1. |
- Kasai, Y., et al.
(författare)
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Validation of stratospheric and mesospheric ozone observed by SMILES from International Space Station
- 2013
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 6:9, s. 2311-2338
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Tidskriftsartikel (refereegranskat)abstract
- We observed ozone (O3) in the vertical region between 250 and 0.0005 hPa (~ 12–96 km) using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the Japanese Experiment Module (JEM) of the International Space Station (ISS) between 12 October 2009 and 21 April 2010. The new 4 K superconducting heterodyne receiver technology of SMILES allowed us to obtain a one order of magnitude better signal-to-noise ratio for the O3 line observation compared to past spaceborne microwave instruments. The non-sun-synchronous orbit of the ISS allowed us to observe O3 at various local times. We assessed the quality of the vertical profiles of O3 in the 100–0.001 hPa (~ 16–90 km) region for the SMILES NICT Level 2 product version 2.1.5. The evaluation is based on four components: error analysis; internal comparisons of observations targeting three different instrumental setups for the same O3 625.371 GHz transition; internal comparisons of two different retrieval algorithms; and external comparisons for various local times with ozonesonde, satellite and balloon observations (ENVISAT/MIPAS, SCISAT/ACE-FTS, Odin/OSIRIS, Odin/SMR, Aura/MLS, TELIS). SMILES O3 data have an estimated absolute accuracy of better than 0.3 ppmv (3%) with a vertical resolution of 3–4 km over the 60 to 8 hPa range. The random error for a single measurement is better than the estimated systematic error, being less than 1, 2, and 7%, in the 40–1, 80–0.1, and 100–0.004 hPa pressure regions, respectively. SMILES O3 abundance was 10–20% lower than all other satellite measurements at 8–0.1 hPa due to an error arising from uncertainties of the tangent point information and the gain calibration for the intensity of the spectrum. SMILES O3 from observation frequency Band-B had better accuracy than that from Band-A. A two month period is required to accumulate measurements covering 24 h in local time of O3 profile. However such a dataset can also contain variation due to dynamical, seasonal, and latitudinal effects
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2. |
- 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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3. |
- Gattinger, R. L., et al.
(författare)
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H Balmer lines in terrestrial aurora : Historical record and new observations by OSIRIS on Odin
- 2010
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 115, s. A09306-
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Tidskriftsartikel (refereegranskat)abstract
- The H Balmer emissions were first identified in terrestrial aurora by Vegard (1939). The earliest photographic spectral observations are reviewed. In the subsequent decade, the intensity ratios for H alpha, H beta, and H gamma were measured, and the well-known line broadening and blue shift were established. Recently, the H alpha, H gamma, H delta, and H epsilon features have been measured by OSIRIS on Odin. The Balmer components are resolved from other auroral features using sets of synthetic spectra. The measured intensity ratios are in good agreement with an extensive set of published model calculations. The presented observations are in the polar region averaged over limb tangent altitudes from 100 to 105 km, approximately perpendicular to the terrestrial magnetic field lines, for this geometry showing Doppler broadening without obvious Doppler shifts. The OSIRIS-measured full-width at half-height of the Ha feature is 2.2 nm corresponding to an H atom velocity of 500 km s(-1) and energy approximately 1.3 keV.
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4. |
- Bourassa, A. E., et al.
(författare)
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Fast NO2 retrievals from Odin-OSIRIS limb scatter measurements
- 2011
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 4:5, s. 965-972
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Tidskriftsartikel (refereegranskat)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.
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5. |
- Sheese, P. E., et al.
(författare)
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Odin observations of Antarctic nighttime NO densities in the mesosphere - lower thermosphere and observations of a lower NO layer
- 2013
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Ingår i: Journal of Geophysical Research. - : American Geophysical Union (AGU). - 0148-0227 .- 2156-2202 .- 2169-897X. ; 118:13, s. 7414-7425
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Tidskriftsartikel (refereegranskat)abstract
- The Optical Spectrograph and Infrared Imaging System (OSIRIS) on the Odin satellite currently has an eight-year dataset of nighttime Antarctic nitric oxide densities, [NO], in the mesosphere–lower thermosphere (MLT) region. In this work, the OSIRIS data are compared with a similar data set from the Sub-Millimeter Radiometer (SMR), also on the Odin satellite. Both of the Odin data sets are compared with twilight [NO] from the Atmospheric Chemistry Experiment–Fourier Transform Spectrometer (ACE-FTS) on the SciSat-I satellite. Direct comparisons of OSIRIS and SMR profiles show large differences, indicating that the individual [NO] profiles of one or both data sets may not be valid. However, when comparing averaged [NO], variations on timescales of weeks-years in all three data sets are in good agreement and correspond to the 27 day and 11 year solar cycles. The averaged OSIRIS values are typically 10% greater than SMR and 30% greater than ACE-FTS, which are within the estimated OSIRIS systematic uncertainties. These results suggest that the satellite-derived data sets can be used for determining polar-mean NO climatology and variations on timescales of weeks-years. The OSIRIS and SMR nighttime data sets show that the [NO] peak height in the MLT decreases throughout the autumn, from an altitude near or above 100 km to a minimum altitude ranging from 90 to 95 km around winter solstice. A similar decrease in [NO] peak height is observed in modeled NO climatology from the Specified Dynamics–Whole Atmosphere Community Climate Model (SD-WACCM), although the SD-WACCM climatology exhibits a decrease throughout autumn from 107 km down to 102 km. The results suggest that global climate models require more sophisticated auroral forcing simulations in order to reproduce observed NO variations in this region.
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