Strengthened causal connections between the MJO and the North Atlantic with climate warming

Abstract

The Madden-Julian oscillation (MJO) has long been identified as an important source of midlatitude weather predictability on subseasonal-to-seasonal (S2S) timescales (∼2 weeks to 3 months) via its teleconnections to higher latitudes. Tropical convection associated with the MJO slowly propagates eastward in a quasiperiodic manner, taking ∼20-90 days to circumnavigate the globe and complete a cycle (Madden & Julian, 1971, 1972; Zhang, 2013). MJO activity can excite Rossby waves which propagate out of the tropics and into the midlatitudes, modifying the large-scale circulation and weather patterns. Because it can take 10-15 days for the teleconnection to reach the midlatitudes, knowing the state of the MJO today can provide information about the evolution of the midlatitude flow in the coming weeks. In fact, multiple studies have demonstrated that the MJO can be used to make skillful forecasts of weather up to 5 weeks in advance across the

Quantifying the Effect of Climate Change on Midlatitude Subseasonal Prediction Skill Provided by the Tropics

“…This suggests that seasonal variability is playing a role in subseasonal prediction skill changes in this region, however, there is also likely a contribution from subseasonal variability to these changes. This is consistent with research that suggests the North Atlantic may become more sensitive to MJO teleconnections in the future (Samarasinghe et al., 2021).…”

“…In addition, our results suggest there is a contribution from both subseasonal and seasonal variability changes to the increase in prediction skill in the North Atlantic. This is consistent with research suggesting the North Atlantic becomes more sensitive to the MJO (Samarasinghe et al., 2021) and ENSO (Drouard & Cassou, 2019; Fereday et al., 2020) in the future. We also identify a substantial decrease in skill over the North Pacific and from our analysis, hypothesize that this decrease is mainly driven by a reduced influence of ENSO teleconnections to this region in the future.…”

“…Zhou et al., 2014) and the MJO (J. Wang et al., 2022; Wolding et al., 2017; W. Zhou et al., 2020) are projected to shift eastward in a warmer climate in a variety of climate models, including CESM2 (Fredriksen et al., 2020; J. Wang et al., 2022). In the North Atlantic, increased skill is also consistent with research suggesting that the North Atlantic may become more sensitive to MJO teleconnections (Samarasinghe et al., 2021) and that the ENSO‐North Atlantic Oscillation (NAO) teleconnection may strengthen (Drouard & Cassou, 2019; Fereday et al., 2020) in the future. The decrease in skill over the North Pacific is also consistent with recent research using a variety of CMIP6 models that suggests the ENSO teleconnection amplitude over the North Pacific may weaken in a warmer climate (e.g., Beverley et al., 2021; Fredriksen et al., 2020).…”

“…However, with the climate continuously warming, it is unclear how transferable this knowledge will be to a future, warmer climate. Therefore, research on subseasonal timescales has examined how the MJO (Maloney et al., 2018) and ENSO (Cai et al., 2021) will change in the future as well as the subsequent changes to their teleconnections (e.g., Beverley et al., 2021; Cui & Li, 2021; Drouard & Cassou, 2019; Fereday et al., 2020; Samarasinghe et al., 2021; W. Zhou et al., 2020; Meehl et al., 2007; Z.‐Q. Zhou et al., 2014).…”

Projected Future Changes in The Equatorial Wave Spectrum in CMIP6

“…(Chang et al, 2015;Bui and Maloney, 2019;Raghavendra et al, 2019;Maloney et al, 2019). Furthermore, by the end of the century the MJO might have less influence on extratropical phenomena in some regions (Bui and Maloney, 2019;Chang et al, 2015), but a stronger influence in others (Samarasinghe et al, 2021).…”