Mitigation of Faraday rotation in ALOS-2/PALSAR-2 full polarimetric SAR imageries

Shradha Mohanty; Gulab Singh

doi:10.1117/12.2223572

5 May 2016 Mitigation of Faraday rotation in ALOS-2/PALSAR-2 full polarimetric SAR imageries

Shradha Mohanty, Gulab Singh

Proceedings Volume 9877, Land Surface and Cryosphere Remote Sensing III; 98772Z (2016) https://doi.org/10.1117/12.2223572
Event: SPIE Asia-Pacific Remote Sensing, 2016, New Delhi, India

Abstract

The ionosphere, which extends from 50-450 kms in earth’s atmosphere, is a particularly important region with regards electromagnetic wave propagation and radio communications in the L-band and lower frequencies. These ions interact with the traversing electromagnetic wave and cause rotation of polarization of the radar signal. In this paper, a potentially computable method for quantifying Faraday rotation (FR), is discussed with the knowledge of full polarimetric ALOS/PALSAR data and ALOS-2/PALSAR-2 data. For a well calibrated monostatic, full-pol ALOS-2/PALSAR-2 data, the reciprocal symmetry of the received scattering matrix is violated due to FR. Apart from FR, other system parameters like residual system noise, channel amplitude, phase imbalance and cross-talk, also account for the non-symmetry. To correct for the FR effect, firstly the noise correction was performed. PALSAR/PALSAR-2 data was converted into 4×4 covariance matrix to calculate the coherence between cross-polarized elements. Covariance matrix was modified by the coherence factor. For FR corrections, the covariance matrix was converted into 4×4 coherency matrix. The elements of coherency matrix were used to estimate FR angle and correct for FR. Higher mean FR values during ALOS-PALSAR measurements can be seen in regions nearer to the equator and the values gradually decrease with increase in latitude. Moreover, temporal variations in FR can also be noticed over different years (2006-2010), with varying sunspot activities for the Niigata, Japan test site. With increasing sunspot activities expected during ALOS-2/PALSAR-2 observations, more striping effects were observed over Mumbai, India. This data has also been FR corrected, with mean FR values of about 8°, using the above mentioned technique.

Citation Download Citation

Shradha Mohanty and Gulab Singh "Mitigation of Faraday rotation in ALOS-2/PALSAR-2 full polarimetric SAR imageries", Proc. SPIE 9877, Land Surface and Cryosphere Remote Sensing III, 98772Z (5 May 2016); https://doi.org/10.1117/12.2223572

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available