-5 Tropospheric No 2 Column Densitymentioning

confidence: 79%

Reduction of Air Pollution in Poland in Spring 2020 during the Lockdown Caused by the COVID-19 Pandemic

2021

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“…During the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) campaign over Baltimore in the US during July 2011, the NASA P-3B aircraft performed extensive profiling of the optical, chemical, and microphysical properties of aerosols (Crumeyrolle et al, 2014).…”

Section: Nasa Aircraft Campaign Datamentioning

confidence: 99%

“…Nevertheless, we did not apply any bias correction to any assimilated measurements in the reanalysis because of the difficulty in estimating the bias structure, including inter-measurement biases. To improve the temporal consistency, a detailed assessment of biases in individual retrievals (e.g., Compernolle, 2020) and between different retrieval products would be helpful, as already tested in the CAMS reanalysis (Inness et al, 2019).…”

Section: Assimilated Data Biases and Availabilitymentioning

confidence: 99%

Updated tropospheric chemistry reanalysis and emission estimates, TCR-2, for 2005–2018

Miyazaki

Bowman

Sekiya

et al. 2020

Earth Syst. Sci. Data

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Abstract. This study presents the results from the Tropospheric Chemistry Reanalysis version 2 (TCR-2) for the period 2005–2018 at 1.1∘ horizontal resolution obtained from the assimilation of multiple updated satellite measurements of ozone, CO, NO2, HNO3, and SO2 from the OMI, SCIAMACHY, GOME-2, TES, MLS, and MOPITT satellite instruments. The reanalysis calculation was conducted using a global chemical transport model MIROC-CHASER and an ensemble Kalman filter technique that optimizes both chemical concentrations of various species and emissions of several precursors, which was efficient for the correction of the entire tropospheric profile of various species and its year-to-year variations. Comparisons against independent aircraft, satellite, and ozonesonde observations demonstrate the quality of the reanalysis fields for numerous key species on regional and global scales, as well as for seasonal, yearly, and decadal scales, from the surface to the lower stratosphere. The multi-constituent data assimilation brought the model vertical profiles and interhemispheric gradient of OH closer to observational estimates, which was important in improving the description of the oxidation capacity of the atmosphere and thus vertical profiles of various species. The evaluation results demonstrate the capability of the chemical reanalysis to improve understanding of the processes controlling variations in atmospheric composition, including long-term changes in near-surface air quality and emissions. The estimated emissions can be employed for the elucidation of detailed distributions of the anthropogenic and biomass burning emissions of co-emitted species (NOx, CO, SO2) in all major regions, as well as their seasonal and decadal variabilities. The data sets are available at https://doi.org/10.25966/9qgv-fe81 (Miyazaki et al., 2019a).

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“…Stratospheric NO 2 columns from STREAM differ by up to 3 × 10 14 molec/cm 2 as compared to results from data assimilation and other modified reference sector methods, within the general uncertainties of stratospheretroposphere separation (Beirle et al, 2016;Boersma et al, 2018). The STREAM stratospheric NO 2 columns show an average bias of 1 × 10 13 molec/cm 2 with respect to the ground-based zenith-scattered light differential optical absorption spectroscopy (ZSL-DOAS) measurements (Compernolle et al, 2020b).…”

Section: Stratosphere-troposphere Separationmentioning

confidence: 76%

An improved tropospheric NO<sub>2</sub> column retrieval algorithm for TROPOMI over Europe

Liu

Valks

Pinardi

et al. 2021

Preprint

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Abstract. Launched in October 2017, the TROPOspheric Monitoring Instrument (TROPOMI) aboard Sentinel-5 Precursor provides the potential to monitor air quality over point sources across the globe with a spatial resolution as high as 5.5 km × 3.5 km (7 km × 3.5 km before 6 August 2019). The nitrogen dioxide (NO2) retrieval algorithm for the TROPOMI instrument consists of three steps: the spectral fitting of the slant column, the separation of stratospheric and tropospheric contributions, and the conversion of the slant column to a vertical column using an air mass factor (AMF) calculation. In this work, an improved tropospheric NO2 retrieval algorithm from TROPOMI measurements over Europe is presented. The stratospheric estimation is implemented using the STRatospheric Estimation Algorithm from Mainz (STREAM), which was developed as a verification algorithm for TROPOMI and does not require chemistry transport model data as input. A directionally dependent STREAM (DSTREAM) is developed to correct for the dependency of the stratospheric NO2 on the viewing geometry by up to 2 × 1014 molec/cm2. Applied to synthetic TROPOMI data, the uncertainty in the stratospheric column is 3.5 × 1014 molec/cm2 for polluted conditions. Applied to actual measurements, the smooth variation of stratospheric NO2 at low latitudes is conserved, and stronger stratospheric variation at higher latitudes are captured. For AMF calculation, the climatological surface albedo data is replaced by geometry-dependent effective Lambertian equivalent reflectivity (GE_LER) obtained directly from TROPOMI measurements with a high spatial resolution. Mesoscale-resolution a priori NO2 profiles are obtained from the regional POLYPHEMUS/DLR chemistry transport model with the TNO-MACC emission inventory. Based on the latest TROPOMI operational cloud parameters, a more realistic cloud treatment is provided by a clouds-as-layers (CAL) model, which treats the clouds as uniform layers of water droplets, instead of the clouds-as-reflecting-boundaries (CRB) model, in which clouds are simplified as Lambertian reflectors. For the error analysis, the tropospheric AMF uncertainty, which is the largest source of NO2 uncertainty for polluted scenarios, ranges between 20 % and 50 %, leading to a total uncertainty in the tropospheric NO2 column in the 30–60 % range. From a validation performed with ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements, the improved tropospheric NO2 data shows good correlations for nine European urban/suburban stations with an average correlation coefficient of 0.78. The implementation of the algorithm improvements leads to a decrease of the relative difference from −55.3 % to −34.7 % on average.

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Validation of Aura-OMI QA4ECV NO<sub>2</sub> climate data records with ground-based DOAS networks: the role of measurement and comparison uncertainties

Cited by 40 publications

References 75 publications

Reduction of Air Pollution in Poland in Spring 2020 during the Lockdown Caused by the COVID-19 Pandemic

Reduction of Air Pollution in Poland in Spring 2020 during the Lockdown Caused by the COVID-19 Pandemic

Updated tropospheric chemistry reanalysis and emission estimates, TCR-2, for 2005–2018

An improved tropospheric NO<sub>2</sub> column retrieval algorithm for TROPOMI over Europe

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Validation of Aura-OMI QA4ECV NO&lt;sub&gt;2&lt;/sub&gt; climate data records with ground-based DOAS networks: the role of measurement and comparison uncertainties

Cited by 40 publications

References 75 publications

Reduction of Air Pollution in Poland in Spring 2020 during the Lockdown Caused by the COVID-19 Pandemic

Reduction of Air Pollution in Poland in Spring 2020 during the Lockdown Caused by the COVID-19 Pandemic

Updated tropospheric chemistry reanalysis and emission estimates, TCR-2, for 2005–2018

An improved tropospheric NO&lt;sub&gt;2&lt;/sub&gt; column retrieval algorithm for TROPOMI over Europe

Contact Info

Product

Resources

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Validation of Aura-OMI QA4ECV NO<sub>2</sub> climate data records with ground-based DOAS networks: the role of measurement and comparison uncertainties

An improved tropospheric NO<sub>2</sub> column retrieval algorithm for TROPOMI over Europe