Internal Wave Dark-Band Signatures in ALOS-PALSAR Imagery Revealed by the Standard Deviation of the Co-Polarized Phase Difference
Open Access
- 22 July 2020
- journal article
- research article
- Published by MDPI AG in Remote Sensing
- Vol. 12 (15), 2372
- https://doi.org/10.3390/rs12152372
Abstract
Analysis of synthetic aperture radar (SAR) images in L-band of short-period internal waves (IWs), and classification of their radar signatures is presented by means of a polarimetric data set from ALOS-PALSAR mission. We choose the polarimetric feature named standard deviation(std) of the co-polarized phase difference (CPD) to identify fundamental differences in SAR signatures of internal waves, and divided them into three different classes, according to their backscattered modulation depths and morphology as well as the std CPD, namely: double-signed, single-negative, and single-positive signatures, for IW normalized image transects that display, respectively, signatures in the form of bright/dark, dark, and bright bands that correspond to positive/negative, negative, or positive variations of radar backscatter. These radar power types of signatures have a counterpart in the std CPD normalized transects, and in this paper we discuss those correlations and decorrelations. We focus in the single-negative type of signature, that is dark bands on gray background, and show that the std CPD is greatly enhanced over the troughs and rear slopes of those IWs. It is suggested that such behavior is consistent with the presence of surface slicks owing to enhanced surfactant concentration. Furthermore, those single-negative SAR signatures appear at locations where and when biological productivity is enhanced. It is found that the modulation depths associated to the std CPD is higher than the one associated to the HH-polarized radar backscatter for single-negative signatures propagating in the range direction, while the reverse occurs for the other types of signatures.This publication has 39 references indexed in Scilit:
- Nonlinear Internal Waves in Synthetic Aperture Radar ImageryOceanography, 2013
- On the co‐polarized phase difference for oil spill observationInternational Journal of Remote Sensing, 2009
- Mapping ocean surface features using biogenic slick-fields and SAR polarimetric decomposition techniquesIEE Proceedings - Radar, Sonar and Navigation, 2006
- First evidence for the detection of natural surface films by the QuikSCAT scatterometerGeophysical Research Letters, 2003
- A semiempirical model of the normalized radar cross‐section of the sea surface 1. Background modelJournal of Geophysical Research: Oceans, 2003
- On the determination of characteristics of the interior ocean dynamics from radar signatures of internal solitary wavesJournal of Geophysical Research: Oceans, 1999
- Role of surface films in ERS SAR signatures of internal waves on the shelf: 1. Short‐period internal wavesJournal of Geophysical Research: Oceans, 1998
- Probability density functions for multilook polarimetric signaturesIEEE Transactions on Geoscience and Remote Sensing, 1994
- Intensity modulation in SAR images of internal wavesNature, 1986
- Theory of radar imaging of internal wavesNature, 1985