Jean-Pierre Dedieu

Université Grenoble Alpes · Computer Science

Information on the spatial-temporal variability of the seasonal snow cover duration over long time periods is critical to study the response of mountain ecosystems to climate change. However, this information is often lacking due to the sparse distribution of in situ observations or the lack of adequate remote sensing products. Here, we combined sn...

The emergence of mining projects for rare earth elements (REEs) in response to rising global demand and geopolitical factors introduces environmental concerns, such as the suspected release of anthropogenic REEs to aquatic systems and the coexistence of radionuclides (U, Th). Northern regions confront heightened challenges from limited research and...

Changes in snowpack associated with climatic warming has drastic impacts on surface energy balance in the cryosphere. Yet, traditional monitoring techniques, such as punctual measurements in the field, do not cover the full snowpack spatial and temporal variability, which hampers efforts to upscale measurements to the global scale. This variability...

Arctic vegetation cover has been increasing over the last 40 years, which has been attributed mostly to increases in temperature. Yet, the temporal dimension of this greening remains overlooked as it is often viewed as a monotonic trend. Here, using 11-year long rolling windows on 30 m resolution Landsat data, we examined the temporal variations in...

In the Central Himalayas, glaciers and snowmelt play an important hydrological role, as they ensure the availability of surface water outside the monsoon period. To compensate for the lack of field measurements in glaciology and hydrology, high temporal and spatial resolution optical remotely sensed data are necessary. The French–Israeli VENµS Eart...

Changes in snowpack associated with climatic warming has drastic impacts on surface energy balance in the cryosphere. Yet, traditional monitoring techniques, such as punctual measurements in the field, do not cover the full snowpack spatial and temporal variability, which hampers efforts to upscale measurements to the global scale. This variability...

Optical sensors are increasingly sought to estimate the amount of chlorophyll a (chl_a) in freshwater bodies. Most, whether empirical or semi-empirical, are data-oriented. Two main limitations are often encountered in the development of such models. The availability of data needed for model calibration, validation, and testing and the locality of t...

In the central part of the Hindu Kush Himalayan region, snowmelt is one of the main inputs that ensures the availability of surface water outside the monsoon period. A common approach for snowpack modeling is based on the degree day factor (DDF) method to represent the snowmelt rate. However, the important seasonal variability of the snow processes...

Background Scientific context • Rapidly increasing temperatures in the Arctic and decreasing snow cover duration have led to longer growing seasons affecting vegetation dynamics (treeline, shrubs advancing, ...). • Arctic greening trends are well documented (Fraser et al., 2011; Tremblay et al., 2012) and this knowledge is essential for understandi...

Arctic snow cover dynamics exhibit strong changes in terms of extent and duration due to recent climate changeconditions (Mudryk et al., 2018; Lemke & Jacobi, 2011). In this context, innovative observation methods arehelpful for a better comprehension of the role of the snow for climate research and hydrology. The spatialvariability of snow propert...

Adjusting to global climate and socio-environmental changes has become a major issue for many societies, especially in the Arctic. Many Inuit wish to better understand the changes taking place. In 2013, an international Observatory of Human–Environment Interactions (OHMi) was established in Nunavik to identify these changes, study their cumulative...

There is increasing interest in community-based environmental monitoring (CBEM) in Canada’s North in response to the rising impacts of resource exploitation and climate change, and with increased recognition of indigenous knowledge. IMALIRIJIIT, meaning those who study water in Inuktitut, is a CBEM program involving science land camps, capacity-bui...

The characterization of snow extent is critical for a wide range of applications. Since 1966, snow maps at different spatial resolutions have been produced using various satellite sensor images. Nowadays, the most widely used products are likely those derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) data, which cover the whole Ear...

Arctic snow cover dynamics offer a changing face in terms of temporal duration and water equivalent, due to recent climate change conditions (Callaghan et al., 2011; Lemke & Jacobi, 2012). Indeed, the Arctic is now experiencing some of the most rapid and severe climate change on earth. In this context, innovative and improved methods are helpful to...

Glaciers are one of the terrestrial essential climate variables (ECVs) as they respond very sensitively to climate change. A key driver of their response is the glacier surface mass balance that is typically derived from field measurements. It deserves to be quantified over long time scales to better understand the accumulation and ablation process...

Cet article présente une vue d’ensemble des avancées récentes en télédétection spatiale appliquée à l’étude des surfaces enneigées et englacées auxquelles la communauté scientifique française a participé. Qu’ils s’agissent de données satellitaires optique, radar, lidar ou gravimétrique, ces travaux sur la couverture nivale saisonnière ou pérenne, l...

Aside from its impact on human activity in various regions around the world, snow also plays an important role in a range of environmental processes. In climatology, snow cover has the effect of lowering temperatures due to its high albedo which reflects between 40 and 95% of incident solar radiation and it can therefore be used as a barometer for...

By looking for heroicness in biographical dictionaries we can place the hero, not as in isolated figure but as part of a larger pantheon that includes all the memorable figures who played a part in building the nation. Only by placing the heroic figure against this backdrop can we comprehend the factors that made them soar above other historical, s...

Remote sensing is a powerful method to reconstruct annual mass-balance series over past decades by exploiting archives of available images, as well as to study glaciers in inaccessible regions. We present the application of a methodological framework based only on optical satellite images to retrieve glacier-wide annual mass balances for 30 glacier...

We investigated snow cover dynamics using time series of moderate (MODIS) to high (SPOT-4/5, Landsat-8) spatial resolution satellite imagery in a 3700 km2 region of the southwestern French Alps. Our study was carried out in the context of the SPOT (Take 5) Experiment initiated by the Centre National d’Etudes Spatiales (CNES), with the aim of explor...

The documentation generated by the offices of the Spanish Royal Exchequer under the Ancien Regime only tells part of the truth about the finances of the Monarchy. Firstly, the king possessed many more resources which are not accounted for in these sources or not expressed in the form of computable numbers in terms of revenue. Nor does it reflect th...

By looking for heroicness in biographical dictionaries we can place the hero, not as in isolated figure but as part of a larger pantheon that includes all the memorable figures who played a part in building the nation. Only by placing the heroic figure against this backdrop can we comprehend the factors that made them soar above other historical, s...

Hydro-meteorological observations coupled with snow and ice measurements are the basic material for a number of scientific and operational issues linked to socio-environmental needs. They are required for studies aiming at understanding and/or modeling climate-environment-society interactions along with their spatial and temporal variations. They c...

Quantifying relationships between snow cover duration and plant community properties remains an important challenge in alpine ecology. This study develops a method to estimate spatial variation in energy availability in the context of a topographically complex, high-elevation watershed, which was used to test the explanatory power of environmental...

This letter introduces an alternative strategy for wet snow detection using multitemporal synthetic aperture radar (SAR) data. The proposed change detection method is primarily based on the comparison between two X-band SAR images acquired during the accumulation (winter) and melting (spring) seasons, in the French Alps. The new decision criterion...

Snow cover is an important control in mountain environments and a shift of the snow‐free period triggered by climate warming can strongly impact ecosystem dynamics. Changing snow patterns can have severe effects on alpine plant distribution and diversity. It thus becomes urgent to provide spatially explicit assessments of snow cover changes that ca...

The main objective of this study is to analyze the radar response of the snow cover under different volume and surface conditions in order to determine whether an explicit relationship can be established between the backscattered signal and the characteristics of the snow, in particular the snow water equivalent. To this end, a calibration procedur...

We present time series of equilibrium-line altitude (ELA) measured from the end-of-summer snow line altitude computed using satellite images, for 43 glaciers in the west-ern Alps over the 1984–2010 period. More than 120 satellite images acquired by Landsat, SPOT and ASTER were used. In parallel, changes in climate variables, summer cumulative posit...

We present time series of equilibrium-line altitude (ELA) measured from the end-of-summer snowline altitude computed using satellite images, for 43 glaciers in the western Alps over the 1984-2010 period. More than 120 satellite images acquired by Landsat, SPOT and ASTER were used. In parallel, changes in climate parameters (summer cumulative positi...

This study compares different methods to retrieve the specific surface area (SSA) of snow from satellite radiance measurements in mountainous terrain. It aims at addressing the effect on the retrieval of topographic corrections of reflectance, namely slope and aspect of terrain, multiple reflections on neighbouring slopes and accounting (or not) fo...

In this paper we describe the benefits of RADARSAT-2 in the analysis of temporal changes in polarimetric parameters linked to the snow cover evolution during the winter season. The presented study took place over an instrumented area in the region of French Alps. The focus is set on the dry snow depth retrieval, using an original method based on pr...

This work presents: i) the results of a new inventory of glaciers in the French Alps (1985-86, 2003, 2011) showing an average withdrawal of about 20% for the last 25 years, and ii) the reconstruction of the annual equilibrium-line altitude for forty glaciers which shows an average increase of 6 m/year for the 1984-2010 period. An analysis of the ch...

This paper proposes the new method for wet snow mapping using SAR data. It represents a modified version of the existing Nagler's mapping method, based on winter/summer image comparison, which is considered as the classic one. Instead of the existing unique threshold, a variable threshold matrix (function of the local incidence angle for each pixel...

This paper provides comprehensive analysis of the dry snow pack backscattering coefficient dependence on the density change, for various SAR sensor parameters and chosen dry snow pack parameters, characteristic for the region of French Alps. As the result, qualitative conclusions, based on applying fundamental scattering theories (Rayleigh scatteri...

The temporal monitoring of snow cover in mountainous areas is a very important challenge in order to predict snow melting. A way to solve this problematic is the snow detection using polarimetric SAR data. By this way, a set of eight Radarsat-2 images have been acquired over the French Alps during 2009 and 2010. This project proposes to apply snow...

The aim of the SOAR #1341 project is to perform temporal analyses of changes in RADARSAT-2 full-polarimetry parameters on snow cover in a mountainous area. The objective of the present study was to determine whether there is a correlation between changes in radar statistics and changes in physical snow parameters during winter and spring. This pape...

This study describes a method to retrieve snow specific surface area (SSA) from satellite radiance reasurements in mountainous terrain. It aims at comparing different retrieval methods and at addressing topographic corrections of reflectance, namely slope and aspect of terrain and multiple reflections on neighbouring slopes. We use an iterative alg...

Hydrometeorological observations are the basic material for a number of scientific and operational issues. They are required for studies aiming at understanding and/or modeling climate-environment-society interactions along with their spatial and temporal variations. They constitute also the basic information for estimating hydrological resources a...

The Kyrgyz Republic is located at the convergence of two mountain systems (Tien Shan and Pamirs) in Central Asia. The region is of great interest all of Central Asia because of its consequent capital in water resources. Theses resources are of importance for electricity production (~15 TWH/year) and irrigation of agricultural land. Over 50% of the...

One of the most obvious impacts of climate change in high mountain areas is the glacial retreat. Since the French glacier inventory carried out by R. Vivian in the late 1960s within the context of the WGI, there was no updated data from the overall French alpine glaciers. We present here the first results of a new diachronic inventory of the French...

Pour de nombreux domaines scientifiques ou opérationnels, l_observation hydrométéorologique est d_une importance capitale. Elle constitue la base principale de toutes les études et analyses visant à comprendre et/ou modéliser les interactions climat-environnement-société ainsi que leurs évolutions spatiales et temporelles. Elle est aussi l_informat...

The only existing glacial inventory from the French Alps, conducted by Robert Vivian and published within the context of the World Glacier Inventory, dates back to the late 60s/early 70s. Glacial withdrawal over the previous decades largely justifies an update of the status of glacial coverage in the French Alps. This work is part of the activities...

For mid-latitude mountain glaciers, the snow line altitude (SLA) at the end of the hydrological year is a good indicator of the equilibrium line altitude and thus of the annual mass balance. This enables SLA evolution to be reconstructed for long time periods from remote sensing data, as the snow line is generally easy to identify using aerial phot...

Territorial administrators (regional parks and reserves, forestry service, national and regional environnemental services) look for precise scientific elements to understand, prevent or mitigate the consequences of climate change on the ecosystem and on the socioeconomic activities of the French Prealps. They wish for example especially to improve...

Carbon and water cycles are closely related to agricultural activities. Agriculture has been indeed identified by IPCC 2007 report as one of the options to sequester carbon in soil. Concerning the water resources, their consumptions by irrigated crops are called into question in view of demographic pressure. In the prospect of an assessment of carb...

Estimation of the Snow Covered Area (SCA) is an important issue for meteorological application and hydrological modeling of runoff. With spectral bands in the visible, near and middle infrared, the MODIS optical satellite sensor can be used to detect snow cover because of large differences between reflectance from snow covered and snow free surface...

La chronologie saisonnière et interannuelle de la hauteur du couvert nival dans le Vercors est étudiée grâce aux données provenant de l'instrumentation météorologique in situ installée sur les hauts plateaux depuis 2004. Avec l'apport des réanalyses climatiques (essentiellement les températures du niveau 850 hPa) provenant du NCAR-NCEP, une analyse...

Estimation of the Snow Covered Area (SCA) is an important issue for meteorological application and hydrological modeling of runoff. With spectral bands in the visible, near and middle infrared, the SPOT-4 and -5 VEGETATION sensors are used to detect snow cover because of large differences between reflectance from snow covered and snow free surfaces...

Estimation of the Snow Covered Area (SCA) is an important issue for meteorological application and hydrological modeling of runoff. With spectral bands in the visible, near and middle infrared, the SPOT-4 and -5 VEGETATION sensors are used to detect snow cover because of large differences between reflectance from snow covered and snow free surfaces...

Poster, Geophysical Research Abstracts, Vol. 10

Annual equilibrium-line altitude (ELA) and surface mass balance of Glacier Blanc, Ecrins region, French Alps, were reconstructed from a 25 year time series of satellite images (1981-2005). The remote-sensing method used was based on identification of the snowline, which is easy to discern on optical satellite images taken at the end of the ablation...

This study presents a new method to analyse some parameters of snow in alpine region: density, wetness. Here are developed the methodology and first results obtained from a set of ASAR-ENVI SAT images registered during 2004 spring period over an experimental river basin located in the French Alps (N 45° 05'/ E 6° 10'). For ENVISAT/ASAR data, a topo...

Poster, Geophysical Research Abstracts, Vol 9