Moisture Mode Theory’s Contribution to Advances in our Understanding of the Madden-Julian Oscillation and Other Tropical Disturbances

Adames, Ángel F.; Maloney, Eric D.

doi:10.1007/s40641-021-00172-4

Cited by 31 publications

(28 citation statements)

References 160 publications

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“…This means that the intraseasonal winds redistribute the mean moisture and create convective tendency at the MJO timescale. The association of mean moisture advection by MJO winds were confirmed by numerous studies[25][26][27][28][29][30][31][32][33][34][35][36] These studies point out that both the meridional (mainly southward) and zonal (mainly westward) advection of mean moisture ahead of the MJO convective center significantly contribute to the moisture (MSE) tendency. However, beyond the west Pacific, the meridional advection of mean moisture becomes dominant as the zonal advection reduces and often negatively contributes (due to dry air advection) to the column moisture tendency.…”

supporting

confidence: 58%

Madden Julian Oscillation moves faster as the meridional moisture gradient intensifies in a warming world

Dasgupta

Roxy

Prajeesh

et al. 2023

Preprint

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Madden Julian Oscillation (MJO), characterized by slow eastward moving (at an average speed of 5 m s-1) largescale cloud bands and associated circulations, is a dominant tropical phenomenon that impacts global weather and climate. Recent studies have reported significant changes in the MJO lifecycle during the post-satellite period (1979 onwards) due to the non-uniform tropical ocean warming. However, the relative roles of natural climate variability and anthropogenic impact in the observed MJO lifecycle change remain unclear and are yet to be determined. In this study, we investigate the observed and projected long-term changes in the MJO lifecycle during the 20th and 21st centuries using four 20th century reanalyses (NCEP-20CRV3, NCEP-20CRV2c, ERA-20C, and CERA-20C) and climate model simulations from the Coupled Model Intercomparison Project phase 6 (CMIP6) under different future emission scenarios. Here, we show for the first time a significant increase in the MJO phase speed by almost 1 m s-1 during the 20th century (1900–2014), potentially caused by the steepening of the meridional moisture distribution due to the increased moisture in the tropics compared to the extra-tropics. We also observe a prominent multidecadal variability of the MJO phase speed due to the changes in the zonal moisture distribution associated with the Pacific Decadal Oscillation (PDO). Future climate projections under shared socioeconomic pathways (SSPs) from CMIP6 indicate an increase in the MJO phase speed by 0.10 (SSP1—sustainable path, low emission scenario), 0.68 (SSP2—intermediate emissions) and 1.18 (SSP5—high emission scenario) m s-1 during the 21st century (2015–2100), in response to further steepening of the meridional moisture distribution over the Indo-Pacific warm pool. The increasing MJO phase speed can potentially impact the MJO-related teleconnections and predictability of global weather and climate, and hence need to be monitored closely.

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supporting

confidence: 58%

Madden Julian Oscillation moves faster as the meridional moisture gradient intensifies in a warming world

Dasgupta

Roxy

Prajeesh

et al. 2023

Preprint

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“…These recent results highlight the limitations of shallow water equatorial wave theory without prognostic moisture variations. Moisture mode theory (Á. F. Adames & Maloney, 2021; Jiang et al., 2020; A. H. Sobel et al., 2001) may be a more reasonable starting point to understand the dynamics of these waves.…”

Section: Discussionmentioning

confidence: 99%

“…Convectively coupled atmospheric waves are often viewed as an extension of dry waves but with a reduced static stability arising from the latent heat release in convection (Haertel & Kiladis, 2004; K. A. Emanuel et al., 1994). However, in recent years it has become clear that interactions between moisture, convection, radiation and circulation are important for the dynamics of convectively coupled waves, especially at the intraseasonal (∼10–100 days) time scale (Á. F. Adames & Kim, 2016; Á. F. Adames & Maloney, 2021; F. Ahmed, 2021; Gonzalez & Jiang, 2019; Raymond, 2001; A. Sobel & Maloney, 2013; A. H. Sobel et al., 2001; Wang & Sobel, 2021). These interactions can cause the dynamics of these waves to significantly differ from those described by dry shallow water theory.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, simple models of convectively coupled waves with prognostic moisture have revealed the existence of moisture modes, which do not exist in dry theory, and whose dynamics are governed by the evolution of moisture (F. Ahmed et al., 2021; Neelin & Yu, 1994; A. H. Sobel et al., 2001; Sugiyama, 2009). The primary signatures of moisture modes are strong moisture tendencies and weak temperature tendencies (Á. Adames et al., 2019; Á. F. Adames & Maloney, 2021; F. Ahmed et al., 2021). The former condition manifests as a tight coupling between moisture and precipitation.…”

Section: Introductionmentioning

confidence: 99%

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Westward‐Propagating Moisture Mode Over the Tropical Western Hemisphere

Mayta

Adames

Ahmed

2022

Geophysical Research Letters

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A westward‐propagating Rossby‐like wave signal is found to explain a large fraction of the intraseasonal variance in cloud brightness over the Western Hemisphere. A series of diagnostic criteria suggest that this wave is a moisture mode: its moisture anomalies dominate the distribution of moist static energy (MSE) and are in phase with the precipitation anomalies; and the thermodynamic equation obeys the weak temperature gradient approximation. The wave propagates westward due to zonal moisture advection by the mean flow and is maintained by radiative heating and meridional moisture advection. These properties compare favorably with the westward propagating Rossby mode in an equatorial beta‐plane model with prognostic moisture, mean meridional moisture gradient, and mean zonal wind. These results underscore the importance of water vapor in the dynamics of slowly evolving tropical systems, and the limitations of dry shallow water theory that rely on a “reduced equivalent depth” to represent moist dynamics.

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“…In terms of the generation, the moisture mode framework postulates that the MJO arises from a positive feedback in which an anomalously moist atmospheric column precipitates more, and the combined effect of anomalous radiative and surface fluxes and anomalous advection due to the resulting circulation further leads to an even moister column, resulting in a positive feedback loop. For a recent review on the moisture mode framework, see Adames and Maloney (2021).…”

mentioning

confidence: 99%

Dependence of Precipitation on Precipitable Water Vapor Over the Maritime Continent and Implications to the Madden‐Julian Oscillation

Chen

Wong

et al. 2021

Geophysical Research Letters

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The Madden-Julian Oscillation (MJO) is the dominant component of the intraseasonal (30-90 days) variability in the tropical atmosphere (Madden & Julian, 1971, 1972. In a typical MJO event, a convectively active envelope of precipitation develops over the western Indian Ocean and slowly propagates eastward along equator to the Pacific Ocean. Over the past decades, there have been extensive studies into both the mechanisms of the MJO and its interaction with the extratropical weather, and other large-scale modes of variability (e.g., the Asian monsoon, the El Nino-Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), etc.,) (e.g.,

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Moisture Mode Theory’s Contribution to Advances in our Understanding of the Madden-Julian Oscillation and Other Tropical Disturbances

Cited by 31 publications

References 160 publications

Madden Julian Oscillation moves faster as the meridional moisture gradient intensifies in a warming world

Madden Julian Oscillation moves faster as the meridional moisture gradient intensifies in a warming world

Westward‐Propagating Moisture Mode Over the Tropical Western Hemisphere

Dependence of Precipitation on Precipitable Water Vapor Over the Maritime Continent and Implications to the Madden‐Julian Oscillation

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