Polarimetric GNSS-R Sea Level Monitoring using I/Q Interference Patterns at Different Antenna Configurations and Carrier Frequencies
Artikel i vetenskaplig tidskrift, 2021

Coastal sea level variation as an indicator of climate change is extremely important due to its large socio-economic and environmental impact. The ground-based Global Navigation Satellite System (GNSS) reflectometry (GNSS-R) is becoming a reliable alternative for sea surface altimetry. We investigate the impact of antenna polarization and orientation on GNSS-R altimetric performance at different carrier frequencies. A one-year dataset of ground-based observations at Onsala Space Observatory using a dedicated reflectometry receiver is used. Interferometric patterns produced by the superposition of direct and reflected signals are analyzed using the Least-Squares Harmonic Estimation (LS-HE) method to retrieve sea surface height. The results suggest that the observations from GPS L1 and L2 frequencies provide similar levels of accuracy. However, the overall performance of the height products from the GPS L1 show slightly better performance owing to more observations. The combination of L1 and L2 observations (L12) improves the accuracy up to 25% and 40% compared to the L1 and L2 heights. The impacts of antenna orientation and polarization are also evaluated. A sea-looking Left-Handed Circular Polarization (LHCP) antenna shows the best performance compared to both zenith- and sea-looking Right-Handed Circular Polarization (RHCP) antennas. The results are presented using different averaging windows ranging from 15-minute to 6-hour. Based on a 6-hour window, the yearly Root Mean Square Error (RMSE) between GNSS-R L12 sea surface heights with collocated tide gauge observations are 2.4, 3.1, and 4.1 cm with the correlation of 0.990, 0.982, and 0.969 for LHCP sea-looking, RHCP sea-looking, and RHCP up-looking antennas, respectively.

L-Band Remote Sensing

Sea level

Altimetry

Antennas

Antenna measurements

Least-Squares Harmonic Estimation (LS-HE)

Coastal Sea Level Monitoring

Sea measurements

GNSS

GPS

Sea surface

Global navigation satellite system

Polarimetric GNSS-R

Global Positioning System

Global Navigation Satellite Systems-Reflectometry (GNSS-R)

Författare

Mahmoud Rajabi

Norges teknisk-naturvitenskapelige universitet

Mostafa Hoseini

Norges teknisk-naturvitenskapelige universitet

Hossein Nahavandchi

Norges teknisk-naturvitenskapelige universitet

Maximilian Semmling

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

Markus Ramatschi

Deutsches GeoForschungsZentrum (GFZ)

Mehdi Goli

Shahrood University of Technology

Rüdiger Haas

Chalmers, Rymd-, geo- och miljövetenskap, Mikrovågs- och optisk fjärranalys

J Wickert

Deutsches GeoForschungsZentrum (GFZ)

IEEE Transactions on Geoscience and Remote Sensing

0196-2892 (ISSN)

Vol. In Press

Ämneskategorier

Meteorologi och atmosfärforskning

Oceanografi, hydrologi, vattenresurser

Klimatforskning

DOI

10.1109/TGRS.2021.3123146

Mer information

Senast uppdaterat

2021-11-17