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| 2. |
- Jones, N., et al.
(författare)
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Stratomesospheric CO measured by a ground-based Fourier Transform Spectrometer over Poker Flat, Alaska: Comparisons with Odin/SMR and a 2-D model
- 2007
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 112:D20
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Tidskriftsartikel (refereegranskat)abstract
- The interseasonal variability of stratomesospheric CO is reported from Poker Flat, Alaska, using spectra from a ground-based Fourier Transform Spectrometer (gb-FTS) for the time period from 2000 to 2004. The CO spectra were analyzed using an optimal estimation technique that separates the tropospheric and stratospheric/mesospheric components into partial columns. The distribution of CO in the polar winter is such that the gb-FTS retrieved partial column is weighted to the mesosphere. The gb-FTS data are compared with measurements of partial column CO from the Sub-Millimeter Radiometer on board the Odin satellite and shown to be in very good agreement despite the relatively small sample size. The mean difference of the two data sets indicates a small positive bias (7.6 +/- 6%) in favor of the Odin data, with a correlation coefficient, r(2) = 0.91. The gb-FTS data indicate that there is a strong seasonal dependence of the CO partial column that is consistent with known winter polar thermospheric descent of CO enriched air. Year-to-year variability is explained in terms of mesospheric wind dynamics, which show 2004 and components of 2002 were affected by earlier than expected breakdown (30 +/- 13 d) of the winter polar circulation compared with 2000 to 2003. Finally, the measured CO data is compared with a 2-D chemical transport model that gives support to the idea that springtime polar mesospheric CO is driven by meridional winds.
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| 4. |
- Wolff, M.A., et al.
(författare)
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Validation of HNO3, ClONO2 and N2O5 from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS)
- 2008
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 8:13, s. 3529-3562
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Tidskriftsartikel (refereegranskat)abstract
- The Atmospheric Chemistry Experiment (ACE) satellite was launched on 12 August 2003. Its two instruments measure vertical profiles of over 30 atmospheric trace gases by analyzing solar occultation spectra in the ultraviolet/visible and infrared wavelength regions. The reservoir gases HNO3, ClONO2, and N2O5 are three of the key species provided by the primary instrument, the ACE Fourier Transform Spectrometer (ACE-FTS). This paper describes the ACE-FTS version 2.2 data products, including the N2O5 update, for the three species and presents validation comparisons with available observations. We have compared volume mixing ratio (VMR) profiles of HNO3, ClONO2, and N2O5 with measurements by other satellite instruments (SMR, MLS, MIPAS), aircraft measurements (ASUR), and single balloon-flights (SPIRALE, FIRS-2). Partial columns of HNO3 and ClONO2 were also compared with measurements by ground-based Fourier Transform Infrared (FTIR) spectrometers. Overall the quality of the ACE-FTS v2.2 HNO3 VMR profiles is good from 18 to 35 km. For the statistical satellite comparisons, the mean absolute differences are generally within ±1 ppbv ±20%) from 18 to 35 km. For MIPAS and MLS comparisons only, mean relative differences lie within±10% between 10 and 36 km. ACE-FTS HNO3 partial columns (~15–30 km) show a slight negative bias of −1.3% relative to the ground-based FTIRs at latitudes ranging from 77.8° S–76.5° N. Good agreement between ACE-FTS ClONO2 and MIPAS, using the Institut für Meteorologie und Klimaforschung and Instituto de Astrofísica de Andalucía (IMK-IAA) data processor is seen. Mean absolute differences are typically within ±0.01 ppbv between 16 and 27 km and less than +0.09 ppbv between 27 and 34 km. The ClONO2 partial column comparisons show varying degrees of agreement, depending on the location and the quality of the FTIR measurements. Good agreement was found for the comparisons with the midlatitude Jungfraujoch partial columns for which the mean relative difference is 4.7%. ACE-FTS N2O5 has a low bias relative to MIPAS IMK-IAA, reaching −0.25 ppbv at the altitude of the N2O5 maximum (around 30 km). Mean absolute differences at lower altitudes (16–27 km) are typically −0.05 ppbv for MIPAS nighttime and ±0.02 ppbv for MIPAS daytime measurements.
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| 5. |
- Baron, P., et al.
(författare)
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AMATERASU: Model for atmospheric TeraHertz Radiation analysis and simulation
- 2008
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Ingår i: Journal of the National Institute of Information and Communications Technology. - 1349-3205. ; 55:1, s. 109-121
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Tidskriftsartikel (refereegranskat)abstract
- We describe the current status of the Advanced Model for Atmospheric TeraHertz Radiation Analysis and Simulation (AMATERASU) that is being developed in the framework of the NICT THz project. This code aims to be used for studying the insterest of the THz frequency region for atmospheric remote sensing, communication systems and estimate the impact of the THz thermal atmospheric emission in the Earth energy budget. This paper presents the first stage of the model development that concerns a non scattering and a horizontal homogeneous atmosphere, e.g., the geophysical parameters are only altitude dependent. A scattering module is being developed but it is presented in an other paper in this issue. The model is based on the Microwave Observation and Lines Estimation and REtrieval code (MOLIERE). The absorption coefficient module has been modified in order to extend the frequency coverage from the submillimeter wavelength to the near InfraRed region. A new radiative transfer module has been implemented that can handle the different types of optical paths and any location for the receiver. AMATERASU includes the original MOLIERE instrument simulator and retrieval codes. The validation methodology is discussed and some examples of the current applications are given. The next steps of the development are presented in the conclusion including the modeling of the horizontal inhomogeneties in the atmopshere.
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| 6. |
- Baron, P., et al.
(författare)
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HO2 measurements in the stratosphere and the mesosphere from the sub-millimetre limb sounder Odin/SMR
- 2009
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Ingår i: International Journal of Remote Sensing. - : Informa UK Limited. - 1366-5901 .- 0143-1161. ; 30:15-16, s. 4195-4208
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents observations of the hydroperoxy radical (HO 2 ) performed by the Odin/SMR instrument from the middle stratosphere to the upper mesosphere (35-90 km). The data set covers the period from October 2003 to December 2005 on a basis of one observation period of 24 hours each month. Odin/SMR can provide two zonal maps of HO 2 per day, with a vertical resolution of 10 km. The non-standard processing applied to the retrievals is described. The consistency between HO 2 observations from three periods in August 2004 demonstrates the robustness of the retrieval method. It also shows that the measurements are sensitive enough to detect changes in the middle and upper mesosphere. The retrieval needs further improvements for studying stratospheric variations. © 2009 Taylor & Francis.
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| 7. |
- Clerbaux, C., et al.
(författare)
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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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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 8, s. 2569-2594
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Kasai, Y., et al.
(författare)
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JEM/SMILES observation capability
- 2009
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819477798 ; 7474
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Konferensbidrag (refereegranskat)abstract
- A new generation of sub-millimeter-wave receivers employing sensitive SIS (Superconductor-Insulator- Superconductor) detector technology will provide new opportunities for precise passive remote sensing observation of minor constituents in atmosphere. Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) was designed to be onbord the Japanese Experiment Module (JEM) on the International Space Station (ISS) as a collaboration project of National Institute of Information and Communications Technology (NICT) and Japan Aerospace Exploration Agency (JAXA). SMILES scheduled to be launch in September 11, 2009 by the H-II Transfer Vehicle (HTV). Mission Objectives are: i) Space demonstration of superconductive mixer and 4-K mechanical cooler for the submillimeter limb emission sounding, and ii) global observations of atmospheric minor constituents. JEM/SMILES will allow to observe the atmospheric species such as O3, H35Cl, H37 Cl, ClO, BrO, HOCl, HO2, and HNO3, CH3CN, and Ozone isotope species with the precisions in a few to several tens percents from upper troposphere to the mesosphere. We have estimated the observation capabilities of JEM/SMILES. This new technology may allow us to open new issues in atmospheric science.
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| 9. |
- Kasai, Y., et al.
(författare)
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Stratospheric Ozone Isotope Enrichment Studied by Sub-Millimeter Wave Heterodyne Radiometry: The Observation Capabilities of SMILES
- 2006
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Ingår i: IEEE Transactions on Geoscience and Remote Sensing. - 0196-2892 .- 1558-0644. ; 44:3, s. 676-693
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Tidskriftsartikel (refereegranskat)abstract
- The isotopic ratio of molecules often provides valuable information about past or presently occurring processes in the atmosphere because chemical and physical processes may give rise to isotope fractionation of molecular species. However, there are so far no published satellite measurements on the spatial and temporal variations of ozone isotopes in the stratosphere. Spectroscopic remote sensing methods can theoretically be used to observe ozone isotope fractionation on a global scale, but sufficient accuracy has not yet been achieved. A new generation of submillimeter-wave receivers employing sensitive superconductor-insulator - superconductor (SIS) detector technology will provide new opportunities for precise remote sensing measurements of ozone isotopes on a global scale. We have estimated the observation capabilities of two different SIS instruments, namely the space-station-borne Japanese Experimental Module/Sub-Millimeter-wave Limb Emission Sounder (JEM/SMILES) instrument, currently planned for launch in 2008, as well as the airborne Submillimeter wave Atmospheric Sounder/Airborne Submillimeter SIS Radiometer (SUMAS/ASUR) sensor. Measurements of the airborne sensor, conducted in 1996, are presented in order to demonstrate the detection of normal-O 3 and asymmetric-18-O 3 in the SMILES frequency bands. In the ideal case, JEM/SMILES has the capability to measure the ozone isotope enrichment (δ M O 3 ) in the middle stratosphere with a precision of ∼12%∼11%‰‰, and ∼9%‰, for asymmetric-18-O 3 , symmetric-17-O 3 , asymmetric-17-O 3 , respectively, for a daily zonal mean product with resolution of 10° in latitude. The systematic error, including contributions of all instrumental and spectroscopic uncertainties, is estimated to be of the order of 100%‰ to 200%‰ and should be reduced by prelaunch laboratory measurements and in-flight calibrations. A remaining bias in the SMILES measurements will have to be quantified by dedicated validation campaigns. JEM/SMILES should then be capable to provide valuable information on the global distribution and seasonal variation of ozone isotope fractionation in the stratosphere. This new technology will allow us to shed new light on this still open issue in atmospheric sciences. © 2006 IEEE.
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