Why Is Decadal Climate Variability Predominantly Observed in the Niño4 Region?
Journal
Geophysical Research Letters
Journal Volume
51
Journal Issue
17
ISSN
0094-8276
1944-8007
Date Issued
2024-09-05
Author(s)
Abstract
This study investigates why observed decadal-scale climate variability is predominantly pronounced in the Niño4 region compared to other equatorial Pacific areas using both observation and model sensitivity experiments. The initial shift to the negative phase of Tropical Pacific Decadal Variability (TPDV) is primarily driven by the upward and eastward migration of isopycnal negative temperature anomalies along the equator. Subsequently, the wind fields associated with the negative phase of the Pacific Meridional Mode (PMM) induce anomalous vertical currents in the equatorial Pacific. This leads to anomalous upwelling and downwelling of mean temperature in the Niño4 and Niño3 regions, respectively, thereby strengthening and weakening the corresponding subsurface-produced sea surface temperature anomalies. Our findings clarify the roles of subsurface temperature anomalies in the phase reversal of TPDV and PMM in amplifying decadal variance, specifically in the equatorial central Pacific.
Subjects
anomalous vertical advection
pacific meridional mode
subsurface temperature anomalies
TPDV phase transition
tropical pacific decadal variability
vertical heat advection
SDGs
Publisher
American Geophysical Union (AGU)
Type
journal article