Contributrion to the improvement of the soil moisture and ocean salinity (SMOS) sea surface salinity retrieval algorithm
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10.5821/dissertation-2117-94481
Inclou dades d'ús des de 2022
Cita com:
hdl:2117/94481
Càtedra / Departament / Institut
Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions
Tipus de documentTesi
Data de defensa2010-11-22
EditorUniversitat Politècnica de Catalunya
Condicions d'accésAccés obert
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Abstract
The European Space Agency's Soil Moisture and Ocean Salinity (SMOS)
satellite was launched on November, 2, 2009 from the Russian cosmodrome
of Plesetsk. Its objective is to globally and regularly collect measurements of
soil moistre and Sea Surface Salinity (SSS). To do that, a pioneering instru-
ment has been developed: the Microwave Imaging Radiometer by Aperture
Synthesis (MIRAS), the rst space-borne, 2-D interferometric radiometer
ever built; it operates at L-band, with a central frequency of 1.4135 GHz,
and consists of 69 antennas arranged in a Y shape array. MIRAS' output
are brightness temperature maps, from which SSS can be derived through
an iterative algorithm, and using auxiliary information. For each overpass
of the satellite an SSS map is produced, with an estimated accuracy of 1
psu (rmse). According to the Global Ocean Data Assimilation Experiment
(GODAE) the mission requirement is instead speci ed as 0.1 psu after av-
eraging in a 10-day and 2 2 spatio-temporal boxes.
In previuos works ((Sabia et al., 2010), or more extensively in Dr. Sabia's
Ph.D. thesis (Sabia, 2008)) the main error sources in retrieving SSS from
SMOS measurements were determined as:
1. Scene-dependent bias in the simulated measurements,
2. L-band forward modeling de nition,
3. Radiometric sensitivity and accuracy,
4. Constraints in the cost function, and
5. Spatio-temporal averaging.
This Ph.D. thesis, is an attempt of reducing part of the aforementioned
errors (the relative to the one-overpass SSS (1 - 4)) by a more sophisticated
data processing.
Firstly, quasi-realistic brightness temperatures have been simulated using
the SMOS End-to-end Performance Simulator (SEPS) in its full mode and
an ocean model, as provider for geophysical parameters. Using this data
set the External Brightness Temperature Calibration technique has been
tested to mitigate the scene-dependent bias, while the error introduced by
inaccuracies in the L-band forward models has been accounted for by the
application of the External Sea Surface Salinity Calibration.
Apart from simulated brightness temperatures, both External Brightness
Temperature Calibration and External Sea Surface Salinity Calibration have
been tested using real synthetic-aperture brightness temperatures, collected
by the Helsinki University of Technology HUT-2D radiometer during the
SMOS Calibration and Validation Rehearsal Campaign in August 2007 and
ten days of data acquired by the SMOS satellite between July 10 and 19,
2010.
Finally, a study of the cost function used to derive SSS has been performed:
the correlation between measurement mis ts has been estimated and the
e ect of including it in the processing have been assessed.
As an outcome of a 3-month internship at the Laboratoire LOCEAN in
Paris, France, a theoretical review of the e ect of the rain on the very top
SSS vertical pro le has been carried out and is presented as Appendix.
Descripció
Premi extraordinari doctorat curs 2010-2011, àmbit d’Enginyeria de les TIC
CitacióTalone, M. Contributrion to the improvement of the soil moisture and ocean salinity (SMOS) sea surface salinity retrieval algorithm. Tesi doctoral, UPC, Departament de Teoria del Senyal i Comunicacions, 2010. ISBN 9788469514788. DOI 10.5821/dissertation-2117-94481. Disponible a: <http://hdl.handle.net/2117/94481>
GuardóDocument premiat
Dipòsit legalB. 39399-2011
ISBN9788469514788
Col·leccions
Fitxers | Descripció | Mida | Format | Visualitza |
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TMT1de1.pdf | 4,368Mb | Visualitza/Obre |