| 1. |
- Bakker, D. C. E., et al.
(författare)
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An update to the surface ocean CO2 atlas (SOCAT version 2)
- 2014
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 6:1, s. 69-90
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Tidskriftsartikel (refereegranskat)abstract
- The Surface Ocean CO2 Atlas (SOCAT), an activity of the international marine carbon research community, provides access to synthesis and gridded fCO2 (fugacity of carbon dioxide) products for the surface oceans. Version 2 of SOCAT is an update of the previous release (version 1) with more data (increased from 6.3 million to 10.1 million surface water fCO 2 values) and extended data coverage (from 1968-2007 to 1968-2011). The quality control criteria, while identical in both versions, have been applied more strictly in version 2 than in version 1. The SOCAT website (http://www.socat.info/) has links to quality control comments, metadata, individual data set files, and synthesis and gridded data products. Interactive online tools allow visitors to explore the richness of the data. Applications of SOCAT include process studies, quantification of the ocean carbon sink and its spatial, seasonal, year-to-year and longerterm variation, as well as initialisation or validation of ocean carbon models and coupled climate-carbon models. © Author(s) 2014. CC Attribution 3.0 License.
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| 2. |
- Bimbot, F, et al.
(författare)
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An overwiev of the CAVE project research activities in speaker verification
- 2000
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Ingår i: Speech Communication. - 0167-6393 .- 1872-7182. ; 31:2-3, s. 155-180
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Tidskriftsartikel (refereegranskat)abstract
- This article presents an overview of the research activities carried out in the European CAVE project, which focused on text-dependent speaker verification on the telephone network using whole word Hidden Markov Models. It documents in detail various aspects of the technology and the methodology used within the project. In particular, it addresses the issue of model estimation in the context of limited enrollment data and the problem of a posteriori decision threshold setting. Experiments are carried out on the realistic telephone speech database SESP. State-of-the-art performance levels are obtained, which validates the technical approaches developed and assessed during the project as well as the working infrastructure which facilitated cooperation between the partners.
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| 3. |
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| 4. |
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| 5. |
- Lindberg, Johan, et al.
(författare)
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Techniques for a priori decision threshold estimation in speaker verification
- 1998
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Konferensbidrag (refereegranskat)abstract
- A key problem for field applications in speaker verification is the issue of a priori threshold setting. In the context of the CAVE project several methods for estimating speakerindependent and speaker-dependent decision thresholds were compared. Relevant parameters are estimated from development data only, i.e. without resorting to additional client data. The various approaches were tested on the Dutch SESP database.
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| 6. |
- Metzl, Nicolas, et al.
(författare)
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Recent acceleration of the sea surface fCO2 growth rate in the North Atlantic subpolar gyre (1993–2008) revealed by winter observations
- 2010
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Ingår i: GLOBAL BIOGEOCHEMICAL CYCLES. - 0886-6236. ; 24
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies based on ocean and atmospheric carbon dioxide (CO2) observations, suggesting that the ocean carbon uptake has been reduced, may help explain the increase in the fraction of anthropogenic CO2 emissions that remain in the atmosphere. Is it a response to climate change or a signal of ocean natural variability or both? Regional process analyses are needed to follow the ocean carbon uptake and to enable better attributions of the observed changes. Here, we describe the evolution of the surface ocean CO2 fugacity (fCO2 oc) over the period 1993–2008 in the North Atlantic subpolar gyre (NASPG). This analysis is based primarily on observations of dissolved inorganic carbon (DIC) and total alkalinity (TA) conducted at different seasons in the NASPG between Iceland and Canada. The fCO2 oc trends based on DIC and TA data are also compared with direct fCO2 measurements obtained between 2003 and 2007 in the same region. During winters 1993–2003, the fCO2 oc growth rate was 3.7 (±0.6) matm yr−1, higher than in the atmosphere, 1.8 (±0.1) matm yr−1. This translates to a reduction of the ocean carbon uptake primarily explained by sea surface warming, up to 0.24 (±0.04) °C yr−1. This warming is a consequence of advection of warm water northward from the North Atlantic into the Irminger basin, which occurred as the North Atlantic Oscillation (NAO) index moved into a negative phase in winter 1995/1996. In winter 2001–2008, the fCO2 oc rise was particularly fast, between 5.8 (±1.1) and 7.2 (±1.3) matm yr−1 depending on the region, more than twice the atmospheric growth rate of 2.1 (±0.2) matm yr−1, and in the winter of 2007–2008 the area was supersaturated with CO2. As opposed to the 1990s, this appears to be almost entirely due to changes in seawater carbonate chemistry, the combination of increasing DIC and decreasing of TA. The rapid fCO2 oc increase was not only driven by regional uptake of anthropogenic CO2 but was also likely controlled by a recent increase in convective processes‐vertical mixing in the NASPG and cannot be directly associated with NAO variability. The fCO2 oc increase observed in 2001–2008 leads to a significant drop in pH of −0.069 (±0.007) decade−1.
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| 7. |
- Pierrot, D., et al.
(författare)
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Recommendations for autonomous underway pCO2 measuring systems and data-reduction routines
- 2009
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Ingår i: Deep-Sea Research II. - : Elsevier BV. - 0967-0645. ; 56:8-10, s. 512-522
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Tidskriftsartikel (refereegranskat)abstract
- In order to facilitate the collection of high quality and uniform surface water pCO2 data, an underway pCO2 instrument has been designed based on community input and is now commercially available. Along with instrumentation, agreements were reached on data reduction and quality control that can be easily applied to data from these systems by using custom-made freeware. This new automated underway pCO2 measuring system is designed to be accurate to within 0.1 μatm for atmospheric pCO2 measurements and to within 2 μatm for seawater pCO2, targeted by the scientific community to constrain the regional air–sea CO2 fluxes to 0.2 Pg C year−1. The procedure to properly reduce the underway pCO2 data and perform the steps necessary for calculation of the fugacity of CO2 from the measurements is described. This system is now widely used by the scientific community on many different types of ships. Combined with the recommended data-reduction procedures, it will facilitate producing data sets that will significantly decrease the uncertainty currently present in estimates of air–sea CO2 fluxes.
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| 8. |
- Pierrot, J-B, et al.
(författare)
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A comparison of a priori threshold setting procedures for speaker verification in the CAVE project
- 1998
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Konferensbidrag (refereegranskat)abstract
- The issue of a priori threshold setting in speaker verification is a key problem for field applications. In the context of the CAVE project, we compared several methods for estimating speaker-independent and speaker-dependent decision thresholds. Relevant parameters are estimated from development data only, i.e. without resorting to additional client data. The various approaches are tested on the Dutch SESP database.
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| 9. |
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