| publications-2031 |
Peer reviewed articles |
2022 |
F. Braga, D. Ciani, S. Colella, E. Organelli, J. Pitarch, V. E. Brando, M. Bresciani, J. A. Concha, C. Giardino, G. M. Scarpa, G. Volpe, M-H Rio, F. Falcini |
COVID-19 lockdown effects on a coastal marine environment: Disentangling perception versus reality |
Science of The Total Environment |
10.1016/j.scitotenv.2022.153002 |
Data Management & Analytics |
Precipitation & Ecological Systems |
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No abstract available |
870349 |
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| publications-2032 |
Peer reviewed articles |
2021 |
Giulia Sent, Beatriz Biguino, Luciane Favareto, Joana Cruz, Carolina Sa, Ana Ines Dogliotti, Carla Palma, Vanda Brotas, Ana C. Brito |
Deriving Water Quality Parameters Using Sentinel-2 Imagery: A Case Study in the Sado Estuary, Portugal |
Remote Sensing |
10.3390/rs13051043 |
Data Management & Analytics |
Irrigation Systems |
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Monitoring water quality parameters and their ecological effects in transitional waters is usually performed through in situ sampling programs. These are expensive and time-consuming, and often do not represent the total area of interest. Remote sensing techniques offer enormous advantages by providing cost-effective systematic observations of a large water system. This study evaluates the potential of water quality monitoring using Sentinel-2 observations for the period 2018–2020 for the Sado estuary (Portugal), through an algorithm intercomparison exercise and time-series analysis of different water quality parameters (i.e., colored dissolved organic matter (CDOM), chlorophyll-a (Chl-a), suspended particulate matter (SPM), and turbidity). Results suggest that Sentinel-2 is useful for monitoring these parameters in a highly dynamic system, however, with challenges in retrieving accurate data for some of the variables, such as Chl-a. Spatio-temporal variability results were consistent with historical data, presenting the highest values of CDOM, Chl-a, SPM and turbidity during Spring and Summer. This work is the first study providing annual and seasonal coverage with high spatial resolution (10 m) for the Sado estuary, being a key contribution for the definition of effective monitoring programs. Moreover, the potential of remote sensing methodologies for continuous water quality monitoring in transitional systems under the scope of the European Water Framework Directive is briefly discussed. |
870349 |
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| publications-2033 |
Peer reviewed articles |
2022 |
Scarpa, G.M., Braga F., Manfe G., Lorenzetti G., Zaggia L. |
Towards an Integrated Observational System to Investigate Sediment Transport in the Tidal Inlets of the Lagoon of Venice |
Remote Sensing |
10.3390/rs14143371 |
Data Management & Analytics |
Hydropower Dams & reservoirs |
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An observation system integrating satellite images, in situ water parameters and hydrodynamic measurements was implemented in a tidal inlet of the Venice Lagoon (Northern Adriatic Sea, Italy). The experimental infrastructure was developed to autonomously investigate suspended sediment dynamics in the two channels of the Lido inlet in relation to the longshore currents in the littoral zone and the tidal circulation along the lagoon channel network. It provided time series of turbidity at the surface, water flow and acoustic backscatter, which was converted into turbidity along the vertical column during different tidal phases and meteo-marine conditions. Accurate turbidity maps were derived from Sentinel-2 (Copernicus) and Landsat 8 (NASA) satellites. Long-term in situ data from field surveys enabled the calibration and intercalibration of the instrumental setup and validation of satellite-derived products. Time series from the instrumental network were analyzed in order to evaluate the temporal variability of suspended sediment in relation to tidal phases and the different meteo-marine conditions. The integration of available datasets with satellite images also permitted the testing of the methodology for a 3-D reconstruction of the suspended sediment pattern in calm sea conditions, under the effect of the sole hydrodynamical forcing. Remotely sensed data provide a synoptic distribution of turbidity in the inlet area allowing the analysis of the surficial patterns of suspended sediment and the inferring of information on the transport processes at different spatial scales. In calm sea conditions, the results show that the transport is driven by tidal currents with a net seaward transport related to a larger export of materials from the northern basin of the Lagoon of Venice. During typical northeasterly storms, materials mobilized on the beaches and in the shoreface are transported into the inlet and distributed into the lagoon channel network, following the flood tidal currents and determining net import of materials. The multitude of information provided by this system can support research on aquatic science (i.e., numerical simulations) and address end-user community practices. The ecosystem management will also benefit operational purposes, such as the monitoring of morphological transformations, erosion processes and planning of coastal defense in the future scenarios of sea level rise. The developed approach will also help to understand how the regulation of the inlet flow introduced by the operation of the flood barriers will affect the fluxes of particles and, in the long term, the lagoon morphodynamics. |
870349 |
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| publications-2034 |
Peer reviewed articles |
2023 |
Florent Domine; Kevin Fourteau; Philippe Choler |
Exploration of Thermal Bridging Through Shrub Branches in Alpine Snow |
Crossref |
10.1029/2023gl105100 |
Simulation & Modeling |
Groundwater |
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AbstractIn the high Arctic, thermal bridging through frozen shrub branches has been demonstrated to cool the ground by up to 4°C during cold spells, affecting snow metamorphism and soil carbon and nutrients. In alpine conditions, the thermal conductivity contrast between shrub branches and snow is much less than in the Arctic, so that the importance of thermal bridging is uncertain. We explore this effect by monitoring ground temperature and liquid water content under green alders and under nearby alpine tundra in the Alps. During a January 2022 cold spell, the ground temperature at 5 cm depth under alders is 1.3°C colder than under alpine tundra. Ground water freezing under alders is complete, while water remains liquid under tundra. Finite element simulations reproduce the observed temperature difference between both sites, showing that thermal bridging does affect ground temperature also under Alpine conditions. |
949516 |
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| publications-2035 |
Peer reviewed articles |
2023 |
Sicart, J. E., Ramseyer, V., Picard, G., Arnaud, L., Coulaud, C., Freche, G., Soubeyrand, D., Lejeune, Y., Marie Dumont, Gouttevin, I., Le Gac, E., Berger, F., Monnet, J.-M., Borgniet, L., Mermin, É., Rutter, N., Webster, C., and Essery, R. |
Snow accumulation and ablation measurements in a midlatitude mountain coniferous forest (Col de Porte, France, 1325 m altitude): the Snow Under Forest (SnoUF) field campaign data set |
Earth Systme Science Data |
10.5194/essd-15-5121-2023 |
Simulation & Modeling |
River Basins |
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Abstract. Forests strongly modify the accumulation, metamorphism and melting of snow in midlatitude and high-latitude regions. Recently, snow routines in hydrological and land surface models were improved to incorporate more accurate representations of forest snow processes, but model intercomparison projects have identified deficiencies, partly due to incomplete knowledge of the processes controlling snow cover in forests. The Snow Under Forest (SnoUF) project was initiated to enhance knowledge of the complex interactions between snow and vegetation. Two field campaigns, during the winters 2016–2017 and 2017–2018, were conducted in a coniferous forest bordering the snow study at Col de Porte (1325 m a.s.l., French Alps) to document the snow accumulation and ablation processes. This paper presents the field site, the instrumentation and the collection and postprocessing methods. The observations include distributed forest characteristics (tree inventory, lidar measurements of forest structure, subcanopy hemispherical photographs), meteorology (automatic weather station and an array of radiometers), snow cover and depth (snow pole transect and laser scan) and snow interception by the canopy during precipitation events. The weather station installed under dense canopy during the first campaign has been maintained since then and has provided continuous measurements throughout the year since 2018. Data are publicly available from the repository of the Observatoire des Sciences de l'Univers de Grenoble (OSUG) data center at https://doi.org/10.17178/SNOUF.2022 (Sicart et al., 2022). |
949516 |
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| publications-2036 |
Peer reviewed articles |
2023 |
Alvaro Robledano, Ghislain Picard, Marie Dumont, Frédéric Flin, Laurent Arnaud, Quentin Libois |
Unraveling the optical shape of snow |
Nature Communications |
10.1038/s41467-023-39671-3 |
Simulation & Modeling |
Groundwater |
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AbstractThe reflection of sunlight off the snow is a major driver of the Earth’s climate. This reflection is governed by the shape and arrangement of ice crystals at the micrometer scale, called snow microstructure. However, snow optical models overlook the complexity of this microstructure by using simple shapes, and mainly spheres. The use of these various shapes leads to large uncertainties in climate modeling, which could reach 1.2 K in global air temperature. Here, we accurately simulate light propagation in three-dimensional images of natural snow at the micrometer scale, revealing the optical shape of snow. This optical shape is neither spherical nor close to the other idealized shapes commonly used in models. Instead, it more closely approximates a collection of convex particles without symmetry. Besides providing a more realistic representation of snow in the visible and near-infrared spectral region (400 to 1400 nm), this breakthrough can be directly used in climate models, reducing by 3 the uncertainties in global air temperature related to the optical shape of snow. |
949516 |
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| publications-2037 |
Peer reviewed articles |
2021 |
Alain Royer; Alain Royer; Ghislain Picard; Céline Vargel; Céline Vargel; Céline Vargel; Alexandre Langlois; Alexandre Langlois; Isabelle Gouttevin; Marie Dumont |
Improved simulation of Arctic circumpolar land area snow properties and soil temperatures |
Frontiers in Earth Science |
10.3389/feart.2021.685140 |
Simulation & Modeling |
Groundwater |
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The impact of high latitude climate warming on Arctic snow cover and its insulating properties has key implications for the surface and soil energy balance. Few studies have investigated specific trends in Arctic snowpack properties because there is a lack of long-term in situ observations and current detailed snow models fail to represent the main traits of Arctic snowpacks. This results in high uncertainty in modeling snow feedbacks on ground thermal regime due to induced changes in snow insulation. To better simulate Arctic snow structure and snow thermal properties, we implemented new parameterizations of several snow physical processes—including the effect of Arctic low vegetation and wind on snowpack—in the Crocus detailed snowpack model. Significant improvements compared to standard Crocus snow simulations and ERA-Interim (ERAi) reanalysis snow outputs were observed for a large set of in-situ snow data over Siberia and North America. Arctic Crocus simulations produced improved Arctic snow density profiles over the initial Crocus version, leading to a soil surface temperature bias of −0.5 K with RMSE of 2.5 K. We performed Crocus simulations over the past 39 years (1979–2018) for circumpolar taiga (open forest) and pan-Arctic areas at a resolution of 0.5°, driven by ERAi meteorological data. Snowpack properties over that period feature significant increase in spring snow bulk density (mainly in May and June), a downward trend in snow cover duration and an upward trend in wet snow (mainly in spring and fall). The pan-Arctic maximum snow water equivalent shows a decrease of −0.33 cm dec−1. With the ERAi air temperature trend of +0.84 K dec−1 featuring Arctic winter warming, these snow property changes have led to an upward trend in soil surface temperature (Tss) at a rate of +0.41 K dec−1 in winter. We show that the implemented snowpack property changes increased the Tss trend by 36% compared to the standard simulation. Winter induced changes in Tss led to a significant increase of 16% (+4 cm dec−1) in the estimated active layer thickness (ALT) over the past 39 years. An increase in ALT could have a significant impact on permafrost evolution, Arctic erosion and hydrology. |
949516 |
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| publications-2038 |
Peer reviewed articles |
2022 |
Fanny Brun; Owen King; Marion Réveillet; Charles Amory; Anton Planchot; Etienne Berthier; Amaury Dehecq; Tobias Bolch; Kévin Fourteau; Julien Brondex; Marie Dumont; Christoph Mayer; Patrick Wagnon |
Brief communication: Everest South Col Glacier did not thin during the last three decades |
The cryosphere |
10.5194/tc-2022-166 |
Simulation & Modeling |
Groundwater |
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Abstract. The South Col Glacier is an iconic small body of ice and snow (approx. 0.2 km2), located on the southern ridge of Mt. Everest. A recent study proposed that South Col Glacier is rapidly losing mass. This seems in contradiction with our comparison of two digital elevation models derived from aerial photographs taken in 1984 and a stereo Pléiades satellite acquisition from 2017, from which we measure a mean elevation change of 0.01 ± 0.07 m a-1. To reconcile these results we investigate wind erosion and surface energy and mass balance, and find that melt is unlikely a dominant process, contrary to previous findings. |
949516 |
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| publications-2039 |
Peer reviewed articles |
2022 |
Marion Réveillet, Marie Dumont, Simon Gascoin, Matthieu Lafaysse, Pierre Nabat, Aurélien Ribes, Rafife Nheili, Francois Tuzet, Martin Ménégoz, Samuel Morin, Ghislain Picard, Paul Ginoux |
Black carbon and dust alter the response of mountain snow cover under climate change |
Nature Communications |
10.1038/s41467-022-32501-y |
Data Management & Analytics |
River Basins |
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AbstractBy darkening the snow surface, mineral dust and black carbon (BC) deposition enhances snowmelt and triggers numerous feedbacks. Assessments of their long-term impact at the regional scale are still largely missing despite the environmental and socio-economic implications of snow cover changes. Here we show, using numerical simulations, that dust and BC deposition advanced snowmelt by 17 ± 6 days on average in the French Alps and the Pyrenees over the 1979–2018 period. BC and dust also advanced by 10-15 days the peak melt water runoff, a substantial effect on the timing of water resources availability. We also demonstrate that the decrease in BC deposition since the 1980s moderates the impact of current warming on snow cover decline. Hence, accounting for changes in light-absorbing particles deposition is required to improve the accuracy of snow cover reanalyses and climate projections, that are crucial for better understanding the past and future evolution of mountain social-ecological systems. |
949516 |
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| publications-2040 |
Peer reviewed articles |
2023 |
Oscar Dick; Léo Viallon-Galinier; François Tuzet; Pascal Hagenmuller; Mathieu Fructus; Benjamin Reuter; Matthieu Lafaysse; Marie Dumont |
Can Saharan dust deposition impact snowpack stability in the French Alps? |
The Cryosphere |
10.5194/tc-17-1755-2023 |
Simulation & Modeling |
Groundwater |
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Abstract. Saharan dust deposits can turn snow-covered mountains into a spectacular orange landscape. When avalanches release, a formerly buried dust layer can become apparent, possibly marking the failure plane. This appearance may suggest a relation between avalanche release and the previously deposited dust, which found mention among recreationists and avalanche professionals alike. While dust deposition affects the absorption of solar energy altering snowpack temperatures and melt rates, to date, there is no clear scientific evidence that dust deposition can significantly modify snow stability. Here we investigate, using an ensemble snow cover model, the impact of dust deposition on snow properties and mechanical stability by comparing simulations with and without dust deposition for synthetic and observed dust deposition events. The study focuses on two typical avalanche situations: artificial triggering on persistent weak layers and natural release of wet-snow avalanches. We study several situations with and without dust deposition and demonstrate how sensitive the impact of dust deposition is to the deposited dust mass, the slope aspect, the elevation and the meteorological conditions following the dust deposition. The additional energy absorbed by the dust layer speeds up warming and may advance surface wetting to ease the formation of a melt-freeze crust. If the crust is buried, the phenomenon of a strong temperature gradient close to the crust may promote the formation of persistent weak layers inside the snowpack. On the other hand, the melt-freeze crust may also lead to an increase in snowpack stability by redistributing the stress applied to weak layers buried below. Regarding wet-snow instability, we show that dust deposition can advance the onset of wet-snow avalanche activity by up to 1 month in spring, as hypothesized in previous studies. Thus, the impact of Saharan dust deposition on snowpack stability can be either neutral, positive or negative, depending on the topographical, snow and meteorological conditions. Even though not all physical processes are implemented, state-of the art snow cover models are able to mimic the speed-up of crust formation, and snow instability models can point out relevant situations for avalanche forecasting. |
949516 |
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