Research > Metrics > Madden-Julian Oscillation (MJO)

Madden-Julian Oscillation (MJO)

These results are based on the work of Ahn et al. (2017). Implementation of the MJO analysis into the PMP is part of a PCMDI collaboration with Prof. Daehyun Kim (University of Washington), his group, and the WGNE MJO Task Force.

The MJO consists of large-scale regions of enhanced and suppressed convection, and associated circulation anomalies in the tropics that propagate eastward, mainly over the eastern hemisphere, with a time scale of ~30-60 days (Madden and Julian 1971, 1972, 1994). Its large-scale nature and period are easily seen via frequency-wavenumber decomposition of near-equatorial data (10°S to 10°N), which partitions the raw anomalies into eastward and westward propagating components and also as a function of frequency (cycles/day). The frequency-wavenumber decomposition technique has been widely used to assess if models properly represent this basic characteristic of the MJO (e.g., CLIVAR MJO Working Group 2009; Kim et al. 2009; Ahn et al. 2017).

Here we apply the frequency-wavenumber decomposition method to precipitation from observations (GPCP-based; 1997-2010) and the CMIP5 and CMIP6 Historical simulations for 1985-2004. For disturbances with wavenumbers 1-3 and frequencies corresponding to 30-60 days it is clear in observations that the eastward propagating signal dominates over its westward propagating counterpart. Thus, an important metric is the eastward/westward power ratio (EWR) for the above-mentioned wavenumbers and frequencies, which is about 2.5 in observations.

Summary statistics in Interactive Bar Charts

General Results


Ahn, M.-S., D. Kim, K. R. Sperber, I.-S. Kang, E. Maloney, D. Waliser, H. Hendon, 2017: MJO simulation in CMIP5 climate models: MJO skill metrics and process-oriented diagnosis. Clim. Dynam., 49, 4023-4045. doi: 10.1007/s00382-017-3558-4.

CLIVAR Madden-Julian Oscillation Working Group (Waliser, D., K. Sperber, H. Hendon, D. Kim, E. Maloney, M. Wheeler, K. Weickmann,, C. Zhang, L. Donner, J. Gottschalck, W. Higgins, I.-S. Kang, D. Legler, M. Moncrieff, S. Schubert, W. Stern, F. Vitart, B. Wang, W. Wang, and S. Woolnough), 2009: MJO simulation diagnostics. J. Clim., 22, 3006-3029. doi: 10.1175/2008JCLI2731.1.

Kim, D., K. R. Sperber, W. S. Stern, D. Waliser, I.-S. Kang, E. Maloney, W. Wang, K. Weickmann, J. Benedict, M. Khairoutdinov, M.-I. Lee, R. Neale, M. Suarez, K. Thayer-Calder, and G. Zhang, 2009: Application of MJO simulation diagnostics to climate models. J. Clim., 22, 6413-6436. doi: 10.1175/2009JCLI3063.1.

Madden, R. A., and P. R. Julian, 1971: Detection of a 40–50 day oscillation in the zonal wind in the tropical Pacific. J. Atmos. Sci., 28, 702–708. doi: 10.1175/1520-0469(1971)028<0702:DOADOI>2.0.CO;2

Madden, R. A., and P. R. Julian, 1972: Description of global-scale circulation cells in the tropics with a 40–50 day period. J. Atmos. Sci., 29, 1109–1123. doi: 10.1175/1520-0469(1972)029<1109:DOGSCC>2.0.CO;2

Madden, R. A., and P. R. Julian, 1994: Observations of the 40–50-day tropical oscillation—A review. Mon. Wea. Rev., 122, 814–837. doi: 10.1175/1520-0493(1994)122<0814:OOTDTO>2.0.CO;2