Subramanian, A., M. Jochum, A. J. Miller, R. Neale, H. Seo, D. Waliser and R. Murtugudde, 2014:
The MJO and global warming: A study in CCSM4
Climate Dynamics, 42, 2019-2031.
Abstract.
The change in MJO amplitude and variance in response to anthropegenic
climate change is assessed in the 1deg nominal resolution CCSM4, which
has a reasonable representation of the MJO characteristics both dynamically and
statistically. The 20th century CCSM4 run is compared with the warmest 21st century
projection (Representative Concentration Pathway 8.5, or RCP8.5). The last
20 years of each simulation are compared in their MJO characteristics, including
spatial variance distributions of winds, precipitation and OLR, histograms of event
amplitude, phase and duration, and composite maps of phases. The RCP8.5 run
exhibits increased variance in intraseasonal precipitation, larger-amplitude MJO
events, stronger MJO rainfall in the central and eastern tropical Pacific, and a
greater frequency of MJO occurrence for phases corresponding to enhanced rain
fall in the Indian Ocean sector. These features are consistent with the concept
of an increased magnitude for the hydrological cycle under greenhouse warming
conditions. Conversely, the number of active MJO days decreases and fewer weak
MJO events occur in the future climate state. These results motivate further study
of these changes since tropical rainfall variability plays such an important role in
the region's socio-economic well being.
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