Marco Lavalle

• National Aeronautics and Space Administration

Soil moisture retrievals based on rigorous physical backscattering models require a comprehensive description of the vegetation structure and biophysical parameters, including the density of the scatters, height, and vegetation water content. Semi-physical models such as the water cloud model (WCM), are also extensively used and rely on estimates o...

Forest degradation is a major issue in ecosystem monitoring, and to take reformative measures, it is important to detect, map, and quantify the losses of forests. Synthetic Aperture Radar (SAR) time-series data have the potential to detect forest loss. However, its sensitivity is influenced by the ecoregion, forest type, and site conditions. In thi...

Accurate mapping of forest above ground biomass (AGB) is essential for understanding changes in the rate of ecosystem processes such as biomass productivity, litter productivity, actual litter decomposition, and potential litter decomposition during secondary succession. They also play a vital role in evaluating forest carbon pools. This study pres...

This paper describes a model-based algorithm for estimating tree height and other bio-physical land parameters from time-series of synthetic aperture radar interferometric coherence and backscatter supported by sparse lidar data. The random-motion-over-ground model (RMoG) is extended to time-series and revisited to capture the short- and long-term...

Recent results have highlighted the potential ability of bi- and multistatic synthetic aperture radar (SAR) tomographers to measure vegetation structure and surface topography. However, the quality of SAR tomographic measurements with multiple platforms is impacted by the phase instability in each platform’s oscillator. The phase noise, if uncompen...

When GNSS signals reflect off of the surfaces of lakes, rivers, wetlands, and other inland water bodies, the surfaces are often sufficiently smooth to produce coherent reflections. The observable produced from coherent reflections made by GNSS Reflectometry (GNSS-R) instruments exhibits particular features with respect to diffusely scattered signal...

This data set is the first-of-its-kind spatial representation of multi-seasonal, global C-band Synthetic Aperture Radar (SAR) interferometric repeat-pass coherence and backscatter signatures. Coverage comprises land masses and ice sheets from 82° Northern to 79° Southern latitudes. The data set is derived from multi-temporal repeat-pass interferome...

This article describes a projection algorithm between radar and map coordinates based on the representation of radar samples as area elements (AEs) rather than point elements. Each AE on the map grid (geographic grid) is associated with a number of radar grid samples that intersect completely or partially the AE. The association enables the geocodi...

Many sensors are suitable for accurate delineation of open water extent, but in vegetated environments, the vegetation canopy can obscure the presence of standing water from detection. Detecting inundation extent in these vegetated environments is especially critical for identifying flooding extent where surface water may exceed flood boundaries an...

A novel metric for detecting coherence in Global Navigation Satellite System Reflectometry (GNSS-R) signals is presented and evaluated. It applies the Von Neumann information entropy metric for density matrices, a powerful indicator of the degree of mixing between states, coherent and incoherent, of the scene under investigation. The metric is appl...

Physics-based algorithms estimating large-scale forest above-ground biomass (AGB) from synthetic aperture radar (SAR) data generally use airborne laser scanning (ALS) or grid of national forest inventory (NFI) to reduce uncertainties in the model calibration. This study assesses the potential of multitemporal L-band ALOS-2/PALSAR-2 data to improve...

In 2015 and 2016, the AfriSAR campaign was carried out as a collaborative effort among international space and National Park agencies (ESA, NASA, ONERA, DLR, ANPN and AGEOS) in support of the upcoming ESA BIOMASS, NASA-ISRO Synthetic Aperture Radar (NISAR) and NASA Global Ecosystem Dynamics Initiative (GEDI) missions. The NASA contribution to the c...

The extended mission of NASA’s CYGNSS satellite constellation has a new focus on land applications, and the CYGNSS Science Team is actively performing land calibration/validation for soil moisture and surface roughness. At the same time, CYGNSS is also producing exciting new terrestrial surface water observations with applications for monitoring we...

3D imaging of Earth’s surface layers (such as canopy, sub-surface, or ice) requires not just the penetration of radar signal into the medium, but also the ability to discriminate multiple scatterers within a slant-range and azimuth resolution cell. The latter requires having multiple radar channels distributed in across-track direction. Here, we de...

Forest height is an important forest biophysical parameter which is used to derive important information about forest ecosystems, such as forest above ground biomass. In this paper, the potential of combining Polarimetric Synthetic Aperture Radar (PolSAR) variables with LiDAR measurements for forest height estimation is investigated. This will be c...

The enduring activity of CYGNSS and TDS-1 observatories has provided clear evidence that ground reflected GNSS signal can be exploited for mapping of geophysical quantities in climate and global monitoring applications. One main challenge is to find out useful variables for determining the level of coherence of the scattered wave in the presence of...

Forest above-ground biomass (AGB) estimation from SAR backscatter is affected by varying imaging and environmental conditions. This paper quantifies and compares the performance of forest biomass estimation from L-band SAR backscatter measured selectively under dry and wet conditions during the 2019 AM-PM NASA airborne campaign. Seven Uninhabited A...

Abstract—This work investigates and demonstrates the suitability of the Sentinel-1 interferometric coherence for land cover and vegetation mapping. In addition, this study analyses the performance of this feature along with polarisation and intensity products according to different classification strategies and algorithms. Seven different classific...

This article demonstrates how 3-D vegetation structure can be approximated by interferometric synthetic aperture radar (InSAR) backscatter-height histograms. Single-look backscatter measurements are plotted against the InSAR phase height and are aggregated spatially over a forest patch to form a 3-D histogram, referred to as InSAR backscatter-heigh...

Presents corrections to the above mentioned paper.

https://esamultimedia.esa.int/docs/EarthObservation/Copernicus_L-band_SAR_mission_ROSE-L_MRD_v2.0_issued.pdf

Our study aims to provide a comparison of the P- and L-band TomoSAR profiles, Land Vegetation and Ice Sensor (LVIS), and discrete return LiDAR to assess the ability for TomoSAR to monitor and estimate the tropical forest structure parameters for enhanced forest management and to support biomass missions. The comparison relies on the unique UAVSAR J...

Our study aims to provide a comparison of the P- and L-band TomoSAR profiles, Land Vegetation and Ice Sensor (LVIS), and discrete return LiDAR to assess the ability for TomoSAR to monitor and estimate the tropical forest structure parameters for enhanced forest management and to support biomass missions. The comparison relies on the unique UAVSAR J...

In order to help scientists in the above ground biomass community and to support the science behind the upcoming BIOMASS, NISAR, and GEDI satellite missions, ESA and NASA are collaborating on the Multi-Mission Algorithm and Analysis Platform (MAAP). The MAAP is a jointly developed and implemented platform that will include not only data (satellite,...

Synthetic Aperture Radar (SAR) backscatter is the coherent combination of the scattering from multiple individual scatterers within the radar resolution cell, which results into a 2-D radar image. Tomographic SAR (TomoSAR) takes advantage of multiple SAR acquisitions to provide 3-D vertical structure of the imaged target. Over forests, parameters s...

Developing and enhancing strategies to characterize actual forests structure is a timely challenge, particularly for tropical forests. P-band synthetic aperture radar (SAR) tomography (TomoSAR) has previously been demonstrated as a powerful tool for characterizing the 3-D vertical structure of tropical forests, and its capability and potential to r...

This paper provides a first hand view of the 3-D structure of the forests when viewed by X-band SAR data. Tomograms are generated using multi-polarimetric space-borne TerraSAR-X/TanDEM-X acquisitions and analysed over a multi-species forest range. The paper analysed these generated tomograms and puts forth-interesting observations of these unique f...

This paper investigates the benefits of integrating polarimetric radar variables with LiDAR measurements using Support Vector Machine (SVM) in order to measure the forest canopy height. Multiple polarimetric variables are required as an input in order to ensure consistent height retrieval performance across a broad range of forest heights. We train...

This paper investigates the benefits of integrating multibaseline polarimetric interferometric SAR (PolInSAR) data with LiDAR measurements using a machine-learning approach in order to obtain improved forest canopy height estimates. Multiple interferometric baselines are required to ensure consistent height retrieval performance across a broad rang...

The random volume over ground (RVoG) model has been widely applied to estimate forest tree height from polarimetric synthetic aperture radar (SAR) interferometry (PolInSAR) data for the past two decades. Successful application of the RVoG model requires certain assumptions to be valid for the imaged forest and the acquisition scenarios in order to...

The InSAR Scientific Computing Environment (ISCE) was first developed under the NASA Advanced Information Systems Technology as a flexible, extensible object-oriented framework for Interferometric Synthetic Aperture Radar (InSAR) processing. The ISCE framework uses Python 3 at the workflow level, controlling modules of compiled code for functional...

This paper presents a new damage-mapping algorithm based on coherence images estimated from multitemporal polarimetric-interferometric synthetic aperture radar (SAR) data. The interferometric coherence has been restricted in the conventional damage-mapping approaches because the decorrelation sources are too complicated to interpret accurately and...

Detection of changes caused by major events—such as earthquakes, volcanic eruptions, and floods—from interferometric synthetic aperture radar (SAR) data is challenging because of the coupled effects with temporal decorrelation caused by natural phenomena, including rain, snow, wind, and seasonal changes. The coupled effect of major events and natur...

This paper addresses the important yet unresolved problem of estimating forest properties from polarimetric-interferometric radar images affected by temporal decorrelation. We approach the problem by formulating a physical model of the polarimetric-interferometric coherence that incorporates both volumetric and temporal decorrelation effects. The m...

In this letter we propose a three-baseline approach to the extraction of forest tree height from synthetic aperture radar data. Three polarimetric–interferometric pairs are used to constrain a physical model that relates forest parameters to multiple repeat-pass coherence observations. The observations may be performed by a dual, compact or full po...

The Advanced Synthetic Aperture Radar (ASAR) on- board Envisat operated successfully for just over 10 years until the failure of Envisat in April 2012. ASAR was ESA’s very first deployment of a C-band phased- array antenna, allowing extended imaging capacity in comparison to its ERS SAR predecessors. As such it operated in various acquisition mod...

This paper describes a physical model of the temporal changes that occur in vegetated land surfaces observed by a repeat-pass radar interferometer. We assume the temporal changes to be caused by a Gaussian-statistic motion of the vegetation elements, with motion variance changing along the vertical direction. We show that the temporal correlation b...

Quantification of the various components of the carbon cycle budget is key to improved climate modeling and projecting anthropogenic affects on climate in the future. Estimating the levels of above ground biomass contained in the world's forests that comprise 86% of the planet's above ground carbon and monitoring the rate of change to these standin...

The world forest systems are dynamic and play an integral role in the Earth's carbon budget. Monitoring of these valuable assets is being mandated by the international community. The requirement of global forest inventories suggests that a global measurement methodology should be adopted and that a verification and validation strategy should be acc...

In this paper we show our first POLINSAR results using the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) developed by the Jet Propulsion Laboratory (JPL). UAVSAR is a L-band repeat-pass polarimetric and interferometric system designed for measuring vegetation structure and monitoring crustal deformations. In order to extract canopy h...

We present an empirical assessment of the impact of temporal decorrelation on interferometric coherence measured over a forested landscape. A series of repeat-pass interferometric radar images with a zero spatial baseline were collected with UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar), a fully polarimetric airborne L-band radar sys...

Biomass is identified by the United Nations Framework Convention on Climate Change (UNFCCC) as an essential climate variable needed to reduce uncertainties in our knowledge of the climate system [1]. Radar remote sensing is the most suitable tool to measure and map Earth's forest biomass, but current methods are limited by saturation issues (backsc...

We use the UAVSAR, an airborne fully polarimetric L-band radar system, to estimate forest canopy structure and biomass through radar backscatter and repeat-pass interferometry. UAVSAR provides backscatter images with a spatial resolution of 5m and is capable of repeat-pass interferometry. Our analysis also includes data from LVIS (Laser vegetation...

Quantification of the various components of the carbon cycle budget is key to improved climate modeling and projecting anthropogenic affects on climate in the future. Estimating the levels of above ground biomass contained in the world's forests that comprise 86% of the planet's above ground carbon and monitoring the rate of change to these standin...

Temporal changes of repeat-pass SAR backscatter over bare ground or forests results mostly from changes in the target's dielectric properties or moisture content; especially when the timescale is on the order of a few days or weeks. It is important to properly correct for moisture content when using SAR based estimates of tree height or biomass. Th...

We present the results of the 2009-2010 airborne L-band radar and lidar campaigns in boreal, temperate and tropical forests. The main objective is to improve canopy height and biomass retrieval from radar data both radiometrically and interferometrically. To achieve this, we assessed and designed models to compensate for the impact of terrain topog...

This contribution deals with the temporal correlation of a vertical ditribution of scatterers observed by a repeat-pass interferometer. We model the temporal correlation of such a semitranparent medium by using a height-dependent function. The expression of the temporal correlation function is found by assuming differential standard deviation for t...

The authors discuss the role and performance of compact polarimetry in SAR interferometry. The considered SAR architecture transmits either a linearly polarised wave oriented at 45° or a circularly polarised one, and receives at horizontal and vertical polarisation. Two polarimetric acquisitions are combined in an interferometric image, characteri...

We model the temporal decorrelation in volumetric media imaged by a repeat-pass SAR interferometer by using a temporal correlation function that varies with depth. An expression of this function is proposed and based on the Brownian motion of the canopy and soil elements. The spatial and temporal correlation terms are merged in a single coherence m...

Cette thèse aborde principalement le rôle que jouent les radars polarimétrique et interférométrique dans les applications de géosciences, tout particulièrement sur les forêts. Il est démontré que les modèles actuels simples de la corrélation spatiale des milieux naturels sont capables d'estimer de manière robuste la hauteur de la forêt et sa biomas...

In this paper we discuss some aspects of the forest height estimation using Polarimetric and Interferometric (POLINSAR) SAR data. Three main issues limit the inversion of the POLINSAR coherence from repeat-pass POLINSAR systems: temporal decorrelation, terrain slope distortions and effects of wave penetration. We show that, if temporal decorrelatio...

The objective of this paper is to make a review of the current status of the PolSARpro v4.0 Software (Polarimetric SAR Data Processing and Educational Toolbox), developed under contract to ESA by a consortium comprising I.E.T.R at the University of Rennes 1, AELc, DLR-HR and Dr mark Williams from Adelaide. The objective of this current project is t...

Due to their large scale of observation and their relatively high revisiting frequency, spaceborne SAR systems offer interesting possibilities for the systematic monitoring of urban areas. Several techniques have been developed to analyze urban areas from single-polarization spaceborne SAR data, based on the statistical properties of the reflectivi...

GeoSAR is a unique dual-band, interferometric SAR (DBInSAR) sensor capable of collecting single-pass, X-band (VV) and P-band (HH) interferometric data simultaneously. In this paper we examine the dependence of the P-band HH interferometric phase centre height upon forest and terrain parameters. We develop a simple model for P-band GeoSAR observatio...

A compact polarimetry (CP) mode can be defined as a dual-pol mode that transmits a generic polar- ized wave, usually circular or linear oriented at 45 deg. In this paper, we first show some observations of the reconstruction algorithms of pseudo full Pol- SAR/PolInSAR information from CP data. Secondly, we discuss the impact of the SAR processor an...

In this paper we discuss the radiometric calibration of dual polarimetric Synthetic Aperture Radar (SAR) data. The polarimetric distortion model of a dual- pol SAR includes four calibration complex parame- ters: the cross-talk on transmit, the receiving channel imbalance and two receiving cross-talks. While these parameters can be estimated in a fu...

This paper presents a new approach to the exploitation of polarimetric and interferometric (POLINSAR) data for the quantitative estimation of the forest height and, in general, of forest parameters. Our procedure aims to match simulations from the coherent scattering model PolSARProSim and real measurables. First, a parametric model analysis is use...

In this paper, we investigate the role and the performance of compact polarimetry in SAR interferometry. The considered SAR architecture is assumed to transmit either a circular polarized wave or a linear polarized one oriented at 45 degrees (pi/4), and to receive at horizontal and vertical polarization. Two polarimetric acquisitions are combined i...

Polarimetric SAR interferometric data can provide estimates of forest biomass density. There are different approaches to deal with the inversion problem, such as neural networks and the traditional optimal estimation approach. This paper presents a study to evaluate their performance by means of quantitative indexes addressing both the computation...