scholarly journals Limb–nadir matching using non-coincident NO<sub>2</sub> observations: Proof of concept and the OMI-minus-OSIRIS prototype product

2016 ◽  
Author(s):  
Cristen Adams ◽  
Elise N. Normand ◽  
Chris A. McLinden ◽  
Adam E. Bourassa ◽  
Nicholas D. Lloyd ◽  
...  
Keyword(s):  
Local Time ◽  
Infrared Imaging ◽  
Imaging System ◽  
Anthropogenic Source ◽  
Ozone Monitoring Instrument ◽  
Spectral Fitting ◽  
Model Following ◽  
Standard Product ◽  
Tropospheric No2 ◽  
One Year

Abstract. A variant of the limb-nadir matching technique for deriving tropospheric NO2 columns is presented in which the stratospheric component of the NO2 slant column density (SCD) measured by the Ozone Monitoring Instrument (OMI) is removed using non-coincident profiles from the Optical Spectrograph and InfraRed Imaging System (OSIRIS). In order to correct their mismatch in local time and the diurnal variation of stratospheric NO2, OSIRIS profiles, which were measured just after sunrise, were mapped to the local time of OMI observations using a photochemical box model. Following the profile time adjustment, OSIRIS NO2 stratospheric vertical columns densities (VCDs) were calculated. For profiles that did not reach down to the tropopause, VCDs were adjusted using the photochemical model. Using air mass factors from the OMI Standard Product (SP), a new tropospheric NO2 VCD product – referred to as OMI-minus-OSIRIS (OmO) – was generated through limb-nadir matching. To accomplish this, the OMI total SCDs were scaled using correction factors derived from the next-generation SCDs that improve upon the spectral fitting used for the current operational products. One year, 2008, of OmO was generated for 60°S to 60°N and a cursory evaluation was performed. The OmO product was found to capture the main features of tropospheric NO2 including a background value of about 0.3 × 1015 molecules/cm2 over the tropical Pacific and values comparable to the OMI operational products over anthropogenic source areas. While additional study is required, these results suggest that a limb-nadir matching approach is feasible for the removal of stratospheric NO2 measured by a polar orbiter from a nadir-viewing instrument in a geostationary orbit such as Tropospheric Emissions: Monitoring of Pollution (TEMPO) or Sentinel-4.

scholarly journals Limb–nadir matching using non-coincident NO<sub>2</sub> observations: proof of concept and the OMI-minus-OSIRIS prototype product

2016 ◽  
Vol 9 (8) ◽  
pp. 4103-4122 ◽  
Author(s):  
Cristen Adams ◽  
Elise N. Normand ◽  
Chris A. McLinden ◽  
Adam E. Bourassa ◽  
Nicholas D. Lloyd ◽  
...  
Keyword(s):  
Local Time ◽  
Infrared Imaging ◽  
Imaging System ◽  
Anthropogenic Source ◽  
Ozone Monitoring Instrument ◽  
Vertical Column ◽  
Model Following ◽  
Standard Product ◽  
Tropospheric No2 ◽  
One Year

Abstract. A variant of the limb–nadir matching technique for deriving tropospheric NO2 columns is presented in which the stratospheric component of the NO2 slant column density (SCD) measured by the Ozone Monitoring Instrument (OMI) is removed using non-coincident profiles from the Optical Spectrograph and InfraRed Imaging System (OSIRIS). In order to correct their mismatch in local time and the diurnal variation of stratospheric NO2, OSIRIS profiles, which were measured just after sunrise, were mapped to the local time of OMI observations using a photochemical box model. Following the profile time adjustment, OSIRIS NO2 stratospheric vertical column densities (VCDs) were calculated. For profiles that did not reach down to the tropopause, VCDs were adjusted using the photochemical model. Using air mass factors from the OMI Standard Product (SP), a new tropospheric NO2 VCD product – referred to as OMI-minus-OSIRIS (OmO) – was generated through limb–nadir matching. To accomplish this, the OMI total SCDs were scaled using correction factors derived from the next-generation SCDs that improve upon the spectral fitting used for the current operational products. One year, 2008, of OmO was generated for 60° S to 60° N and a cursory evaluation was performed. The OmO product was found to capture the main features of tropospheric NO2, including a background value of about 0.3 × 1015 molecules cm−2 over the tropical Pacific and values comparable to the OMI operational products over anthropogenic source areas. While additional study is required, these results suggest that a limb–nadir matching approach is feasible for the removal of stratospheric NO2 measured by a polar orbiter from a nadir-viewing instrument in a geostationary orbit such as Tropospheric Emissions: Monitoring of Pollution (TEMPO) or Sentinel-4.

scholarly journals Fast NO<sub>2</sub> retrievals from Odin-OSIRIS limb scatter measurements

2011 ◽  
Vol 4 (5) ◽  
pp. 965-972 ◽  
Author(s):  
A. E. Bourassa ◽  
C. A. McLinden ◽  
C. E. Sioris ◽  
S. Brohede ◽  
A. F. Bathgate ◽  
...  
Keyword(s):  
Infrared Imaging ◽  
Imaging System ◽  
Computational Cost ◽  
Data Sets ◽  
Proof Of Concept ◽  
Spectral Fitting ◽  
Analysis Technique ◽  
Order Of Magnitude ◽  
Very High ◽  
Good Agreement

Abstract. The feasibility of retrieving vertical profiles of NO2 from space-based measurements of limb scattered sunlight has been demonstrated using several different data sets since the 1980's. The NO2 data product routinely retrieved from measurements made by the Optical Spectrograph and InfraRed Imaging System (OSIRIS) instrument onboard the Odin satellite uses a spectral fitting technique over the 437 to 451 nm range, over which there are 36 individual wavelength measurements. In this work we present a proof of concept technique for the retrieval of NO2 using only 4 of the 36 OSIRIS measurements in this wavelength range, which reduces the computational cost by almost an order of magnitude. The method is an adaptation of a triplet analysis technique that is currently used for the OSIRIS retrievals of ozone at Chappuis band wavelengths. The results obtained are shown to be in very good agreement with the spectral fit method, and provide an important alternative for applications where the computational burden is very high. Additionally this provides a baseline for future instrument design in terms of cost effectiveness and reducing spectral range requirements.

scholarly journals The version 3 OMI NO<sub>2</sub> standard product

2017 ◽  
Vol 10 (9) ◽  
pp. 3133-3149 ◽  
Author(s):  
Nickolay A. Krotkov ◽  
Lok N. Lamsal ◽  
Edward A. Celarier ◽  
William H. Swartz ◽  
Sergey V. Marchenko ◽  
...  
Keyword(s):  
Western Europe ◽  
Transport Model ◽  
A Priori ◽  
Eastern China ◽  
Ozone Monitoring Instrument ◽  
Vertical Column ◽  
Spectral Fitting ◽  
Standard Product ◽  
Fitting Algorithm

Abstract. We describe the new version 3.0 NASA Ozone Monitoring Instrument (OMI) standard nitrogen dioxide (NO2) products (SPv3). The products and documentation are publicly available from the NASA Goddard Earth Sciences Data and Information Services Center (https://disc.gsfc.nasa.gov/datasets/OMNO2_V003/summary/). The major improvements include (1) a new spectral fitting algorithm for NO2 slant column density (SCD) retrieval and (2) higher-resolution (1° latitude and 1.25° longitude) a priori NO2 and temperature profiles from the Global Modeling Initiative (GMI) chemistry–transport model with yearly varying emissions to calculate air mass factors (AMFs) required to convert SCDs into vertical column densities (VCDs). The new SCDs are systematically lower (by ∼ 10–40 %) than previous, version 2, estimates. Most of this reduction in SCDs is propagated into stratospheric VCDs. Tropospheric NO2 VCDs are also reduced over polluted areas, especially over western Europe, the eastern US, and eastern China. Initial evaluation over unpolluted areas shows that the new SPv3 products agree better with independent satellite- and ground-based Fourier transform infrared (FTIR) measurements. However, further evaluation of tropospheric VCDs is needed over polluted areas, where the increased spatial resolution and more refined AMF estimates may lead to better characterization of pollution hot spots.

scholarly journals Fast NO<sub>2</sub> retrievals from Odin-OSIRIS limb scatter measurements

2010 ◽  
Vol 3 (6) ◽  
pp. 5499-5519
Author(s):  
A. E. Bourassa ◽  
C. A. McLinden ◽  
C. E. Sioris ◽  
S. Brohede ◽  
E. J. Llewellyn ◽  
...  
Keyword(s):  
Infrared Imaging ◽  
Imaging System ◽  
Computational Cost ◽  
Data Sets ◽  
Proof Of Concept ◽  
Spectral Fitting ◽  
Analysis Technique ◽  
Order Of Magnitude ◽  
Very High ◽  
Good Agreement

Abstract. The feasibility of retrieving vertical profiles of NO2 from space-based measurements of limb scattered sunlight has been demonstrated using several different data sets since the 1980's. The NO2 data product routinely retrieved from measurements made by the Optical Spectrograph and InfraRed Imaging System (OSIRIS) instrument onboard the Odin satellite uses a spectral fitting technique over the 437 to 451 nm range, over which there are 36 individual wavelength measurements. In this work we present a proof of concept technique for the retrieval of NO2 using only 4 of the 36 OSIRIS measurements in this wavelength range, which reduces the computational cost by almost an order of magnitude. The method is an adaptation of a triplet analysis technique that is currently used for the OSIRIS retrievals of ozone at Chappuis band wavelengths. The results obtained are shown to be in very good agreement with the spectral fit method, and provide an important alternative for two dimensional tomographic algorithms where the computational burden is very high. Additionally this provides a baseline for future instrument design in terms of cost effectiveness and boosting signal to noise by reducing spectral resolution requirements.

scholarly journals Validation of OMI tropospheric NO<sub>2</sub> column data using MAX-DOAS measurements deep inside the North China Plain in June 2006

2008 ◽  
Vol 8 (2) ◽  
pp. 8243-8271 ◽  
Author(s):  
H. Irie ◽  
Y. Kanaya ◽  
H. Akimoto ◽  
H. Tanimoto ◽  
Z. Wang ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Optical Absorption Spectroscopy ◽  
Ozone Monitoring Instrument ◽  
The North ◽  
The North China Plain ◽  
Standard Product ◽  
The Us ◽  
Tropospheric No2 ◽  
Independent Observations

Abstract. A challenge for the quantitative analysis of tropospheric nitrogen dioxide (NO2) column data from satellite observations is posed mainly by the lack of satellite-independent observations for validation. We performed such observations of the tropospheric NO2 column using the ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) technique in the North China Plain (NCP) from 29 May to 29 June 2006. Comparisons between tropospheric NO2 columns measured by MAX-DOAS and the Ozone Monitoring Instrument (OMI) onboard the Aura satellite indicate that OMI data (the standard product, version 3) over NCP may have a positive bias of 1.6×1015 molecules cm−2 (20%), where the estimated random error in the OMI data is 0.6×1015 molecules cm−2 or approximately 8%. Combining these results with literature validation results for the US, Europe, and Pacific Ocean suggests that a bias of +20%/–30% is a reasonable estimate, accounting for different regions. Considering the uncertainty estimated here will pave the way for quantitative studies using OMI NO2 data, especially over NCP.

scholarly journals Improved spectral fitting of nitrogen dioxide from OMI in the 405–465 nm window

2014 ◽  
Vol 7 (10) ◽  
pp. 10619-10671 ◽  
Author(s):  
J. H. G. M. van Geffen ◽  
K. F. Boersma ◽  
M. Van Roozendael ◽  
F. Hendrick ◽  
E. Mahieu ◽  
...  
Keyword(s):  
Nitrogen Dioxide ◽  
Water Vapour ◽  
Cross Section ◽  
Liquid Water ◽  
Ozone Monitoring Instrument ◽  
Wavelength Calibration ◽  
Spectral Fitting ◽  
Starting Point ◽  
Tropospheric No2 ◽  
Rms Error

Abstract. An improved nitrogen dioxide (NO2) slant column density retrieval for the Ozone Monitoring Instrument (OMI) in the 405–465 nm spectral region is presented. Since the launch of OMI on board NASA's EOS-Aura satellite in 2004, DOAS retrievals of NO2 slant column densities have been the starting point for the KNMI DOMINO (v2.0) and NASA SP (v2.1) retrievals. However, recent intercomparisons between NO2 retrievals from OMI and other UV/Vis and limb spectrometers, as well as ground-based measurements, clearly suggested that OMI stratospheric NO2 is biased high. This study revises the OMI NO2 retrieval in detail. The representation of the OMI slit function to convolve high-resolution reference spectra onto the relevant spectral grid is improved. The window used for the wavelength calibration is optimised, leading to much-reduced fitting errors. Ozone and water vapour spectra used in the fit are updated, reflecting the recently improved knowledge on their absorption cross section as documented in the literature. The improved spectral fit also accounts for absorption by the O2–O2 collision complex and by liquid water over clear-water areas. The main changes in the improved spectral fitting result from the updates related to the wavelength calibration: the RMS error of the fit is reduced by 23% and the NO2 slant column by 0.85 × 1015 molec cm−2, independent of latitude, solar zenith angle and NO2 value. Including O2–O2 and liquid water absorption and updating the O3 and water vapour cross-section spectra further reduces NO2 slant columns on average by 0.35 × 1015 molec cm−2, accompanied with a further 9% reduction in the RMS error of the fit. The improved OMI NO2 slant columns are consistent with independent NO2 retrievals to within a range that can be explained by photo-chemically driven diurnal increases in stratospheric NO2 and by small differences in fitting window and fitting approach. The revisions indicate that current OMI NO2 slant columns suffered mostly from an additive, positive offset that is removed by the improved wavelength calibration and representation of the OMI slit function. It is therefore anticipated that the improved NO2 slant columns are most important to retrievals of spatially homogeneous stratospheric NO2 rather than to heterogeneous tropospheric NO2.

scholarly journals A new stratospheric and tropospheric NO<sub>2</sub> retrieval algorithm for nadir-viewing satellite instruments: applications to OMI

2013 ◽  
Vol 6 (10) ◽  
pp. 2607-2626 ◽  
Author(s):  
E. J. Bucsela ◽  
N. A. Krotkov ◽  
E. A. Celarier ◽  
L. N. Lamsal ◽  
W. H. Swartz ◽  
...  
Keyword(s):  
Wave Pattern ◽  
Retrieval Algorithm ◽  
Ozone Monitoring Instrument ◽  
Transport Models ◽  
Standard Product ◽  
Tropospheric No2 ◽  
Novel Method ◽  
Made In ◽  
Satellite Instruments

Abstract. We describe a new algorithm for the retrieval of nitrogen dioxide (NO2) vertical columns from nadir-viewing satellite instruments. This algorithm (SP2) is the basis for the Version 2.1 OMI This algorithm (SP2) is the basis for the Version 2.1 Ozone Monitoring Instrument (OMI) NO2 Standard Product and features a novel method for separating the stratospheric and tropospheric columns. NO2 Standard Product and features a novel method for separating the stratospheric and tropospheric columns. The approach estimates the stratospheric NO2 directly from satellite data without using stratospheric chemical transport models or assuming any global zonal wave pattern. Tropospheric NO2 columns are retrieved using air mass factors derived from high-resolution radiative transfer calculations and a monthly climatology of NO2 profile shapes. We also present details of how uncertainties in the retrieved columns are estimated. The sensitivity of the retrieval to assumptions made in the stratosphere–troposphere separation is discussed and shown to be small, in an absolute sense, for most regions. We compare daily and monthly mean global OMI NO2 retrievals using the SP2 algorithm with those of the original Version 1 Standard Product (SP1) and the Dutch DOMINO product. The SP2 retrievals yield significantly smaller summertime tropospheric columns than SP1, particularly in polluted regions, and are more consistent with validation studies. SP2 retrievals are also relatively free of modeling artifacts and negative tropospheric NO2 values. In a reanalysis of an INTEX-B validation study, we show that SP2 largely eliminates an ~20% discrepancy that existed between OMI and independent in situ springtime NO2 SP1 measurements.

scholarly journals The version 3 OMI NO<sub>2</sub> standard product

2017 ◽  
Author(s):  
Nickolay A. Krotkov ◽  
Lok N. Lamsal ◽  
Edward A. Celarier ◽  
William H. Swartz ◽  
Sergey V. Marchenko ◽  
...  
Keyword(s):  
Western Europe ◽  
Transport Model ◽  
A Priori ◽  
Eastern China ◽  
Ozone Monitoring Instrument ◽  
Vertical Column ◽  
Spectral Fitting ◽  
Standard Product ◽  
Fitting Algorithm

Abstract. We describe the new, version 3.0 NASA Ozone Monitoring Instrument (OMI) standard nitrogen dioxide (NO2) products (SPv3). The products and documentation are publicly available from the NASA Goddard Earth Sciences Data and Information Services Center (https://disc.gsfc.nasa.gov/uui/datasets/OMNO2_V003/summary). The major improvements include: (1) new spectral fitting algorithm for NO2 slant column density (SCD) retrieval; (2) higher resolution (1° latitude and 1.25° longitude) a priori NO2 and temperature profiles from the Global Modeling Initiative (GMI) chemistry-transport model with yearly varying emissions to calculate air-mass factors (AMFs) required to convert SCDs into vertical column densities (VCDs). The new SCDs are systematically lower (by ~ 10 %–40 %) than previous, version 2, estimates. Most of this reduction in SCDs is propagated into stratospheric VCDs. Tropospheric NO2 VCDs are also reduced over polluted areas, especially over Western Europe, the eastern US and eastern China. Initial evaluation over unpolluted areas has shown that the new SPv3 products agree better with independent satellite and ground based FTIR measurements. However, further evaluation of tropospheric VCDs is needed over polluted areas, where the increased spatial resolution and more refined AMF estimates may lead to better characterization of pollution hotspots.

scholarly journals Validation of OMI tropospheric NO<sub>2</sub> column data using MAX-DOAS measurements deep inside the North China Plain in June 2006: Mount Tai Experiment 2006

2008 ◽  
Vol 8 (22) ◽  
pp. 6577-6586 ◽  
Author(s):  
H. Irie ◽  
Y. Kanaya ◽  
H. Akimoto ◽  
H. Tanimoto ◽  
Z. Wang ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Optical Absorption Spectroscopy ◽  
Ozone Monitoring Instrument ◽  
The North ◽  
The North China Plain ◽  
Standard Product ◽  
The Us ◽  
Tropospheric No2 ◽  
Independent Observations

Abstract. A challenge for the quantitative analysis of tropospheric nitrogen dioxide (NO2) column data from satellite observations is posed partly by the lack of satellite-independent observations for validation. We performed such observations of the tropospheric NO2 column using the ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) technique in the North China Plain (NCP) from 29 May to 29 June, 2006. Comparisons between tropospheric NO2 columns measured by MAX-DOAS and the Ozone Monitoring Instrument (OMI) onboard the Aura satellite indicate that OMI data (the standard product, version 3) over NCP may have a positive bias of 1.6×1015 molecules cm−2 (20%), yet within the uncertainty of the OMI data. Combining these results with literature validation results for the US, Europe, and Pacific Ocean suggests that a bias of +20%/−30% is a reasonable estimate, accounting for different regions.

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