North and South Pacific Meridional Modes contributions to ENSO and Tropical Decadal Variability
Abstract
North and South Pacific Meridional Modes (NPMM and SPMM) are known precursors of El Niño-Southern Oscillation (ENSO) and Tropical Pacific decadal variability (TPDV). However, the relative importance of these precursors and the timescale on which they impact the tropics, remains unclear. Using a 30-member ensemble of the Community Earth System Model as the control climate, we generate two additional members where the NPMM and SPMM are selectively suppressed. We find that both meridional modes energize the tropical variance independently on different timescales. The absence of NPMM leads to a significant reduction of the tropical interannual variability (~35%), while the absence of the SPMM has no appreciable impact on ENSO but significantly reduces the TPDV (~30%). While the relative importance of the NPMM and SPMM may be model dependent, the stochastic atmospheric variability in the extra-tropics that energizes the meridional modes emerges as a key source of TPDV.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A21M2746L
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 3339 Ocean/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 4513 Decadal ocean variability;
- OCEANOGRAPHY: PHYSICAL;
- 4522 ENSO;
- OCEANOGRAPHY: PHYSICAL