Nazzareno Pierdicca - Profile on Academia.edu (original) (raw)

Papers by Nazzareno Pierdicca

Precipitation signature on side-looking aperture radar imaging: Sensitivity analysis to surface effects at C, X and Ku band

Previous studies have shown the potentiality of X-band synthetic aperture radar in measuring rain... more Previous studies have shown the potentiality of X-band synthetic aperture radar in measuring rainfall. A microwave forward model describes the Normalized Radar Cross Section (NRCS) as composed by a surface contribution and a volumetric contribution and inversion techniques were used to derive the precipitation over land, particularly over bare soil. However, different surfaces may affect the SAR precipitation signature, so here, we present a sensitivity analysis to the surface effects for three different frequencies such as C-, X- and Ku-band using a two-layer precipitating cloud system composed by rain and snow. Particular attention is given to the effects of sea surface whose variability is strongly related to the surface winds. The main results show that as the frequency increases, the NRCS increases. Moreover, when the wind speed becomes higher, the SAR response due to precipitation is mainly influenced by the surface contribution so that the sensibility to precipitating cloud decreases. This behaviour can be ascribed to the increasing sea surface roughness.

Precipitation evidences on X-Band Synthetic Aperture Radar imagery: an approach for quantitative detection and estimation

EGU General Assembly Conference Abstracts, Apr 1, 2017

Spaceborne synthetic aperture radars (SARs) operating at L-band and above are nowadays a well-est... more Spaceborne synthetic aperture radars (SARs) operating at L-band and above are nowadays a well-established tool for Earth remote sensing; among the numerous civil applications we can indicate flood areas detection and monitoring, earthquakes analysis, digital elevation model production, land use monitoring and classification. Appealing characteristics of this kind of instruments is the high spatial resolution ensured in almost all-weather conditions and with a reasonable duty cycle and coverage. This result has achieved by the by the most recent generation of SAR missions, which moreover allow polarimetric observation of the target. Nevertheless, atmospheric clouds, in particular the precipitating ones, can significantly affect the signal backscattered from the ground surface (e.g. Ferrazzoli and Schiavon, 1997), on both amplitude and phase, with effects increasing with the operating frequency. In this respect, proofs are given by several recent works (e.g. Marzano et al., 2010, Baldini et al., 2014) using X-Band SAR data by COSMO-SkyMed (CSK) and TerraSAR-X (TSX) missions. On the other hand, this sensitivity open interesting perspectives towards the SAR observation, and eventually quantification, of precipitations. In this respect, a proposal approach for X-SARs precipitation maps production and cloud masking arise from our work. Cloud masking allows detection of precipitation compromised areas. Respect precipitation maps, satellite X-SARs offer the unique possibility to ingest within flood forecasting model precipitation data at the catchment scale. This aspect is particularly innovative, even if work has been done the late years, and some aspects need to still address. Our developed processing framework allows, within the cloud masking stage, distinguishing flooded areas, precipitating clouds together with permanent water bodies, all appearing dark in the SAR image. The procedure is mainly based on image segmentation techniques and fuzzy logic (e.g. Pulvirenti et al. 2014 and Mori et al. 2012); ancillary data, such as local incident angle and land cover, are used. This stage is necessary to tune the precipitation map stage and to avoid severe misinterpretations on the precipitation map routines. The second stage consist of estimating the local cloud attenuation. Finally the precipitation map is estimated, using the the retrieval algorithm developed by Marzano et al. (2011), applied only to pixels where rain is known to be present. Within the FP7 project EartH2Observe we have applied this methodology to 14 study cases, acquired within TSX and CSK missions over Italy and United States. This choice allows analysing both hurricane-like intense events and continental mid-latitude precipitations, with the possibility to verify and validate the proposed methodology through the available weather radar networks. Moreover it allows in same extent analysing the contribution of orography and quality of ancillary data (i.e. landcover). In this work we will discuss the results obtained until now in terms of improved rain cell localization and precipitation quantification

Effects of atmospheric precipitations and turbulence on satellite Ka-band synthetic aperture radar

Spaceborne synthetic aperture radars (SARs) operating at L-band and above are nowadays a well-est... more Spaceborne synthetic aperture radars (SARs) operating at L-band and above are nowadays a well-established tool for Earth remote sensing. In this respect, a new frontier of technological and scientific progress is represented by satellite Ka-Band SARs. Since approximately 2010, a number of European Space Agency (ESA) studies have been funded in this direction. The main identified benefit of Ka-band systems is that the short wavelength allows the implementation on a single platform of single-pass interferometry, both cross-track and along-track, with adequate interferometric sensitivity. Ka-band is also interesting due to the low penetration in media such as ice, snow, and vegetation. In principle, the 500 MHz allocation also enables high-resolution measurements. Atmospheric effects represent a severe limitation to Ka-Band SARs. Gases and water particles introduce attenuation and path delay also in clear-sky condition; raindrops also depolarization. Finally, atmospheric turbulence causes scintillation effects. Unfortunately, very few studies and experiments exist at Ka Band. With this general context, the project KaBandSARApp aims to consolidate a Ka-band SAR mission concept, linking user (product-level) observation requirements to mission requirements, and evaluating and highlighting the expected performances for a set of relevant applications. This purpose will be pursued through the development of an End-to-End (E2E) performance tool, where atmospheric effects have been simulated through a Forward Model (FM) of SAR response. This work describes the developed forward model in the general context of atmospheric effects on SAR retrieved signal. A case study relative to a quite common and light cloud (alto-stratus) will be presented and discussed.

Lessons learned from using COSMO-SkyMed imagery for flood mapping: some case studies

Proceedings of SPIE, Nov 21, 2012

ABSTRACT Synthetic Aperture Radar (SAR) systems represent the most powerful tool to monitor flood... more ABSTRACT Synthetic Aperture Radar (SAR) systems represent the most powerful tool to monitor flood events because of their allweather capability that allows them to collect suitable images even in cloudy conditions. The quality of flood monitoring using SAR is increasing thanks to the improved spatial resolution of the new generation of instruments and to the short revisit time of the present and future satellite constellations. In particular, the COSMO-SkyMed mission offers a unique opportunity to obtain all weather radar images characterized by short revisit time. To fully exploit these technological advances, the methods to interpret images and produce flood maps must be upgraded, so that an accurate interpretation of the multitemporal radar signature, accounting for system parameters (frequency, polarization, incidence angle) and land cover, becomes very important. The COSMO-SkyMed system has been activated several times in the last few years in consequence of the occurrence of flood events all over the world in order to provide very high resolution X-band SAR images useful for flood detection purposes. This paper discusses the major outcomes of the experiences gained from using COSMO-SkyMed data for the purpose of near real time generation of flood maps. A review of the mechanisms which determine the imprints of the inundation on the radar images is provided and the approach designed to process the data and to generate the flood maps is also summarized. Then, the paper illustrates a number of significant case studies in which flood events have been monitored through COSMO-SkyMed images. These examples demonstrate the potential of the COSMO-SkyMed system and the suitability of the approach developed for generating the final products, but they also highlight some critical aspects that require further investigations to improve the reliability of the flood maps.

Detection and quantification of precipitations signatures on synthetic aperture radar imagery at X band

Proceedings of SPIE, Oct 18, 2016

Nowadays a well-established tool for Earth remote sensing is represented by Spaceborne synthetic ... more Nowadays a well-established tool for Earth remote sensing is represented by Spaceborne synthetic aperture radars (SARs) operating at L-band and above that offers a microwave perspective at very high spatial resolution in almost all-weather conditions. Nevertheless, atmospheric precipitating clouds can significantly affect the signal backscattered from the ground surface on both amplitude and phase, as assessed by numerous recent works analyzing data collected by COSMO-SkyMed (CSK) and TerraSAR-X (TSX) missions. On the other hand, such sensitivity could allow detecting and quantifying precipitations through SARs. In this work, we propose an innovative processing framework aiming at producing X-SARs precipitation maps and cloud masks. While clouds masks allow the user to detect areas interested by precipitations, precipitation maps offer the unique opportunity to ingest within flood forecasting model precipitation data at the catchment scale. Indeed, several issues still need to be fully addressed. The proposed approach allows distinguishing flooded areas, precipitating clouds together with permanent water bodies. The detection procedure uses image segmentation techniques, fuzzy logic and ancillary data such as local incident angle map and land cover; an improved regression empirical algorithm gives the precipitation estimation. We have applied the proposed methodology to 16 study cases, acquired within TSX and CSK missions over Italy and United States. This choice allows analysing different typologies of events, and verifying the proposed methodology through the available local weather radar networks. In this work, we will discuss the results obtained until now in terms of improved rain cell localization and precipitation quantification.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Identification of building double-bounces feature in very high resoultion SAR data for earthquake damage mapping

Nowadays very high resolution (VHR) Synthetic Aperture Radar (SAR) systems can provide near real ... more Nowadays very high resolution (VHR) Synthetic Aperture Radar (SAR) systems can provide near real time earthquake damage maps with an high degree of details to stakeholders in charge of managing the emergency phase. However, the increased resolution introduces new challenges to interpret and detect changes in urban areas caused by seismic events. In metric resolution SAR sensors a building appears as a complex of image structures associated to different scattering mechanisms, preventing the use of pixel-based algorithms. In this paper we propose an object oriented approach, focusing the attention on the double-bounce return from buildings, trying to detect damages looking at changes of these particular image patterns. The identification of double-bounce regions is performed using open and close morphological filters and assuming linear structuring elements with different orientation and length. The change detection analysis based on a pre- and a post-event image is carried out using four change detection indicators, such as: intensity ratio, interferometric coherence, intensity correlation and Kullback-Leibler divergence. All change features are extracted using all pixels within each identified object, i.e., double-bounce regions. The test case is the earthquake that hit L'Aquila city (Italy) on April 6, 2009, while the dataset is composed of two X-band COSMO-SkyMed SAR images acquired before and after the event. A macro-seismic survey map was available to evaluate the obtained results.

Incorporating Sentinel-derived products into numerical weather models: the ESA STEAM project

The STEAM (SaTellite Earth observation for Atmospheric Modelling) project, funded by the European... more The STEAM (SaTellite Earth observation for Atmospheric Modelling) project, funded by the European Space Agency, aims at investigating new areas of synergy between high-resolution numerical weather prediction (NWP) models and data from spaceborne remote sensing sensors. An example of synergy is the incorporation of high-resolution remote sensing data products in NWP models. The rationale is that NWP models are presently able to produce forecasts with a spatial resolution in the order of 1 km, but unreliable surface information or poor knowledge of the initial state of the atmosphere may imply an inaccurate simulation of the weather phenomena. It is expected that forecast inaccuracies could be reduced by ingesting high resolution Earth Observation derived products into models operated at cloud resolving grid spacing. In this context, the Copernicus Sentinel satellites represent an important source of data, because they provide a set of high-resolution observations of physical variables (e.g. soil moisture, land/sea surface temperature, wind speed, columnar water vapor) used NWP models runs. This paper presents the first results of the experiments carried out in the framework of the STEAM project, regarding the ingestion/assimilation of surface information derived from Sentinel data into a NWP model. The experiments concern a flood event occurred in Tuscany (Central Italy) in September 2017. Moreover, in view of the assimilation of water vapor maps obtained by applying the SAR Interferometry technique to Sentinel-1 data, the results of the assimilation of Zenith total delay data derived from global navigation satellite system (GNSS) are also presented.

Atmospheric precipitation impact on synthetic aperture radar imagery: Numerical model at X and KA bands

Recent spaceborne polarimetric Synthetic Aperture Radars (SARs) enable the complete characterizat... more Recent spaceborne polarimetric Synthetic Aperture Radars (SARs) enable the complete characterization of target scattering and extinction properties. Several missions are operating at X band while there are plans and analyses for systems operating at higher frequencies, such as Ka band. Systems operating at these frequencies have interesting and distinctive applications in the field of geosciences such as Cartography, Surface deformation detection, Forest cover mapping and many others. However, the detected ground surface response can be affected by atmospheric effects in both signal amplitude and phase, especially in presence of atmospheric precipitations. In this work we will introduce a simulation framework developed to characterize how precipitating clouds affect spaceborne X- and Ka-band SARs systems. The proposed framework is able to simulate the polarimetric SAR ground responses in terms of Normalized Radar Cross Sections (NRCS) and complex correlation coefficient, both for realistic atmosphere-ground scenarios and for synthetic canonical ones. Some preliminary results will be shown and discussed.

2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

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Analysis Of Atmoshperic Effects On X-Band Synthetic Aperture Radar Observations And Precipitations Estimation

ESA Living Planet Symposium, Dec 1, 2013

Advances in Global Change Research, 2020

Spaceborne Synthetic Aperture Radars (SARs), operating at L-band and above, offer microwave obser... more Spaceborne Synthetic Aperture Radars (SARs), operating at L-band and above, offer microwave observations of the Earth at very high spatial resolution in almost all-weather conditions. Nevertheless, precipitating clouds can significantly affect the signal backscattered from the ground surface in both amplitude and phase, especially at X band and beyond. This evidence has been assessed by numerous recent efforts analyzing data collected by COSMO-SkyMed (CSK) and TerraSAR-X (TSX) missions at X band. This sensitivity can be exploited to detect and quantify precipitations from SARs at the spatial resolution of a few hundred meters, a very appealing feature considering the current resolution of precipitation products from space. Forward models of SAR response in the presence of precipitation have been developed for analyzing SAR signature sensitivity and developing rainfall retrieval algorithms. Precipitation retrieval algorithms from SARs have also been proposed on a semi-empirical basis. This chapter will review experimental evidences, modelling approaches, retrieval methods and recent applications of X-band SAR data to rainfall estimation.

European geosciences union general assembly, 2014

GEROS-ISS (GEROS hereafter) stands for GNSS REflectometry, Radio Occultation and Scatterometry on... more GEROS-ISS (GEROS hereafter) stands for GNSS REflectometry, Radio Occultation and Scatterometry onboard the International Space Station. It is a scientific experiment, proposed to the European Space Agency (ESA) in 2011 for installation aboard the ISS and was accepted by ESA to proceed to Phase A. GEROS is an innovative ISS experiment primarily focused on exploiting reflected signals of opportunity from Global Navigation Satellite Systems (GNSS) at Lband to measure key parameters of ocean surfaces. GEROS will utilize the U.S. American GPS (Global Positioning System) and pioneer the exploitation of signals from Galileo and possibly other GNSS systems (GLONASS, QZSS, BeiDou), for reflectometry and occultation, thereby improving the accuracy as well as the spatio-temporal resolution of the derived geophysical properties. The GEROS mission idea and the current status are briefly reviewed.

Assimilation experiments of Sentinel-derived and GNSS-derived products to improve the WRF forecasts of extreme events: results of the STEAM project

2020 XXXIIIrd General Assembly and Scientific Symposium of the International Union of Radio Science, 2020

Navigation signals reflected by the Earth surface, collected by a receiver in relative movement w... more Navigation signals reflected by the Earth surface, collected by a receiver in relative movement with respect to the source and the surface, can exhibit temporal fluctuations. Their features are related to the characteristics of the surface roughness and they can be observed even in the presence of almost flat surfaces with gentle undulations, i.e., those whose horizontal scale can be comparable with the impinging wavelength. In this work, a full-wave solution of the scattering based on the Kirchhoff approximation is implemented to characterize the temporal variability of scattered signals of opportunity. A numerical solution is compared with a simple closed-form expression achieved considering omnidirectional sources. The analysis can provide useful information for the interpretation of GNSS data, especially those collected by means of satellite platforms, which presents an intrinsic variability that can significantly affect the retrieval of bio-geophysical parameters.

GEROS was selected in result of a complex review process, initiated by ESA. The review results an... more GEROS was selected in result of a complex review process, initiated by ESA. The review results and decision on further activities was officially announced end of 2012. An interdisciplinary and international Science Advisory Group (SAG) of acknowledged experts in Oceanography, Geodesy, Atmosphere and GNSS Science started to work in June 2013 on details of the preparation of the GEROS mission. This SAG consists of key members of the proposing GEROS team and additional experts, nominated by ESA. The begin of two competitive industrial phase A studies for the GEROS mission implementation is foreseen for early 2014. According to the current schedule and in case of successful preparative studies and provision of appropriate funding, a launch of GEROS can be expected for 2018.

IEEE Geoscience and Remote Sensing Magazine, 2021

This work presents an overview of the activity developed in the frame of a project funded by the ... more This work presents an overview of the activity developed in the frame of a project funded by the European Space Agency. The research was focused on the study of the potential applications of Global Navigation Satellite System Reflectometry (GNSS-R) over land, with emphasis on soil moisture and biomass. A study about the sensitivity with respect to the freeze-thaw dynamics was considered as well. The work started with an analysis of the sensitivity of GNSS-R reflectivity collected by the TechDemoSAT-1 experimental satellite. Although to a limited extent, the CyGNSS (Cyclone Global Navigation Satellite System) constellation was considered as well. The encouraging sensitivity outcomes led to the development of retrieval algorithms, three different approaches for soil moisture and one for biomass based on neural networks. A more theoretical investigation was carried out to better understand and predict the signal from a satellite platform, which required to update two different models. Topography effects and sensitivity to moisture and roughness of a rough soil were included, as well as the effect of vegetation cover. The project was carried out by a large team involving different research groups in Europe. It has led to main conclusions and recommendations derived from a beneficial collaboration and fertilization of ideas. The main approaches and outcomes are summarized here also in comparison to the recent literature.

URSI Radio Science Bulletin, 2020

The possibility of exploiting signals of opportunity such as navigation signals for remote-sensin... more The possibility of exploiting signals of opportunity such as navigation signals for remote-sensing applications has been the object of extensive scientifi c research. Over the years, the potential of this technique has been mainly investigated for wind scatterometry and sea-surface altimetry, resulting in mission concepts and prototypes currently in orbit or under study. More recently, the potential of the Global Navigation Satellite System (GNSS) has attracted signifi cant scientifi c and industrial interest, especially for land applications. The possibility of retrieving soil moisture and vegetation biomass by means of GNSS refl ections, originally demonstrated through theoretical models and simulations, has been confi rmed through the analysis of ground-based and airborne measurements. Even if these campaigns signifi cantly contributed to consolidating the physics that is behind the interaction between navigation signals and some important geophysical parameters of the illuminated surface, a complete understanding of the experiments still needs further scientifi c eff orts, especially for satellite observations. In this work, we review the main progress that has recently been made at two universities of Rome, Sapienza and Tor Vergata, as well as by some other research groups. Current challenges and modeling approaches are summarized, focusing the attention on the potential off ered by GNSS refl ectometry with respect to more established passive and active remote-sensing techniques. An electromagnetic model and the corresponding numerical simulator designed to characterize the fi eld scattered under bistatic illumination and for the study of the signal at the receiver generated by sources of opportunity are reviewed and summarized.

Precipitation signature on side-looking aperture radar imaging: Sensitivity analysis to surface effects at C, X and Ku band

Precipitation evidences on X-Band Synthetic Aperture Radar imagery: an approach for quantitative detection and estimation

EGU General Assembly Conference Abstracts, Apr 1, 2017

Effects of atmospheric precipitations and turbulence on satellite Ka-band synthetic aperture radar

Spaceborne synthetic aperture radars (SARs) operating at L-band and above are nowadays a well-est... more Spaceborne synthetic aperture radars (SARs) operating at L-band and above are nowadays a well-established tool for Earth remote sensing. In this respect, a new frontier of technological and scientific progress is represented by satellite Ka-Band SARs. Since approximately 2010, a number of European Space Agency (ESA) studies have been funded in this direction. The main identified benefit of Ka-band systems is that the short wavelength allows the implementation on a single platform of single-pass interferometry, both cross-track and along-track, with adequate interferometric sensitivity. Ka-band is also interesting due to the low penetration in media such as ice, snow, and vegetation. In principle, the 500 MHz allocation also enables high-resolution measurements. Atmospheric effects represent a severe limitation to Ka-Band SARs. Gases and water particles introduce attenuation and path delay also in clear-sky condition; raindrops also depolarization. Finally, atmospheric turbulence causes scintillation effects. Unfortunately, very few studies and experiments exist at Ka Band. With this general context, the project KaBandSARApp aims to consolidate a Ka-band SAR mission concept, linking user (product-level) observation requirements to mission requirements, and evaluating and highlighting the expected performances for a set of relevant applications. This purpose will be pursued through the development of an End-to-End (E2E) performance tool, where atmospheric effects have been simulated through a Forward Model (FM) of SAR response. This work describes the developed forward model in the general context of atmospheric effects on SAR retrieved signal. A case study relative to a quite common and light cloud (alto-stratus) will be presented and discussed.

Lessons learned from using COSMO-SkyMed imagery for flood mapping: some case studies

Proceedings of SPIE, Nov 21, 2012

Detection and quantification of precipitations signatures on synthetic aperture radar imagery at X band

Proceedings of SPIE, Oct 18, 2016

Identification of building double-bounces feature in very high resoultion SAR data for earthquake damage mapping

Incorporating Sentinel-derived products into numerical weather models: the ESA STEAM project

Atmospheric precipitation impact on synthetic aperture radar imagery: Numerical model at X and KA bands

2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

Analysis Of Atmoshperic Effects On X-Band Synthetic Aperture Radar Observations And Precipitations Estimation

ESA Living Planet Symposium, Dec 1, 2013

Advances in Global Change Research, 2020

European geosciences union general assembly, 2014

Assimilation experiments of Sentinel-derived and GNSS-derived products to improve the WRF forecasts of extreme events: results of the STEAM project

2020 XXXIIIrd General Assembly and Scientific Symposium of the International Union of Radio Science, 2020

IEEE Geoscience and Remote Sensing Magazine, 2021

URSI Radio Science Bulletin, 2020