The Nature of the Stochastic Wind Forcing of ENSO

Capotondi, Antonietta; Sardeshmukh, Prashant D.; Ricciardulli, Lucrezia

doi:10.1175/jcli-d-17-0842.1

i

The Nature of the Stochastic Wind Forcing of ENSO

2018
By Capotondi, Antonietta ; Sardeshmukh, Prashant D. ; Ricciardulli, Lucrezia

Details

Journal Title:

Journal of Climate
Personal Author:

Capotondi, Antonietta ; Sardeshmukh, Prashant D. ; Ricciardulli, Lucrezia
NOAA Program & Office:

OAR (Oceanic and Atmospheric Research) ; CIRES (Cooperative Institute for Research in Environmental Sciences)
Description:

El Nino-Southern Oscillation (ENSO) is commonly viewed as a low-frequency tropical mode of coupled atmosphere-ocean variability energized by stochastic wind forcing. Despite many studies, however, the nature of this broadband stochastic forcing and the relative roles of its high- and low-frequency components in ENSO development remain unclear. In one view, the high-frequency forcing associated with the subseasonal Madden-Julian oscillation (MJO) and westerly wind events (WWEs) excites oceanic Kelvin waves leading to ENSO. An alternative view emphasizes the role of the low-frequency stochastic wind components in directly forcing the low-frequency ENSO modes. These apparently distinct roles of the wind forcing are clarified here using a recently released high-resolution wind dataset for 1990-2015. A spectral analysis shows that although the high-frequency winds do excite high-frequency Kelvin waves, they are much weaker than their interannual counterparts and are a minor contributor to ENSO development. The analysis also suggests that WWEs should be viewed more as short-correlation events with a flat spectrum at low frequencies that can efficiently excite ENSO modes than as strictly high-frequency events that would be highly inefficient in this regard. Interestingly, the low-frequency power of the rapid wind forcing is found to be higher during El Nino than La Nina events, suggesting a role also for state-dependent (i.e., multiplicative) noise forcing in ENSO dynamics.
Source:

Journal of Climate, 31(19), 8081-8099.
DOI:

https://doi.org/10.1175/jcli-d-17-0842.1
Document Type:

Journal Article
Rights Information:

Other
Compliance:

Submitted
Main Document Checksum:

urn:sha256:865307046c2192f3b9bd5a6f9c28fb754ac995162a335580acb1aa179496acae
Download URL:

https://repository.library.noaa.gov/view/noaa/20974/noaa_20974_DS1.pdf
File Type:

[PDF - 4.52 MB ]

Evolution of the Global Coupled Climate Response to Arctic Sea Ice Loss during 1990-2090 and Its Contribution to Climate Change

The role of transient Arctic sea ice loss in the projected greenhouse gas-induced late-twentieth- to late-twenty-first-century climate change is inves ...

Sun, Lantao ;

Alexander, Michael
Diminishing Arctic Sea Ice Promotes Stronger Surface Wind

Projections of Arctic sea ice through the end of the twenty-first century indicate the likelihood of a strong reduction in ice area and thickness in a ...

Mioduszewski, John

;

Vavrus, Stephen

ON THIS PAGE

Details Related Documents

The NOAA IR serves as an archival repository of NOAA-published products including scientific findings, journal articles, guidelines, recommendations, or other information authored or co-authored by NOAA or funded partners. As a repository, the NOAA IR retains documents in their original published format to ensure public access to scientific information.