| 1. |
- Perrin, A., et al.
(författare)
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Molecular line parameters for the "MASTER" (Millimeter Wave Acquisitions for Stratosphere/Troposphere Exchange Research) database
- 2005
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Ingår i: Journal of Atmospheric Chemistry. - : Springer Science and Business Media LLC. - 0167-7764 .- 1573-0662. ; 51:2, s. 161-205
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Tidskriftsartikel (refereegranskat)abstract
- In order to investigate the upper troposphere/lower stratosphere (UTLS) region of the earth's atmosphere, ESA/ESTEC (European space agency) is considering the opportunity to develop the spaceborne limb sounding millimeter sensor "MASTER" (millimeter wave acquisitions for stratosphere/troposphere exchange research). This instrument is part of the "atmospheric composition explorer for chemistry and climate interactions" (ACECHEM) project. In addition, ESA/ESTEC is developing the "MARSCHALS" (millimeter-wave airborne receiver for spectroscopic characterization of atmospheric limb sounding) airborne instrument which will demonstrate the feasibility of MASTER. The present paper describes the line-by-line database which was generated in order to meet at best the needs of the MASTER (or MARSCHALS) instrument. The linelist involves line positions, line intensities, line broadening and line shift parameters in the 294-305, 316-325, 342-348, 497-506 and 624-626 GHz spectral microwindows. This database was first generated for the target molecules for MASTER (H2O, O3, N2O, CO, O2, HNO3, HCl, ClO, CH3Cl, BrO). In addition, ten additional molecules (SO2, NO2, OCS, H2CO, HOCl, HCN, H2O2, COF2, HO2 and HOBr) had also to be considered in the database as "possible interfering species" for the retrieval of the target molecules of MASTER. The line parameters were derived, depending on their estimated accuracy, (i) from a combination of spectral parameters included in the JPL and HITRAN catalogs (ii) from data taken into the literature or (iii) using data obtained through experimental measurements (and/or) calculations performed during the present study.
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| 2. |
- Verdes, C. L., et al.
(författare)
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A sensitivity study on spectroscopic parameter accuracies for a mm/sub-mm limb sounder instrument
- 2005
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Ingår i: Journal of Molecular Spectroscopy. - : Elsevier BV. - 0022-2852 .- 1096-083X. ; 229:2, s. 266-275
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to perform a detailed error analysis for a mm/sub-mm limb sounding instrument with respect to spectroscopic parameters. This is done in order to give some insight into the most crucial spectroscopic parameters and to work out a list of recommendations for measurements that would yield the largest possible benefit for an accurate retrieval. The investigations cover a variety of spectroscopic line parameters, such as line intensity, line position, air and self broadening parameters and their temperature exponents, and pressure shift. The retrieval process is performed with the optimal estimation method (OEM). The OEM allows one to perform an assessment of the total statistical error, as well as of the model parameter error, such as the error coming from spectroscopic parameters. The instrument parameters assumed are those of the MASTER instrument studied by the European Space Agency, one of the candidate instruments for a future atmospheric chemistry mission. However, the same principle and method of analysis can be applied to any other millimeter/sub-millimeter limb sounding instrument, for instance the Japanese instrument JEM/SMILES, the Swedish instrument Odin, and the Earth Observing System Microwave Limb Sounder. We find that an uncertainty in the intensity of the strong lines give an error of similar magnitude on the retrieved species to which the lines belong. Uncertainties in the line position have overall a small impact on the retrieval, indicating that the line positions are known with sufficient accuracy. The air broadening parameters and their temperature exponents of a few strong lines dominate the error budget. On the other hand, the self broadening parameters and the pressure shifts are found to have a rather small impact on the retrieval.
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