Projected Changes in the Seasonal Cycle of Madden‐Julian Oscillation Precipitation and Wind Amplitude

Bui, Hien X.; Hsu, Pang‐Chi

doi:10.1029/2022gl101773

Cited by 4 publications

(2 citation statements)

References 61 publications

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“…In addition, tropical rainfall is produced by different cloud and storm systems, such as monsoon depressions, typhoons (hurricanes), mesoscale convective systems and the Madden-Julian oscillation. Some pioneering studies have been done for the annual cycle changes of typhoons/hurricanes (Shan et al 2023) and Madden-Julian Oscillation (Bui and Hsu 2023) and definitely more researches are needed in the future. Quantifying rainfall changes requires understanding the contributions of different storm types to the tropical rainfall annual cycles and how they respond to global warming.…”

Section: Quantificationmentioning

confidence: 99%

Advances in understanding the changes of tropical rainfall annual cycle: a review

Song,

Leung,

et al. 2023

Environ. Res.: Climate

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Aided by progress in the theoretical understanding, new knowledge on tropical rainfall annual cycle changes under a global warming background has been advanced in the past decade. In this review, we focus on recent advances in understanding the changes of tropical rainfall annual cycle, including its four distinct features: amplitude, spatial pattern shift, phase and wet/dry season length changes. Here, amplitude refers to the local summer-winter rainfall contrast and phase refers to the timing of rainfall annual cycle. In a warming climate, the amplitude is enhanced, more evidently over ocean, while the phase is delayed, mainly over land. The former is explained by the wet-get-wetter mechanism and the latter is explained by the enhanced effective atmospheric heat capacity and increased convective barrier. The phase delay over land has already emerged in the past four decades. The spatial pattern shift under warming is marked by two features: equatorward shift of the ITCZ throughout the year and the land-to-ocean precipitation shift in the rainy season. The former is explained by the upped-ante mechanism and/or related to the enhanced equatorial warming in a warmer world. The latter may be caused by the opposite land and ocean surface temperature annual cycle changes in the tropics. Over tropical rainforest regions such as Amazon and Congo Basin, the dry season has lengthened in the recent decades, but the fundamental reason is still unclear. Despite the notable progress in the research of tropical rainfall annual cycle change, many gaps remain in understanding its mechanisms, quantifying and attributing its historical emergence, narrowing the inter-model uncertainty of its future projections, and evaluating its global impact, motivating future work guided by some directions proposed in this review.

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Section: Quantificationmentioning

confidence: 99%

Advances in understanding the changes of tropical rainfall annual cycle: a review

Song,

Leung,

et al. 2023

Environ. Res.: Climate

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“…Because of their strong societal impacts, much research has been done to determine if the MJO and TCs are intensifying in our warming climate. Multiple studies have shown that the MJO has intensified during the last century [16][17][18][19], and many models predict that MJO rainfall and/or circulations will increase during the rest of the 21st century [20][21][22][23][24][25][26][27][28], although some climate models predict little or no additional MJO intensification [29]. Observations suggest that while global TCs have become fewer in number in recent decades, storms have intensified more rapidly as the oceans have warmed, with a greater proportion reaching category 4 or 5 strength [30].…”

Section: Introductionmentioning

confidence: 99%

Potential Strengthening of the Madden–Julian Oscillation Modulation of Tropical Cyclogenesis

Haertel,

Liang

2024

Atmosphere

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A typical Madden–Julian Oscillation (MJO) generates a large region of enhanced rainfall over the equatorial Indian Ocean that moves slowly eastward into the western Pacific. Tropical cyclones often form on the poleward edges of the MJO moist-convective envelope, frequently impacting both southeast Asia and northern Australia, and on occasion Eastern Africa. This paper addresses the question of whether these MJO-induced tropical cyclones will become more numerous in the future as the oceans warm. The Lagrangian Atmosphere Model (LAM), which has been carefully tuned to simulate realistic MJO circulations, is used to study the sensitivity of MJO modulation of tropical cyclogenesis (TCG) to global warming. A control simulation for the current climate is compared with a simulation with enhanced radiative forcing consistent with that for the latter part of the 21st century under Shared Socioeconomic Pathway (SSP) 585. The LAM control run reproduces the observed MJO modulation of TCG, with about 70 percent more storms forming than monthly climatology predicts within the MJO’s convective envelope. The LAM SSP585 run suggests that TCG enhancement within the convective envelope could reach 170 percent of the background value under a high greenhouse gas emissions scenario, owing to a strengthening of Kelvin and Rossby wave components of the MJO’s circulation.

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MJO representation in the Community Earth System Model 2 Large Ensemble: detection, seasonality and amplitude

Henderson,

Hottovy,

Barrett

2024

Preprint

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The Madden-Julian Oscillation (MJO) is the leading mode of tropical intraseasonal variability in the atmosphere and impacts weather and climate, both locally in the tropics as well as globally through tropical–extratropical interactions. Various metrics have been used to classify the intensity and character of the MJO. One popular metric is the Real-time Multivariate MJO (RMM) index, which is based on an empirical orthogonal function (EOF) of zonal winds at 850 hPa and 200 hPa and outgoing longwave radiation (OLR). To date, many climate models have struggled to reproduce a realistic MJO RMM signal, due to issues associated with model tropical convective schemes and failure to capture the eastward propagation of the MJO circulation. In this study, we assess the seasonality and amplitude of the MJO in the CESM2 Large Ensemble version 2 (CESM2-LE) experiment. We reproduce the RMM index from model output to explore the utility of OLR versus precipitation in MJO representation. Overall, we find that the model climatologies of MJO look similar to those present in the NCEP–NCAR reanalysis (for winds) and NOAA polar-orbiting satellites (for OLR). Both OLR and precipitation are found to be good indicators of MJO activity. When considering MJO amplitude over four categories (inactive, RMM < 1.0; active, RMM > 1.0; very active, RMM > 1.5; and extremely active, RMM > 2.5) the CESM2-LE model tends produce more inactive and fewer very active MJO events. Dynamically, MJO events in the CESM2-LE model are slower to propagate and weaker than observed. This is further demonstrated by model tendencies for strong MJO events to transition to weaker events faster than observed, particularly over the Indian Ocean and Maritime Continent.

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Projected Changes in the Seasonal Cycle of Madden‐Julian Oscillation Precipitation and Wind Amplitude

Cited by 4 publications

References 61 publications

Advances in understanding the changes of tropical rainfall annual cycle: a review

Advances in understanding the changes of tropical rainfall annual cycle: a review

Potential Strengthening of the Madden–Julian Oscillation Modulation of Tropical Cyclogenesis

MJO representation in the Community Earth System Model 2 Large Ensemble: detection, seasonality and amplitude

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