scholarly journals Shipborne MAX-DOAS measurements for validation of TROPOMI NO<sub>2</sub> products

2020 ◽  
Vol 13 (3) ◽  
pp. 1413-1426 ◽  
Author(s):  
Ping Wang ◽  
Ankie Piters ◽  
Jos van Geffen ◽  
Olaf Tuinder ◽  
Piet Stammes ◽  
...  
Keyword(s):  
Column Density ◽  
Transport Model ◽  
Massively Parallel ◽  
Optical Absorption Spectroscopy ◽  
Vertical Column ◽  
Chemistry Transport Model ◽  
The Pacific ◽  
Tropospheric No2 ◽  
Vertical Column Density ◽  
Good Agreement

Abstract. Tropospheric NO2 and stratospheric NO2 vertical column densities are important TROPOspheric Monitoring Instrument (TROPOMI) data products. In order to validate the TROPOMI NO2 products, KNMI Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) instruments have measured NO2 on ship cruises over the Atlantic and the Pacific oceans. The MAX-DOAS instruments have participated in five cruises on board RV Sonne (in 2017 and 2019) and RV Maria S. Merian (in 2018). The MAX-DOAS measurements were acquired over 7 months and spanned about 90∘ in latitude and 300∘ in longitude. During the cruises aerosol measurements from Microtops sun photometers were also taken. The MAX-DOAS measured stratospheric NO2 columns between 1.5×1015 and 3.5×1015 molec cm−2 and tropospheric NO2 up to 0.6×1015 molec cm−2. The MAX-DOAS stratospheric NO2 vertical column densities have been compared with TROPOMI stratospheric NO2 vertical column densities and the stratospheric NO2 vertical column densities simulated by the global chemistry Transport Model, version 5, Massively Parallel model (TM5-MP). Good correlation is found between the MAX-DOAS and TROPOMI and TM5 stratospheric NO2 vertical column densities, with a correlation coefficient of 0.93 or larger. The TROPOMI and TM5 stratospheric NO2 vertical column densities are about 0.4×1015 molec cm−2 (19 %) higher than the MAX-DOAS measurements. The TROPOMI tropospheric NO2 also has good agreement with the MAX-DOAS measurements. The tropospheric NO2 vertical column density is as low as 0.5×1015 molec cm−2 over remote oceans.

scholarly journals Operational total and tropospheric NO<sub>2</sub> column retrieval for GOME-2

2011 ◽  
Vol 4 (7) ◽  
pp. 1491-1514 ◽  
Author(s):  
P. Valks ◽  
G. Pinardi ◽  
A. Richter ◽  
J.-C. Lambert ◽  
N. Hao ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Optical Absorption Spectroscopy ◽  
Chemistry Transport Model ◽  
Air Mass ◽  
Cloud Properties ◽  
The Pacific ◽  
Tropospheric No2 ◽  
Data Processor ◽  
Radiance Data

Abstract. This paper presents the algorithm for the operational near real time retrieval of total and tropospheric NO2 columns from the Global Ozone Monitoring Experiment (GOME-2). The retrieval is performed with the GOME Data Processor (GDP) version 4.4 as used by the EUMETSAT Satellite Application Facility on Ozone and Atmospheric Chemistry Monitoring (O3M-SAF). The differential optical absorption spectroscopy (DOAS) method is used to determine NO2 slant columns from GOME-2 (ir)radiance data in the 425–450 nm range. Initial total NO2 columns are computed using stratospheric air mass factors, and GOME-2 derived cloud properties are used to calculate the air mass factors for scenarios in the presence of clouds. To obtain the stratospheric NO2 component, a spatial filtering approach is used, which is shown to be an improvement on the Pacific reference sector method. Tropospheric air mass factors are computed using monthly averaged NO2 profiles from the MOZART-2 chemistry transport model. An error analysis shows that the random error in the GOME-2 NO2 slant columns is approximately 0.45 × 1015 molec cm−2. As a result of the improved quartz diffuser plate used in the GOME-2 instrument, the systematic error in the slant columns is strongly reduced compared to GOME/ERS-2. The estimated uncertainty in the GOME-2 tropospheric NO2 column for polluted conditions ranges from 40 to 80 %. An end-to-end ground-based validation approach for the GOME-2 NO2 columns is illustrated based on multi-axis MAXDOAS measurements at the Observatoire de Haute Provence (OHP). The GOME-2 stratospheric NO2 columns are found to be in good overall agreement with coincident ground-based measurements at OHP. A time series of the MAXDOAS and the GOME-2 tropospheric NO2 columns shows that pollution episodes at OHP are well captured by GOME-2. Monthly mean tropospheric columns are in very good agreement, with differences generally within 0.5 × 1015 molec cm−2.

scholarly journals Comparisons between SCIAMACHY atmospheric CO<sub>2</sub> retrieved using (FSI) WFM-DOAS to ground based FTIR data and the TM3 chemistry transport model

2006 ◽  
Vol 6 (3) ◽  
pp. 5387-5425 ◽  
Author(s):  
M. P. Barkley ◽  
P. S. Monks ◽  
U. Frieß ◽  
R. L. Mittermeier ◽  
H. Fast ◽  
...  
Keyword(s):  
Near Infrared ◽  
Transport Model ◽  
Weighting Function ◽  
Unknown Origin ◽  
Optical Absorption Spectroscopy ◽  
Vertical Column ◽  
Chemistry Transport Model ◽  
Relative Scatter ◽  
Atmospheric Co2 Concentrations ◽  
Good Agreement

Abstract. Atmospheric CO2 concentrations, retrieved from spectral measurements made in the near infrared (NIR) by the SCIAMACHY instrument, using Full Spectral Initiation Weighting Function Modified Differential Optical Absorption Spectroscopy (FSI WFM-DOAS), are compared to ground based Fourier Transform Infrared (FTIR) data and to the output from a global chemistry-transport model. Analysis of the FSI WFM-DOAS retrievals with respect to the ground based FTIR instrument, located at Egbert, Canada, show good agreement with an average negative bias of approximately −4.0% with a standard deviation of ~3.0%. This bias which exhibits an apparent seasonal trend, is of unknown origin, though slight differences between the averaging kernels of the instruments and the limited temporal coverage of the FTIR data may be the cause. The relative scatter of the retrieved vertical column densities is comparable to the spread of the FTIR measurements themselves. Normalizing the CO2 columns using the surface pressure does not affect the magnitude of this bias although it slightly increases the scatter of the FSI data. Comparisons of the FSI retrievals to the TM3 global chemistry-transport model, performed over four selected Northern Hemisphere scenes show good agreement. The correlation, between the time series of the SCIAMACHY and model monthly scene averages, are ~0.7 or greater, demonstrating the ability of SCIAMACHY to detect seasonal changes in the CO2 distribution. The amplitude of the seasonal cycle, peak to peak, observed by SCIAMACHY however, is overestimated by a factor of 2–3, which cannot be explained. The yearly means detected by SCIAMACHY are within 2% of those of the model with the mean difference between the CO2 distributions also approximately 2.0%. Additionally, analysis of the retrieved CO2 distributions reveals structure not evident in the model fields which correlates well with land classification type. From these comparisons, the overall precision and bias of the CO2 columns retrieved by the FSI algorithm are estimated to be close to 1.0% and <4.0% respectively.

scholarly journals Operational total and tropospheric NO<sub>2</sub> column retrieval for GOME-2

2011 ◽  
Vol 4 (2) ◽  
pp. 1617-1676 ◽  
Author(s):  
P. Valks ◽  
G. Pinardi ◽  
A. Richter ◽  
J.-C. Lambert ◽  
N. Hao ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Optical Absorption Spectroscopy ◽  
Chemistry Transport Model ◽  
Air Mass ◽  
Cloud Properties ◽  
The Pacific ◽  
Tropospheric No2 ◽  
Data Processor ◽  
Radiance Data

Abstract. This paper presents the algorithm for the operational near real time retrieval of total and tropospheric NO2 columns from the Global Ozone Monitoring Experiment (GOME-2). The retrieval is performed with the GOME Data Processor (GDP) version 4.4 as used by the EUMETSAT Satellite Application Facility on Ozone and Atmospheric Chemistry Monitoring (O3M-SAF). The Differential Optical Absorption Spectroscopy (DOAS) method is used to determine NO2 slant columns from GOME-2 (ir)radiance data in the 425–450 nm range. Initial total NO2 columns are computed using stratospheric air mass factors, and GOME-2 derived cloud properties are used to calculate the air mass factors for scenarios in the presence of clouds. To obtain the stratospheric NO2 component, a spatial filtering approach is used, which is shown to be an improvement on the Pacific reference sector method. Tropospheric air mass factors are computed using monthly averaged NO2 profiles from the MOZART-2 chemistry transport model. An error assessment shows that the random error in the GOME-2 NO2 slant columns is approximately 0.45 × 1015 molec cm−2. As a result of the improved quartz diffuser plate used in the GOME-2 instrument, the systematic error in the slant columns is strongly reduced compared to GOME/ERS-2. The estimated uncertainty in the GOME-2 tropospheric NO2 column for polluted conditions ranges from 40 to 80%. An end-to-end ground-based validation approach for the GOME-2 NO2 columns is illustrated based on MAX-DOAS measurements at the Observatoire de Haute Provence (OHP). The GOME-2 stratospheric NO2 columns are found to be in good overall agreement with coincident ground-based measurements at OHP. A time series of the MAX-DOAS and the GOME-2 tropospheric NO2 columns shows that pollution episodes at OHP are well captured by GOME-2. Monthly mean tropospheric columns are in very good agreement, with differences generally within 0.5 × 1015 molec cm−2.

scholarly journals Long-Term Variation in the Tropospheric Nitrogen Dioxide Vertical Column Density over Korea and Japan from the MAX-DOAS Network, 2007–2017

2021 ◽  
Vol 13 (10) ◽  
pp. 1937
Author(s):  
Yongjoo Choi ◽  
Yugo Kanaya ◽  
Hisahiro Takashima ◽  
Hitoshi Irie ◽  
Kihong Park ◽  
...  
Keyword(s):  
Nitrogen Dioxide ◽  
Column Density ◽  
Optical Absorption Spectroscopy ◽  
Industrial Complex ◽  
Vertical Column ◽  
Source Regions ◽  
Potential Source ◽  
Vertical Column Density ◽  
Good Agreement

We investigated long-term observations of the tropospheric nitrogen dioxide vertical column density (NO2 TropVCD) from the Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) network in Russia and ASia (MADRAS) from 2007 to 2017 at urban (Yokosuka and Gwangju) and remote (Fukue and Cape Hedo) sites in East Asia. The monthly mean in the NO2 TropVCD from MAX-DOAS measured at ~13:30 local time, which is the Ozone Monitoring Instrument (OMI) overpass time, shows good agreement with OMI data during summer, but differences between the two datasets increase in winter. The Theil-Sen slope of the long-term trend indicate a relatively rapid and gradual reduction in NO2 at Yokosuka and two remote sites (Fukue and Cape Hedo), respectively, regardless of the season except for fall at Fukue, but significant changes in NO2 are not observed at Gwangju, Korea. In contrast, OMI satellite data reveal an increase in the NO2 TropVCD at all sites except for Yokosuka, where a decreasing trend common to MAX-DOAS is found, suggesting that the results from satellites need to be cautiously used for investigating long-term trends in less polluted or remote areas. Using backward trajectories, potential source regions are identified for the two urban sites. The spatial distribution from OMI data shows good agreement with the potential source regions at Yokosuka. The potential source regions in Gwangju are identified as the National Industrial Complex in Yeosu and Gwangyang, while the transport route is not clearly visible with OMI data because of their low sensitivity in less polluted areas. The proposed approach is suitable for identifying potential source areas that might not be recognized by satellite observations.

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

2021 ◽  
Author(s):  
Song Liu ◽  
Pieter Valks ◽  
Gaia Pinardi ◽  
Jian Xu ◽  
Ka Lok Chan ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Transport Model ◽  
Estimation Algorithm ◽  
Point Sources ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Algorithm ◽  
Vertical Column ◽  
Chemistry Transport Model ◽  
Total Uncertainty ◽  
Tropospheric No2

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.

scholarly journals Tropospheric NO<sub>2</sub> column densities deduced from zenith-sky DOAS measurements in Shanghai, China, and their application to satellite validation

2009 ◽  
Vol 9 (11) ◽  
pp. 3641-3662 ◽  
Author(s):  
D. Chen ◽  
B. Zhou ◽  
S. Beirle ◽  
L. M. Chen ◽  
T. Wagner
Keyword(s):  
Satellite Data ◽  
Urban Site ◽  
Optical Absorption Spectroscopy ◽  
Vertical Column ◽  
Error Sources ◽  
Satellite Validation ◽  
Tropospheric No2 ◽  
Realistic Information ◽  
Good Agreement

Abstract. Zenith-sky scattered sunlight observations using differential optical absorption spectroscopy (DOAS) technique were carried out in Shanghai, China (31.3° N, 121.5° E) since December 2006. At this polluted urban site, the measurements provided NO2 total columns in the daytime. Here, we present a new method to extract time series of tropospheric vertical column densities (VCDs) of NO2 from these observations. The derived tropospheric NO2 VCDs are important quantities for the estimation of emissions and for the validation of satellite observations. Our method makes use of assumptions on the relative NO2 height profiles and the diurnal variation of stratospheric NO2 VCDs. The main error sources arise from the uncertainties in the estimated stratospheric slant column densities (SCDs) and the determination of tropospheric NO2 air mass factor (AMF). For a polluted site like Shanghai, the accuracy of our method is conservatively estimated to be <25% for solar zenith angle (SZA) lower than 70°. From simultaneously performed long-path DOAS measurements, the NO2 surface concentrations at the same site were observed and the corresponding tropospheric NO2 VCDs were estimated using the assumed seasonal NO2 profiles in the planetary boundary layer (PBL). By making a comparison between the tropospheric NO2 VCDs from zenith-sky and long-path DOAS measurements, it is found that the former provides more realistic information about total tropospheric pollution than the latter, so it's more suitable for satellite data validation. A comparison between the tropospheric NO2 VCDs from ground-based zenith-sky measurements and SCIAMACHY was also made. Satellite validation for a strongly polluted area is highly needed, but exhibits also a great challenge. Our comparison shows good agreement, considering in particular the different spatial resolutions between the two measurements. Remaining systematic deviations are most probably related to the uncertainties of satellite data caused by the assumptions on aerosol properties as well as the layer heights of aerosols and NO2.

scholarly journals Intercomparison of Pandora Stratospheric NO<sub>2</sub> Slant Column Product with the NIWA M07 NDACC Standard

2017 ◽  
Author(s):  
Travis N. Knepp ◽  
Richard Querel ◽  
Paul Johnston ◽  
Larry Thomason ◽  
David Flittner ◽  
...  
Keyword(s):  
Column Density ◽  
Atmospheric Composition ◽  
Reference Spectrum ◽  
Vertical Column ◽  
Common Reference ◽  
Retrieval Algorithms ◽  
Vertical Column Density ◽  
Mass Factor ◽  
Validation Tool ◽  
Good Agreement

Abstract. In September 2014 a Pandora multi-spectral photometer operated by the SAGE-III project was sent to Lauder, New Zealand to operate side-by-side with the National Institute of Water and Atmospheric Research's (NIWA) Network for Detection of atmospheric Composition Change (NDACC) standard zenith slant column NO2 instrument to allow intercomparison between the two instruments, and evaluation of the Pandora unit as a potential SAGE-III validation tool for stratospheric NO2. This intercomparison spanned a full year, from September 2014–September 2015. Both datasets were produced using their respective native algorithms using a common reference spectrum (i.e. 12:00 on 26 February 2015). Throughout the entire deployment period both instruments operated in a zenith-only observation configuration. Though conversion from slant column density (SCD) to vertical-column density is routine (by application of an air mass factor), we limit the current analysis to SCD only. This omission is beneficial in that it provides a strict intercomparison of the two instruments and the retrieval algorithms as opposed to introducing an AMF-dependence in the intercomparison as well. It was observed that the current hardware configurations and retrieval algorithms are in good agreement (R > 0.95). The detailed results of this investigation are presented herein.

scholarly journals Tropospheric NO<sub>2</sub> column densities deduced from zenith-sky DOAS measurements in Shanghai, China, and their application to satellite validation

2008 ◽  
Vol 8 (4) ◽  
pp. 16713-16762 ◽  
Author(s):  
D. Chen ◽  
B. Zhou ◽  
S. Beirle ◽  
L. M. Chen ◽  
T. Wagner
Keyword(s):  
Solar Zenith Angle ◽  
Surface Concentration ◽  
Urban Site ◽  
Optical Absorption Spectroscopy ◽  
Vertical Column ◽  
Satellite Validation ◽  
Tropospheric No2 ◽  
Realistic Information ◽  
Good Agreement

Abstract. Zenith-sky scattered sunlight observations using differential optical absorption spectroscopy (DOAS) technique were carried out in Shanghai, China (31.3° N, 121.5° E) since December 2006. At this polluted urban site, the measurement provided NO2 total columns in the daytime. Here, we present a new method to extract time series of tropospheric vertical column densities (VCD) of NO2 from these observations. The derived tropospheric NO2 VCD is an important quantity for the estimation of emissions and for the validation of satellite observations. Our method makes use of assumptions on the relative NO2 height profiles and on the diurnal variation of the stratospheric NO2 VCD. The influence of these parameters on the retrieved tropospheric NO2 VCD is discussed; for a polluted site like Shanghai, the accuracy of our method is estimated to be <20% for solar zenith angle (SZA) lower than 85°. From simultaneously performed long-path DOAS measurement, the NO2 surface concentration at the same site was observed and the corresponding tropospheric NO2 VCD was estimated using the assumed seasonal NO2 profiles in the planetary boundary layer (PBL). By making a comparison between the tropospheric NO2 VCD from zenith-sky and long-path DOAS measurements, it was found that the former provided more realistic information about total tropospheric pollution than the latter, so it's more suitable for satellite data validation than the in situ measurement. A comparison between the tropospheric NO2 VCD from ground-based zenith-sky measurement and SCIAMACHY was also made. Satellite validation for a strongly polluted area is highly needed, but exhibits also a great challenge. Our comparison showed good agreement, considering in particular the different spatial resolutions between the two measurements.

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