Smoothing radio occultation bending angles above 40 km
The 'statistically optimal' approach to smoothing bending angles derived from radio occultation (RO) measurements is outlined. This combines a measured bending angle profile with an <i>a priori </i>or background estimate derived from climatology, in order to obtain the most...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2001-04-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/19/459/2001/angeo-19-459-2001.pdf |
| _version_ | 1828928227383443456 |
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| author | S. B. Healy |
| author_facet | S. B. Healy |
| author_sort | S. B. Healy |
| collection | DOAJ |
| description | The 'statistically
optimal' approach to smoothing bending angles derived from radio occultation
(RO) measurements is outlined. This combines a measured bending angle profile
with an <i>a priori </i>or background estimate derived from climatology, in
order to obtain the most probable bending angle profile. However, the method is
only optimal if the error statistics of both the measured and background
profiles are known and applied accurately. In this work it is shown that
correlations in the background estimate have a significant role in determining
the degree of smoothing in the solution. We find that smooth profiles,
consistent with the measured values, can be derived if the correlations are
approximated analytically with a Gaussian, assuming a scale length of 6km. In
regions where the observed and background error levels are comparable, the
solutions take the general shape from the background estimate, centred on the
observation data. The effects of correlated observation errors are also
considered. It is shown that the quality of the temperature retrievals can be
significantly affected by the choice of climatology used for background
estimate.<br><br><b>Key words. </b>Atmosphere composition
and structure (pressure, density and temperature) – Radio science (remote
sensing) |
| first_indexed | 2024-12-14T00:01:14Z |
| format | Article |
| id | doaj.art-cefd4eff640d49db83970911247ab808 |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-14T00:01:14Z |
| publishDate | 2001-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-cefd4eff640d49db83970911247ab8082022-12-21T23:26:19ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762001-04-011945946810.5194/angeo-19-459-2001Smoothing radio occultation bending angles above 40 kmS. B. Healy0NWP Division, The Met Office, London Road, Bracknell, RG12 2SZ, UKThe 'statistically optimal' approach to smoothing bending angles derived from radio occultation (RO) measurements is outlined. This combines a measured bending angle profile with an <i>a priori </i>or background estimate derived from climatology, in order to obtain the most probable bending angle profile. However, the method is only optimal if the error statistics of both the measured and background profiles are known and applied accurately. In this work it is shown that correlations in the background estimate have a significant role in determining the degree of smoothing in the solution. We find that smooth profiles, consistent with the measured values, can be derived if the correlations are approximated analytically with a Gaussian, assuming a scale length of 6km. In regions where the observed and background error levels are comparable, the solutions take the general shape from the background estimate, centred on the observation data. The effects of correlated observation errors are also considered. It is shown that the quality of the temperature retrievals can be significantly affected by the choice of climatology used for background estimate.<br><br><b>Key words. </b>Atmosphere composition and structure (pressure, density and temperature) – Radio science (remote sensing)https://www.ann-geophys.net/19/459/2001/angeo-19-459-2001.pdf |
| spellingShingle | S. B. Healy Smoothing radio occultation bending angles above 40 km Annales Geophysicae |
| title | Smoothing radio occultation bending angles above 40 km |
| title_full | Smoothing radio occultation bending angles above 40 km |
| title_fullStr | Smoothing radio occultation bending angles above 40 km |
| title_full_unstemmed | Smoothing radio occultation bending angles above 40 km |
| title_short | Smoothing radio occultation bending angles above 40 km |
| title_sort | smoothing radio occultation bending angles above 40 km |
| url | https://www.ann-geophys.net/19/459/2001/angeo-19-459-2001.pdf |
| work_keys_str_mv | AT sbhealy smoothingradiooccultationbendinganglesabove40km |