Gallery: Scatterometer RFI
Radio Frequency Interference (RFI) can cause errors in the salinity estimated by Aquarius by affecting the signal received by the microwave radiometers and the scatterometer.
The scatterometer is important for correcting for the effect of ocean waves (surface roughness).
The images below (click to enlarge) show global monthly RFI for ascending/descending passes as detected by the scatterometer (Le Vine and de Matthaeis, 2014).
The data are presented in three different projections (Mollweide, Orthographic Northern Hemisphere, and Orthographic Southern Hemisphere) at 1.26 GHz, the frequency of the Aquarius scatterometer.
Maps showing data collected only during ascending (northward) passes and descending (southward) passes of the satellite are also available.
Maps in Plate Carrée projection are available upon request.
Each data point represents the average of scatterometer measurements over 1.44 seconds (the fundamental data block in Aquarius Level 2 data). The color scale indicates the percentage of radiometer measurements within this window that are identified as RFI by the RFI detection algorithm (Le Vine and de Matthaeis, 2014). Measurements identified as RFI are removed from processing and not used to calculate salinity. Red colors indicate areas where over 80% of the sampled data are flagged for RFI presence. Dark blues show relatively little detected RFI, with less than about 10% of samples flagged in these regions.
The scatterometer operated in a band shared with other active "services" including air traffic control radars, which are known sources of interference. Fortunately, over the ocean where the scatterometer data are needed most, the interference is small; however, over land there is significant and persistent interference with the scatterometer signal.
Images are provided by Paolo de Matthaeis, NASA Goddard Space Flight Center.
Each data point represents the average of scatterometer measurements over 1.44 seconds (the fundamental data block in Aquarius Level 2 data). The color scale indicates the percentage of radiometer measurements within this window that are identified as RFI by the RFI detection algorithm (Le Vine and de Matthaeis, 2014). Measurements identified as RFI are removed from processing and not used to calculate salinity. Red colors indicate areas where over 80% of the sampled data are flagged for RFI presence. Dark blues show relatively little detected RFI, with less than about 10% of samples flagged in these regions.
The scatterometer operated in a band shared with other active "services" including air traffic control radars, which are known sources of interference. Fortunately, over the ocean where the scatterometer data are needed most, the interference is small; however, over land there is significant and persistent interference with the scatterometer signal.
References
Le Vine, D. and de Matthaeis, P. (2014). Aquarius Active/Passive RFI Environment at L-band, IEEE T. Geosci. Remote Let, 11 (10), 1747-1751.
Images are provided by Paolo de Matthaeis, NASA Goddard Space Flight Center.
Global (Mollweide Projection)
May 2015 | April 2015 | March 2015 | February 2015 | |||
January 2015 | December 2014 | November 2014 | October 2014 | |||
September 2014 | August 2014 | July 2014 | June 2014 | |||
May 2014 | April 2014 | March 2014 | February 2014 | |||
January 2014 | December 2013 | November 2013 | October 2013 | |||
September 2013 | August 2013 | July 2013 | June 2013 | |||
May 2013 | April 2013 | March 2013 | February 2013 | |||
January 2013 | December 2012 | November 2012 | October 2012 | |||
September 2012 | August 2012 | July 2012 | June 2012 | |||
May 2012 | April 2012 | March 2012 | February 2012 | |||
January 2012 | December 2011 | November 2011 | October 2011 | |||
September 2011 |
Northern Hemisphere
May 2015 | April 2015 | March 2015 | February 2015 | |||
January 2015 | December 2014 | November 2014 | October 2014 | |||
September 2014 | August 2014 | July 2014 | June 2014 | |||
May 2014 | April 2014 | March 2014 | February 2014 | |||
January 2014 | December 2013 | November 2013 | October 2013 | |||
September 2013 | August 2013 | July 2013 | June 2013 | |||
May 2013 | April 2013 | March 2013 | February 2013 | |||
January 2013 | December 2012 | November 2012 | October 2012 | |||
September 2012 | August 2012 | July 2012 | June 2012 | |||
May 2012 | April 2012 | March 2012 | February 2012 | |||
January 2012 | December 2011 | November 2011 | October 2011 | |||
September 2011 |
Southern Hemisphere
May 2015 | April 2015 | March 2015 | February 2015 | |||
January 2015 | December 2014 | November 2014 | October 2014 | |||
September 2014 | August 2014 | July 2014 | June 2014 | |||
May 2014 | April 2014 | March 2014 | February 2014 | |||
January 2014 | December 2013 | November 2013 | October 2013 | |||
September 2013 | August 2013 | July 2013 | June 2013 | |||
May 2013 | April 2013 | March 2013 | February 2013 | |||
January 2013 | December 2012 | November 2012 | October 2012 | |||
September 2012 | August 2012 | July 2012 | June 2012 | |||
May 2012 | April 2012 | March 2012 | February 2012 | |||
January 2012 | December 2011 | November 2011 | October 2011 | |||
September 2011 |