References of "Barth, Alexander"
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See detailDINCAE 1.0: a convolutional neural network with error estimates to reconstruct sea surface temperature satellite observations
Barth, Alexander ULiege; Alvera Azcarate, Aida ULiege; Licer, Matjaz et al

in Geoscientific Model Development (2020), 13(3), 1609--1622

A method to reconstruct missing data in sea surface temperature data using a neural network is presented. Satellite observations working in the optical and infrared bands are affected by clouds, which ... [more ▼]

A method to reconstruct missing data in sea surface temperature data using a neural network is presented. Satellite observations working in the optical and infrared bands are affected by clouds, which obscure part of the ocean underneath. In this paper, a neural network with the structure of a convolutional auto-encoder is developed to reconstruct the missing data based on the available cloud-free pixels in satellite images. Contrary to standard image reconstruction with neural networks, this application requires a method to handle missing data (or data with variable accuracy) in the training phase. The present work shows a consistent approach which uses the satellite data and its expected error variance as input and provides the reconstructed field along with its expected error variance as output. The neural network is trained by maximizing the likelihood of the observed value. The approach, called DINCAE (Data INterpolating Convolutional Auto-Encoder), is applied to a 25-year time series of Advanced Very High Resolution Radiometer (AVHRR) sea surface temperature data and compared to DINEOF (Data INterpolating Empirical Orthogonal Functions), a commonly used method to reconstruct missing data based on an EOF (empirical orthogonal function) decomposition. The reconstruction error of both approaches is computed using cross-validation and in situ observations from the World Ocean Database. DINCAE results have lower error while showing higher variability than the DINEOF reconstruction. [less ▲]

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See detailD10.8: DIVA online operational in VRE
Troupin, Charles ULiege; Barth, Alexander ULiege; Beckers, Jean-Marie ULiege

Conference (2019, October 15)

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See detailPlankton Data Products
Barth, Alexander ULiege; Beauchard, Olivier; Herman, Peter et al

Conference (2019, May 15)

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See detailOnline DIVAnd Recent progress & hurdles
Barth, Alexander ULiege; Beckers, Jean-Marie ULiege; Troupin, Charles ULiege

Conference (2019, May 10)

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See detailDIVA & DIVAnd interpolation tools: All you need to know about them
Troupin, Charles ULiege; Barth, Alexander ULiege; Watelet, Sylvain ULiege et al

Conference (2019, April 11)

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See detailFrom in situ observations to gridded fields using DIVAnd and the cloud
Troupin, Charles ULiege; Barth, Alexander ULiege; Watelet, Sylvain ULiege et al

Conference (2019, April 09)

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See detailUpscaling of a local model in a regional-scale model
Vandenbulcke, Luc ULiege; Barth, Alexander ULiege

in Ocean Science (2019), 15(2), 291-305

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See detailModel-observations synergy in the coastal ocean
De Mey-Frémaux, Pierre; Ayoub, Nadia; Barth, Alexander ULiege et al

in Frontiers in Marine Science (2019), 6(JUL),

Integration of observations of the coastal ocean continuum, from regional oceans to shelf seas and estuaries/deltas with models, can substantially increase the value of observations and enable a wealth of ... [more ▼]

Integration of observations of the coastal ocean continuum, from regional oceans to shelf seas and estuaries/deltas with models, can substantially increase the value of observations and enable a wealth of applications. In particular, models can play a critical role at connecting sparse observations, synthesizing them, and assisting the design of observational networks; in turn, whenever available, observations can guide coastal model development. Coastal observations should sample the two-way interactions between nearshore, estuarine and shelf processes and open ocean processes, while accounting for the different pace of circulation drivers, such as the fast atmospheric, hydrological and tidal processes and the slower general ocean circulation and climate scales. Because of these challenges, high-resolution models can serve as connectors and integrators of coastal continuum observations. Data assimilation approaches can provide quantitative, validated estimates of Essential Ocean Variables in the coastal continuum, adding scientific and socioeconomic value to observations through applications (e.g., sea-level rise monitoring, coastal management under a sustainable ecosystem approach, aquaculture, dredging, transport and fate of pollutants, maritime safety, hazards under natural variability or climate change). We strongly recommend an internationally coordinated approach in support of the proper integration of global and coastal continuum scales, as well as for critical tasks such as community-agreed bathymetry and coastline products. © 2019 De Mey-Frémaux, Ayoub, Barth, Brewin, Charria, Campuzano, Ciavatta, Cirano, Edwards, Federico, Gao, Garcia Hermosa, Garcia Sotillo, Hewitt, Hole, Holt, King, Kourafalou, Lu, Mourre, Pascual, Staneva, Stanev, Wang and Zhu. [less ▲]

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See detailSynergies in operational oceanography: The intrinsic need for sustained ocean observations
Davidson, F. J.; Alvera Azcarate, Aida ULiege; Barth, Alexander ULiege et al

in Frontiers in Marine Science (2019), 6(JUL),

Operational oceanography can be described as the provision of routine oceanographic information needed for decision-making purposes. It is dependent upon sustained research and development through the end ... [more ▼]

Operational oceanography can be described as the provision of routine oceanographic information needed for decision-making purposes. It is dependent upon sustained research and development through the end-to-end framework of an operational service, from observation collection to delivery mechanisms. The core components of operational oceanographic systems are a multi-platform observation network, a data management system, a data assimilative prediction system, and a dissemination/accessibility system. These are interdependent, necessitating communication and exchange between them, and together provide the mechanism through which a clear picture of ocean conditions, in the past, present, and future, can be seen. Ocean observations play a critical role in all aspects of operational oceanography, not only for assimilation but as part of the research cycle, and for verification and validation of products. Data assimilative prediction systems are advancing at a fast pace, in tandem with improved science and the growth in computing power. To make best use of the system capability these advances would be matched by equivalent advances in operational observation coverage. This synergy between the prediction and observation systems underpins the quality of products available to stakeholders, and justifies the need for sustained ocean observations. In this white paper, the components of an operational oceanographic system are described, highlighting the critical role of ocean observations, and how the operational systems will evolve over the next decade to improve the characterization of ocean conditions, including at finer spatial and temporal scales. © 2019 Davidson, Chassignet, Vinayachandran, Lu, Smith, Zhu, Wang, Liu, De Mey-Frémaux, Kourafalou, Hernandez, Moore, Siddorn, Martin, Alvera Azcarate and Brassington. [less ▲]

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See detailOcean reanalyses: Recent advances and unsolved challenges
Storto, A.; Alvera Azcarate, Aida ULiege; Balmaseda, M. A. et al

in Frontiers in Marine Science (2019), 6(JUL),

Ocean reanalyses combine ocean models, atmospheric forcing fluxes, and observations using data assimilation to give a four-dimensional description of the ocean. Metrics assessing their reliability have ... [more ▼]

Ocean reanalyses combine ocean models, atmospheric forcing fluxes, and observations using data assimilation to give a four-dimensional description of the ocean. Metrics assessing their reliability have improved over time, allowing reanalyses to become an important tool in climate services that provide a more complete picture of the changing ocean to end users. Besides climate monitoring and research, ocean reanalyses are used to initialize sub-seasonal to multi-annual predictions, to support observational network monitoring, and to evaluate climate model simulations. These applications demand robust uncertainty estimates and fit-for-purpose assessments, achievable through sustained advances in data assimilation and coordinated inter-comparison activities. Ocean reanalyses face specific challenges: i) dealing with intermittent or discontinued observing networks, ii) reproducing inter-annual variability and trends of integrated diagnostics for climate monitoring, iii) accounting for drift and bias due e.g. to air-sea flux or ocean mixing errors, iv) optimizing initialization and improving performances during periods and in regions with sparse data. Other challenges such as multi-scale data assimilation to reconcile mesoscale and large-scale variability and flow-dependent error characterization for rapidly evolving processes, are amplified in long-term reanalyses. The demand to extend reanalyses backward in time requires tackling all these challenges, especially in the emerging context of earth system reanalyses and coupled data assimilation. This mini-review aims at documenting recent advances from the ocean reanalysis community, discussing unsolved challenges that require sustained activities for maximizing the utility of ocean observations, supporting data rescue and advancing specific research and development requirements for reanalyses. © 2019 Storto, Alvera Azcarate, Balmaseda, Barth, Chevallier, Counillon, Domingues, Drévillon, Drillet, Forget, Garric, Haines, Hernandez, Iovino, Jackson, Lellouche, Masina, Mayer, Oke, Penny, Peterson, Yang and Zuo. [less ▲]

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See detailEvaluation of HF Radar Blending
Subekti Mujiasih, ULiege; Hartanto, Dwi; Barth, Alexander ULiege et al

Conference (2018, December 07)

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See detailGenerating ocean climatologies from in situ observations
Barth, Alexander ULiege; Troupin, Charles ULiege; Watelet, Sylvain ULiege et al

in IMDIS 2018 International Conference on Marine Data and Information Systems, Book of Abstracts (2018, November 07)

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See detailThe 48th Liege colloquium: submesoscale processes: mechanisms, implications, and new frontiers
Barth, Alexander ULiege; Mahadevan, Amala; Pascual, Ananda et al

in Ocean Dynamics (2018), 68(8), 1067-1069

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See detailHistory of the participation to the Colloquium: spatial analysis and time series
Troupin, Charles ULiege; Peelen, Charlotte ULiege; Alvera Azcarate, Aida ULiege et al

Conference (2018, June 01)

Since 1969, the Liège Colloquium on Ocean (Hydro)Dynamics is organised on a yearly basis and has gathered more than 3300 scientists in editions articulated around specific topics covering a wide range of ... [more ▼]

Since 1969, the Liège Colloquium on Ocean (Hydro)Dynamics is organised on a yearly basis and has gathered more than 3300 scientists in editions articulated around specific topics covering a wide range of disciplines and many sub-regions of the global ocean. Following the 3rd Edition (1971), the organizing committee proposed to make the Colloquium an annual event: “It is a great joy for the Organizing Committee to realize that, in the same time, the continuation of the Colloquia was deeply desired by all the participants and that their gratifying determination was indeed answerable for making, from now on, the Liège Colloquium on Ocean Hydrodynamics an annual meeting.” The present work presents a first analysis of the data collected on 1. the number of participants, 2. the abstracts received and 3. the articles published in the special editions. The data were processed in order to produce choropleth maps and time series. For the most recent editions, the information was available from the colloquium websites and from the journals publishing the special issue, whereas for the first editions, the printed versions of the journals were the only source of information. As of January 2017, the information from the 1990’s could not be recovered due to the absence of participant lists in the journals and the probable loss of lists, either in paper and electronic formats. While the attendance was not the main target for the successive organising committees since the topics were often very specific, it is worth noting a general increase in the number of participants and the represented countries. For instance, the 2013 edition, dedicated to the “Primary production in the ocean: from the synoptic to the global scale”, was attended by 220 scientists from 35 countries. An EOF approach was used to estimate the missing values in the different times series. In particular, based on the past editions and the number of abstracts received before the deadline, we use the DINEOF tool to estimate the number of participant for this edition. The forecast value is 112 participants. All the data and source codes are made available through GitHub (https://github.com/gher-ulg/Liege-Colloquium-on-Ocean-Dynamics), while the interactive maps and times series are displayed at https://gher-ulg.github.io/Liege-Colloquium/, with the idea that these datasets and maps will be updated every year and that more sophisticated analysis will be performed. [less ▲]

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See detailModelling the hydrodynamics of the Southern Bight of the North Sea: Skills assessment of different configurations (i.e. nesting) in the perspective of coupling with sediment transport
Ivanov, Evgeny ULiege; Capet, Arthur ULiege; Barth, Alexander ULiege et al

Poster (2018, May)

The impact of offshore wind farm installation and dredging activities on the spatial distribution and dynamics of sediment grain size, biogeochemistry and biodiversity will be estimated in the Southern ... [more ▼]

The impact of offshore wind farm installation and dredging activities on the spatial distribution and dynamics of sediment grain size, biogeochemistry and biodiversity will be estimated in the Southern Bight of the North Sea (SBNS) with a focus on the Belgian Coastal Zone (BCZ) in the frame of the FaCE-It research project (Functional biodiversity in a Changing sedimentary Environment: Implications for biogeochemistry and food webs in a managerial setting). The three-dimensional hydrodynamical model ROMS-COAWST was implemented for simulation of the complex hydrodynamics of SBNS and sediment transport. The first level of nesting with the resolution of 1 km was used in the area of Belgian Economical Zone. In order to reach a fine resolution of 250 m in the BCZ, the second level of nesting will be used. Six-hourly ECMWF ERA-interim meteorological data was used to force the model at the sea-air boundary and the coarse resolution model results available from Copernicus Marine Environment Monitoring Service were used to force the model at the open boundaries. Tides and rivers were also considered. Next types of long-run simulations have been conducted: a 10-years climatological simulation and an interannual simulation over 2004-2013 in order to investigate the interannual dynamics. The model accuracy was evaluated through validation of its outputs against observed salinity, temperature and currents data (remote sensing and in-situ). Results validation of currents and temperature and salinity horizontal fields and vertical profiles against available satellite fields and in-situ data, i.e. from the project field campaign, is conducted and discussed. Application of the nested grid and its benefits for results accuracy is also presented. [less ▲]

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See detailHydrodynamic and sediment transport modelling in the North Sea. Assessment of wind farms impact
Ivanov, Evgeny ULiege; Capet, Arthur ULiege; Barth, Alexander ULiege et al

Scientific conference (2018, April 26)

Detailed reference viewed: 81 (11 ULiège)