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- Clerbaux, C., et al.
(author)
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CO measurements from the ACE-FTS satellite instrument: data analysis and validation using ground-based, airborne and spaceborne observations
- 2008
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In: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 8, s. 2569-2594
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Journal article (peer-reviewed)abstract
- The Atmospheric Chemistry Experiment (ACE) mission was launched in August 2003 to sound the atmosphere by solar occultation. Carbon monoxide (CO), a good tracer of pollution plumes and atmospheric dynamics, is one of the key species provided by the primary instrument, the ACE-Fourier Transform Spectrometer (ACE-FTS). This instrument performs measurements in both the CO 1-0 and 2-0 ro-vibrational bands, from which vertically resolved CO concentration profiles are retrieved, from the mid-troposphere to the thermosphere. This paper presents an updated description of the ACE-FTS version 2.2 CO data product, along with a comprehensive validation of these profiles using available observations (February 2004 to December 2006). We have compared the CO partial columns with ground-based measurements using Fourier transform infrared spectroscopy and millimeter wave radiometry, and the volume mixing ratio profiles with airborne (both high-altitude balloon flight and airplane) observations. CO satellite observations provided by nadir-looking instruments (MOPITT and TES) as well as limb-viewing remote sensors (MIPAS, SMR and MLS) were also compared with the ACE-FTS CO products. We show that the ACE-FTS measurements provide CO profiles with small retrieval errors (better than 5% from the upper troposphere to 40 km, and better than 10% above). These observations agree well with the correlative measurements, considering the rather loose coincidence criteria in some cases. Based on the validation exercise we assess the following uncertainties to the ACE-FTS measurement data: better than 15% in the upper troposphere (8–12 km), than 30% in the lower stratosphere (12–30 km), and than 25% from 30 to 100 km.
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- Barret, B., et al.
(author)
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Intercomparisons of trace gases profiles from the Odin/SMR and Aura/MLS limb sounders
- 2006
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In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 111:D21
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Journal article (peer-reviewed)abstract
- This paper presents the intercomparison of O(3), HNO(3), ClO, N(2)O and CO profiles measured by the two spaceborne microwave instruments MLS ( Microwave Limb Sounder) and SMR ( Submillimetre Radiometer) on board the Aura and Odin satellites, respectively. We compared version 1.5 level 2 data from MLS with level 2 data produced by the French data processor version 222 and 225 and by the Swedish data processor version 2.0 for several days in September 2004 and in March 2005. For the five gases studied, an overall good agreement is found between both instruments. Most of the observed discrepancies between SMR and MLS are consistent with results from other intercomparison studies involving MLS or SMR. O(3) profiles retrieved from the SMR 501.8 GHz band are noisier than MLS profiles but mean biases between both instruments do not exceed 10%. SMR HNO(3) profiles are biased low relative to MLS's by similar to 30% above the profile peak. In the lower stratosphere, MLS ClO profiles are biased low by up to 0.3 ppbv relative to coincident SMR profiles, except in the Southern Hemisphere polar vortex in the presence of chlorine activation. N(2)O profiles from both instruments are in very good agreement with mean biases not exceeding 15%. Finally, the intercomparison between SMR and MLS CO profiles has shown a good agreement from the middle stratosphere to the middle mesosphere in spite of strong oscillations in the MLS profiles. In the upper mesosphere, MLS CO concentrations are biased high relative to SMR while negative values in the MLS retrievals are responsible for a negative bias in the tropics around 30 hPa.
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| 4. |
- Berthet, G., et al.
(author)
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Nighttime chlorine monoxide observations by the Odin satellite and implications for the ClO/Cl2O2 equilibrium
- 2005
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In: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 32:11, s. 1-5
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Journal article (peer-reviewed)abstract
- We use measurements of chlorine monoxide (ClO) by the SMR instrument onboard the Odin satellite to study the nighttime thermal equilibrium between ClO and its dimer Cl2O2. Observations performed in the polar vortex during the 2002-2003 Arctic winter showed enhanced amounts of nighttime ClO over a wide range of stratospheric temperatures (185
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| 5. |
- Dupuy, E., et al.
(author)
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Strato-mesospheric Measurements of Carbon Monoxide with the Odin Sub-millimetre Radiometer: Retrieval and First Results
- 2004
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In: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 31:20
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Journal article (peer-reviewed)abstract
- The Sub-Millimetre Radiometer (SMR) aboard the Odin satellite has been measuring vertical profiles of atmospheric trace gases since August 2001. We present the inversion methodology developed for CO measurements and the first retrieval results. CO can be retrieved from a single scan measurement throughout the middle atmosphere, with a typical resolution of similar to3 km and a relative error of similar to10% to similar to25%. Retrieval results are evaluated through comparison with data from the Whole Atmosphere Community Climate Model (WACCM) and observations of the Improved Stratospheric and Mesospheric Sounder (ISAMS) on board the Upper Atmospheric Research Satellite (UARS). Considering the large natural variability of CO, the SMR retrievals give good confirmation of the WACCM results, with an overall agreement within a factor of 2. ISAMS abundances are higher than SMR mixing ratios by a factor of 5-10 above 0.5 hPa from similar to80degreesS to similar to50degreesN.
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| 9. |
- Urban, Joachim, 1964, et al.
(author)
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Odin/SMR Limb Observations of Stratospheric Trace Gases: Level 2 Processing of ClO, N2O, O3, and HNO3
- 2005
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In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 110:D14, s. 1-20
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Journal article (peer-reviewed)abstract
- The Sub-Millimetre Radiometer (SMR) on board the Odin satellite, launched on 20 February 2001, observes key species with respect to stratospheric chemistry and dynamics such as O-3, ClO, N2O, and HNO3 using two bands centered at 501.8 and 544.6 GHz. We present the adopted methodology for level 2 processing and the achieved in-orbit measurement capabilities of the SMR radiometer for these species in terms of altitude range, altitude resolution, and measurement precision. The characteristics of the relevant level 2 data versions, namely version 1.2 of the operational processor as well as versions 222 and 223 of the reference code, are discussed and differences are evaluated. An analysis of systematic retrieval errors, resulting from spectroscopic and instrumental uncertainties, is also presented.
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| 10. |
- Urban, Joachim, 1964, et al.
(author)
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Odin/SMR limb observations of stratospheric trace gases: Validation of N2O
- 2005
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In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 110:9, s. D09301-20
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Journal article (peer-reviewed)abstract
- The Sub-Millimetre Radiometer (Odin/SMR) on board the Odin satellite, launched on 20 February 2001, performs regular measurements of the global distribution of stratospheric nitrous oxide (N2O) using spectral observations of the J = 20→ 19 rotational transition centered at 502.296 GHz. We present a quality assessment for the retrieved N2O profiles (level 2 product) by comparison with independent balloonborne and aircraftborne validation measurements as well as by cross-comparing with preliminary results from other satellite instruments. An agreement with the airborne validation experiments within 28 ppbv in terms of the root mean square (RMS) deviation is found for all SMR data versions (v222, v223, and v1.2) under investigation. More precisely, the agreement is within 19 ppbv for N2O volume mixing ratios (VMR) lower than 200 ppbv and within 10% for mixing ratios larger than 150 ppbv. Given the uncertainties due to atmospheric variability inherent to such comparisons, these values should be interpreted as upper limits for the systematic error of the Odin/SMR N2O measurements. Odin/SMR N2O mixing ratios are systematically slightly higher than nonvalidated data obtained from the Improved Limb Atmospheric Spectrometer-II (ILAS-II) on board the Advanced Earth Observing Satellite-II (ADEOS-II). Root mean square deviations are generally within 23 ppbv (or 20% for VMR-N2O > 100 ppbv) for versions 222 and 223. The comparison with data obtained from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on the Envisat satellite yields a good agreement within 9-17 ppbv (or 10% for VMR-N2O > 100 ppbv) for the same data versions. Odin/SMR version 1.2 data show somewhat larger RMS deviations and a higher positive bias.
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