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| Titel |
The horizontal resolution of MIPAS |
| VerfasserIn |
T. Clarmann, C. Clercq, M. Ridolfi, M. Höpfner, J.-C. Lambert |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 2, no. 1 ; Nr. 2, no. 1 (2009-02-18), S.47-54 |
| Datensatznummer |
250000426
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| Publikation (Nr.) |
 copernicus.org/amt-2-47-2009.pdf |
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| Zusammenfassung |
| Limb remote sensing from space provides atmospheric composition measurements at
high vertical resolution while the information is smeared in the horizontal
domain. The horizontal components of two-dimensional (altitude and along-track
coordinate) averaging kernels of a limb retrieval constrained to
horizontal homogeneity can be used to estimate the horizontal resolution of
limb retrievals. This is useful for comparisons of measured data with modeled
data, to construct horizontal observation operators in data assimilation
applications or when measurements of different horizontal resolution are
intercompared. We present these averaging kernels for retrievals of
temperature, H2O, O3, CH4, N2O, HNO3 and NO2 from MIPAS
(Michelson Interferometer for Passive Atmospheric Sounding) high-resolution
limb emission spectra. The horizontal smearing of a MIPAS retrieval in terms
of full width at half maximum of the rows of the horizontal averaging kernel
matrix varies typically between about 200 and 350 km for most species, altitudes
and atmospheric conditions. The range where 95% of the information originates
from varies from about 260 to 440 km for these cases. This information spread
is smaller than the MIPAS horizontal sampling, i.e. MIPAS data are horizontally
undersampled, and the effective horizontal resolution is driven by the sampling
rather than the smearing. The point
where the majority of the information originates from is displaced from the
tangent point towards the satellite by typically less than 10 km for trace
gas profiles and about 50 to 100 km for temperature, with
a few exceptions for uppermost altitudes. The geolocation of a MIPAS profile is
defined as the tangent point of the middle line of sight in a MIPAS limb scan.
The majority of the information displacement with respect to this nominal
geolocation of the measurement is caused by the satellite movement and the
geometrical displacement of the actual tangent point as a function of the
elevation angle. |
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