Tracing Shifts: Interdecadal Variations of NAO and PNA Patterns from the Nineteenth Century across Multiple Reanalyses

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378289%3A_____%2F25%3A00618415" target="_blank" >RIV/68378289:_____/25:00618415 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11310/25:10503852

Výsledek na webu

<a href="https://journals.ametsoc.org/view/journals/clim/38/6/JCLI-D-24-0037.1.xml" target="_blank" >https://journals.ametsoc.org/view/journals/clim/38/6/JCLI-D-24-0037.1.xml</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1175/JCLI-D-24-0037.1" target="_blank" >10.1175/JCLI-D-24-0037.1</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Tracing Shifts: Interdecadal Variations of NAO and PNA Patterns from the Nineteenth Century across Multiple Reanalyses

Popis výsledku v původním jazyce

This study examines the spatial structures of the North Atlantic Oscillation (NAO) and Pacific-North American (PNA) pattern across five reanalyses and investigates their temporal changes. Using winter monthly mean anomalies of 500-hPa geopotential heights from ensemble mean fields and individual ensemble members, we apply a moving principal component analysis (PCA) to 40-yr periods. Our findings reveal that the modes can vary significantly even with slight changes in the analyzed period. We observe that the lack of constraint over the North Pacific leads to different PNA patterns in individual ensemble members, resulting in a smoothed and weaker PNA in the ensemble mean. Therefore, we recommend using ensemble members instead of the ensemble mean before 1900 when analyzing low-frequency variability in 20CRv2 or 20CRv3. Despite differences in data assimilation, period length, and models among reanalyses, trends in explained variance and spatial changes of both PNA and NAO are similar. We also identified a decrease in the similarity of the NAO pattern around 1962-2001 across all datasets, linked to a sudden southward shift in the mode, indicating a change in variability in the reanalyses, independent of the data source or the model. The temporal changes, including long-term trends, likely have a fundamental basis, although sudden changes from period to period are rather artifacts from the PCA.

Název v anglickém jazyce

Tracing Shifts: Interdecadal Variations of NAO and PNA Patterns from the Nineteenth Century across Multiple Reanalyses

Popis výsledku anglicky

This study examines the spatial structures of the North Atlantic Oscillation (NAO) and Pacific-North American (PNA) pattern across five reanalyses and investigates their temporal changes. Using winter monthly mean anomalies of 500-hPa geopotential heights from ensemble mean fields and individual ensemble members, we apply a moving principal component analysis (PCA) to 40-yr periods. Our findings reveal that the modes can vary significantly even with slight changes in the analyzed period. We observe that the lack of constraint over the North Pacific leads to different PNA patterns in individual ensemble members, resulting in a smoothed and weaker PNA in the ensemble mean. Therefore, we recommend using ensemble members instead of the ensemble mean before 1900 when analyzing low-frequency variability in 20CRv2 or 20CRv3. Despite differences in data assimilation, period length, and models among reanalyses, trends in explained variance and spatial changes of both PNA and NAO are similar. We also identified a decrease in the similarity of the NAO pattern around 1962-2001 across all datasets, linked to a sudden southward shift in the mode, indicating a change in variability in the reanalyses, independent of the data source or the model. The temporal changes, including long-term trends, likely have a fundamental basis, although sudden changes from period to period are rather artifacts from the PCA.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10509 - Meteorology and atmospheric sciences

Projekt

<a href="/cs/project/GA17-07043S" target="_blank" >GA17-07043S: Dálkové vazby - hlavní stavební kameny atmosférické cirkulace</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Climate

ISSN

0894-8755

e-ISSN

1520-0442

Svazek periodika

38

Číslo periodika v rámci svazku

6

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

13

Strana od-do

1521-1533

Kód UT WoS článku

001443757600001

EID výsledku v databázi Scopus

2-s2.0-86000721264