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norskBlar i forfatter "Nilsen, Tine"
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Are there multiple scaling regimes in Holocene temperature records?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-04-28)In this article it is discussed how temperature variability on centennial timescales and longer can be described in a simplistic way. By analysing the scaling in late Holocene temperature reconstructions and longer temperature records from Greenland and Antarctic ice cores, we find that the choice of model depends heavily on the data material and timescale one chooses to emphasize. Ignoring data ... -
Are there multiple scaling regimes in Holocene temperature records?
(Journal article; Tidsskriftartikkel, 2015-07-17)The concept of multiple scaling regimes in temperature time series is examined, with emphasis on the question whether or not a mono-scaling model can be rejected from the data at hand. A model with only one regime is simpler and is preferred if this 5 explains the observed variability. Our analysis of spectra from reconstructed air temperature from Greenland and Antarctica ice cores shows that ... -
Assessing the performance of the BARCAST climate field reconstruction technique for a climate with long-range memory
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-29)The skill of the state-of-the-art climate field reconstruction technique BARCAST (Bayesian Algorithm for Reconstructing Climate Anomalies in Space and Time) to reconstruct temperature with pronounced long-range memory (LRM) characteristics is tested. A novel technique for generating fields of target data has been developed and is used to provide ensembles of LRM stochastic processes with a prescribed ... -
Constraining two climate field reconstruction methodologies over the North Atlantic realm using pseudo-proxy experiments
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-06)This study presents pseudo-proxy experiments to quantify the reconstruction skill of two climate field reconstruction methodologies for a marine proxy network subject to age uncertainties. The BARCAST methodology (Bayesian Algorithm for Reconstructing Climate Anomalies in Space and Time) is tested for sea surface temperature (SST) reconstruction for the first time over the northern North Atlantic ... -
Is there a break in scaling on centennial time scales in Holocene temperature records?
(Conference object; Konferansebidrag, 2017) -
Late Holocene climate variability in the North Atlantic realm from paleo data and climate simulations
(Master thesis; Mastergradsoppgave, 2013-05-31)This thesis presents the results of the comparative analysis of surface temperature series from paleoproxy reconstructions and climate simu- lations. The proxy to model comparison is done using the results from 12 simulations produced by 5 different climate models covering the pe- riod of the late Holocene. Agreement between the model results and the paleoproxy reonstrcuctions is analyzed both on ... -
Long-range memory in Earth's climate response - analysis of paleoclimatic records and climate model simulations
(Doctoral thesis; Doktorgradsavhandling, 2018-01-22)The memory properties in paleoclimate temperature records based on model simulations and proxy-reconstructions have been investigated, to find out if these records exhibit long-range memory in a similar manner as many instrumental temperature records. On time scales from years to centuries and even millennia, long-range memory is identified in the paleoclimate records using a toolbox of statistical ... -
Long-range memory in internal and forced dynamics of millennium-long climate model simulations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014)Northern Hemisphere (NH) temperature records from a palaeoclimate reconstruction and a number of millennium-long climate model experiments are investigated for long-range memory (LRM). The models are two Earth system models and two atmosphere–ocean general circulation models. The periodogram, detrended fluctuation analysis and wavelet variance analysis are applied to examine scaling properties ... -
Long-Range Memory in Millennium-Long ESM and AOGCM Experiments
(Others; Andre, 2014)Consider the Earth’s global mean surface temperature time series (GMST) as a realization of a stochastic process. Based on a number of studies, a long-range memory (LRM) stochastic process seems to describe the GMST better than a shortrange memory model, such as the AR(1)-process. We want to study the persistence in climate model simulations, to find out if simulated temperature data exhibit the ... -
Spatio-temporal variability of Arctic summer temperatures over the past 2 millennia
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-24)<p>In this article, the first spatially resolved and millennium-length summer (June–August) temperature reconstruction over the Arctic and sub-Arctic domain (north of 60°N) is presented. It is based on a set of 44 annually dated temperature-sensitive proxy archives of various types from the revised PAGES2k database supplemented with six new recently updated proxy records. As a major advance, an ... -
The Structure of Climate Variability Across Scales
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-05)One of the most intriguing facets of the climate system is that it exhibits variability across all temporal and spatial scales; pronounced examples are temperature and precipitation. The structure of this variability, however, is not arbitrary. Over certain spatial and temporal ranges, it can be described by scaling relationships in the form of power laws in probability density distributions and ... -
The Structure of Climate Variability Across Scales
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-05)One of the most intriguing facets of the climate system is that it exhibits variability across all temporal and spatial scales; pronounced examples are temperature and precipitation. The structure of this variability, however, is not arbitrary. Over certain spatial and temporal ranges, it can be described by scaling relationships in the form of power laws in probability density distributions and ...
