Correction of the Sea State Impact in the L-Band Brightness Temperature by Means of Delay-Doppler Maps of Global Navigation Satellite Signals Reflected Over the Sea Surface

• Published in: IEEE transactions on geoscience and remote sensing Vol. 46; no. 10; pp. 2914 - 2923
• Main Authors: Marchan-Hernandez, J.F., Rodriguez-Alvarez, N., Camps, A., Bosch-Lluis, X., Ramos-Perez, I., Valencia, E.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01-10-2008; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied geophysics; Area measurement; Brightness temperature; Convolution; Delay; Delay-Doppler Map (DDM); Distributed decision making; Earth; Earth sciences; Earth, ocean, space; Exact sciences and technology; Global Navigation Satellite Systems (GNSSs); Internal geophysics; L-band; Marine; Navigation satellites; Noise; Ocean temperature; Receivers; Satellite navigation systems; Satellites; Sea measurements; sea state; Sea states; Sea surface; projects; maps; Space remote sensing; Delay-Doppler Map (DDM); Global Positioning System; navigation; instruments; brightness temperature; corrections; ocean; positioning; sea state; noise; reflectometry; Global Navigation Satellite Systems (GNSSs)
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2008.922144

This paper presents an efficient procedure based on 2-D convolutions to obtain delay-Doppler maps (DDMs) of Global Navigation Satellite Signals reflected (GNSS-R) over the sea surface and collected by a spaceborne receiver. Two DDM-derived observables (area and volume) are proposed to link the sea-state-induced brightness temperature to the measured normalized DDM. Finally, the requirements to use Global Positioning System reflectometry to accurately correct for the sea state impact on the L-band brightness temperature (quantization levels, decimation, truncation, and noise impact) are analyzed in view of its implementation in the Passive Advanced Unit instrument of the Spanish Earth Observation Satellite (SeoSAT/INGENIO) project.