LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 6 of total 6

Search options

  1. Article: Assessing the skill of the Pacific Decadal Oscillation (PDO) in a decadal prediction experiment

    Boer, George J / Sospedra-Alfonso, Reinel

    Climate dynamics. 2019 Nov., v. 53, no. 9-10

    2019  

    Abstract: A modified approach to the assessment of the prediction skill of “modes of variability” is proposed and applied to a decadal prediction experiment. In particular, the skill of predicting the Pacific Decadal Oscillation (PDO) is investigated. The approach ...

    Abstract A modified approach to the assessment of the prediction skill of “modes of variability” is proposed and applied to a decadal prediction experiment. In particular, the skill of predicting the Pacific Decadal Oscillation (PDO) is investigated. The approach depends on separately calculating the EOFs of the observations, the ensemble of forecasts, and an ensemble of simulations made with the same model and external forcing. The skill of predicting and simulating the spatial structure of the modes is captured by comparing forecast and simulated EOFs with the observation-based EOFs. This is in contrast to the case where forecasts and simulations are expanded in observation-based EOFs, or other structure functions, which gives no direct information about the model-based EOF structures themselves. The skill of predicting the temporal evolution of EOFs is separately captured by comparing the associated expansion functions. Finally, the contribution of the modes to the overall prediction skill is obtained by weighting the spatial and temporal skills with the variances involved. The behaviour of the first mode, identified as the PDO, is given particular attention. Perhaps not unexpectedly, the EOF structure of the forecasts more closely resembles that of the simulations than that of the observations, but both reproduce the structure of the observed PDO quite well with spatial correlations near 0.8. The temporal correlation of the expansion functions is near 0.7 for year 1 forecasts and declines toward zero subsequently. The overall correlation skill for the North Pacific is dominated by the PDO with a small contribution from the second mode and none from the third mode.
    Keywords climate ; models ; prediction
    Language English
    Dates of publication 2019-11
    Size p. 5763-5775.
    Publishing place Springer Berlin Heidelberg
    Document type Article
    ZDB-ID 1471747-5
    ISSN 1432-0894 ; 0930-7575
    ISSN (online) 1432-0894
    ISSN 0930-7575
    DOI 10.1007/s00382-019-04896-w
    Database NAL-Catalogue (AGRICOLA)

    Full text online

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  2. Book ; Online: Improving permafrost physics in the coupled Canadian Land Surface Scheme (v.3.6.2) and Canadian Terrestrial Ecosystem Model (v.2.1) (CLASS-CTEM)

    Melton, Joe R. / Verseghy, Diana L. / Sospedra-Alfonso, Reinel / Gruber, Stephan

    eISSN: 1991-9603

    2019  

    Abstract: The Canadian Land Surface Scheme and Canadian Terrestrial Ecosystem Model (CLASS-CTEM) together form the land surface component of the Canadian Earth System Model (CanESM). Here, we investigate the impact of changes to CLASS-CTEM that are designed to ... ...

    Abstract The Canadian Land Surface Scheme and Canadian Terrestrial Ecosystem Model (CLASS-CTEM) together form the land surface component of the Canadian Earth System Model (CanESM). Here, we investigate the impact of changes to CLASS-CTEM that are designed to improve the simulation of permafrost physics. Overall, 18 tests were performed, including changing the model configuration (number and depth of ground layers, different soil permeable depth datasets, adding a surface moss layer), and investigating alternative parameterizations of soil hydrology, soil thermal conductivity, and snow properties. To evaluate these changes, CLASS-CTEM outputs were compared to 1570 active layer thickness (ALT) measurements from 97 observation sites that are part of the Global Terrestrial Network for Permafrost (GTN-P), 105 106 monthly ground temperature observations from 132 GTN-P borehole sites, a blend of five observation-based snow water equivalent (SWE) datasets (Blended-5), remotely sensed albedo, and seasonal discharge for major rivers draining permafrost regions. From the tests performed, the final revised model configuration has more ground layers (increased from 3 to 20) extending to greater depth (from 4.1 to 61.4 m) and uses a new soil permeable depths dataset with a surface layer of moss added. The most beneficial change to the model parameterizations was incorporation of unfrozen water in frozen soils. These changes to CLASS-CTEM cause a small improvement in simulated SWE with little change in surface albedo but greatly improve the model performance at the GTN-P ALT and borehole sites. Compared to the GTN-P observations, the revised CLASS-CTEM ALTs have a weighted mean absolute error (wMAE) of 0.41–0.47 m (depending on configuration), improved from >2.5 m for the original model, while the borehole sites see a consistent improvement in wMAE for most seasons and depths considered, with seasonal wMAE values for the shallow surface layers of the revised model simulation of at most 3.7 ∘ C, which is 1.2 ∘ C more than the wMAE of the screen-level air temperature used to drive the model as compared to site-level observations (2.5 ∘ C). Subgrid heterogeneity estimates were derived from the standard deviation of ALT on the 1 km 2 measurement grids at the GTN-P ALT sites, the spread in wMAE in grid cells with multiple GTN-P ALT sites, as well as from 35 boreholes measured within a 1200 km 2 region as part of the Slave Province Surficial Materials and Permafrost Study. Given the size of the model grid cells (approximately 2.8 ∘ ), subgrid heterogeneity makes it likely difficult to appreciably reduce the wMAE of ALT or borehole temperatures much further.
    Subject code 333
    Language English
    Publishing date 2019-10-24
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

    More links

    Kategorien

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  3. Article ; Online: Energy and shape relaxation in binary atomic systems with realistic quantum cross sections.

    Sospedra-Alfonso, Reinel / Shizgal, Bernie D

    The Journal of chemical physics

    2013  Volume 139, Issue 4, Page(s) 44113

    Abstract: We use the spatially homogeneous linear Boltzmann equation to study the time evolution of an initial non-equilibrium distribution function of an ensemble of test particles dilutely dispersed in a background gas at thermal equilibrium. The systems ... ...

    Abstract We use the spatially homogeneous linear Boltzmann equation to study the time evolution of an initial non-equilibrium distribution function of an ensemble of test particles dilutely dispersed in a background gas at thermal equilibrium. The systems considered are energetic N in He and Xe in He. We employ the quantum mechanical differential cross section to define the collision operator in the Boltzmann equation. The Boltzmann equation is solved with a moment method based on the expansion of the distribution function in the Sonine (Laguerre) polynomials as well as with a direct simulation Monte Carlo method. The moment method provides the approximate eigenvalues and eigenfunctions of the linear Boltzmann collision operator. The reciprocal of the eigenvalues is a measure of the relaxation times to equilibrium. For hard sphere cross sections, the relaxation of the average energy and the shape of the distribution function can be characterized by a single time scale determined by the momentum transfer cross section. We show that this is also the case for realistic quantum cross sections with dominant small angle scattering contributions.
    Language English
    Publishing date 2013-07-28
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3113-6
    ISSN 1089-7690 ; 0021-9606
    ISSN (online) 1089-7690
    ISSN 0021-9606
    DOI 10.1063/1.4816279
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    In stock of ZB MED Bonn / Germany

    Z 4' 49/16: Show issues

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  4. Article ; Online: Kullback-Leibler entropy in the electron distribution shape relaxation for electron-atom thermalization.

    Sospedra-Alfonso, Reinel / Shizgal, Bernie D

    Physical review. E, Statistical, nonlinear, and soft matter physics

    2011  Volume 84, Issue 4 Pt 1, Page(s) 41202

    Abstract: We study the thermalization of energetic electrons dilutely dispersed in inert gas atomic moderators, with and without the presence of an external electric field. We investigate the shape relaxation of the electron distribution function relative to the ... ...

    Abstract We study the thermalization of energetic electrons dilutely dispersed in inert gas atomic moderators, with and without the presence of an external electric field. We investigate the shape relaxation of the electron distribution function relative to the steady-state distribution by means of the Kullback-Leibler entropy. The departure of the distribution function from a local Maxwellian parametrized by the temperature of the electrons is also considered with a functional analogous to the Kullback-Leibler entropy. For neon and argon as moderators, we found no evidence for the formation of a local Maxwellian followed by a slower relaxation to equilibrium. The momentum-transfer cross section for e-Ne collisions is almost constant with energy, whereas the e-Ar momentum-transfer cross section has a deep Ramsauer-Townsend minimum and a strong energy dependence. The role of the Ramsauer minimum in the relaxation processes is investigated. The time-dependent Lorentz-Fokker-Planck equation is solved for the speed distribution of the electrons with a finite difference method. A pseudospectral method is also used to investigate the spectral properties of the Fokker-Planck operator. In spite of the multi-exponential time dependence of the speed distribution function, we show that a single average relaxation time can be defined to characterize the relaxation to equilibrium.
    Language English
    Publishing date 2011-10
    Publishing country United States
    Document type Journal Article
    ISSN 1550-2376
    ISSN (online) 1550-2376
    DOI 10.1103/PhysRevE.84.041202
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  5. Book ; Online: Improvements in the Canadian Earth System Model (CanESM) through systematic model analysis

    Sigmond, Michael / Anstey, James / Arora, Vivek / Digby, Ruth / Gillett, Nathan / Kharin, Viatcheslav / Merryfield, William / Reader, Catherine / Scinocca, John / Swart, Neil / Virgin, John / Abraham, Carsten / Cole, Jason / Lambert, Nicolas / Lee, Woo-Sung / Liang, Yongxiao / Malinina, Elizaveta / Rieger, Landon / Salzen, Knut /
    Seiler, Christian / Seinen, Clint / Shao, Andrew / Sospedra-Alfonso, Reinel / Wang, Libo / Yang, Duo

    eISSN: 1991-9603

    CanESM5.0 and CanESM5.1

    2023  

    Abstract: The Canadian Earth System Model version 5.0 (CanESM5.0), the most recent major version of the global climate model developed at the Canadian Centre for Climate Modelling and Analysis (CCCma) at Environment and Climate Change Canada (ECCC), has been used ... ...

    Abstract The Canadian Earth System Model version 5.0 (CanESM5.0), the most recent major version of the global climate model developed at the Canadian Centre for Climate Modelling and Analysis (CCCma) at Environment and Climate Change Canada (ECCC), has been used extensively in climate research and for providing future climate projections in the context of climate services. Previous studies have shown that CanESM5.0 performs well compared to other models and have revealed several model biases. To address these biases, CCCma has recently initiated the ‘Analysis for Development’ (A4D) activity, a coordinated analysis activity in support of CanESM development. Here we describe the goals and organization of this effort and introduce two variants (``p1'' and ``p2'') of a new CanESM version, CanESM5.1, which features substantial improvements as a result of the A4D activity. These improvements include the elimination of spurious stratospheric temperature spikes and an improved simulation of tropospheric dust. Other climate aspects of the p1 variant of CanESM5.1 are similar to those of CanESM5.0, while the p2 variant of CanESM5.1 features reduced equilibrium climate sensitivity and improved ENSO variability as a result of intentional tuning of the atmospheric component. The A4D activity has also led to the improved understanding of other notable CanESM5.0/5.1 biases, including the overestimation of North Atlantic sea ice, a cold bias over sea ice, biases in the stratospheric circulation and a cold bias over the Himalayas. It provides a potential framework for the broader climate community to contribute to CanESM development, which will facilitate further model improvements and ultimately lead to improved climate change information.
    Subject code 333
    Language English
    Publishing date 2023-04-04
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

    More links

    Kategorien

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  6. Article ; Online: Global Carbon Budget 2023

    Friedlingstein, Pierre / O'Sullivan, Michael / Jones, Matthew W. / Andrew, Robbie M. / Bakker, Dorothee C. E. / Hauck, Judith / Landschützer, Peter / Le Quéré, Corinne / Luijkx, Ingrid T. / Peters, Glen P. / Peters, Wouter / Pongratz, Julia / Schwingshackl, Clemens / Sitch, Stephen / Canadell, Josep G. / Ciais, Philippe / Jackson, Robert B. / Alin, Simone R. / Anthoni, Peter /
    Barbero, Leticia / Bates, Nicholas R. / Becker, Meike / Bellouin, Nicolas / Decharme, Bertrand / Bopp, Laurent / Brasika, Ida Bagus Mandhara / Cadule, Patricia / Chamberlain, Matthew A. / Chandra, Naveen / Chau, Thi-Tuyet-Trang / Chevallier, Frédéric / Chini, Louise P. / Cronin, Margot / Dou, Xinyu / Enyo, Kazutaka / Evans, Wiley / Falk, Stefanie / Feely, Richard A. / Feng, Liang / Ford, Daniel J. / Gasser, Thomas / Ghattas, Josefine / Gkritzalis, Thanos / Grassi, Giacomo / Gregor, Luke / Gruber, Nicolas / Gürses, Özgür / Harris, Ian / Hefner, Matthew / Heinke, Jens / Houghton, Richard A. / Hurtt, George C. / Iida, Yosuke / Ilyina, Tatiana / Jacobson, Andrew R. / Jain, Atul / Jarníková, Tereza / Jersild, Annika / Jiang, Fei / Jin, Zhe / Joos, Fortunat / Kato, Etsushi / Keeling, Ralph F. / Kennedy, Daniel / Klein Goldewijk, Kees / Knauer, Jürgen / Korsbakken, Jan Ivar / Körtzinger, Arne / Lan, Xin / Lefèvre, Nathalie / Li, Hongmei / Liu, Junjie / Liu, Zhiqiang / Ma, Lei / Marland, Greg / Mayot, Nicolas / McGuire, Patrick C. / McKinley, Galen A. / Meyer, Gesa / Morgan, Eric J. / Munro, David R. / Nakaoka, Shin-Ichiro / Niwa, Yosuke / O'Brien, Kevin M. / Olsen, Are / Omar, Abdirahman M. / Ono, Tsuneo / Paulsen, Melf / Pierrot, Denis / Pocock, Katie / Poulter, Benjamin / Powis, Carter M. / Rehder, Gregor / Resplandy, Laure / Robertson, Eddy / Rödenbeck, Christian / Rosan, Thais M. / Schwinger, Jörg / Séférian, Roland / Smallman, T. Luke / Smith, Stephen M. / Sospedra-Alfonso, Reinel / Sun, Qing / Sutton, Adrienne J. / Sweeney, Colm / Takao, Shintaro / Tans, Pieter P. / Tian, Hanqin / Tilbrook, Bronte / Tsujino, Hiroyuki / Tubiello, Francesco / van der Werf, Guido R. / van Ooijen, Erik / Wanninkhof, Rik / Watanabe, Michio / Wimart-Rousseau, Cathy / Yang, Dongxu / Yang, Xiaojuan / Yuan, Wenping / Yue, Xu / Zaehle, Sönke / Zeng, Jiye / Zheng, Bo

    2023  

    Abstract: Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of ...

    Abstract Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (E-FOS) are based on energy statistics and cement production data, while emissions from land-use change (E-LUC), mainly deforestation, are based on land-use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly, and its growth rate (G(ATM)) is computed from the annual changes in concentration. The ocean CO2 sink (S-OCEAN) is estimated with global ocean biogeochemistry models and observation-based fCO(2) products. The terrestrial CO2 sink (S-LAND) is estimated with dynamic global vegetation models. Additional lines of evidence on land and ocean sinks are provided by atmospheric inversions, atmospheric oxygen measurements, and Earth system models. The resulting carbon budget imbalance (B-IM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and incomplete understanding of the contemporary carbon cycle. All uncertainties are reported as +/- 1 sigma. For the year 2022, E-FOS increased by 0.9% relative to 2021, with fossil emissions at 9.9 +/- 0.5 GtC yr(-1) (10.2 +/- 0.5 GtC yr(-1) when the cement carbonation sink is not included), and E-LUC was 1.2 +/- 0.7 GtC yr(-1), for a total anthropogenic CO2 emission (including the cement carbonation sink) of 11.1 +/- 0.8 GtC yr(-1) (40.7 +/- 3.2 GtCO(2) yr(-1)). Also, for 2022, G(ATM) was 4.6 +/- 0.2 GtC yr(-1) (2.18 +/- 0.1 ppm yr(-1); ppm denotes parts per million), S-OCEAN was 2.8 +/- 0.4 GtC yr(-1), and S-LAND was 3.8 +/- 0.8 GtC yr(-1), with a ...
    Subject code 551
    Language English
    Publishing date 2023-12-05
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

    More links

    Kategorien

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

To top