Bimodal ISO index

The tropical intraseasonal oscillation (ISO) shows distinct variability centers and propagation patterns between boreal winter and summer. To accurately represent the state of the ISO at any particular time of year, a bimodal ISO index was developed. It consists of Madden-Julian Oscillation (MJO) mode with predominant eastward propagation along the equator and Boreal Summer ISO (BSISO) mode with prominent northward propagation and large variability in off-equatorial monsoon trough regions.

For more information please refer to the Bimodal ISO index web page.


Kikuchi, K., B. Wang, and Y. Kajikawa, 2012: Bimodal representation of the tropical intraseasonal oscillation. Clim. Dyn., 38, 1989-2000, doi:10.1007/s00382-011-1159-1.

Kikuchi, K. and B. Wang, 2010: Formation of tropical cyclones in the northern Indian Ocean associated with two types of tropical intraseasonal oscillation modes. J. Meteor. Soc. Japan, 88, 475-496.

daily reconstructed olr anomalies of the mjo mode
daily reconstructed olr anomalies of the bsiso mode
Zonal 0 E to 357.5 E by 2.5 deg
Meridional -30 N to 30 N by 2.5 deg
Vertical N/A
Temporal historical: Mar 22, 1979 to Oct 22, 2013 by 1 day
realtime: Mar 22, 2002 to Present by 1 day
Volume 476 MB
Acquired Jul 24, 2014
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