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.

Reprint (pdf)