Why is the North Atlantic Oscillation More Predictable in December?

The prediction skill of the Climate Forecast System, version 2 (CFSv2), for the North Atlantic Oscillation (NAO) is evaluated in three winter months (December, January, and February). The results show that the CFSv2 model can skillfully predict the December NAO one month in advance. There are two ma...

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Main Authors: Baoqiang Tian, Ke Fan
Format: Article
Language:English
Published: MDPI AG 2019-08-01
Series:Atmosphere
Subjects:
Online Access:https://www.mdpi.com/2073-4433/10/8/477
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author Baoqiang Tian
Ke Fan
author_facet Baoqiang Tian
Ke Fan
author_sort Baoqiang Tian
collection DOAJ
description The prediction skill of the Climate Forecast System, version 2 (CFSv2), for the North Atlantic Oscillation (NAO) is evaluated in three winter months (December, January, and February). The results show that the CFSv2 model can skillfully predict the December NAO one month in advance. There are two main contributors to NAO predictability in December. One is the predictability of the relationship between the North Atlantic sea surface temperature anomaly (SSTA) tripole and the NAO and the other is the second empirical orthogonal function (EOF) mode of the geopotential height at 50 hPa (Z50-EOF2). The relationship between the NAO and SSTA tripole index in December is the most significant in the three winter months. The significant monthly differences of surface heat fluxes in December over the whole North Atlantic are favorable for promoting the interaction between the NAO and North Atlantic SSTAs, in addition to improving the predictability of the December NAO. When the NAO is in a positive phase, easterly anomalies are located at the low and high latitudes and westerly anomalies prevail in the mid-latitudes of the troposphere. The correlation between the December Z50-EOF2 and zonal-mean zonal wind anomalies shows a similar spatial structure to that for the NAO. The possible reason why the CFSv2 model can predict the December NAO one month ahead is that it can reasonably reproduce the relationship between the December NAO and both the North Atlantic SST and stratospheric circulation.
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spelling doaj.art-7c7a43dae1af4dfb8844ae0270adc5f82022-12-21T18:55:27ZengMDPI AGAtmosphere2073-44332019-08-0110847710.3390/atmos10080477atmos10080477Why is the North Atlantic Oscillation More Predictable in December?Baoqiang Tian0Ke Fan1Nansen-Zhu International Research Centre, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaNansen-Zhu International Research Centre, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaThe prediction skill of the Climate Forecast System, version 2 (CFSv2), for the North Atlantic Oscillation (NAO) is evaluated in three winter months (December, January, and February). The results show that the CFSv2 model can skillfully predict the December NAO one month in advance. There are two main contributors to NAO predictability in December. One is the predictability of the relationship between the North Atlantic sea surface temperature anomaly (SSTA) tripole and the NAO and the other is the second empirical orthogonal function (EOF) mode of the geopotential height at 50 hPa (Z50-EOF2). The relationship between the NAO and SSTA tripole index in December is the most significant in the three winter months. The significant monthly differences of surface heat fluxes in December over the whole North Atlantic are favorable for promoting the interaction between the NAO and North Atlantic SSTAs, in addition to improving the predictability of the December NAO. When the NAO is in a positive phase, easterly anomalies are located at the low and high latitudes and westerly anomalies prevail in the mid-latitudes of the troposphere. The correlation between the December Z50-EOF2 and zonal-mean zonal wind anomalies shows a similar spatial structure to that for the NAO. The possible reason why the CFSv2 model can predict the December NAO one month ahead is that it can reasonably reproduce the relationship between the December NAO and both the North Atlantic SST and stratospheric circulation.https://www.mdpi.com/2073-4433/10/8/477December NAOpredictability sourcesNorth Atlantic SSTstratosphere
spellingShingle Baoqiang Tian
Ke Fan
Why is the North Atlantic Oscillation More Predictable in December?
Atmosphere
December NAO
predictability sources
North Atlantic SST
stratosphere
title Why is the North Atlantic Oscillation More Predictable in December?
title_full Why is the North Atlantic Oscillation More Predictable in December?
title_fullStr Why is the North Atlantic Oscillation More Predictable in December?
title_full_unstemmed Why is the North Atlantic Oscillation More Predictable in December?
title_short Why is the North Atlantic Oscillation More Predictable in December?
title_sort why is the north atlantic oscillation more predictable in december
topic December NAO
predictability sources
North Atlantic SST
stratosphere
url https://www.mdpi.com/2073-4433/10/8/477
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