Ocean wind and roughness retrieval with spaceborne GNSS-Reflectometry: first results from the UK TechDemoSat-1 mission
0
Citation
0
Reference
20
Related Paper
Keywords:
Reflectometry
Cite
An assessment of non-geophysical effects in spaceborne global navigation satellite system reflectometry (GNSS-R) data from the UK TechDemoSat-1 (TDS-1) mission is presented. TDS-1 was launched in July 2014 and provides the first new spaceborne GNSS-R data since the pioneering UK-disaster monitoring constellation experiment in 2003. Non-geophysical factors evaluated include ambient L-band noise, instrument operating mode, and platform-related parameters. The findings are particularly relevant to users of uncalibrated GNSS-R signals for the retrieval of geophysical properties of the Earth surface. Substantial attitude adjustments of the TDS-1 platform are occasionally found to occur that introduce large uncertainties in parts of the TDS-1 GNSS-R dataset, particularly for specular points located outside the main beam of the nadir antenna where even small attitude errors can lead to large inaccuracies in the geophysical inversion. Out of eclipse however, attitude adjustments typically remain smaller than 1.5°, with larger deviations of up to 10° affecting less than 5% of the overall sun-lit data. Global maps of L1 ambient noise are presented for both automatic and programmed gain modes of the receiver, revealing persistent L-band noise hotspots along the Equator that can reach up to 2.5 dB, most likely associated with surface reflection of signals from other GNSS transmitters and constellations. Sporadic high-power noise events observed in certain regions point to sources of human origin. Relevant conclusions of this study are that platform attitude knowledge is essential and that radiometric calibration of GNSS-R signals should be used whenever possible. Care should be taken when considering using noise measurements over the equatorial oceans for calibration purposes, as ambient noise and correlated noise in delay-Doppler maps both show more variation than might be expected over these regions.
Reflectometry
Nadir
Cite
Citations (31)
Instrumentation
Satellite broadcasting
space technology
Cite
Citations (3)
Reflectometry
Python
Cite
Citations (10)
Radar altimeter
Mode (computer interface)
Space-based radar
Cite
Citations (0)
The European Space Agency ERS (European Remote Sensing) mission consists of two satellites, ERS-I launched in July 1991 and ERS-2 launched in April 1995 year. The satellites were designed to increase our scientific understanding of coastal zones, global ocean processes and polar regions and to develop economic and commercial applications. Based on an improved knowledge of ocean parameters and sea-state conditions, surveillance and planning of coastal and marine activities world-wide was defined as a primary target for applications development. This article describes the arrangement that have been made for developing various observational and commercial programmes and projects.
Launched
Ocean observations
Cite
Citations (1)
At the present time the European Space Agency is making preparations for a European Remote Sensing Satellite Programme. Within this programme, the first satellite to be launched will be ERS-1, an ocean monitoring satellite carrying as payload a multi-spectral scanner and a number of active microwave instruments, namely a Synthetic Aperture Radar (SAR), a scatterometer, an altimeter, and very likely a scientific payload still to be determined. This paper addresses that portion of the programme concerned with the preparation of the ground facilities necessary for the control of the satellite on the one hand and payload acquisition, processing, archiving and distribution of the payload data on the other.
Payload (computing)
Scatterometer
Ground segment
Radar altimeter
Space-based radar
Cite
Citations (1)