Abstract
Studies of the Madden-Julian Oscillation (MJO) have progressed considerably during the past decades in observations, numerical modeling, and theoretical understanding. Many theoretical attempts have been made to identify the most essential processes responsible for the existence of the MJO. Criteria are proposed to separate a hypothesis from a theory (based on the first principles with quantitative and testable assumptions, able to predict quantitatively the fundamental scales and eastward propagation of the MJO). Four MJO theories are selected to be summarized and compared in this article: the skeleton theory, moisture-mode theory, gravity-wave theory, and trio-interaction theory of the MJO. These four MJO theories are distinct from each other in their key assumptions, parameterized processes, and, particularly, selection mechanisms for the zonal spatial scale, time scale, and eastward propagation of the MJO. The comparison of the four theories and more recent development in MJO dynamical approaches lead to a realization that theoretical thinking of the MJO is diverse and understanding of MJO dynamics needs to be further advanced.
| Original language | English |
|---|---|
| Article number | e2019RG000685 |
| Journal | Reviews of Geophysics |
| Volume | 58 |
| Issue number | 3 |
| DOIs | |
| State | Published - Sep 1 2020 |
| Externally published | Yes |
Funding
The authors would like to thank Brandon Wolding and two anonymous reviewers for their candid and constructive comments on earlier versions of this manuscript. We also thank coauthors of the original papers on the theories, Daehyun Kim and Sam Stechmann, for their comments on the manuscript. Discussions with and comments from Eric Maloney, Adam Sobel, and Sulian Thual on various parts of this article are appreciated. This study was supported by the National Oceanic and Atmospheric Administration (NOAA) Grant NA15OAR4310099 and the National Science Foundation (NSF) Climate Dynamics Division Grants AGS‐1540783 to B. W.; by the NSF Climate Dynamics Division Grant AGS‐1841559 to Á. F. A.; by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, Climate and Environmental Sciences Division, Regional & Global Climate Modeling Program, under Award DE‐AC02‐05CH11231, the Laboratory Directed Research and Development (LDRD) funding from Berkeley Lab, provided by the Director, Office of Science, of the U.S. Department of Energy under Contract DE‐AC02‐05CH11231, a Packard Fellowship for Science and Engineering to D. Y.; and by NOAA Grant NA13OAR310161 and Office of Naval Research PISTON grant via Colorado State University to C. Z. This is PMEL Contribution 4789 (CZ).
Keywords
- Madden-Julian Oscillation
- gravity-wave model
- moisture-mode model
- skeleton model
- theory
- trio-interaction model