Sylvain Mangiarotti

Institute of Research for Development | IRD · Centre d'Etudes Spatiales de la Biosphère

Using the classical inverse barometer (IB) correction and the Modèle d'Onde de Gravité à 2 Dimensions (MOG2D) barotropic model in the Mediterranean Sea during the 1993-2002 period, it is shown that surface pressure and wind stress forcing significantly contribute to sea level elevation variations observed with Ocean Topography Experiment (TOPEX)/Po...

A plague epidemic broke out in Bombay in 1896 and became endemic. From 1905 to 1911, the epidemic was closely monitored by an Advisory Committee appointed to investigate the causes of the disease in any way. An impressive quantity of information was gathered, analyzed and published. Published data include records of the number of people who died fr...

Crop detection from remote sensed images is of major interest for land use and land cover mapping. Classification techniques often require multi-temporal images. However, most of these techniques assume that the cultural cycle occurs at the same dates across plots or for a given crop and do not take into account the sensitivity to initial condition...

The hydrological dynamics of karstic systems are generally highly nonlinear and weakly predictable. This paper introduces, for the first time, a hydrological modelling approach based on chaos theory. Although this modelling approach may be extended to multi-variables, as a first step in exploring its applicability, the focus is on the simple case o...

Collective musical improvisations are often based on a support called a chord progression which offers improvisers a reference and a framework. This common reference brings a specific cohesion between the improvisers for the exploration of sound spaces that free improvisation could not allow. But such a framework can also prove to be too restrictiv...

A data-driven approach insensitive to the initial conditions was developed to extract governing equations for the concentration of CO2 in the Altamira cave (Spain) and its two main drivers: the outside temperature and the soil moisture. This model was then reformulated in order to use satellite observations and meteorological predictions, as a forc...

Controlling chaos is fundamental in many applications, and for this reason, many techniques have been proposed to address this problem. Here, we propose a strategy based on an optimal placement of the sensor and actuator providing global observability of the state space and global controllability to any desired state. The first of these two conditi...

A chaotic attractor was obtained from remote sensing data, for the first time, in the early 2010s, its Poincaré section revealing a weakly dissipative dynamics. This attractor was captured from a time series of vegetation index, for the cycles of cereal crops in semi-arid region. This attractor was fully unexpected, since it was also the first attr...

The epidemic of COVID-19 has shown different developments in Africa compared to the other continents. Three different approaches were used in this study to analyze this situation. In the first part, basic statistics were performed to estimate the contribution of the elderly people to the total numbers of cases and deaths in comparison to the other...

Multifractal analysis was applied to evidence spatial properties, in particular scaling behaviour, of Sentinel-2 surface reflectances and optical indexes acquired over the Southwest region of France. Considering the significant impact of clouds on the spatial properties of optical products, no study to our knowledge has focused on the multifractal...

Considering in situ observations, chaos theory was taken as a basis to study the activity of anecic earthworms based on cast production from September 2016 to January 2018 in the Dong Cao watershed (Vietnam). To study this activity, the global modeling technique was used to obtain deterministic models of ordinary differential equations directly fro...

When a chaotic attractor is produced by a three-dimensional strongly dissipative system, its ultimate characterization is reached when a branched manifold—a template—can be used to describe the relative organization of the unstable periodic orbits around which it is structured. If topological characterization was completed for many chaotic attracto...

The purpose of this paper is to model numerically the dynamics of CO 2 and 222 Rn in cave atmospheres, particularly in the noteworthy Cave of Altamira (Spain). We aim to get a better understanding of the nature of these dynamics and their couplings with climatic controls, more specifically the soil water content, which role in the said dynamics pos...

While predicting the course of an epidemic is difficult, predicting the course of a pandemic from an emerging virus is even more so. The validity of most predictive models relies on numerous parameters, involving biological and social characteristics often unknown or highly uncertain. Data of the COVID-19 epidemics in China, Japan, South Korea and...

Predicting the course of an epidemic is difficult, predicting the course of a pandemic from an emerging virus even more so. The validity of most predictive models relies on numerous parameters, involving biological and social characteristics often unknown or highly uncertain. COVID-19 pandemic brings additional factors such as population density an...

Lagrangian transport in the dynamical systems approach has so far been investigated disregarding the connection between the whole state space and the concept of observability. Key issues such as the definitions of Lagrangian and chaotic mixing are revisited under this light, establishing the importance of rewriting nonautonomous flow systems derive...

Soil moisture has a strong impact on climate, hydrology and agronomy at different space scales, from the continent global scale to the local watershed. Passive microwave sensors, like SMOS satellite (Soil Moisture and Ocean Salinity), allow a global study of soil moisture on the entire globe. To have access to kilometric variability, disaggregation...

The aim of the present work is to investigate the possibility to retrieve the original sets of dynamical equations directly from observational time series when all the system variables are observed. Time series are generated from chosen dynamical systems, and the global modeling technique is applied to obtain optimal models of parsimonious structur...

One of the main tasks in network theory is to infer relations among interacting elements. We propose global modeling as a tool to detect links between nodes and their nature. Various situations using small network motifs are investigated under the assumption that the variable to be measured at each node provides full observability when isolated. Su...

We study multi-scale statistical properties of disaggregated satellite soil moisture product DisPATCh. We apply spectral and multifractal analysis (in the framework of Universal Multifractal) to disaggregated soil moisture, original SMOS soil moisture, and MODIS auxiliary data. Disaggregated soil moisture shows a behavior similar to that of the ori...

Testing the existence of scaling properties in Sentinel-2/MAJA products based on two main tools: 2D Fourier power spectra and first order structure functions. Sentinel-2 surface reflectances exhibit a strong spatial variability that is due to both natural variability and strong anthropogenic effects. From an image processing viewpoint, Sentinel-2 p...

Model validation from experimental data is an important and not trivial topic which is too often reduced to a simple visual inspection of the state portrait spanned by the variables of the system. Synchronization was suggested as a possible technique for model validation. By means of a topological analysis, we revisited this concept with the help o...

Evaluating multiscale variability of disaggregated satellite soil moisture product (DisPATCh), by applying spectral and multifractal analysis (in the framework of Universal Multifractal).

Evaluating multiscale variability of disaggregated satellite soil moisture product (DisPATCh), by applying spectral and multifractal analysis (in the framework of Universal Multifractal).

If recent advances in oncology emphasized the role of microenvironment in tumor growth, the role of delays for modeling tumor growth is still uncertain. In this paper, we considered a model, describing the interactions of tumor cells with their microenvironment made of immune cells and host cells, in which we inserted, as suggested by the clinician...

An epidemic of Ebola Virus Disease (EVD) broke out in Guinea in December 2013. It was only identified in March 2014 while it had already spread out in Liberia and Sierra Leone. The spill over of the disease became uncontrollable and the epidemic could not be stopped before 2016. The time evolution of this epidemic is revisited here with the global...

To understand the time evolution of ground water, it is important to be able to distinguish crops for which water demand is high. Numerous methods based on optical remote sensing dedicated to crop identification have been developed. However, their application remains difficult where plots do not exceed a few hectares, with a high heterogeneity in t...

Spatially distributed systems are rather difficult to investigate due to two distinct problems which can be sometimes combined. First, the spatial extension is taken into account by monitoring the system evolution at different locations. Second, the dynamics cannot always be continuously tracked in time, and segments of data – sometimes recorded at...

Groundwater is one of the main water reservoirs used for irrigation in regions of scarce water resources. For this reason, crop irrigation is expected to have a direct influence on this reservoir. To understand the time evolution of the groundwater table and its storage changes, it is important to delineate irrigated crops, whose evaporative demand...

Monitoring of water resources and a better understanding of the eco-hydrological processes governing their dynamics are necessary to anticipate and develop measures to adapt to climate and water-use changes. Focusing on this aim, a research project carried out within the framework of French–Moroccan cooperation demonstrated how remote sensing can h...

A suspension of a map consists of the flow for which the Poincaré section is that map. Designing a suspension of a given map remains a non-trivial task in general. The case of suspending the Hénon map is here considered. Depending on the parameter values, the Hénon map is orientation preserving or reversing; it is here shown that while a tridimensi...

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Theory of chaos deals with deterministic behaviors that are unpredictable at long term. This theory modifies fundamentally our concept of determinism, and shows the need to develope new analysis and modeling approaches in order to account for this essential property. One of these approaches is the global modeling technique which aim is to obtain mo...

The dynamics underlying cereal crops in the northern region of Morocco is investigated using a global modelling technique applied to a vegetation index time series derived from satellite measurements, namely, the normalized difference vegetation index from 1982 to 2008. Two three-dimensional chaotic global models of reduced size (14-term and 15-ter...

Compte-tenu de l'importance de la production de blé pour l'économie marocaine, les décideurs doivent disposer d'informations précises sur la production de blé tôt dans la saison afin d'anticiper les besoins en importation. Dans cette étude, nous avons analysé (1) les rendements en blé tendre (1983-2008) de la province de Settat (2) les précipitatio...

Il a été récemment montré que des modèles dynamiques pouvaient être directement obtenus du signal d'agriculture pluvial observé depuis l'espace. L'analyse de ce modèle a permis de révéler un régime chaotique, c'est-à-dire à la fois déterministe et très sensible aux conditions initiales. De tels modèles ne nécessitent pas de forçage et peuvent donc...

La théorie du chaos concerne les comportements déterministes imprévisibles à long terme. Cette théorie modifie fondamentalement notre conception du déterminisme et conduit à développer de nouvelles approches d'analyse et de modélisation permettant de prendre en compte cette propriété. L'une des approches ayant découlée de cette théorie est la techn...

The global modeling approach aims to obtain parsimonious models of observed dynamics from few or single time series (Letellier et al. 2009). Specific algorithms were developed and validated for this purpose (Mangiarotti et al. 2012a). This approach was applied to the dynamics of cereal crops in semi-arid region using the vegetation index derived fr...

We briefly present a nonlinear method for the prediction of vegetation states from Normalized Difference Vegetation Index data, and its performance at four study sites in a semi-arid region (Gourma, Mali). Based on 25 years of NDVI used in this study, this approach leads to a mean prediction error of approximately 20% (resp. 40%) RMS over a horizon...

Global modeling aims to build mathematical models of concise description. Polynomial Model Search (PoMoS) and Global Modeling (GloMo) are two complementary algorithms (freely downloadable at the following address: http://www.cesbio.ups-tlse.fr/us/pomos_et_glomo.html) designed for the modeling of observed dynamical systems based on a small set of ti...

The NOAA-AVHRR Normalised Difference Vegetation Index (NDVI) dataset is used to investigate the predictability of the vegetation cycle in an area centred on the Gourma region in Sahelian Mali at scales varying from 8 km2 to 1024 km2 over a period spanning from 1982 to 2004. The predictability of the vegetation cycle is analysed with a model based o...

Causal relationships existing between observed levels of groundwater in a semi-arid sub-basin of the Kabini River basin (Karnataka state, India) are investigated in this study. A Vector Auto Regressive model is used for this purpose. Its structure is built on an upstream/downstream interaction network based on observed hydro-physical properties. Ex...

The Center for Spatial Studies of the Biosphere (CESBIO, Toulouse, France) and the National Center of Studies and Researches on Water and Energy (CNEREE, Marrakech) are co-leader of a Joint International Laboratory entitled "Remote sensing and water ressources in the semi-arid Mediterranean area" funded by the French Research Institute for Developm...

The predictability of the vegetation cycle is analyzed as a function of the spatial scale over West Africa during the period 1982–2004. The NDVI–AVHRR satellite data time series are spatially aggregated over windows covering a range of sizes from 8 × 8 km2 to 1024 × 1024 km2. The times series are then embedded in a low-dimensional pseudo-phase spac...

The Gourma site in Mali is one of the 3 instrumented meso-scale sites deployed in West- Africa as part of the African Monsoon Multidisciplinary Analysis (AMMA) project. Located both in the Sahelian zone sensu stricto, and in the Saharo-Sahelian transition zone, the Gourma meso-scale window is the northernmost site of the AMMA-CATCH observatory reac...

In the last two decades, significant changes have taken place in the semi-arid areas of the Kabini River basin (an area of 10 000 km 2 and a sub-basin of Cauvery River basin) in the south of India on the use of groundwater for irrigation. Depletion of water tables due to over-extraction of groundwater has become a critical issue in some parts of th...

This paper presents a method to monitor the dynamics of herbaceous vegetation in the Sahel. The approach is based on the assimilation of Normalized Difference Vegetation Index (NDVI) data acquired by the VEGETATION instrument on board SPOT 4/5 into a simple sahelian vegetation dynamics model. The study region is located in the Gourma region of Mali...

Satellite radar backscattering coefficient σ0 data from ENVISAT-ASAR and Normalized Difference Vegetation Index (NDVI) data from SPOT-VEGETATION are assimilated in the STEP model of vegetation dynamics. The STEP model is coupled with a radiative transfer model of the radar backscattering and NDVI signatures of the soil and herbaceous vegetation. Th...

SUMMARYA joint analysis of TOPEX-Poseidon satellite altimetry and tide gauge data is used to estimate sea level trends along the Mediterranean Sea coast from 1993 January to 2002 February. A generalized least squares (GLS) method allows us to take into account the space-time distribution of the data and their respective error budgets. Nearly optima...

The NOAA-AVHRR Normalized Difference Vegetation Index NDVI data set used here is the last updated and NOAA-16 calibrated data set Data are extracted over Sahel window lat 12 5N -- 17 5N long 17 5W -- 17 5E and spatially aggregated in windows of 8km 2 no aggregation 128km 2 and 1024km 2 respectively providing sets of time series with 828 samples eac...

Situe a la limite nord de l'extension de la mousson ouest africaine, le Sahel est caracterise par une tres forte variabilite spatiale et temporelle des precipitations. Cette variabilite, qui s'exprime a diverses echelles temporelles : saisonniere, interannuelle et decennale, a un impact majeur sur le developpement et le fonctionnement de la vegetat...

Temporal variations of surface mass redistribution among atmosphere, oceans and continental water reservoirs deform the Earth's crust, in particular in the vertical direction. Vertical crustal motions are now detectable by space geodesy techniques. On time scales in the range of ~1-10 years, these motions mostly result from surface loading. Space g...

Temporal variations of surface mass redistribution among atmosphere, oceans and continental water reservoirs deform the Earth's crust, in particular in the vertical direction. The center of mass of the Earth is also moving with respect to the solid Earth on a seasonnal time scale due to these mass redistributions. Vertical crustal motions and geoce...

Using altimetry data of the Topex/Poseidon satellite available since early 1993, we show that the eastern Mediterranean sea level has been continuously rising during 1993-1999, at a rate up to 20 mm/yr southeast of Crete. Sea level rise is also observed in the Algerian-Provencal basin as well as in the Tyrrhenian and Adriatic seas. The north Ionian...

Temporal variations of surface mass redistribution among atmosphere, oceans, and continental water reservoirs deform the Earth's crust, in particular in the vertical direction. These displacements can now be measured by space geodesy and predicted from climatic loading data. In this study we first compute globally theoretical vertical displacements...

We have developed a generalised least squares method for combining Topex-Poseidon and ERS satellite altimetry with tide gauges data in the coastal areas of the Mediter- ranean basin. Several parameters of the covariance fonction used in the inversion sys- tem, are optimized in order to get the best possible agreement between the sea level time seri...

With the launch of Jason-1, the extension of the nearly decade- long altimetry data set collected by TOPEX/POSEIDON will allow studies of interannual sea level change, and possibly detection of the climatic signal associated with global change. Our contribution to the Jason-1 mission will consist in (1) validating Jason-1 sea level data using tide...