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Meridional Modes and Increasing Pacific Decadal Variability Under Anthropogenic Forcing
Author(s) -
Liguori Giovanni,
Di Lorenzo Emanuele
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl076548
Subject(s) - climatology , pacific decadal oscillation , environmental science , extratropical cyclone , forcing (mathematics) , radiative forcing , sea surface temperature , climate model , climate change , zonal and meridional , atmospheric sciences , oceanography , geology
Pacific decadal variability has strong impacts on the statistics of weather, atmosphere extremes, droughts, hurricanes, marine heatwaves, and marine ecosystems. Sea surface temperature (SST) observations show that the variance of the El Niño‐like decadal variability has increased by ~30% (1920–2015) with a stronger coupling between the major Pacific climate modes. Although we cannot attribute these trends to global climate change, the examination of 30 members of the Community Earth System Model Large Ensemble (LENS) forced with the RCP8.5 radiative forcing scenario (1920–2100) suggests that significant anthropogenic trends in Pacific decadal variance will emerge by 2020 in response to a more energetic North Pacific Meridional Mode (PMM)—a well‐known El Niño precursor. The PMM is a key mechanism for energizing and coupling tropical and extratropical decadal variability. In the LENS, the increase in PMM variance is consistent with an intensification of the winds‐evaporation‐SST thermodynamic feedback that results from a warmer mean climate.