A modified seasonal cycle during MIS31 super-interglacial favors stronger interannual ENSO and monsoon variability
<p>It has long been recognized that the amplitude of the seasonal cycle can substantially modify climate features in distinct timescales. This study evaluates the impact of the enhanced seasonality characteristic of the Marine Isotope Stage 31 (MIS31) on the El Niño–Southern Oscillation (ENSO)...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-04-01
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| Series: | Climate of the Past |
| Online Access: | https://www.clim-past.net/15/735/2019/cp-15-735-2019.pdf |
| Summary: | <p>It has long been recognized that the amplitude of the seasonal cycle can
substantially modify climate features in distinct timescales. This study
evaluates the impact of the enhanced seasonality characteristic of the Marine
Isotope Stage 31 (MIS31) on the El Niño–Southern Oscillation (ENSO). Based
upon coupled climate simulations driven by present-day
(CTR) and MIS31 boundary
conditions, we demonstrate that the CTR simulation shows a significant
concentration of power in the 3–7-year band and on the multidecadal
timescale between 15 and 30 years. However, the MIS31 simulation shows
drastically modified temporal variability of the ENSO, with stronger power
spectrum at interannual timescales but the absence of decadal periodicity.
Increased meridional gradient of sea surface temperature (SST) and wind
stress in the Northern Hemisphere subtropics are revealed to be the primary
candidates responsible for changes in the equatorial variability. The oceanic
response to the MIS31 ENSO extends to the extratropics, and fits nicely with
SST anomalies delivered by paleoreconstructions. The implementation of the
MIS31 conditions results in a distinct global monsoon system and its link to
the ENSO in respect to current conditions. In particular, the Indian monsoon
intensified but no correlation with ENSO is found in the MIS31 climate,
diverging from conditions delivered by our current climate in which this
monsoon is significantly correlated with the NIÑO34 index. This indicates
that monsoonal precipitation for this interglacial is more closely connected
to hemispherical features than to the tropical–extratropical climate
interaction.</p> |
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| ISSN: | 1814-9324 1814-9332 |