search
Include:
The following results are related to Canada. Are you interested to view more results? Visit OpenAIRE - Explore.
150 Research products, page 1 of 15

  • Canada
  • Other research products
  • GR
  • EU
  • English

10
arrow_drop_down
Relevance
arrow_drop_down
  • Other research product . 1898
    Open Access English
    Publisher: Nanaimo Free Press
    Country: Canada

    https://viurrspace.ca/bitstream/handle/10613/18174/Apr29-1898.pdf?sequence=2

  • Open Access English
    Authors: 
    Adams, C.; Strong, K.; Batchelor, R. L.; Bernath, P. F.; Brohede, S.; Boone, C.; Degenstein, D.; Daffer, W. H.; Drummond, J. R.; Fogal, P. F.; +19 more
    Project: NSERC , EC | NORS (284421)

    The Optical Spectrograph and Infra-Red Imager System (OSIRIS) and the Atmospheric Chemistry Experiment (ACE) have been taking measurements from space since 2001 and 2003, respectively. This paper presents intercomparisons between ozone and NO2 measured by the ACE and OSIRIS satellite instruments and by ground-based instruments at the Polar Environment Atmospheric Research Laboratory (PEARL), which is located at Eureka, Canada (80° N, 86° W) and is operated by the Canadian Network for the Detection of Atmospheric Change (CANDAC). The ground-based instruments included in this study are four zenith-sky differential optical absorption spectroscopy (DOAS) instruments, one Bruker Fourier transform infrared spectrometer (FTIR) and four Brewer spectrophotometers. Ozone total columns measured by the DOAS instruments were retrieved using new Network for the Detection of Atmospheric Composition Change (NDACC) guidelines and agree to within 3.2%. The DOAS ozone columns agree with the Brewer spectrophotometers with mean relative differences that are smaller than 1.5%. This suggests that for these instruments the new NDACC data guidelines were successful in producing a homogenous and accurate ozone dataset at 80° N. Satellite 14–52 km ozone and 17–40 km NO2 partial columns within 500 km of PEARL were calculated for ACE-FTS Version 2.2 (v2.2) plus updates, ACE-FTS v3.0, ACE-MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) v1.2 and OSIRIS SaskMART v5.0x ozone and Optimal Estimation v3.0 NO2 data products. The new ACE-FTS v3.0 and the validated ACE-FTS v2.2 partial columns are nearly identical, with mean relative differences of 0.0 ± 0.2% and −0.2 ± 0.1% for v2.2 minus v3.0 ozone and NO2, respectively. Ozone columns were constructed from 14–52 km satellite and 0–14 km ozonesonde partial columns and compared with the ground-based total column measurements. The satellite-plus-sonde measurements agree with the ground-based ozone total columns with mean relative differences of 0.1–7.3%. For NO2, partial columns from 17 km upward were scaled to noon using a photochemical model. Mean relative differences between OSIRIS, ACE-FTS and ground-based NO2 measurements do not exceed 20%. ACE-MAESTRO measures more NO2 than the other instruments, with mean relative differences of 25–52%. Seasonal variation in the differences between NO2 partial columns is observed, suggesting that there are systematic errors in the measurements and/or the photochemical model corrections. For ozone spring-time measurements, additional coincidence criteria based on stratospheric temperature and the location of the polar vortex were found to improve agreement between some of the instruments. For ACE-FTS v2.2 minus Bruker FTIR, the 2007–2009 spring-time mean relative difference improved from −5.0 ± 0.4% to −3.1 ± 0.8% with the dynamical selection criteria. This was the largest improvement, likely because both instruments measure direct sunlight and therefore have well-characterized lines-of-sight compared with scattered sunlight measurements. For NO2, the addition of a ±1° latitude coincidence criterion improved spring-time intercomparison results, likely due to the sharp latitudinal gradient of NO2 during polar sunrise. The differences between satellite and ground-based measurements do not show any obvious trends over the missions, indicating that both the ACE and OSIRIS instruments continue to perform well.

  • Other research product . 1900
    Open Access English
    Publisher: Nanaimo Free Press
    Country: Canada

    https://viurrspace.ca/bitstream/handle/10613/17011/May18-1900.pdf?sequence=2

  • Open Access English
    Publisher: Nanaimo Free Press
    Country: Canada

    https://viurrspace.ca/bitstream/handle/10613/19132/Jun26-1875.pdf?sequence=2&isAllowed=y

  • Open Access English
    Authors: 
    Grillakis, Manolis G.; Koutroulis, Aristeidis G.; Daliakopoulos, Ioannis N.; Tsanis, Ioannis K.;
    Project: EC | HELIX (603864)

    Bias correction of climate variables is a standard practice in climate change impact (CCI) studies. Various methodologies have been developed within the framework of quantile mapping. However, it is well known that quantile mapping may significantly modify the long-term statistics due to the time dependency of the temperature bias. Here, a method to overcome this issue without compromising the day-to-day correction statistics is presented. The methodology separates the modeled temperature signal into a normalized and a residual component relative to the modeled reference period climatology, in order to adjust the biases only for the former and preserve the signal of the later. The results show that this method allows for the preservation of the originally modeled long-term signal in the mean, the standard deviation and higher and lower percentiles of temperature. To illustrate the improvements, the methodology is tested on daily time series obtained from five Euro CORDEX regional climate models (RCMs).

  • Open Access English
    Authors: 
    Schneider, M.; Barthlott, S.; Hase, F.; González, Y.; Yoshimura, K.; García, O. E.; Sepúlveda, E.; Gomez-Pelaez, A.; Gisi, M.; Kohlhepp, R.; +16 more
    Project: NSERC , EC | MUSICA (256961)

    Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologue data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change). We present a new method allowing for an extensive and straightforward characterisation of the complex nature of such isotopologue remote sensing datasets. We demonstrate that the MUSICA humidity profiles are representative for most of the troposphere with a vertical resolution ranging from about 2 km (in the lower troposphere) to 8 km (in the upper troposphere) and with an estimated precision of better than 10%. We find that the sensitivity with respect to the isotopologue composition is limited to the lower and middle troposphere, whereby we estimate a precision of about 30‰ for the ratio between the two isotopologues HD16O and H216O. The measurement noise, the applied atmospheric temperature profiles, the uncertainty in the spectral baseline, and the cross-dependence on humidity are the leading error sources. We introduce an a posteriori correction method of the cross-dependence on humidity, and we recommend applying it to isotopologue ratio remote sensing datasets in general. In addition, we present mid-infrared CO2 retrievals and use them for demonstrating the MUSICA network-wide data consistency. In order to indicate the potential of long-term isotopologue remote sensing data if provided with a well-documented quality, we present a climatology and compare it to simulations of an isotope incorporated AGCM (Atmospheric General Circulation Model). We identify differences in the multi-year mean and seasonal cycles that significantly exceed the estimated errors, thereby indicating deficits in the modeled atmospheric water cycle.

  • Open Access English
    Authors: 
    Morris, K. J.; Herrera, S.; Gubili, C.; Tyler, P. A.; Rogers, A.; Hauton, C.;
    Project: EC | HERMIONE (226354)

    Despite being an abundant group of significant ecological importance the phylogenetic relationships of the Octocorallia remain poorly understood and very much understudied. We used 1132 bp of two mitochondrial protein-coding genes, nad2 and mtMutS (previously referred to as msh1), to construct a phylogeny for 161 octocoral specimens from the Atlantic, including both Isididae and non-Isididae species. We found that four clades were supported using a concatenated alignment. Two of these (A and B) were in general agreement with the of Holaxonia–Alcyoniina and Anthomastus–Corallium clades identified by previous work. The third and fourth clades represent a split of the Calcaxonia–Pennatulacea clade resulting in a clade containing the Pennatulacea and a small number of Isididae specimens and a second clade containing the remaining Calcaxonia. When individual genes were considered nad2 largely agreed with previous work with MtMutS also producing a fourth clade corresponding to a split of Isididae species from the Calcaxonia–Pennatulacea clade. It is expected these difference are a consequence of the inclusion of Isisdae species that have undergone a gene inversion in the mtMutS gene causing their separation in the MtMutS only tree. The fourth clade in the concatenated tree is also suspected to be a result of this gene inversion, as there were very few Isidiae species included in previous work tree and thus this separation would not be clearly resolved. A~larger phylogeny including both Isididae and non Isididae species is required to further resolve these clades.

  • Open Access English
    Authors: 
    Fletcher, Tamara L.; Warden, Lisa; Sinninghe Damsté, Jaap S.; Brown, Kendrick J.; Rybczynski, Natalia; Gosse, John C.; Ballantyne, Ashley P.;
    Project: NSERC , EC | PACEMAKER (226600), NSF | Collaborative Research: A... (1418421), NWO | Perturbations of System E... (11030)

    The mid-Pliocene is a valuable time interval for investigating equilibrium climate at current atmospheric CO2 concentrations because atmospheric CO2 concentrations are thought to have been comparable to the current day and yet the climate and distribution of ecosystems were quite different. One intriguing, but not fully understood, feature of the early to mid-Pliocene climate is the amplified Arctic temperature response and its impact on Arctic ecosystems. Only the most recent models appear to correctly estimate the degree of warming in the Pliocene Arctic and validation of the currently proposed feedbacks is limited by scarce terrestrial records of climate and environment. Here we reconstruct the summer temperature and fire regime from a subfossil fen-peat deposit on west–central Ellesmere Island, Canada, that has been chronologically constrained using cosmogenic nuclide burial dating to 3.9+1.5/-0.5 Ma. The estimate for average mean summer temperature is 15.4±0.8 ∘C using specific bacterial membrane lipids, i.e., branched glycerol dialkyl glycerol tetraethers. This is above the proposed threshold that predicts a substantial increase in wildfire in the modern high latitudes. Macro-charcoal was present in all samples from this Pliocene section with notably higher charcoal concentration in the upper part of the sequence. This change in charcoal was synchronous with a change in vegetation that included an increase in abundance of fire-promoting Pinus and Picea. Paleo-vegetation reconstructions are consistent with warm summer temperatures, relatively low summer precipitation and an incidence of fire comparable to fire-adapted boreal forests of North America and central Siberia. To our knowledge, this site provides the northernmost evidence of fire during the Pliocene. It suggests that ecosystem productivity was greater than in the present day, providing fuel for wildfires, and that the climate was conducive to the ignition of fire during this period. The results reveal that interactions between paleo-vegetation and paleoclimate were mediated by fire in the High Arctic during the Pliocene, even though CO2 concentrations were similar to modern values.

  • Other research product . 1898
    Open Access English
    Publisher: Nanaimo Free Press
    Country: Canada

    https://viurrspace.ca/bitstream/handle/10613/18192/May19-1898.pdf?sequence=2

  • Other research product . 2008
    Open Access English
    Authors: 
    Fundulaki, Irini; Amer-Yahia, Sihem; Laks, Lakshmanan;
    Publisher: Dagstuhl Seminar Proceedings. 08111 - Ranked XML Querying
    Country: Germany

    In PIMENTO we advocate a novel approach to XML search that leverages user information to return more relevant query answers. This approach is based on formalizing {em user profiles} in terms of {em scoping rules} which are used to rewrite an input query, and of {em ordering rules} which are combined with query scoring to customize the ranking of query answers to specific users.

search
Include:
The following results are related to Canada. Are you interested to view more results? Visit OpenAIRE - Explore.
150 Research products, page 1 of 15
  • Other research product . 1898
    Open Access English
    Publisher: Nanaimo Free Press
    Country: Canada

    https://viurrspace.ca/bitstream/handle/10613/18174/Apr29-1898.pdf?sequence=2

  • Open Access English
    Authors: 
    Adams, C.; Strong, K.; Batchelor, R. L.; Bernath, P. F.; Brohede, S.; Boone, C.; Degenstein, D.; Daffer, W. H.; Drummond, J. R.; Fogal, P. F.; +19 more
    Project: NSERC , EC | NORS (284421)

    The Optical Spectrograph and Infra-Red Imager System (OSIRIS) and the Atmospheric Chemistry Experiment (ACE) have been taking measurements from space since 2001 and 2003, respectively. This paper presents intercomparisons between ozone and NO2 measured by the ACE and OSIRIS satellite instruments and by ground-based instruments at the Polar Environment Atmospheric Research Laboratory (PEARL), which is located at Eureka, Canada (80° N, 86° W) and is operated by the Canadian Network for the Detection of Atmospheric Change (CANDAC). The ground-based instruments included in this study are four zenith-sky differential optical absorption spectroscopy (DOAS) instruments, one Bruker Fourier transform infrared spectrometer (FTIR) and four Brewer spectrophotometers. Ozone total columns measured by the DOAS instruments were retrieved using new Network for the Detection of Atmospheric Composition Change (NDACC) guidelines and agree to within 3.2%. The DOAS ozone columns agree with the Brewer spectrophotometers with mean relative differences that are smaller than 1.5%. This suggests that for these instruments the new NDACC data guidelines were successful in producing a homogenous and accurate ozone dataset at 80° N. Satellite 14–52 km ozone and 17–40 km NO2 partial columns within 500 km of PEARL were calculated for ACE-FTS Version 2.2 (v2.2) plus updates, ACE-FTS v3.0, ACE-MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) v1.2 and OSIRIS SaskMART v5.0x ozone and Optimal Estimation v3.0 NO2 data products. The new ACE-FTS v3.0 and the validated ACE-FTS v2.2 partial columns are nearly identical, with mean relative differences of 0.0 ± 0.2% and −0.2 ± 0.1% for v2.2 minus v3.0 ozone and NO2, respectively. Ozone columns were constructed from 14–52 km satellite and 0–14 km ozonesonde partial columns and compared with the ground-based total column measurements. The satellite-plus-sonde measurements agree with the ground-based ozone total columns with mean relative differences of 0.1–7.3%. For NO2, partial columns from 17 km upward were scaled to noon using a photochemical model. Mean relative differences between OSIRIS, ACE-FTS and ground-based NO2 measurements do not exceed 20%. ACE-MAESTRO measures more NO2 than the other instruments, with mean relative differences of 25–52%. Seasonal variation in the differences between NO2 partial columns is observed, suggesting that there are systematic errors in the measurements and/or the photochemical model corrections. For ozone spring-time measurements, additional coincidence criteria based on stratospheric temperature and the location of the polar vortex were found to improve agreement between some of the instruments. For ACE-FTS v2.2 minus Bruker FTIR, the 2007–2009 spring-time mean relative difference improved from −5.0 ± 0.4% to −3.1 ± 0.8% with the dynamical selection criteria. This was the largest improvement, likely because both instruments measure direct sunlight and therefore have well-characterized lines-of-sight compared with scattered sunlight measurements. For NO2, the addition of a ±1° latitude coincidence criterion improved spring-time intercomparison results, likely due to the sharp latitudinal gradient of NO2 during polar sunrise. The differences between satellite and ground-based measurements do not show any obvious trends over the missions, indicating that both the ACE and OSIRIS instruments continue to perform well.

  • Other research product . 1900
    Open Access English
    Publisher: Nanaimo Free Press
    Country: Canada

    https://viurrspace.ca/bitstream/handle/10613/17011/May18-1900.pdf?sequence=2

  • Open Access English
    Publisher: Nanaimo Free Press
    Country: Canada

    https://viurrspace.ca/bitstream/handle/10613/19132/Jun26-1875.pdf?sequence=2&isAllowed=y

  • Open Access English
    Authors: 
    Grillakis, Manolis G.; Koutroulis, Aristeidis G.; Daliakopoulos, Ioannis N.; Tsanis, Ioannis K.;
    Project: EC | HELIX (603864)

    Bias correction of climate variables is a standard practice in climate change impact (CCI) studies. Various methodologies have been developed within the framework of quantile mapping. However, it is well known that quantile mapping may significantly modify the long-term statistics due to the time dependency of the temperature bias. Here, a method to overcome this issue without compromising the day-to-day correction statistics is presented. The methodology separates the modeled temperature signal into a normalized and a residual component relative to the modeled reference period climatology, in order to adjust the biases only for the former and preserve the signal of the later. The results show that this method allows for the preservation of the originally modeled long-term signal in the mean, the standard deviation and higher and lower percentiles of temperature. To illustrate the improvements, the methodology is tested on daily time series obtained from five Euro CORDEX regional climate models (RCMs).

  • Open Access English
    Authors: 
    Schneider, M.; Barthlott, S.; Hase, F.; González, Y.; Yoshimura, K.; García, O. E.; Sepúlveda, E.; Gomez-Pelaez, A.; Gisi, M.; Kohlhepp, R.; +16 more
    Project: NSERC , EC | MUSICA (256961)

    Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologue data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change). We present a new method allowing for an extensive and straightforward characterisation of the complex nature of such isotopologue remote sensing datasets. We demonstrate that the MUSICA humidity profiles are representative for most of the troposphere with a vertical resolution ranging from about 2 km (in the lower troposphere) to 8 km (in the upper troposphere) and with an estimated precision of better than 10%. We find that the sensitivity with respect to the isotopologue composition is limited to the lower and middle troposphere, whereby we estimate a precision of about 30‰ for the ratio between the two isotopologues HD16O and H216O. The measurement noise, the applied atmospheric temperature profiles, the uncertainty in the spectral baseline, and the cross-dependence on humidity are the leading error sources. We introduce an a posteriori correction method of the cross-dependence on humidity, and we recommend applying it to isotopologue ratio remote sensing datasets in general. In addition, we present mid-infrared CO2 retrievals and use them for demonstrating the MUSICA network-wide data consistency. In order to indicate the potential of long-term isotopologue remote sensing data if provided with a well-documented quality, we present a climatology and compare it to simulations of an isotope incorporated AGCM (Atmospheric General Circulation Model). We identify differences in the multi-year mean and seasonal cycles that significantly exceed the estimated errors, thereby indicating deficits in the modeled atmospheric water cycle.

  • Open Access English
    Authors: 
    Morris, K. J.; Herrera, S.; Gubili, C.; Tyler, P. A.; Rogers, A.; Hauton, C.;
    Project: EC | HERMIONE (226354)

    Despite being an abundant group of significant ecological importance the phylogenetic relationships of the Octocorallia remain poorly understood and very much understudied. We used 1132 bp of two mitochondrial protein-coding genes, nad2 and mtMutS (previously referred to as msh1), to construct a phylogeny for 161 octocoral specimens from the Atlantic, including both Isididae and non-Isididae species. We found that four clades were supported using a concatenated alignment. Two of these (A and B) were in general agreement with the of Holaxonia–Alcyoniina and Anthomastus–Corallium clades identified by previous work. The third and fourth clades represent a split of the Calcaxonia–Pennatulacea clade resulting in a clade containing the Pennatulacea and a small number of Isididae specimens and a second clade containing the remaining Calcaxonia. When individual genes were considered nad2 largely agreed with previous work with MtMutS also producing a fourth clade corresponding to a split of Isididae species from the Calcaxonia–Pennatulacea clade. It is expected these difference are a consequence of the inclusion of Isisdae species that have undergone a gene inversion in the mtMutS gene causing their separation in the MtMutS only tree. The fourth clade in the concatenated tree is also suspected to be a result of this gene inversion, as there were very few Isidiae species included in previous work tree and thus this separation would not be clearly resolved. A~larger phylogeny including both Isididae and non Isididae species is required to further resolve these clades.

  • Open Access English
    Authors: 
    Fletcher, Tamara L.; Warden, Lisa; Sinninghe Damsté, Jaap S.; Brown, Kendrick J.; Rybczynski, Natalia; Gosse, John C.; Ballantyne, Ashley P.;
    Project: NSERC , EC | PACEMAKER (226600), NSF | Collaborative Research: A... (1418421), NWO | Perturbations of System E... (11030)

    The mid-Pliocene is a valuable time interval for investigating equilibrium climate at current atmospheric CO2 concentrations because atmospheric CO2 concentrations are thought to have been comparable to the current day and yet the climate and distribution of ecosystems were quite different. One intriguing, but not fully understood, feature of the early to mid-Pliocene climate is the amplified Arctic temperature response and its impact on Arctic ecosystems. Only the most recent models appear to correctly estimate the degree of warming in the Pliocene Arctic and validation of the currently proposed feedbacks is limited by scarce terrestrial records of climate and environment. Here we reconstruct the summer temperature and fire regime from a subfossil fen-peat deposit on west–central Ellesmere Island, Canada, that has been chronologically constrained using cosmogenic nuclide burial dating to 3.9+1.5/-0.5 Ma. The estimate for average mean summer temperature is 15.4±0.8 ∘C using specific bacterial membrane lipids, i.e., branched glycerol dialkyl glycerol tetraethers. This is above the proposed threshold that predicts a substantial increase in wildfire in the modern high latitudes. Macro-charcoal was present in all samples from this Pliocene section with notably higher charcoal concentration in the upper part of the sequence. This change in charcoal was synchronous with a change in vegetation that included an increase in abundance of fire-promoting Pinus and Picea. Paleo-vegetation reconstructions are consistent with warm summer temperatures, relatively low summer precipitation and an incidence of fire comparable to fire-adapted boreal forests of North America and central Siberia. To our knowledge, this site provides the northernmost evidence of fire during the Pliocene. It suggests that ecosystem productivity was greater than in the present day, providing fuel for wildfires, and that the climate was conducive to the ignition of fire during this period. The results reveal that interactions between paleo-vegetation and paleoclimate were mediated by fire in the High Arctic during the Pliocene, even though CO2 concentrations were similar to modern values.

  • Other research product . 1898
    Open Access English
    Publisher: Nanaimo Free Press
    Country: Canada

    https://viurrspace.ca/bitstream/handle/10613/18192/May19-1898.pdf?sequence=2

  • Other research product . 2008
    Open Access English
    Authors: 
    Fundulaki, Irini; Amer-Yahia, Sihem; Laks, Lakshmanan;
    Publisher: Dagstuhl Seminar Proceedings. 08111 - Ranked XML Querying
    Country: Germany

    In PIMENTO we advocate a novel approach to XML search that leverages user information to return more relevant query answers. This approach is based on formalizing {em user profiles} in terms of {em scoping rules} which are used to rewrite an input query, and of {em ordering rules} which are combined with query scoring to customize the ranking of query answers to specific users.