On scale interactions between the MJO and synoptic scale

Dubey, S.; Krishnamurti, T. N.; Kumar, Vinay

doi:10.1002/qj.3400

Cited by 6 publications

(5 citation statements)

References 85 publications

(146 reference statements)

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“…Instead, low‐level moisture is observed to slightly lead precipitation (~30° shift in phasing) (G. Chen & Wang, 2017). The literature is also divided on the role of upscale interactions in the MJO, with some studies suggesting that the MJO's momentum generation occurs at the planetary, intraseasonal scale (Dubey et al, 2018; L. Zhou, Neale, et al, 2012), while others suggest it comes from the synoptic and mesoscale (Khouider et al, 2012; Q. Yang et al, 2019).…”

Section: Recent Progress In Understanding Modeling and Predicting Tmentioning

confidence: 99%

Fifty Years of Research on the Madden‐Julian Oscillation: Recent Progress, Challenges, and Perspectives

et al. 2020

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Since its discovery in the early 1970s, the crucial role of the Madden‐Julian Oscillation (MJO) in the global hydrological cycle and its tremendous influence on high‐impact climate and weather extremes have been well recognized. The MJO also serves as a primary source of predictability for global Earth system variability on subseasonal time scales. The MJO remains poorly represented in our state‐of‐the‐art climate and weather forecasting models, however. Moreover, despite the advances made in recent decades, theories for the MJO still disagree at a fundamental level. The problems of understanding and modeling the MJO have attracted significant interest from the research community. As a part of the AGU's Centennial collection, this article provides a review of recent progress, particularly over the last decade, in observational, modeling, and theoretical study of the MJO. A brief outlook for near‐future MJO research directions is also provided.

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Section: Recent Progress In Understanding Modeling and Predicting Tmentioning

confidence: 99%

Fifty Years of Research on the Madden‐Julian Oscillation: Recent Progress, Challenges, and Perspectives

et al. 2020

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“…6f). More detailed processes of advection can be unveiled by decomposing all variables into three scales (Maloney 2009;Zhou et al 2012b;Dubey et al 2018): the background state (obtained with a 100-day low-pass filter; denoted with a bar), the intraseasonal anomaly (obtained with a bandpass filter between 20-100 days; denoted with a prime), and the high-frequency component (obtained with a 20-day high-pass filter; denoted with a double prime). For example, the specific humidity is decomposed as q 5 q 1 q 0 1 q 00 .…”

Section: B Meridional Transport Across the Equatormentioning

confidence: 99%

Impacts of Detoured Madden-Julian Oscillations on the South Pacific Convergence Zone

2021

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Madden-Julian Oscillations (MJOs) are a major component of tropical intraseasonal variabilities. There are two paths for MJOs across the Maritime Continent; one is a detoured route into the Southern Hemisphere and the other one is around the equator across the Maritime Continent. Here, it is shown that the detoured and non-detoured MJOs have significantly different impacts on the South Pacific convergence zone (SPCZ). The detoured MJOs trigger strong cross-equatorial meridional winds from the Northern Hemisphere into the Southern Hemisphere. The associated meridional moisture and energy transports due to the background states carried by the intraseasonal meridional winds are favorable for reinforcing the SPCZ. In contrast, the influences of non-detoured MJOs on either hemisphere or the meridional transports across the equator are much weaker. The detoured MJOs can extend their impacts to the surrounding regions by shedding Rossby waves. Due to different background vorticity during detoured MJOs in boreal winter, more ray paths of Rossby waves traverse the Maritime Continent connecting the southern Pacific Ocean and the eastern Indian Ocean, but far fewer Rossby wave paths traverse Australia. Further studies on such processes are expected to contribute to a better understanding of extreme climate and natural disasters on the rim of the southern Pacific and Indian Oceans.

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“…Saltzman (1957) laid the foundation for this framework to study global energetics and used a spherical coordinate system. Subsequently, studies such as Dubey et al (2018) have used the same to study the energy exchanges between synoptic-scale zonally averaged flows and associated waves (e.g., the Madden-Julian Oscillation). Krishnamurti et al (2005) retailored Saltzman's equations for a TC, by casting the system of equations in a storm-centric, cylindrical coordinate system thereby enabling the study of azimuthal asymmetries.…”

Section: Scale Interactionsmentioning

confidence: 99%

Characterizing the Energetics of Vortex-Scale and Sub-Vortex-Scale Asymmetries during Tropical Cyclone Rapid Intensity Changes

Bhalachandran

Chavas

Marks

et al. 2020

Journal of the Atmospheric Sciences

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Our collective understanding of azimuthally-asymmetric features within the coherent structure of a tropical cyclone (TC) continues to improve with the availability of more detailed observations and high-resolution model outputs. However, a precise understanding of how these asymmetries impact TC intensity changes is lacking. Prior attempts at investigating the asymmetric impacts follow a mean-eddy partitioning that condenses the effect of all the asymmetries into one term and fails to highlight the differences in the role of asymmetries at different scales. In this study, we present a novel energetics-based approach to analyze the asymmetric impacts at multiple lengthscales during periods of TC rapid intensity changes. Using model outputs of TCs under low and high shear, we compute the different energy pathways that enhance/suppress the growth of multiscale asymmetries in the wavenumber (WN) domain. We then compare and contrast the energetics of the mean flow field (WN 0) with that of the persistent, coherent vortex-scale asymmetric structures (WNs 1,2) and the more local, transient, sub-vortex-scale asymmetries (WNs ≥ 3). We find in our case-studies that the dominant mechanisms of growth/decay of the asymmetries are the baroclinic conversion from available potential to kinetic energy at individual scales of asymmetries, and the transactions of kinetic energy between the asymmetries of various length-scales; rather than the barotropic mean-eddy transactions as is typically assumed. Our case-study analysis further shows that the growth/decay of asymmetries is largely independent of the mean. Certain aspects of eddy energetics can potentially serve as early-warning indicators of TC rapid intensity changes.

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On scale interactions between the MJO and synoptic scale

Cited by 6 publications

References 85 publications

Fifty Years of Research on the Madden‐Julian Oscillation: Recent Progress, Challenges, and Perspectives

Fifty Years of Research on the Madden‐Julian Oscillation: Recent Progress, Challenges, and Perspectives

Impacts of Detoured Madden-Julian Oscillations on the South Pacific Convergence Zone

Characterizing the Energetics of Vortex-Scale and Sub-Vortex-Scale Asymmetries during Tropical Cyclone Rapid Intensity Changes

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