CICS-NC: RMM (Real-time Multivariate MJO) Index
Wheeler and Hendon (2004) constructed the RMM index for monitoring the MJO. This index consists of the first two principal components (PCs) of OLR, 850-hPa zonal wind, and 200-hPa zonal wind averaged 15S-15N.
This page takes that simple index and breaks it down into its components, either by variable, longitude, or latitude. In each case, the original RMM emperical orthogonal functions (EOFs) are used, but only a subset of the data is projected onto them. All of these plots are re-standardized based on their 1980-2010 time series. This step is necessary for comparison because the OLR PCs, for example, have significantly lower amplitudes.
The Hovmöllers show longitude-time plots for OLR, U-850, and U-200. The shading indicates the observed anomalies, while the contours are the projection of those anomalies onto the RMM EOFs.
|Summary of all modes|
|Original: The original Wheeler-Hendon (2004) methodology of subtracting the 120-day running mean||Total||Components by Variable|
|Total: As above, but retaining the interannual (120-day) signal||Total||Components by Variable|
|MJO: MJO-filtered OLR, U-850, and U-200 projected onto the original Wheeler-Hendon EOFs||Total||Components by Variable|
|Low: Lowpss-filtered (> 120 days) OLR, U-850, and U-200 projected onto the original Wheeler-Hendon EOFs||Total||Components by Variable|
|ER: OLR, U-850, and U-200 filtered for Equatorial Rossby (ER) waves and projected onto the original Wheeler-Hendon EOFs||Total||Components by Variable|
|Kelvin: OLR, U-850, and U-200 filtered for Kelvin waves and projected onto the original Wheeler-Hendon EOFs||Total||Components by Variable|
|Total RMM||40 days||90 days|
|RMM by variable||40 days||90 days|
|RMM by latitude||40 days||90 days|
|RMM by longitude||40 days||90 days|
|RMM of 120-day running average||120 days||240 days|
|Hovmöller with 120-day mean removed||40 days||90 days|
|Hovmöller of 120-day running mean||90 days||180 days|
DISCLAIMER: Please note these pages present experimental analyses developed by researchers at CICS-NC and/or of interest to the CICS-NC community and their collaborators. These analyses are subject to change as our understanding of the Earth’s climate system improves and/or our interests change. There is no guarantee on their future availability.