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Combining point correlation maps with self-organising maps to compare observed and simulated atmospheric teleconnection patterns

Combining point correlation maps with self-organising maps to compare observed and simulated atmospheric teleconnection patterns
Combining point correlation maps with self-organising maps to compare observed and simulated atmospheric teleconnection patterns
We use a new method based on point correlation maps and self-organising maps (SOMs) to identify teleconnection patterns in 60 yr of National Centres for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR) sea level pressure (SLP) re-analysis data. The most prevalent patterns are the El Nino Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO) and the Southern Annular Mode (SAM). Asymmetries are found between base points in opposite centres of action of the NAO and the Pacific North America pattern (PNA). The SOM-based method is a powerful tool that allows us to efficiently assess how realistically teleconnections are reproduced in any climate model. The degree of agreement between modelled and re-analysis-based teleconnections (or between different models) can be summarised in a single plot. Here, we illustrate this by assessing the skill of the medium complexity climate model FORTE (Fast Ocean Rapid Troposphere Experiment). FORTE reproduces some realistic teleconnections, such as the Arctic Oscillation (AO), the NAO, the PNA, the SAM, the African Monsoon and ENSO, along with several other teleconnections, which resemble to varying degrees the corresponding NCEP patterns. However, FORTE tends to underestimate the strength of the correlation patterns and the patterns tend to be slightly too zonal. The accuracy of frequency of occurrence is variable between patterns. The Indian Ocean is a region where FORTE performs poorly, as it does not reproduce the teleconnection patterns linked to the Indian Monsoon. In contrast, the North and equatorial Pacific and North Atlantic are reasonably well reproduced.
teleconnections, self-organising map, climate model, North Atlantic Oscillation, El Nino Southern Oscillation, empirical orthogonal function
0280-6495
20822
Hunt, F.K.
e3cb0020-9efe-4c78-8681-72cd4a5c726f
Hirschi, J.J-M.
c8a45006-a6e3-4319-b5f5-648e8ef98906
Sinha, Bablu
544b5a07-3d74-464b-9470-a68c69bd722e
Oliver, Kevin
588b11c6-4d0c-4c59-94e2-255688474987
Wells, Neil
4c27167c-f972-4822-9614-d6ca8d8223b5
Hunt, F.K.
e3cb0020-9efe-4c78-8681-72cd4a5c726f
Hirschi, J.J-M.
c8a45006-a6e3-4319-b5f5-648e8ef98906
Sinha, Bablu
544b5a07-3d74-464b-9470-a68c69bd722e
Oliver, Kevin
588b11c6-4d0c-4c59-94e2-255688474987
Wells, Neil
4c27167c-f972-4822-9614-d6ca8d8223b5

Hunt, F.K., Hirschi, J.J-M., Sinha, Bablu, Oliver, Kevin and Wells, Neil (2013) Combining point correlation maps with self-organising maps to compare observed and simulated atmospheric teleconnection patterns. Tellus A, 65, 20822. (doi:10.3402/tellusa.v65i0.20822).

Record type: Article

Abstract

We use a new method based on point correlation maps and self-organising maps (SOMs) to identify teleconnection patterns in 60 yr of National Centres for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR) sea level pressure (SLP) re-analysis data. The most prevalent patterns are the El Nino Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO) and the Southern Annular Mode (SAM). Asymmetries are found between base points in opposite centres of action of the NAO and the Pacific North America pattern (PNA). The SOM-based method is a powerful tool that allows us to efficiently assess how realistically teleconnections are reproduced in any climate model. The degree of agreement between modelled and re-analysis-based teleconnections (or between different models) can be summarised in a single plot. Here, we illustrate this by assessing the skill of the medium complexity climate model FORTE (Fast Ocean Rapid Troposphere Experiment). FORTE reproduces some realistic teleconnections, such as the Arctic Oscillation (AO), the NAO, the PNA, the SAM, the African Monsoon and ENSO, along with several other teleconnections, which resemble to varying degrees the corresponding NCEP patterns. However, FORTE tends to underestimate the strength of the correlation patterns and the patterns tend to be slightly too zonal. The accuracy of frequency of occurrence is variable between patterns. The Indian Ocean is a region where FORTE performs poorly, as it does not reproduce the teleconnection patterns linked to the Indian Monsoon. In contrast, the North and equatorial Pacific and North Atlantic are reasonably well reproduced.

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Submitted date: 11 March 2013
Published date: 23 July 2013
Keywords: teleconnections, self-organising map, climate model, North Atlantic Oscillation, El Nino Southern Oscillation, empirical orthogonal function
Organisations: Marine Systems Modelling, Physical Oceanography

Identifiers

Local EPrints ID: 347546
URI: http://eprints.soton.ac.uk/id/eprint/347546
ISSN: 0280-6495
PURE UUID: b1101861-1f9e-441c-ba21-7796eecce980

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Date deposited: 24 Jul 2013 08:51
Last modified: 14 Mar 2024 12:49

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Contributors

Author: F.K. Hunt
Author: J.J-M. Hirschi
Author: Bablu Sinha
Author: Kevin Oliver
Author: Neil Wells

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