SAGE II inversion algorithm

Chu, William; McCormick, M. P.; Lenoble, J.; Brogniez, Colette; Pruvost, Pierre

doi:10.1029/jd094id06p08339

Cited by 284 publications

(208 citation statements)

References 18 publications

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“…[28] Slant columns of NO 2 are calculated from the 448 nm and 453 nm channels using a differential technique [Chu and McCormick, 1989]. Vertical profiles are then retrieved between 15 km and 60 km using an onion peeling procedure, where the NO 2 slant columns are smoothed prior to peeling.…”

Section: Sage II Instrumentmentioning

confidence: 99%

Validation of Odin/OSIRIS stratospheric NO₂ profiles

Brohede¹,

Haley²,

McLinden³

et al. 2007

J. Geophys. Res.

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[1] This paper presents the validation study of stratospheric NO 2 profiles retrieved from Odin/OSIRIS measurements of limb-scattered sunlight (version 2.4). The Optical Spectrograph and Infrared Imager System (OSIRIS) NO 2 data set is compared to coincident solar occultation measurements by the Halogen Occultation Experiment (HALOE), Stratospheric Aerosol and Gas Experiment (SAGE) II, SAGE III, and Polar Ozone and Aerosol Measurement (POAM) III during the 2002-2004 period. Comparisons with seven Systeme d'Analyse par Observation Zenithal (SAOZ) balloon measurements are also presented. All comparisons show good agreement, with differences, both random and systematic, of less than 20% between 25 km and 35 km. Inconsistencies with SAGE III below 25 km are found to be caused primarily by diurnal effects from varying NO 2 concentrations along the SAGE III line-of-sight. On the basis of the differences, the OSIRIS random uncertainty is estimated to be 16% between 15 km and 25 km, 6% between 25 km and 35 km, and 9% between 35 km and 40 km. The estimated systematic uncertainty is about 22% between 15 and 25 km, 11-21% between 25 km and 35 km, and 11-31% between 35 km and 40 km. The uncertainties for AM (sunrise) profiles are generally largest and systematic deviations are found to be larger at equatorial latitudes. The results of this validation study show that the OSIRIS NO 2 profiles are well behaved, with reasonable uncertainty estimates between 15 km and 40 km. This unique NO 2 data set, with more than hemispheric coverage and high vertical resolution will be of particular interest for studies of nitrogen chemistry in the middle atmosphere, which is closely linked to ozone depletion.

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Section: Sage II Instrumentmentioning

confidence: 99%

Validation of Odin/OSIRIS stratospheric NO₂ profiles

Brohede¹,

Haley²,

McLinden³

et al. 2007

J. Geophys. Res.

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“…Furthermore, different quantities may be implied as, for instance, the mean radius ro, the standard deviation ln(s), or the refractive index rt r. This could require the selection of a different order for the inversions, i.e., vertical first, spectral second [see Chu et al, 1989], for which the amount of work has to be compared with respect to the gained accuracy. Indeed, in this approach, which has been implemented by the LOA group in order to validate the SAGE II generic algorithm, the total extinction coefficient is computed first for each stratospheric layer before the species separation.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore the difficult problem of determining the optimal regularization for an underlying unknown distribution is replaced by a simple smoothness constraint on its integral which is easily verified by a polynomial. Once again, we underline that the choice of a polynomial in X is arbitrary and that many other forms could be used, for instance, the one depending on ln(X) in the Laboratoire d'Optique Atmosph6rique (LOA) algorithm [see Chu et al, 1989]. The main point is that the determination of the optimal R value is now irrelevant.…”

Section: The Interpolation Problemmentioning

confidence: 99%

A critical analysis of the Stratospheric Aerosol and Gas Experiment II spectral inversion algorithm

Fussen¹

1998

J. Geophys. Res.

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Abstract. The ozone long-term trends derived from the Stratospheric Aerosol and Gas Experiment II have been shown to be biased by the level of volcanic aerosol. We have investigated the spectral algorithm used to separate the partial optical thicknesses associated with ozone and aerosols. We present two possible causes of inaccuracies capable of producing relative errors on the slant path ozone optical thickness as large as 5-15%. The first one is related to the interpolation of the aerosol optical thickness at 0.6 /am which is not very well performed by solving the inverse problem of the unknown size distribution. The second error cause lies in the assumed altitude independence of the aerosol optical properties. Both error causes are discussed, and possible corrections are presented.

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“…A radiative transfer model [7] is used to calculate simulated limb radiances, with inputs from nearby SAGE II [8] ozone, aerosol, and NO 2 profiles, as well as NCEP temperature and pressure that accompany the SAGE files, so as to accurately model limb scattering radiances at the GOMOS measurement location, and characterize stray light signals. Radiance profiles were constructed at selected pixels relevant to the retrieval algorithm and compared to GOMOS measurements.…”

Section: Figure 2: Example Of Radiance Level Of Contamination By Stramentioning

confidence: 99%

<title>Global ozone monitoring by occultation of stars</title>

Bertaux¹

1991

Future European and Japanese Remote-Sensing Sensors and Programs

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We analyzed a set of GOMOS bright limb measurements with solar zenith angles less than 80 o , and within 150 km of SAGE II measurements. In order to perform any species retrieval, GOMOS measurements were first corrected for stray light contamination. Ozone profile retrievals were performed using GOMOS data in the OMPS limb profiler algorithm in order to evaluate code functionality under different atmospheric conditions, assess the accuracy of the pointing algorithm, and identify potential improvements.The OMPS algorithm performs a simultaneous optimal estimation inversion of both Hartley-Huggins and Chappuis band radiances. GOMOS ozone retrievals are restricted to 25-53 km because of signal saturation and residual stray light. The retrieved ozone profiles agree with collocated SAGE II measurements on average to within 10%, and with a standard deviation of 10%. Retrieval results were consistent for both upper and lower GOMOS detector bands.

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SAGE II inversion algorithm

Cited by 284 publications

References 18 publications

Validation of Odin/OSIRIS stratospheric NO₂ profiles

Validation of Odin/OSIRIS stratospheric NO₂ profiles

A critical analysis of the Stratospheric Aerosol and Gas Experiment II spectral inversion algorithm

<title>Global ozone monitoring by occultation of stars</title>

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SAGE II inversion algorithm

Cited by 284 publications

References 18 publications

Validation of Odin/OSIRIS stratospheric NO2 profiles

Validation of Odin/OSIRIS stratospheric NO2 profiles

A critical analysis of the Stratospheric Aerosol and Gas Experiment II spectral inversion algorithm

<title>Global ozone monitoring by occultation of stars</title>

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Validation of Odin/OSIRIS stratospheric NO₂ profiles

Validation of Odin/OSIRIS stratospheric NO₂ profiles