1. 1 © ACRI-ST, all rights reserved – 2012 Isotropic RFI detection Jean-Luc Vergely (ACRI-ST) Claire Henocq (ACRI-ST) Philippe Waldteufel (LATMOS)

2. 2 © ACRI-ST, all rights reserved – 2012 Introduction Principal aims of this study : Looking for strong isotropic source -> RFI St1, A3 and A4 analysis.

3. 3 © ACRI-ST, all rights reserved – 2012 Data set Data set to be used 2010 and 2011 reprocessed data. Philosophy: -> use L1c browse products for global analysis: source detection on ocean and land targets.

4. 4 © ACRI-ST, all rights reserved – 2012 Data set Land/ocean L1c browse products L1c browse products over two years (2010 and 2011) : - four polarizations (in FP mode) at the same geometry - TB at antenna level - TB at 42.5° incidence - TB errors Allow global analysis on 5 FOV zones Zone 1 Zone 2 Zone 3 Zone 4 Zone 5

5. 5 © ACRI-ST, all rights reserved – 2012 Introduction St1,A3 or A4 emission Is the signal observed on descending and ascending orbits ? Is the signal isotropic? Is the signal variable or constant ? Is the signal spatially coherent ?

6. 6 © ACRI-ST, all rights reserved – 2012 Isotropic source Detected in the 5 zones in ascending and descending -> good azimuth coverage. Normalization to be done because of using zones affected by different OTT correction. Applying a threshold. St1 and A4 For A3 : ascending and descending zone 3

7. 7 © ACRI-ST, all rights reserved – 2012 St1 isotropic source Isotropic source detection

8. 8 © ACRI-ST, all rights reserved – 2012 St1 isotropic source Isotropic source detection

9. 9 © ACRI-ST, all rights reserved – 2012 St1 isotropic source

10. 10 © ACRI-ST, all rights reserved – 2012 A4 isotropic sources Threshold of 3 K Only RFI …

11. 11 © ACRI-ST, all rights reserved – 2012 A4 isotropic source Isotropic source detection

12. 12 © ACRI-ST, all rights reserved – 2012 A3 asc/desc sources Threshold of 7 K

13. 13 © ACRI-ST, all rights reserved – 2012 A3 isotropic source Isotropic source detection

14. 14 © ACRI-ST, all rights reserved – 2012 Principal conclusions Looking for RFI from St1, A3 and A4 SMOS measurements: isotropic sources For RFI detection : do not use A4 (correlated with A3). Only few isotropic sources have been detected. Constant isotropic source for St1 could be RFI. Distinction between sources and Gibbs effect to be done. -> further works : play with different thresholds (adaptation of the threshold according to the target (ocean or land).