Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

Tropical Pacific Decadal Variability and ENSO Precursor in CMIP5 Models

TitleTropical Pacific Decadal Variability and ENSO Precursor in CMIP5 Models
Publication TypeJournal Article
Year of Publication2020
AuthorsZhao, Yingying, Di Lorenzo Emanuele, Newman Matthew, Stevenson Samantha, and Van Roekel Luke
JournalJournal of Climate
Pages1
Abstract / Summary

Observational analyses suggest that a significant fraction of the Tropical Pacific Decadal Variability (TPDV) (∼60%-70%) is energized by the combined action of extra-tropical precursors of the El Niño Southern Oscillation (ENSO) originating from the North and South Pacific. Specifically, the growth and decay of the basin-scale TPDV pattern (∼timescale=1.5-2 years) is linked to the sequence: ENSO precursors (extra-tropics, growth phase) → ENSO (tropics, peak phase) → ENSO successors (extra-tropics, decay phase) resulting from ENSO teleconnections. This sequence of teleconnections is an important physical basis for Pacific climate predictability. Here we examine the TPDV and its connection to extra-tropical dynamics in 20 models from phase 5 of the Coupled Model Intercomparison Project (CMIP). We find that most models (∼80%) can simulate the observed spatial pattern (R>0.6) and frequency characteristics of the TPDV. In 12 models, more than 65% of the basin-wide Pacific Decadal Variability (PDV) originates from TPDV, which is comparable with observations (∼70%). However, despite reproducing the basic spatial and temporal statistics, models underestimate the influence of the North and South Pacific ENSO precursors to the TPDV, and most of the models’ TPDV originates in the tropics. Only 35%-40% of the models reproduce the observed extra-tropical ENSO precursor patterns (R>0.5). Models with a better representation of the ENSO precursors show (1) better basin-scale signatures of TPDV, and (2) stronger ENSO teleconnection from/to the tropics that are consistent with observations. These results suggest that better representation of ENSO precursor dynamics in CMIP may lead to improved Pacific decadal variability dynamics and predictability.

URLhttps://doi.org/10.1175/JCLI-D-20-0158.1
DOI10.1175/JCLI-D-20-0158.1
Journal: Journal of Climate
Year of Publication: 2020
Pages: 1
Publication Date: 11/2020

Observational analyses suggest that a significant fraction of the Tropical Pacific Decadal Variability (TPDV) (∼60%-70%) is energized by the combined action of extra-tropical precursors of the El Niño Southern Oscillation (ENSO) originating from the North and South Pacific. Specifically, the growth and decay of the basin-scale TPDV pattern (∼timescale=1.5-2 years) is linked to the sequence: ENSO precursors (extra-tropics, growth phase) → ENSO (tropics, peak phase) → ENSO successors (extra-tropics, decay phase) resulting from ENSO teleconnections. This sequence of teleconnections is an important physical basis for Pacific climate predictability. Here we examine the TPDV and its connection to extra-tropical dynamics in 20 models from phase 5 of the Coupled Model Intercomparison Project (CMIP). We find that most models (∼80%) can simulate the observed spatial pattern (R>0.6) and frequency characteristics of the TPDV. In 12 models, more than 65% of the basin-wide Pacific Decadal Variability (PDV) originates from TPDV, which is comparable with observations (∼70%). However, despite reproducing the basic spatial and temporal statistics, models underestimate the influence of the North and South Pacific ENSO precursors to the TPDV, and most of the models’ TPDV originates in the tropics. Only 35%-40% of the models reproduce the observed extra-tropical ENSO precursor patterns (R>0.5). Models with a better representation of the ENSO precursors show (1) better basin-scale signatures of TPDV, and (2) stronger ENSO teleconnection from/to the tropics that are consistent with observations. These results suggest that better representation of ENSO precursor dynamics in CMIP may lead to improved Pacific decadal variability dynamics and predictability.

DOI: 10.1175/JCLI-D-20-0158.1
Citation:
Zhao, Y, E Di Lorenzo, M Newman, S Stevenson, and L Van Roekel.  2020.  "Tropical Pacific Decadal Variability and ENSO Precursor in CMIP5 Models."  Journal of Climate 1.  https://doi.org/10.1175/JCLI-D-20-0158.1.