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Titel |
Recent advances in the salinity retrieval algorithms for Aquarius and Soil
Moisture Active Passive (SMAP) |
VerfasserIn |
Thomas Meissner, Frank Wentz, Tong Lee |
Konferenz |
EGU General Assembly 2017
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Medientyp |
Artikel
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Sprache |
en
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 19 (2017) |
Datensatznummer |
250139151
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Publikation (Nr.) |
EGU/EGU2017-2330.pdf |
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Zusammenfassung |
Our presentation discusses the latest improvements in the salinity retrievals both for Aquarius
and Soil Moisture Active-Passive (SMAP) since the last releases. The Aquarius V4.0 was
released in June 2015. The final V5.0 release is planned for late 2017. SMAP V 2.0 has been
released in September 2016. We will present validation results for both Aquarius V5.0
pre-release and SMAP V2.0 salinity comparing with near-surface salinity measurements from
Argo floats.
We show that salty biases at higher northern latitudes in Aquarius V4.0 can be explained
by inaccuracy in the model used in correcting for the absorption by atmospheric oxygen.
These biases will be mitigated in V5.0 by fine-tuning the parameters in the oxygen absorption
model.
The full 360–degree look capability of SMAP makes it possible to take observations
from the forward and backward looking direction at the same instance of time.
This two-look capability aids the salinity retrievals. One of the largest spurious
contaminations in the salinity retrievals is caused by the galactic reflection from the ocean
surface. Because in most instances the reflected galaxy appears only in either the
forward or the backward look, it is possible to determine its contribution by taking
the difference of the measured SMAP brightness temperatures between the two
looks. Our result suggests that the surface roughness that is used in the galactic
correction needs to be increased and also the estimated strength of some of the
galactic sources need to be slightly adjusted. The improved galaxy correction has been
implemented in SMAP V2.0 retrieval and will be included in Aquarius V5.0 as well. It
helps the mitigation of residual zonal and temporal biases that were present in both
products.
Another major cause of the observed zonal biases in SMAP is the emissive SMAP mesh
antenna. In order to correct for it, an accurate knowledge of the emissivity of the antenna and
its physical temperature are required. We discuss the improvements in the correction for the
emissive SMAP antenna in SMAP V2.0 over V1.0. |
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