Journal ArticleDOI
Simulation of recent northern winter climate trends by greenhouse-gas forcing
TLDR
The authors used several different climate-model versions to demonstrate that the observed sea-level-pressure trends, including their magnitude, can be simulated by realistic increases in greenhouse-gas concentrations, while changes in ozone concentrations are not necessary to simulate the observed climate trends.Abstract:
The temperature of air at the Earth's surface has risen during the past century1, but the fraction of the warming that can be attributed to anthropogenic greenhouse gases remains controversial. The strongest warming trends have been over Northern Hemisphere land masses during winter, and are closely related to changes in atmospheric circulation. These circulation changes are manifested by a gradual reduction in high-latitude sea-level pressure, and an increase in mid-latitude sea-level pressure associated with one phase of the Arctic Oscillation (a hemisphere-scale version of the North Atlantic Oscillation)2. Here we use several different climate-model versions to demonstrate that the observed sea-level-pressure trends, including their magnitude, can be simulated by realistic increases in greenhouse-gas concentrations. Thus, although the warming appears through a naturally occurring mode of atmospheric variability, it may be anthropogenically induced and may continue to rise. The Arctic Oscillation trend is captured only in climate models that include a realistic representation of the stratosphere, while changes in ozone concentrations are not necessary to simulate the observed climate trends. The proper representation of stratospheric dynamics appears to be important to the attribution of climate change, at least on a broad regional scale.read more
Citations
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Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
TL;DR: Drafting Authors: Neil Adger, Pramod Aggarwal, Shardul Agrawala, Joseph Alcamo, Abdelkader Allali, Oleg Anisimov, Nigel Arnell, Michel Boko, Osvaldo Canziani, Timothy Carter, Gino Casassa, Ulisses Confalonieri, Rex Victor Cruz, Edmundo de Alba Alcaraz, William Easterling, Christopher Field, Andreas Fischlin, Blair Fitzharris.
Journal ArticleDOI
Annular Modes in the Extratropical Circulation. Part I: Month-to-Month Variability*
TL;DR: In this article, the authors compared the structure and seasonality of the Southern Hemisphere (SH) annular mode and the Northern Hemisphere (NH) mode, referred to as the Arctic Oscillation (AO), based on data from the National Centers for Environmental Prediction and National Center for Atmospheric Research reanalysis and supplementary datasets.
Book ChapterDOI
An overview of the North Atlantic Oscillation
TL;DR: The North Atlantic Oscillation (NAO) is one of the most prominent and recurrent patterns of atmospheric circulation variability as discussed by the authors, and it dictates climate variability from the eastern seaboard of the United States to Siberia and from the Arctic to the subtropical Atlantic, especially during boreal winter.
Journal ArticleDOI
Interpretation of recent Southern Hemisphere climate change
TL;DR: In this article, it is argued that the largest and most significant tropospheric trends can be traced to recent trends in the lower stratospheric polar vortex, which are due largely to photochemical ozone losses, and the trend toward stronger circumpolar flow has contributed substantially to the observed warming over the Antarctic Peninsula and Patagonia and to the cooling over eastern Antarctica and the Antarctic plateau.
Journal ArticleDOI
Warming of the World Ocean
TL;DR: In this article, the authors quantify the interannual-to-decadal variability of the heat content (mean temperature) of the world ocean from the surface through 3000-meter depth for the period 1948 to 1998, showing that the global volume mean temperature increase for the 0- to 300-meter layer was 0.31°C, corresponding to an increase in heat content for this layer of ∼10 23 joules between the mid-1950s and mid-1990s.
References
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Journal ArticleDOI
The Arctic oscillation signature in the wintertime geopotential height and temperature fields
TL;DR: The Arctic Oscillation (AO) as mentioned in this paper is the signature of modulations in the strength of the polar vortex aloft, and it resembles the NAO in many respects; but its primary center of action covers more of the Arctic, giving it a more zonally symmetric appearance.
Journal ArticleDOI
Teleconnections in the Geopotential Height Field during the Northern Hemisphere Winter
John M. Wallace,David S. Gutzler +1 more
TL;DR: In this paper, a review of existing literature on the subject reveals the existence of at least four such patterns: the North Atlantic and North Pacific Oscillations identified by Walker and Bliss (1932), a zonally symmetric seesaw between sea level pressures in polar and temperature latitudes, first noted by Lorenz (1951), and what we will refer to as the Pacific/North American pattern, which has been known to operational long-range forecasters in this country since the 1950's.
Journal ArticleDOI
Sampling Errors in the Estimation of Empirical Orthogonal Functions
TL;DR: In this paper, the authors reviewed the necessary weighting factors for gridded data and the sampling errors incurred when too small a sample is available, and a rule of thumb indicating when an EOF is likely to be subject to large sampling fluctuations is presented.
Journal ArticleDOI
An Intercomparison of Methods for Finding Coupled Patterns in Climate Data
TL;DR: In this paper, the authors introduce a conceptual framework for comparing methods that isolate important coupled modes of variability between time series of two fields, including principal component analysis with the fields combined (CPCA), canonical correlation analysis (CCA), and singular value decomposition of the covariance matrix between the two fields (SVD).
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