Global‐scale convective aggregation: Implications for the Madden‐Julian Oscillation

By N. Arnold, David A. Randall. 2015

160 citations recorded by the source corpus.

Previous work has shown that convection will self‐organize in cloud‐system‐resolving model simulations of radiative‐convective equilibrium, and it has been suggested that the convective envelope of the Madden‐Julian oscillation (MJO) may be organized by similar processes on a much larger scale. Here we present support for that hypothesis based on simulations with SP‐CAM with globally uniform SST. Without rotation, convection self‐organizes into large (∼4000 km) clusters surrounded by dry regions, while with Earth‐like rotation the model produces a robust MJO. The nonrotating aggregation and MJO are found to have similar budgets of moist static energy, both being supported by diabatic feedbacks, particularly cloud‐longwave interaction. Mechanism denial experiments show that longwave heating anomalies associated with high clouds are essential to the nonrotating aggregation, and amplify the MJO. Simulations using the conventional CAM show a weaker MJO and a much weaker tendency for nonrotating aggregation, and both MJO activity and aggregation intensity are found to increase with the entrainment rate in the deep convection parameterization.

Subfields: Atmospheric Science, Global and Planetary Change, Plant Science

View Paper: https://www.semanticscholar.org/paper/ab23891cb3beede45afdb0a742f4ae7686d1fc09

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In Atmospheric Science

1. Sandrine Bony
2. A. Wing
3. Kerry A. Emanuel
4. D. Coppin
5. C. Muller
6. E. Maloney
7. C. DeMott
8. N. Klingaman

In Global and Planetary Change

1. Sandrine Bony
2. A. Wing
3. Kerry A. Emanuel
4. D. Coppin
5. C. Muller
6. E. Maloney
7. C. DeMott
8. N. Klingaman

In Plant Science

1. C. Muller
2. C. Holloway
3. Kerry A. Emanuel
4. A. Wing

Citations in the corpus

• The MJO as a Dispersive, Convectively Coupled Moisture Wave: Theory and Observations (2016, unknown): “Such a result would be in agreement with results from Bretherton et al. (2005) and Arnold and Randall (2016), who found that longwave radiative feedbacks in association with upper-level clouds are responsible for large-scale self-aggregation of convection.”
• Convective Self-Aggregation in Numerical Simulations: A Review (2017, methodology): “…et al, 2005; Muller and Held, 2012; Posselt et al, 2012; Wing and Emanuel, 2014; Emanuel et al, 2014; Muller and Bony, 2015; Coppin and Bony, 2015; Arnold and Randall, 2015; Wing and Cronin, 2016; Holloway and Woolnough, 2016), shortwave radiation (Wing and Emanuel, 2014; Wing and Cronin, 2016),…”
• Fifty Years of Research on the Madden‐Julian Oscillation: Recent Progress, Challenges, and Perspectives (2020, background): “38 of 64 climate models is for the increased SST and stronger lower tropospheric vertical moisture gradient associated with climate warming to result in increased MJO precipitation variance (e.g., Arnold et al., 2015; Bui & Maloney, 2018; Haertel, 2018; Rushley et al., 2019; Takahashi et al., 2011; ”
• Could Machine Learning Break the Convection Parameterization Deadlock? (2018, background): “…predicting the response of clouds and precipitation to global warming, as well as modes of climate variability [ Jeevanjee and Romps , 2013; Wing and Emanuel , 2014; Arnold and Randall , 2015; Bony et al. , 2015; Bretherton and Khairoutdinov , 2015; Coppin and Bony , 2015; Muller and Bony , 2015].”
• Physical mechanisms controlling the initiation of convective self‐aggregation in a General Circulation Model (2015, background): “…organization of convection tends to promote the development of large-scale ascents [Tobin et al., 2013], and by a numerical study showing that MJO and self-aggregation exhibit similar budgets of moist static energy (MSE) and are supported by the same diabatic feedbacks [Arnold and Randall, 2015].”