Maurizio Migliaccio

Polarimetric signature for oil spill observation

Synthetic aperture radar (SAR) oil spill observation is not at all an easy task since the presence of many natural phenomena and surfactants call for complex and time-consuming classification techniques, generally based on the use of ancillary external data. In this study, polarization diversity is employed to assist oil spill observation techniques. The polarization signature, commonly used for land application, is firstly read in terms of a sea surface scattering mechanism with and without surface slicks. Experiments, accomplished over multilook complex (MLC) C-band SIR-C/X-SAR data, show that the polarization signature can be useful both for observing oil spills and for distinguishing between oil spills and biogenic look-alikes.

Sea wave numerical simulations with COSMO-SkyMed © SAR data

ABSTRACT Benassai G, Migliaccio M., Montuori A., 2013. Sea wave numerical simulations with Cosmo-SkyMed SAR data. In this paper, X-band COSMO-SkyMed© Synthetic Aperture Radar (SAR) data are first experimented as wind field forcing of coastal wind-wave oceanographic modeling for sea-wave numerical simulation. The SWAN wave numerical simulations run with Cosmo-SkyMed SAR wind data were performed with respect to some relevant wave storms in the Southern Thyrrenian Sea area during the winter season of 2010. The wind forcing is provided by X-band COSMO-SkyMed© SAR-based wind field estimations which are properly blended with both buoys wave data and ECMWF model winds to retrieve meaningful wave parameters (e.g. significant wave height, wave directions and periods) as physical descriptors of storm events. Experimental results accomplished with X-band COSMO-SkyMed© SAR-based wind field forcing are successfully compared with the ones gathered by using both buoys wave field data and ECMWF model winds, only. The results obtained with the use of blended COSMO-SkyMed©-ECMWF data are satisfactory in terms of sea storm reconstruction, so this source of data can be used also for coastal management purposes.

Wavelet polarimetric SAR signature analysis of sea oil spills and look-alike features

Marine dark features in SAR imagery related to oil spills, biogenic look-alikes and low wind areas are analyzed by means of the wavelet polarimetric signature (WASP) tool. The WASP encapsulates in a graph the dependency of the wavelet variance on dyadic scale and polarization state. Experiments on SIR-C/X-SAR C-band data showed the effectiveness of this analysis in characterizing textural features of the areas of study.

Wind speed estimation in the Tyrrhenian Sea by means of X-band COSMO-SkyMed SAR data

In this paper, the SAR-based wind speed estimation at sea is investigated over X-band COSMO-SkyMed© SAR data in the test area of Tyrrhenian Sea basin. The SAR data set consists of X-band VV-polarized Level 1B Detected Ground Multi-look (DGM) StripMap HImage and ScanSAR Huge Region COSMO-SkyMed© SAR measurements, collected in the test area on 2009 and 2010, respectively. The sea surface wind speed estimation is accomplished by means of the SAR wind speed algorithm based on the Azimuth cut-off procedure, which is properly extended to the non trivial X-band case and therefore calibrated over both StripMap HImage and ScanSAR Huge Region modes SAR data. The reference wind speed, which is used as ground truth for both calibration and SAR-based wind speed estimation purposes, is provided by timely and spatially co-located 25km × 25km QuikSCAT and 12.5km × 12.5km ASCAT scatterometer wind speed for the StripMap HImage and ScanSAR Huge Region SAR data sets, respectively. Experimental results demonstrate the effectiveness of the proposed approach for sea surface wind speed estimation purposes, taking full benefits of X-band COSMO-SkyMed© SAR data.

An Estimate of the Probability Density Function of the Sum of a Random Number N of Independent Random Variables

A new estimate of the probability density function (PDF) of the sum of a random number of independent and identically distributed (IID) random variables is shown. The sum PDF is represented as a sum of normal PDFs weighted according to the PDF. The analytical model is verified by numerical simulations. The comparison is made by the Chi-Square Goodness-of-Fit test.

Polarimetric SAR and oil spill observation

A study on the use of SAR fully polarimetric data for oil spill observation is accomplished. The study makes use of the parameters of the <;H/A/Alpha> Cloude-Pottier decomposition and the extended Bragg scattering model. Experiments are accomplished over SIR-C/X-SAR C-band data.

Tandem-X bistatic polarimetrie mode for maritime applications

In this study, TanDEM-X full-polarimetrlc bistatic and monostatic imagery are exploited for maritime applications purposes. The Mueller matrix and the phase difference between co-polarized channels (CPD) are exploited to deal with both the monostatic and the bistatic scenes. Subtle differences are found between the Mueller matrix collected in bistatic/monostatic mode; while similar performance is achieved when the CPD is exploited.

Time-series of dual-polarimetric synthetic aperture radar data to observe oil seeps

In this study, SAR oil spill observation is investigated for different polarizations, incidence angles and wind conditions. The dataset is composed by a time-series of 42 TerraSAR-X dualpol SAR images acquired between July 2011 and April 2016. The incidence angle, wind speed and polarization dependency for oil spill observation is shown for the first time using a large time-series of the same oil type. Experimental results show that the oil seepage observation is impaired with increasing the incidence angle and strongly depends on wind conditions. However, those effects are more pronounced using the single-polarization channels, while they are mitigated by using dual-polarimetric channels.

Monitoring waterline variation of the Monte Cotugno lake using dual-polarimetric SAR data

In this study, dual-polarimetric (DP) Synthetic Aperture Radar (SAR) data collected by the Sentinel-1 SAR mission are exploited to monitor the change of surface water area of the dam of Monte Cotugno, Basilicata (Italy). The key point is extracting waterline using a reliable technique based on an incoherent combination of co- and cross-polarized SAR channels. Once the water covered area is estimated, an in depth analysis is undertaken to understand the dominant scattering mechanism of the observed scene, i.e. water and surrounding land. Experimental results show that dual-polarization methods allows correctly extracting the water-line. Then the profile of the artificial lake is used to detect the changes.

Targets observation at sea exploiting reflection symmetry extracted from X-band dual-polarimetric SAR data

A polarimetric model to observe metallic targets at sea in dual-polarimetric Synthetic Aperture Radar (SAR) data is here first investigated in X-band. The model gives an understanding of the different symmetry properties that characterize sea surface with and without metallic targets in terms of the correlation between like- and cross-polarized channels. Following the sensitivity study, a simple and very effective filter is designed to observe targets at sea. The model is tested on both HH/HV and VV/VH Single look Slant range Complex (SSC) dual-polarimetric TerraSAR-X data and the filter’s outputs are verified against available Automatic Identification System (AIS) ground truth messages.