Assessing General Circulation Model Simulations of Atmospheric Teleconnection Patterns

Abstract

The ability of coupled atmosphere-ocean general circulation models (AOGCMs) to simulate variability in regional and global atmospheric dynamics is an important aspect of model evaluation. This is particularly true for recurring large-scale patterns known to be correlated with surface climate anomalies. Here, the authors evaluate the ability of all Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) historical Twentieth-Century Climate in Coupled Models (20C3M) AOGCM simulations for which the required output fields are available to simulate three patterns of large-scale atmospheric internal variability in the North Atlantic region: the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO), and the Atlantic multidecadal oscillation (AMO); and three in the North Pacific region: the El Niñ o-Southern Oscillation (ENSO), the Pacific decadal oscillation (PDO), and the Pacific-North American Oscillation (PNA). These patterns are evaluated in two ways: first, in terms of their characteristic temporal variability and second, in terms of their magnitude and spatial locations.It is found that historical total-forcing simulations from many of the AOGCMs produce seasonal spatial patterns that clearly resemble the teleconnection patterns resulting from identical calculation methods applied to reanalysis and/or observed fields such as the 40-yr ECMWF Re-Analysis, NCEP-NCAR, or Kaplan sea surface temperatures (SSTs), with the exception of the lowest-frequency pattern, AMO, which is only reproduced by a few models. AOGCM simulations also show some significant biases in both spatial and temporal characteristics of the six patterns. Many models tend to either under-or overestimate the strength of the spatial patterns and exhibit rotation about the polar region or east-west displacement. Based on spectral analysis of the time series of each index, models also appear to vary in their ability to simulate the temporal variability of the teleconnection patterns, with some models producing oscillations that are too fast and others that are too slow relative to those observed. A few models produce a signal that is too periodic, most likely because of a failure to adequately simulate the natural chaotic behavior of the atmosphere. These results have implications for the selection and use of specific AOGCMs to simulate climate over the Northern Hemisphere, with some models being clearly more successful at (i.e., displaying less bias in) simulating large-scale, low-frequency patterns of temporal and spatial variability over the North Atlantic and Pacific regions relative to others.

Description and basic evaluation of Beijing Normal University Earth System Model (BNU-ESM) version 1

“…During the positive (negative) phase of PDO, waters in the east tropical Pacific and along the North American west coast are anomalously warm (cool) while waters in the northern, western, and southern Pacific are colder (warmer) than normal. Coupled climate models can simulate some aspects of PDO, although linkages between the tropical and North Pacific are usually weaker than observed (Stoner et al, 2009;Furtado et al, 2011). Figure …”

GCM projections for the Pacific Decadal Oscillation under greenhouse forcing for the early 21st century

“…A more careful examination of these ten models' ability to simulate the AO might show that the GCMs best at simulating the AO are those producing results compatible with the concurrent PDO projection. In particular, the AO might be more accurately projected by a higher geopotential height and/or PCA method (Stoner et al, 2009), rather than our use of a two-point SLP difference method based on the NAO.…”

“…Because of the importance of recurring large-scale climate patterns (e.g. the PDO, ENSO) for regional climates, researchers have begun to critically examine these CMIP3 runs for their capacity to model atmosphere-ocean climate oscillations (Muller and Roeckner, 2006;IPCC4, 2007;Overland and Wang, 2007;Oshima and Tanimoto, 2009;Stoner et al, 2009;Wang et al, 2010). From the 23 GCMs with archived data, we chose those best able to simulate the PDO, using comparisons of spatial and temporal patterns of variability from the 20th-century observed records, the 20th-century simulations and the control runs.…”

Evaluation of Relationship Between Large‐scale Atmospheric Circulation Patterns With Precipitation Over Northwestern Iran in the Northern Hemisphere

“…The spatial and temporal aspects of teleconnections can be interpreted in terms of the large-scale dynamical structure of the atmosphere (Leathers and et al,1991).In other words, The word "teleconnection" has been commonly used to describe relationships in the low-frequency variability of the tropical and extra tropical atmospheric circulations, precipitation, and temperatures (Trenberth and et al 1998). These patterns have implications for future change, as long-term shifts in the frequency and/or intensity of natural cycles could alter the range of surface climate conditions experienced in many locations around the world (Anne Marie and et al 2009). …”