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| Titel |
Cloud retrieval using the oxygen A-band in support of trace gas retrievals from TROPOMI |
| VerfasserIn |
Maarten Sneep, Johan de Haan, Pepijn Veefkind |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048313
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| Zusammenfassung |
| TROPOMI (TROPOspheric Monitoring Instrument) is a nadir viewing shortwave
spectrometer to measure the tropospheric composition for climate and air quality
applications. The TROPOMI instrument, an initiative from the Netherlands and developed in
co-operation with ESA, will be launched in December 2014 as a single payload on the
ESA/GMES Sentinel 5 Precursor mission. This mission is an important step forward from
the current OMI on NASA EOS Aura and SCIAMACHY on Envisat towards the operational
Sentinel 5 mission that is planned around 2020.
TROPOMI will measure the UV-visible wavelength range from (270 – 500 nm), the near
infrared (710 – 770 nm) and the shortwave infrared (2314 – 2382 nm). TROPOMI will have an
unprecedented spatial resolution of about 7 Ã 7km2 at nadir. The spatial resolution is
combined with a wide swath to allow for daily global coverage.
The science requirements formulated for the trace-gases are challenging, requiring
advanced retrieval techniques. One of the areas where the TROPOMI science team wants to
improve upon the current generation of retrieval algorithms is in the estimated precision of
the retrieved values. This will require appropriate error propagation and the use of a-priori
information to guide the retrieval. This suggests that optimal estimation is the method of
choice for TROPOMI level 2 retrievals.
A characterization of cloud in the field of view is needed for the trace gas retrievals. For
some trace gases – such as methane – this cloud information acts as a filter, removing
cloud-contaminated pixels altogether. For other trace gases there is room within the science
requirements to include clouds in the retrieval, and obtain results from a larger number of
observations. The O2Â A-band observations of TROPOMI are intended for accurate cloud
corrections. To take the presence of clouds into account in the precision estimate for the
(tropospheric) trace gas column, the cloud product will need to provide a full error
covariance matrix. This allows the trace gas retrieval to pick up where the cloud retrieval
finished.
In this presentation some early model results will be shown. Also some anticipated
challenges in the operational use of this algorithm will be discussed. |
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