Research activities

2023 - 2025 - Project manager - MUR PRIN funded project. (230K Euro) "multi-layEr ap- proaCh to detect and analyze cOastal aggregation of MAcRo-plastic littEr (ECOMARE)".

2023 - Project manager - Rai Way s.p.a. funded project. (20K Euro) "Verifica della funzionalità dei rivelatori a soglia NIR in dotazione al personale Rai Way".

2022 - Unit member - Rai Way s.p.a. funded project. (18K Euro) "Verifica metodologie RaiWay per la zonizzazione".

2021- 2023 - Scientific coordinator - Italian Space Agency (ASI) funded project . (106K Euro) “APPLICAVEMARS - Approccio multi-frequenza e multi-polarizzazione per la stima del campo di vento marino da immagini SAR”.

2021-2024 - Project Manager - ESA-NERSCC ESA-MOST Dragon-5 Cooperation Programme (50K Euro): “Monitoring hArsh Coastal environments and Ocean Surveillance using radar remote sensing (MAC-OS)”

2019-2021 - Unit member - Research project funded by Italian Ministry of research (MIUR) under the label Programma nazionale di ricerca in Antartide (PNRA) 2018 (15K Euro) Sea ice and Wave-ice Interaction Monitoring for a safe Marginal Ice NaviGation (SWIMMING).

2019-2020 - Unit member - Research and development project in the frame of PNR 2015- 2010 (ARS01 00922) (170K Euro) FORmation flying of CubEsat assemblies for remote sensing (FORCE).

2019-2020 - Unit member - Research and development project in the frame of PNR 2015-2010 (ARS01 00922) (40K Euro) “Deployable Optics for Remote sensing Applications”

2020 - Project Manager - AIRBUS Defence, Spain - Contract of Services (40K Euro): Phase A/B1 of Passive Microwave Imaging Mission (CIMR)

2019 - Project Manager - Polytechnic University of Catalonia (UPC) - Contract of Services (15K Euro): "Pre-development of the Resolution enhancement Algorithm in order to support the CIMR mission". 

2017-2020 - Project Manager - ESA-NERSCC ESA-MOST Dragon-4 Cooperation Programme (70K Euro): Microwave satellite measurements for coastal area and extreme weather monitoring - The project includes partners from Italy, Spain, UK, Netherlands, France and China.

2014-2016 - Project manager - ESA Support to the training of European young scientists in the framework of the Dragon cooperation 2013-2016 (30K Euro).

2013-2016 - Project Manager - ESA-NERSCC ESA-MOST Dragon-3 Cooperation Pro- gramme: Oil spill monitoring - The project includes partners from Italy, Iceland, Spain and China.

2013-2015 - Unit member - Brazilian air commission in Europe funded project. (20K Euro) Synthetic Aperture Radar (SAR) observation of ships and metallic targets at sea.

2011-103 - co-PI - ESA Project (40K) PolSARapp: Polarimetric SAR Apps Demonstration.
2010-2013 - Unit member - Italian Space Agency (ASI) Project (100K) - SAR Remote Sensing for Sea Oil Spill Observation.

Polarimetric scattering, water pollution, polarimetric models, SAR.

Description: Polarimetric models and analysis tools have been developed to observe sea oil slicks and have shown that some polarimetric features (derived from either conventional polarimetric SAR measurements of compact-polarimetric ones), namely the correlation between co-pol channels, unpolarized backscattered energy and scene depolarization capabilities, can be successfully used to both observe oil slicks and distinguish them from weak-damping look-alikes. These results represent a fundamental breakthrough to former knowledge, which, in a nutshell, considered radar polarimetry unsatisfactory for sea oil slick observation.

All these new physical approaches share a common physical rationale that relies on the fact that, under low-to-moderate wind conditions (3 − 12 m/s) and at intermediate incidence angles, both slick-free and weak-damping slick-covered sea surfaces call for Bragg scattering, whereas in the case of oil-covered sea surfaces, a completely different, i.e., non-Bragg scattering mechanism, is in place. These studies boosted the development of operational methods to detect and to classify sea oil slicks in full-, dual- and compact-polarimetric SAR imagery.

Multi-polarization scattering, IEM, BPM, two-scale scattering models, SAR.

Description: Electromagnetic models to describe the scattering from randomly rough surfaces are specialized to the sea surface case and augmented with damping models to predict slick-free and slick-covered sea surface scattering. The models (belonging to the family of the boundary perturbation models (BPM) and two-scale Improved Integral Equation Model (IIEM)) are developed under the - more general – bistatic scattering framework and then specialized to the backscatter case to contrast theoretical predictions with actual measurements remotely sensed by SAR under slick-free and slick-covered sea surface conditions.

All these approaches share a common physical rationale, namely a two-scale scattering model is augmented with a damping model that accounts for the reduction of the sea surface roughness by the surfactant. With respect to the state-of-the-art prof. Nunziata pioneered the inclusion of additional effects related to the pollutant; namely, the reduction of the input energy from the wind to the sea (through a reduced friction velocity) and the modification of the Fresnel reflection coefficients in case of thicker oil layers or emulsified oils. Prof. Nunziata was among the first scientists to test the sensitivity of X-band backscatter to marine litter which showed promising results. 

Reflection symmetry, metallic targets, polarimetry, SAR

Description: Prof. Nunziata proposed a new paradigm to observe metallic targets at sea in dual-polarimetric SAR measurements that “looks” at metallic targets at sea as targets that break the reflection symmetry that characterizes natural scenes, e.g., ocean surface. The new coherent approach relies on intrinsic Maxwell’s equation properties and ensures effective results independently of the wind blowing direction and over a large range of incidence angles and wind conditions. Prof. Nunziata proposed a robust and simple method to exploit the different symmetry properties which characterize sea surface with and without man-made metallic targets through the correlation between the cross-polarized polarimetric channels that was successfully verified on L-, C- and X-band SAR data.

Prof. Nunziata also developed a model that relates the correlation between the co-polarized channels, in case of sea surface with and without metallic targets, to the time offset between bursts related to the HH and VV polarimetric channels - measured by the Italian CosmoSkyMed imagery collected according to the PingPong mode - in a fashion like a polarimetric along-track interferometry to sort out the dynamic sea background.

Prof Nunziata also deeply investigated the role of the SAR incidence angle in the observation of metallic platforms using multi-polarization SAR measurements. This analysis demonstrated that the straightforward image-processing approach that consists of detecting metallic targets at sea as bright spots in the SAR image plane presents severe limitations that can be overcome by an intelligent combination of multi-polarization measurements. All the physical approaches are computer time effective, robust to sea state conditions and more reliable than single-polarimetric approach. 

Speckle, 2D random walk, targets at sea, SAR

Description: Prof Nunziata pioneered the use of speckle as a source of information to observe metallic targets at sea in single look complex (SLC) SAR imagery. When large targets are present the speckle model changes and this allows detecting the target, when the target has a strong scattering response, but it is small, one cannot expect to have a change into the speckle model and must analyze the speckle pdf tail. Of course, while the single-polarimetric approach has the benefit of a fine spatial resolution they are less robust since there may present environmental phenomena generating similar scattering, especially in the small target case.

This approach has been applied to detect target and dark areas in co- and cross-polarized SAR imagery.

Crop phenology, multi-polarization, time series of SAR imagery

Description: Time series of multi-polarization SAR data are exploited to retrieve the phenological stages of crops. Two classes of methods are proposed.

The first class is based on a data-driven procedure that consists of classifying phenological stages using polarimetric features and single-polarization intensity channels. The procedure is success- fully verified on actual polarimetric SAR data collected by RadarSAT-2 and CosmoSkyMed over different crop fields, including rice and onion fields.

The second class consists of a new methodology to estimate crop phenology using time-series of polarimetric SAR data. The procedure constitutes an effective methodology for all the steps involved in the phenology retrieval. Phenological intervals and training areas are identified evaluating the distances among polarimetric covariance matrices obtained from time series of PolSAR data. Consequently, the computation of PolSAR observable, which is the main step of state-of-the-art methods, is no longer needed and the proposed approach can be applied in the same way to any crop type.

Coastline, dual-polarimetric SAR

Description: Prof. Nunziata proposed a completely new paradigm to use SAR measurement to map the coastline, i.e., to distinguish the boundary between land and sea in SAR imagery, which relies on the inherent imaging characteristics of the COSMO-SkyMed dual-polarization Ping-Pong mode. According to this imaging mode, the two polarimetric channels are acquired with a time lag that is long enough to make sea surface uncorrelated at X-band and, therefore, easy to be sorted out from land. Further, a new approach that exploits the inter-channel correlation was proposed to extract coastline in C- and X-band SAR measurements that triggered the development of several applications suitable for end-users.

Inland water, time-series, SAR

Description: Prof. Nunziata proposed a model to deal with the use of time-series of multi-polarization SAR measurements to monitor inland water and to extract key parameters, e.g., the water-area coverage and rough info about the bathymetry.

From an electromagnetic viewpoint, these models also shed light on the peculiarities of the scattering from inland waters that distinguish it from the well-known sea surface scattering. These findings explain, for instance, the physics that makes the cross-pol channel uninformative.

Change detection, damage assessment, earthquakes, SAR

Description: Prof Nunziata pioneered the development of new bi-temporal approaches which, based on a proper modeling of dual-polarimetric scattering, allow detecting damages related to earthquakes. The proposed modeling consists of designing a scattering-based polarimetric change detector metric that maximizes the difference between a pair of covariance matrices acquired before and after the earthquake event.

In addition, a novel approach that exploits the reflection symmetry to classify areas affected by earthquake-related damages is also proposed. The approach models that damaged built up areas more “reflection-symmetric” than non-damaged built-up areas.

The accuracy of the proposed approaches in detecting damaged areas and providing information on the level of damages using dual-polarimetric SAR imagery is verified against ground surveys.

Inverse problems, Hilbert and Banach spaces, microwave radiometer

Description: The use of large-scale microwave sensors for coastal area applications poses two main problems: non-imaging capabilities and coarse spatial resolution. Both problems can be mathematically framed as inverse ill-posed problems that must be handled with care.

Prof Nunziata pioneered the development of new physically based algorithms suitable to generate images at native and enhanced spatial resolution that have been verified using actual microwave radiometer measurements. Both the instruments do not generally provide "image" products, i.e., their measurements are not inherently arranged in a uniform gridded format. This very often prevents their use in Earth Observation (EO) applications where the spatial information is important. This is the case, for instance, of climate-related studies where parameters must be derived at fixed locations trough time. Accordingly, reconstructions techniques aimed at generating gridded products in an effective way have been proposed that can be formulated as an inverse problem. Within this context, Prof. Nunziata:

- Developed a completely new paradigm that allows taking care of the inversion in the Banach spaces in a robust and effective way and, therefore, overcoming the classical over-smoothing and the Gibb’s oscillations that arise from the minimization of the conventional energy norm in the Hilbert spaces. From a mathematical viewpoint, spatial resolution enhancement leads to an underdetermined problem that, from a mathematical viewpoint, implies that no unique inverse operator exists; therefore, additional constraints must be imposed on the sought solution. Two classes of approaches have been proposed to deal with spatial resolution enhancement of microwave radiometer data based on the minimum p-norm constraint, with 1 < p ≤ 2. The first class consists of choosing p = 2; hence, reconstructions in Hilbert space are obtained. The second class consists of choosing 1 < p < 2, i.e., reconstructions are obtained in Banach spaces. The latter are shown to overcome the drawbacks of classical approaches in Hilbert space, i.e., over-smoothness and Gibbs oscillations.

Prof Nunziata first promoted an innovative processing scheme that adapts the p-norm to the scenario to be reconstructed, i.e., the so-called variable p-exponent reconstruction that provides a better reconstruction of abrupt discontinuities (e.g., the land/sea boundary) without any artifact when reconstructing smoother gradient.

Prof. Nunziata also addressed both theoretically and experimentally a key issue that arises with the enhancement of the spatial resolution of conical-scanning microwave radiometer measurements, i.e., noise amplification by discussing mathematically and experimentally the tradeoff between the enhancement of the spatial resolution and the noise amplification.

Recently prof. Nunziata pioneered a mathematically based approach to augment spatial resolution in multi-frequency radiometers by “augmenting” the lower-frequency (coarser spatial resolution) channel with tailored information extracted from the higher-frequency (finer spatial resolution) channel.

The methods developed by Prof. Nunziata were also used to design a L1-b product for the forthcoming Copernicus CIMR mission in the frame of a joint project carried out together with AIRBUS Spain.

Inverse problems, radar image, GNSS-R

Description: Prof Nunziata pioneered the development of a high-level Global Navigation Satellite System – Reflectometry (GNSS-R) product that includes normalized radar cross sections (NCRSs) arranged in a gridded format. This product can be successfully used for imaging remote sensing applications. To obtain this high-level product an ill-conditioned inverse problem is to be solved. Prof. Nunziata proposed new de-convolution methods to deal with the reconstruction problem in both Hilbert and Banach spaces.

The suite of methods was successfully verified against simulated and actual measurements and triggered the development of new added-values products for coastal area applications.W

Wave polarization, 2D planar waves, 3D non-planar waves, reverberation chamber

Description: The research activities concern polarization properties of both 2D and 3D electromagnetic waves. The differences between the degrees of partial polarization of electro- magnetic beam-like wave fields on time average and in the frequency domain is analyzed. It is pointed out that the spectral degree of polarization depends on the temporal coherence properties of the field, but the same is not true for the time-domain degree of polarization. Consequently, the degrees of polarization in the two domains assume, in general, different values. For example, a field that is fully unpolarized in the time domain can be fully po- larized at every frequency. However, a field that is fully polarized in the time domain is also fully polarized in the frequency domain.

The electromagnetic field within a Reverberating Chamber (RC) has a random three-dimensional structure that must be properly taken into account to analyze it. A model for three-dimensional degree of polarization is applied to analyze the randomness of the 3D electromagnetic field generated within a RC. Experiments, under- taken at the RC of Universit`a degli Studi di Napoli Parthenope, show: a) the field within the well stirred RC is three-dimensional; b) the measurements and the physical meaning of the three indexes provide a quantitative evaluation of the effectiveness of the stirring process and hence of the randomness of the electromagnetic field within the RC.

Reverberation chamber, power delay profile, total radiated power

Description: These activities are devoted to the modeling, the identification and the measurements of properties associated to the wireless communication emulated in the reverberation chamber. A model, based on the generalized K (GK) distribution, is developed to identify distinguish not only line-of-sight (LOS) and non-line-of-sight configurations but also to provide a better granularity within these two macro groups (i.e. distinguishing the clear LOS condition from the near LOS one, that typically applies when an object partially shadows the link).

Total radiated power (TRP) is typically measured using an array of sensors with the anechoic chamber. Prof. Nunziata pioneered a completely different approach that consists of using the peculiarities of the reverberation chamber, i.e., generating an electromagnetic field that is isotropic and uniform in the average sense, to measure the total power radiated by a mobile phone (MP). A model is proposed to describe the mobile phone (MP) under test inside the working volume of the Reverberation Chamber to the real external wireless communication system. Then, a method is proposed to evaluate the total radiated power by the MP under both LOS and NLOS conditions and the results are inter-compared with open literature.

The Power delay profile (PDP) of a wireless channel emulated within the reverberation chamber is characterized using a completely new measurement setup that consists of using the conventional central barrier, i.e.; absorbing material arranged on the floor of the RC, together with anechoic corners. The latter are built covering the two side of a chamber’s edge and nearby floor with absorbing material. This configuration is shown to outperform the conventional one since it provides a remarkably good fit with actual in field measurements.

Mission Advisory Group (MAG)

Italian Space Agency -  COSMO-SkyMed

Italian Space Agency - L-band Synthetic Aperture Radar

Societies

2023 – now         He chairs the IEEE Geoscience and Remote Sensing South Italy Chapter.

2022 – now:        He chairs the Ocean remote Sensing Technology Committee of the IEEE Oceanic Engineering Society (OES).

2016 – now:        IEEE member of the Oceanic Engineering Society (OES).

2014 – now:        He serves as Theme coordinator/Session Organizer the IGARSS organizing committee.

2014 – 2022:       He is secretary of the IEEE Geoscience and Remote Sensing South Italy Chapter

2013 – 2020:       He chairs the Young Professionals (YP) Affinity Group (AG) of the IEEE Italy Section.

2011 – 2017:       He chairs the Young Professionals (YP) program of the IEEE GRSS

2008 – now:        He is Member of the IGARSS scientific committee.

2005 – 2014:       He chairs the Student Branch @ Università degli Studi di Napoli Parthenope

2003 – now         Member of the Italian Society of Electromagnetics (SIEm).

2003 – now         Member of the Geoscience and Remote Sensing Society (GRSS).

Associate Editor

2019 – now:   He is Associate Editor of the IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing (JSTARS).

2018-now:     He is Associate Editor of MDPI Remote Sensing.

2022:                    Co-Editor (with Dr Christian Bignami, INGV, Italy and X. Yang, Chinese Academy of Sciences, Beijing, China) of the Special Issue of Frontiers in Environmental Science “Remotely sensed measurements to manage inland and coastal water”.

2022:              Co-Editor (with Prof. Weizeng Shao, Dr Juhong Zou and Dr Gang Zheng) of the Special Issue of MDPI Remote Sensing “Marine Disaster Monitoring Using Satellites”.

2019-2021:    He is Associate Editor of MDPI Ocean.

2019 – 2019:  He was guest editor of a Special Issue for JSTARS: “H.-C.Li, S.R.Cloude, J.Yang and F.Nunziata, Compact Polarimetric SAR, 2019.”

2017:            Co-Editor (with Dr Armando Marino, University of Stirling, UK and Dr Domenico Velotto, German Aerospace Center, Germany) of the Special Issue of MDPI Remote Sensing “Remote Sensing of Target Detection in Marine Environment”

2016:            Co-Editor (with Dr Xiaofeng Yang, Chinese Academy of Sciences, Beijing, China, Dr Alexis Mouche, IFREMER, France and Xiaofeng Li, NOAA, USA) of the Special Issue of MDPI Remote Sensing “Ocean Remote Sensing with Synthetic Aperture Radar”.

2015             Guest editor of the Special Issue of European Journal of Remote Sensing “Young Professionals – Remote Sensing”.