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BMRC is now part of CAWCR: The Centre for Australian Weather and Climate Research.
For more information on The Centre please go to http://www.cawcr.gov.au

An All-season Real-time Multivariate MJO Index

Using an objectively-defined index to monitor and predict the climate and weather variations related to the tropical Madden-Julian Oscillation (MJO)

Background on the MJO

The Index: RMM1 and RMM2

Based on the first two Empirical Orthogonal Functions (EOFs) of the combined fields of near-equatorially-averaged 850 hPa zonal wind, 200 hPa zonal wind, and satellite-observed outgoing longwave radiation (OLR) data. Projection of the daily observed data onto such multiple-variable EOFs, with the annual cycle and components of interannual variability removed, yields principal component (PC) time series that vary mostly on the intraseasonal time scale of the MJO only. This projection thus serves as an effective filter for the MJO without the need for time filtering, making the PC time series an effective index for real time use. We call the two PC time series that form the index the Real-time Multivariate MJO series 1 (RMM1), and RMM2. For the observations, the OLR data is that measured by the NOAA polar-orbitting satellites, while for the winds we use the NCEP/NCAR Reanalyses and the GASP analyses. The index is usually available in near real time about 12 hours after the end of each Greenwich day (i.e. at about 1200 UTC). For more details, see Wheeler and Hendon (2004).

Spatial structures of leading multivariate (combined) EOFs
Code for projecting model/observed data onto RMM EOFs
Phase Diagrams of RMM1 and RMM2 from Observations
- Latest 90 days, Latest 40 days, This time last year, With interannual part retained
- ARCHIVE
- Statistical forecast of RMM1/2 using methodology of Maharaj and Wheeler (2005).
Time-Longitude Plots of "Monitoring" Fields
- MJO-reconstructed fields
  OLR, 850 hPa U, 200hPa U, ( OLR and 850hPa U, OLR and 200hPa U )
- MJO-associated fields superimposed on daily anomaly fields
  OLR, 850 hPa U, 200hPa U, ( OLR and 850hPa U, OLR and 200hPa U )
- Summed plots of MJO and ENSO-associated anomalies
  OLR, 850 hPa U, 200hPa U, ( OLR and 850hPa U, OLR and 200hPa U )
- Summed plots of MJO, seasonal cycle, and ENSO-associated values
  OLR, 850 hPa U, 200hPa U, ( OLR and 850hPa U, OLR and 200hPa U )
Empirical Forecast Fields
(Based on seasonally-varying lagged linear regression with RMM1 and RMM2 as predictors, see Jiang et al. 2008.)
- Maps of MJO-associated anomalies
  OLR and 850hPa winds, 850 hPa winds (and OLR), 200 hPa winds (and OLR), 200 hPa Psi and Chi
- Maps of summed MJO and low-frequency anomalies
  OLR and 850hPa winds, 850 hPa winds (and OLR), 200 hPa winds (and OLR), 200 hPa Psi and Chi
- Maps of summed MJO anomalies, low-frequency component, and seasonal cycle
  OLR and 850hPa winds, 200 hPa Chi,
Text file of RMM1 and RMM2 values for 1974 to present, (RMM values with interannual part retained)
"First Guess" file, using more up-to-date winds only for an estimate of the current day
Time series of MJO variance/amplitude
Composites formed from the index

Related Sites

Created and maintained by Matthew Wheeler

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