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Microwave temperature and pressure measurements with the Odin satellite: II. Retrieval method

Ridal, M. and Murtagh, D. P. and Merino, F. and Pardo, J. R. and Pagani, L. (2002) Microwave temperature and pressure measurements with the Odin satellite: II. Retrieval method. Canadian Journal of Physics, 80 (4). pp. 455-467. ISSN 0008-4204. doi:10.1139/p02-021.

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The millimetre receiver on the Swedish satellite Odin, will be used for detection of the 118.750 GHz oxygen line. The temperature and pressure will be determined from the output of a three-channel filter bank measurement. One frequency bin is centred over the emission-line frequency while the other two cover parts of the line wing, where the opacity is less, providing a useful signal at lower altitudes. The bandwidth of each channel is 40 MHz. The signal in the frequency bin covering the line centre is modeled by a high-resolution model including the Zeeman effect, developed by the Observatoire de Paris-Meudon. The other two 40 MHz bins are modeled using the much faster standard Odin forward model, developed at the Department of Meteorology at Stockholm University together with Chalmers University of Technology. The operational retrievals employ an iterative method that uses simulated signals from a reference atmosphere as a lookup table for the pressure. The temperature is then calculated from the equation of hydrostatic equilibrium, and a new lookup table computed. This process is repeated until a convergence criterion is reached. Simulations, including known error sources, show that the temperature can be retrieved with a root mean square (rms) around 3 K, in the altitude range ~ 25-90 km using the operational temperature retrieval method (the filter bank method). A sub-millimetre receiver on board Odin will also be used to observe the oxygen line at 487.249 GHz. Both this line and the 118.750 GHz line can be observed in high resolution (150 kHz) for detailed studies of the Zeeman splitting. Retrievals from the high-resolution measurements are expected to give a precision of ± 2 K rms at that resolution. However, this kind of observation will occupy an entire spectrometer and will not be made on a regular basis.

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Additional Information:© 2002 NRC Canada. Received 1 May 1999. Accepted 15 January 2001. Published on the NRC Research Press Web site at on 18 April 2002. The work by the MISU group has been supported by grants from the Swedish National Space Board. J.R.P. gratefully acknowledges the financial support of the NASA-Goddard Institute for Space Studies, the Observatoire de Paris-Meudon, CNES, and Meteo-France for the development of this work.
Funding AgencyGrant Number
Swedish National Space BoardUNSPECIFIED
NASA-Goddard Institute for Space StudiesUNSPECIFIED
Observatoire de Paris-MeudonUNSPECIFIED
Centre National d'Études Spatiales (CNES) (France)UNSPECIFIED
Issue or Number:4
Classification Code:PACS: 07.57Yb, 94.10Dy, 95.75Rs
Record Number:CaltechAUTHORS:20111031-145628494
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:27532
Deposited By: Tony Diaz
Deposited On:01 Nov 2011 21:29
Last Modified:09 Nov 2021 16:49

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