 |
| Titel |
Performance of the line-by-line radiative transfer model (LBLRTM) for temperature and species retrievals: IASI case studies from JAIVEx |
| VerfasserIn |
M. W. Shephard, S. A. Clough, V. H. Payne, W. L. Smith, S. Kireev, K. E. Cady-Pereira |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 19 ; Nr. 9, no. 19 (2009-10-05), S.7397-7417 |
| Datensatznummer |
250007667
|
| Publikation (Nr.) |
 copernicus.org/acp-9-7397-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| Presented here are comparisons between the Infrared Atmospheric Sounding
instrument (IASI) and the "Line-By-Line Radiative Transfer Model"
(LBLRTM). Spectral residuals from radiance closure studies during the IASI
JAIVEx validation campaign provide insight into a number of spectroscopy
issues relevant to remote sounding of temperature, water vapor and trace
gases from IASI. In order to perform quality IASI trace gas retrievals, the
temperature and water vapor fields must be retrieved as accurately as
possible. In general, the residuals in the CO2 ν2 region are of
the order of the IASI instrument noise. However, outstanding issues with the
CO2 spectral regions remain. There is a large residual ~−1.7 K in
the 667 cm−1 Q-branch, and residuals in the CO2 ν2 and
N2O/CO2 ν3 spectral regions that sample the troposphere
are inconsistent, with the N2O/CO2 ν3 region being too
negative (warmer) by ~0.7 K. Residuals on this lower wavenumber side
of the CO2 ν3 band will be improved by line parameter
updates, while future efforts to reduce the residuals reaching ~−0.5 K
on the higher wavenumber side of the CO2 ν3 band will focus
on addressing limitations in the modeling of the CO2 line shape (line
coupling and duration of collision) effects. Brightness temperature
residuals from the radiance closure studies in the ν2 water vapor
band have standard deviations of ~0.2–0.3 K with some large peak
residuals reaching ±0.5–1.0 K. These are larger than the instrument
noise indicating that systematic errors still remain. New H2O line
intensities and positions have a significant \mbox{impact} on the
retrieved water vapor, particularly in the upper troposphere where the water
vapor retrievals are 10% drier when using line intensities
compared with HITRAN 2004. In addition to O3, CH4, and CO,
of the IASI instrument combined with an accurate
forward model allows for the detection of minor species with weak
atmospheric signatures in the nadir radiances, such as HNO3 and OCS. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|