| 11. |
- Brohede, Samuel, 1977
(författare)
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Satellite Limb-Scatter Observations of Stratospheric NO2 and O3 -Retrievals, Validation and Applications
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Global observations of vertically resolved atmospheric constituents with high temporal and spatial sampling are crucial for various scientific assessments of ozone depletion and climate change. This thesis explains how such data can be retrieved from satellite limb-scatter observations. The main focus is stratospheric NO2 and O3 measured by the the Optical Spectrograph and Infra-Red Imager System (OSIRIS) aboard the Swedish satellite Odin, although the principles can be used for any similar instrument, for other gases and atmospheric regions. The entire process from detector photon counts to a validated operational data product is covered.Transformations of observed radiances to effective column densities for NO2 and Chappuis triplets for O3 in combination with a normalization, significantly reduces the sensitivity to aerosol, clouds, instrument effects and absolute calibration. A maximum a posteriori inversion method produces well behaved data and provides estimates of measurement uncertainty and vertical resolution for individual profiles. Credible data are generally found between 12 and 42 km with a vertical resolution of around 2 km and random uncertainties of about 5\% for O3 and 10\% for NO2. External comparisons reveal good agreement between 25 and 35 km and long-term stability. Sensitivity studies identify four major concerns; stray light contamination, inaccurate pointing, atmospheric inhomogeneities and clouds.Applications of OSIRIS data and the construction of global climatologies of NO2, O3 and NOy are also presented together with model comparisons which indicate inaccurate simulations of heterogeneous nitrogen processes.
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| 12. |
- Brohede, Samuel, 1977, et al.
(författare)
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Validation of Odin/OSIRIS stratospheric NO2 profiles
- 2007
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 112:D07310
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the validation study of stratospheric NO2 profiles retrieved from Odin/OSIRIS measurements of limb-scattered sunlight (version 2.4). The Optical Spectrograph and Infrared Imager System (OSIRIS) NO2 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 NO2 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 NO2 profiles are well behaved, with reasonable uncertainty estimates between 15 km and 40 km. This unique NO2 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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| 13. |
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| 14. |
- Haley, C. S., et al.
(författare)
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Retrievals of stratospheric O3 and NO2 profiles from Odin Optical Spectrograph and InfraRed Imager System (OSIRIS) limb-scattered sunlight measurements
- 2004
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 109:D16
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Tidskriftsartikel (refereegranskat)abstract
- Scientific studies of the major environmental questions of global warming and ozone depletion require global data sets of atmospheric constituents with relevant temporal and spatial resolution. In this paper global number density profiles of O3 and NO2 are retrieved from Odin/OSIRIS limb-scattered sunlight measurements, using the Maximum A Posteriori estimator. Differential Optical Absorption Spectroscopy is applied to OSIRIS radiances as an intermediate step, using the wavelength windows 571-617 nm for O3 and 435-451 nm for NO2. The method is computationally efficient for processing OSIRIS data on an operational basis. Results show that a 2-3 km height resolution is generally achievable between about 12 km and 45 km for O3 with an estimated accuracy of 13\% at the peak and between about 15 km and 40 km for NO2 with an estimated accuracy of 10\% at the peak. First validations of the retrieved data indicate a good agreement both with other retrieval techniques applied to OSIRIS measurements and with the results of other instruments. Once the validation has reached a confident level, the retrieved data will be used to study important stratospheric processes relevant to global environmental problems. The unique NO2 data set will be of particular interest for studies of nitrogen chemistry in the middle atmosphere.
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| 15. |
- Haley, C. S., et al.
(författare)
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Status of the Odin/OSIRIS stratospheric O3 and NO2 data products
- 2007
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Ingår i: Canadian Journal of Physics. - 0008-4204 .- 1208-6045. ; 85:11, s. 1177-1194
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the status of the stratospheric ozone and nitrogen dioxide data products from the Optical Spectrograph and InfraRed Imager System (OSIRIS) instrument on the Odin satellite. The current version of the data products is 3.0, covering the period from November 2001 to the present. The O3 and NO2 retrieval methods are reviewed along with an overview of the error analyses and geophysical validation status.
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| 16. |
- Jones, A., et al.
(författare)
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Technical Note: A trace gas climatology derived from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) data set
- 2012
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 12:11, s. 5207-5220
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Tidskriftsartikel (refereegranskat)abstract
- The Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) aboard the Canadian satellite SCISAT (launched in August 2003) was designed to investigate the composition of the upper troposphere, stratosphere, and mesosphere. ACE-FTS utilizes solar occultation to measure temperature and pressure as well as vertical profiles of over thirty chemical species including O-3, H2O, CH4, N2O, CO, NO, NO2, N2O5, HNO3, HCl, ClONO2, CCl3F, CCl2F2, and HF. Global coverage for each species is obtained approximately over a three month period and measurements are made with a vertical resolution of typically 3-4 km. A quality-controlled climatology has been created for each of these 14 baseline species, where individual profiles are averaged over the period of February 2004 to February 2009. Measurements used are from the ACE-FTS version 2.2 data set including updates for O-3 and N2O5. The climatological fields are provided on a monthly and three-monthly basis (DJF, MAM, JJA, SON) at 5 degree latitude and equivalent latitude spacing and on 28 pressure surfaces (26 of which are defined by the Stratospheric Processes And their Role in Climate (SPARC) Chemistry-Climate Model Validation Activity). The ACE-FTS climatological data set is available through the ACE website.
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| 17. |
- Kerzenmacher, T., et al.
(författare)
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Validation of NO2 and NO from the Atmospheric Chemistry Experiment (ACE)
- 2008
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 8:19, s. 5801--5841-
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Tidskriftsartikel (refereegranskat)abstract
- Vertical profiles of NO2 and NO have been obtained from solar occultation measurements by the Atmospheric Chemistry Experiment (ACE), using an infrared Fourier Transform Spectrometer (ACE-FTS) and (for NO2) an ultraviolet-visible-near-infrared spectrometer, MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation). In this paper, the quality of the ACE-FTS version 2.2 NO2 and NO and the MAESTRO version 1.2 NO2 data are assessed using other solar occultation measurements (HALOE, SAGE II, SAGE III, POAM III, SCIAMACHY), stellar occultation measurements (GOMOS), limb measurements (MIPAS, OSIRIS), nadir measurements (SCIAMACHY), balloon-borne measurements (SPIRALE, SAOZ) and ground-based measurements (UV-VIS, FTIR). Time differences between the comparison measurements were reduced using either a tight coincidence criterion, or where possible, chemical box models. ACE-FTS NO2 and NO and the MAESTRO NO2 are generally consistent with the correlative data. The ACE-FTS and MAESTRO NO2 volume mixing ratio (VMR) profiles agree with the profiles from other satellite data sets to within about 20% between 25 and 40 km, with the exception of MIPAS ESA (for ACE-FTS) and SAGE II (for ACE-FTS (sunrise) and MAESTRO) and suggest a negative bias between 23 and 40 km of about 10%. MAESTRO reports larger VMR values than the ACE-FTS. In comparisons with HALOE, ACE-FTS NO VMRs typically (on average) agree to ±8% from 22 to 64 km and to +10% from 93 to 105 km, with maxima of 21% and 36%, respectively. Partial column comparisons for NO2 show that there is quite good agreement between the ACE instruments and the FTIRs, with a mean difference of +7.3% for ACE-FTS and +12.8% for MAESTRO.
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| 18. |
- Khosravi, Maryam, 1975, et al.
(författare)
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Climatologies of stratospheric short-lived species from Odin/SMR: Methodology for ClO
- 2013
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Ingår i: Proceedings ESA Living Planet Symposium, 9-13 September 2013, Edinburgh (UK). ESA-SP-722 : European Space Agency, Noordwijk, The Netherlands. - 1609-042X. - 9789292212865 ; , s. 1-6
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Sub-Millimetre Radiometer (SMR) on board theOdin satellite has been measuring short-lived strato-spheric species such as chlorine monoxide (ClO) sinceOdin’s launch in 2001. Odin/SMR at its sun-synchronousorbit measures at certain local times observations aroundsunrise and sunset at the equator. Due to the drift ofOdin’s orbit in local solar time and the fact that mea-surements are done at different local times, a correctionis required before a monthly zonal mean climatologycan be calculated and trends of ClO can be evaluated.To deal with this, scaling factors are calculated using aphoto-chemical box model for correction of the mixingratios respective to a reference time. The uncertaintiesand limitations of this method are estimated by checkingthe internal consistency of the results, so that comparingthe scaled a.m. ClO time-series to p.m. scaled time-series should give the same results. We found out thatscaling SMR ClO to the ascending time of MicrowaveLimb Sounder (MLS) as reference at about 1.30 a.m. atthe equator gives better result compared to the scalingClO to MLS descending node at about 1.30. p.m. Thetime series calculated for the morning SMR ClO scaled(to 1.30 a.m.) agrees with the evening ClO scaled.
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| 19. |
- Llewellyn, E.J., et al.
(författare)
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The OSIRIS Instrument on the Odin Spacecraft
- 2004
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Ingår i: Canadian Journal of Physics. - 0008-4204 .- 1208-6045. ; 82:6, s. 411-422
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Tidskriftsartikel (refereegranskat)abstract
- The optical spectrograph and infrared imager system (OSIRIS) on board the Odin spacecraft is designed to retrieve altitude profiles of terrestrial atmospheric minor species by observing limb-radiance profiles. The grating optical spectrograph (OS) obtains spectra of scattered sunlight over the range 280-800 nm with a spectral resolution of approximately 1 nm. The Odin spacecraft performs a repetitive vertical limb scan to sweep the OS 1 km vertical field of view over selected altitude ranges from approximately 10 to 100 km. The terrestrial absorption features that are superimposed on the scattered solar spectrum are monitored to derive the minor species altitude profiles. The spectrograph also detects the airglow, which can be used to study the mesosphere and lower thermosphere. The other part of OSIRIS is a three-channel infrared imager (IRI) that uses linear array detectors to image the vertical limb radiance over an altitude range of approximately 100 km. The IRI observes both scattered sunlight and the airglow emissions from the oxygen infrared atmospheric band at 1.27 mum and the OH (3-1) Meinel band at 1.53 mum. A tomographic inversion technique is used with a series of these vertical images to derive the two-dimensional distribution of the emissions within the orbit plane.
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| 20. |
- McLinden, C. A., et al.
(författare)
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OSIRIS: A Decade of Scattered Light
- 2012
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Ingår i: Bulletin of the American Meteorological Society. - 0003-0007 .- 1520-0477. ; 93:12, s. 1845-1863
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Tidskriftsartikel (refereegranskat)abstract
- Into year 11 of a 2-yr mission, OSIRIS is redefining how limb-scattered sunlight can be used to probe the atmosphere, even into the upper troposphere.
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