The potential impacts of improved MJO prediction on the prediction of MJO teleconnections in the UFS global fully coupled model

September 8, 2025

A new paper entitled “The potential impacts of improved MJO prediction on the prediction of MJO teleconnections in the UFS global fully coupled model” was recently published in Climate Dynamics by CW3E researcher Jiabao Wang, Daniela I. V. Domeisen (University of Lausanne and ETH Zurich, Switzerland), Chaim Garfinkel (Hebrew University of Jerusalem, Israel), Andrea Jenney (Oregon State University), Hyemi Kim (Ewha Womans University, Korea), Zheng Wu (University of Albany), Cheng Zheng (Stony Brook University), and Cristiana Stan (George Mason University). This research, supported by the California Department of Water Resources and NOAA/OAR Weather Program Office, investigates the value of Madden-Julian oscillation (MJO) prediction for extratropical subseasonal forecasts by examining the extent to which reliable MJO simulation translates to reliable simulation of its teleconnections. This work supports the Advanced Precipitation and Streamflow Prediction priority in CW3E’s 2025-2029 Strategic Plan by advancing understanding of “forecasts of opportunity” where sub-seasonal prediction skill can be improved.

This study examines the prediction of the MJO and its teleconnections in two NOAA Unified Forecast System (UFS) coupled model prototypes: Prototype 7 (UFS7) and Prototype 8 (UFS8). These are the prototypes for the development of a fully coupled atmosphere-ocean-sea ice-wave-aerosol model, which will be implemented in the next generation of NOAA operational forecast systems. They share some common standard features in terms of the dynamical core, resolution, and coupling. UFS8 has additional coupling with aerosols and upgraded model physics. Results show that the MJO is skillfully predicted at a lead time of 27 days in UFS8, which is a considerable improvement (~ one-week skill increase) compared to UFS7 (Fig. 1). The MJO eastward propagation is also better captured in UFS8 with the amplitude of convection and wind anomalies closer to reanalysis and more realistic easterly winds to the east of the active convection center. For its teleconnections, a more realistic prediction of the pattern and amplitude of the geopotential height response and its evolution following active MJO events is observed in UFS8 (Fig. 2). Both UFS7 and UFS8 reproduce the PNA pattern in Week 1 with a pattern correlation greater than 0.95. However, starting in Week 2, a large difference emerges between the two prototypes. While UFS7 has large biases such as a notably weaker response over North America, UFS8 is able to capture the evolution of the PNA such as a southeastward extension of the trough towards the North American West Coast. The Week 4 PNA pattern is difficult to predict for both prototypes, but it is generally better predicted in UFS8. Note that this systematic improvement in UFS8 is not observed in weak MJO cases, suggesting that the enhanced performance is more due to improved MJO predictions and subsequent excitation of poleward-propagating Rossby waves, rather than reduced growth of biases from the atmospheric initial conditions.

The effect of the enhanced MJO prediction skill on MJO teleconnection prediction via other tropospheric and stratospheric pathways is also examined. The results show that the dipole response in the storm tracks over the North Pacific, the upward wave propagation, and the subsequent weakening of the polar vortex are better simulated in UFS8. These prototypes, however, still struggle to predict the downstream impacts in the North Atlantic and Europe, and the precipitation and temperature responses.

This study suggests that the potential for increasing the MJO teleconnection prediction skill, although not in all variables, lies in improving MJO predictions in dynamical models with more coupled components and upgraded model physics. The results better address the importance of enhancing the understanding and prediction of MJO, the dominant source of subseasonal prediction, which has potential value to stakeholders, including water resource managers.

Figure 1. a–c Longitude-time composites of outgoing longwave radiation (OLR; shading; W m^-2) and 850-hPa zonal wind (U850; contours; interval 0.3 m s^-1) anomalies averaged over 15° S–15° N for active MJO events in reanalysis, UFS7, and UFS8, respectively. The results are for events initialized during MJO phases 2 and 3. The vertical lines indicate 120°E (approximately the center of the Maritime Continent). A 5-day moving average is applied. d MJO prediction skill for UFS7 and UFS8 reforecasts initialized with active MJO events. The prediction skill is evaluated based on ACC (solid lines) and RMSE (dashed lines) between the model and reanalysis RMM indices. The gray solid horizontal line indicates an ACC of 0.5. Figure 1 from Wang et al. (2025).

Figure 2. Weekly averaged phase composites of 500-hPa geopotential height anomalies (Z500a) after MJO phases 2 and 3 for the lead times from week 1 to week 4 in a–d reanalysis, e–h UFS7, and i–l UFS8. The dotted areas indicate the significance at the 0.05 level. The numbers in the upper right corner of each plot indicate the spatial correlation between the model and reanalysis over the region. Figure 3 from Wang et al. (2025).

Wang, J., Domeisen, D. I. V., Garfinkel, C. I., Jenney, A. M., Kim, H., Wu, Z., Zheng, C., & Stan, C. (2025). The potential impacts of improved MJO prediction on the prediction of MJO teleconnections in the UFS global fully coupled model. Climate Dynamics, 63, 312. https://doi.org/10.1007/s00382-025-07783-9