Clive Rodgers

Abstract:

Atmospheric measurements from new high spectral resolution remote sensing instruments will contain a huge amount of information. To use these data efficiently it is necessary to select a subset of the measurements for use in the retrieval of atmospheric profiles. The use of sections of spectrum, 'microwindows', increases the efficiency of forward model calculations. An objective scheme has been developed to select microwindows, which are optimal in spectral and altitude range, using the reduction in retrieval error. The method has been applied to MIPAS-B measurements, a balloon-borne Fourier transform infrared spectrometer. Results show reasonable retrieval errors. An assessment of the best achievable accuracy has been made, and the most important error sources are thus demonstrated.

Abstract:

Measurements of IR emissions from CO at 4.6 mu m in the middle atmosphere were recorded for nearly one year, from September 1991 to July 1992 by the Improved Stratospheric and Mesospheric Sounder (ISAMS) on board the Upper Atmosphere Research Satellite (UARS). These have been used to retrieve carbon monoxide abundances and study their distribution and variability in the middle atmosphere. Observations of carbon monoxide in this atmospheric region and from transitions of the same vibrational-rotational band were also carried out, using the solar occultation technique with fine altitude resolution, by the high resolution interferometer ATMOS during the ATLAS-1 mission (late March and early April 1992). Comparisons between these simultaneous emission and absorption experiments have been performed in order to improve and validate both data sets. Some of the first results and conclusions are presented and discussed. (C) 1999 COSPAR. Published by Elsevier Science Ltd.

Abstract:

The HIRDLS instrument is an infrared limb sounder which will be part of the NASA EOS-Chem payload to be launched in 2002. It will measure temperature, various minor constituents, polar stratospheric clouds, aerosols and geopotential height gradients in the upper troposphere and middle atmosphere with a much better combined vertical and horizontal spatial resolution than has hitherto been possible. The limb scanning technique provides pressure registration of the limb scans by means of radiometric measurement of emission from atmospheric carbon dioxide. By inclusion of a gyroscope on the instrument optical bench, it is possible to obtain very precise knowledge of variations of the instrument line-of-sight tangent height above the Earth's surface. Fields of geopotential height will be derived by combining this knowledge with the pressure information. (C) 1999 COSPAR. Published by Elsevier Science Ltd.

Abstract:

An analysis of the day-night enhancements on the 6.9 mu m H2O emission measured by the Improved Stratospheric and Mesospheric Sounder (ISAMS) on the Upper Atmospher Research Sounder (UARS) is presented. A characterization of these differences With parameters such as the solar zenith angle (SZA) and kinetic temperature has been done and explained in terms of atmospheric processes by using a non-LTE radiative transfer model. The goal of these continuing studies is to implement these non-LTE effects in the operational retrieval of H2O. (C) 1999 COSPAR. Published by Elsevier Science Ltd.