Barrier Effect of the Indo-Pacific Maritime Continent on the MJO: Perspectives from Tracking MJO Precipitation

Zhang, Chidong; Jian, Ling

doi:10.1175/jcli-d-16-0614.1

Cited by 188 publications

(257 citation statements)

References 83 publications

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“…Day 0 composite RMM amplitudes for each event type are ≈1 or greater, although the day 0 RMM amplitude of a few individual events of each type is <1. In these cases, weak projection of the wind anomalies onto the wind components of the RMM index reduces its amplitude (Straub, ; Zhang & Ling, ). Despite the weak projection of wind anomalies onto the RMM indices in ED events, all three event types exhibit eastward propagation of the MJO signal.…”

Section: Methodsmentioning

confidence: 99%

“…For example, MC‐crossing MJO events feature anomalous dry conditions to the east of MJO convection (Kim et al, ), enhanced eastward and equatorward moisture gradients in the vicinity of the MC (Gonzalez & Jiang, ; Kim et al, ), and moist preconditioning by low‐level horizontal moisture advection (Adames & Wallace, ; Kiranmayi & Maloney, ; Maloney, , and many others). Non‐MC‐crossing MJO events exhibit weak or nonexistent dry phases east of MJO convection (Kim et al, ), a lack of low‐level moistening by horizontal and vertical moisture advection (Hsu & Li, ), seasonal and interannual variability (Kerns & Chen, ), and a lack of convection over the Indonesian Seas (Zhang & Ling, ). Recently, Feng et al () hypothesized that convection in non‐MC‐crossing MJO events was disrupted by Rossby wave‐like westward propagating midlevel dry anomalies originating in the central Equatorial Pacific.…”

Section: Introductionmentioning

confidence: 99%

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Atmospheric Mechanisms for MJO Decay Over the Maritime Continent

et al. 2018

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Eastward propagating Madden‐Julian oscillation (MJO) events that develop in the Indian Ocean from November to April are separated into events whose convective anomalies do and do not propagate across the Maritime Continent (MC). Propagating (P) events are divided into strong (sP) and weak (wP) subsets based on the initial amplitudes of their convective anomalies. Eastward decaying (ED) MJO events have initial amplitudes similar to those of wP events. Roughly half of all MJO events encounter westward propagating transient dry precursor (TDP) signals over the MC. These TDPs, which are external to the MJO circulation system, overwhelm the weak, eastward propagating moist anomaly in ED events, leading to MJO termination. In wP events, the MJO moist anomaly is stronger than the TDP dry anomaly, and the MJO propagates beyond the MC. ED MJO events that do not encounter TDPs decay because of insufficient moistening in the southern MC region. The background states of TDP‐ and non‐TDP‐affected MJO events resemble La Niña and El Niño conditions, respectively. The regional regulation of TDP activity and background moisture gradients by El Niño–Southern Oscillation can both be understood in terms of the zonal shift and the meridional expansion or contraction of Warm Pool moisture in response to El Niño–Southern Oscillation sea surface temperature anomalies. Our results demonstrate that modulation of TDPs by the background state moisture can affect the MJO in a manner that reinforces its propagation or decay via the interaction of MJO circulation anomalies and background moisture gradients.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Atmospheric Mechanisms for MJO Decay Over the Maritime Continent

et al. 2018

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“…Zhang 2005Zhang , 2013, which are regarded as an important factor governing the medium-range variability of global weather and climate. A recent study by Zhang and Ling (2017) shows a "barrier effect" of the IMC on more than 75% of MJOs. More detailed observational and theoretical studies may be necessary to identify the mechanisms weakening MJOs, but the synchronous diurnal cycle noted above may play an important role.…”

Section: Control Of the Global Climatementioning

confidence: 98%

“…These feedback mechanisms may be suppressed, because the hydrologic and energy cycles close approximately on a diurnal time scale (including clear/dry land in the morning) over the IMC, and the standard features of ISVs/MJOs along the ITCZ over the Indian and Pacific Oceans (e.g., Julian 1971, 1994;Wheeler and Hendon 2004;Zhang 2005Zhang , 2013Yoneyama et al 2008Yoneyama et al , 2013 are greatly modified over the IMC. For example, passage of ISVs/MJOs over the IMC is shifted to the southern side of the equator, which gives a decrease in rainfall over the IMC from west to east (e.g., Nitta et al 1992;Shibagaki et al 2006;Hidayat and Kizu 2010;Fujita et al 2011;Kamimera et al 2012;Peatman et al 2014;Zhang and Ling 2017).…”

Section: Diurnal Cycle Observed Around the Imc Coastlinesmentioning

confidence: 99%

Maritime continent coastlines controlling Earth’s climate

Yamanaka

Ogino

et al. 2018

Prog Earth Planet Sci

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During the Monsoon Asian Hydro−Atmosphere Scientific Research and Prediction Initiative (MAHASRI; 2006-16), we carried out two projects over the Indonesian maritime continent (IMC), constructing the Hydrometeorological Array for Intraseasonal Variation−Monsoon Automonitoring (HARIMAU; 2005-10) radar network and setting up a prototype institute for climate studies, the Maritime Continent Center of Excellence (MCCOE; 2009-14). Here, we review the climatological features of the world's largest "regional" rainfall over the IMC studied in these projects. The fundamental mode of atmospheric variability over the IMC is the diurnal cycle generated along coastlines by land−sea temperature contrast: afternoon land becomes hotter than sea by clear-sky insolation before noon, with the opposite contrast before sunrise caused by evening rainfall-induced "sprinkler"-like land cooling (different from the extratropical infrared cooling on clear nights). Thus, unlike the extratropics, the diurnal cycle over the IMC is more important in the rainy season. The intraseasonal, seasonal to annual, and interannual climate variabilities appear as amplitude modulations of the diurnal cycle. For example, in Jawa and Bali the rainy season is the southern hemispheric summer, because land heating in the clear morning and water vapor transport by afternoon sea breeze is strongest in the season of maximum insolation. During El Niño, cooler sea water surrounding the IMC makes morning maritime convection and rainfall weaker than normal. Because the diurnal cycle is almost the only mechanism generating convective clouds systematically near the equator with little cyclone activity, the local annual rainfall amount in the tropics is a steeply decreasing function of coastal distance (e-folding scale 100-300 km), and regional annual rainfall is an increasing function of "coastline density" (coastal length/land area) measured at a horizontal resolution of 100 km. The coastline density effect explains why rainfall and latent heating over the IMC are twice the global mean for an area that makes up only 4% of the Earth's surface. The diurnal cycles appearing almost synchronously over the whole IMC generate teleconnections between the IMC convection and the global climate. Thus, high-resolution (<< 100 km; << 1 day) observations and models over the IMC are essential to improve both local disaster prevention and global climate prediction.

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“…Note that westward propagation mainly occurs over the WP but not so much over the Indian Ocean, where eastward propagation is still evident during winter 2014–2015. This behavior is possibly related to the barrier effects on the MJO propagation by the Maritime Continent (e.g., Kim et al, ; Salby & Hendon, ; Zhang & Ling, ). Westward propagating disturbances whose convection initiates just east of the Dateline and weakens over the Maritime Continent, similar to Figures d and f, exist during many other years in the 37 winter season (1979–2016) record of lag‐regressed OLR anomalies (not shown).…”

Section: Introductionmentioning

confidence: 99%

Distinct Propagation Characteristics of Intraseasonal Variability Over the Tropical West Pacific

Gonzalez

Jiang

2019

JGR Atmospheres

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Tropical intraseasonal variability, with the Madden‐Julian oscillation (MJO) as its most prominent mode, exerts extensive influences on global weather extremes. It is found that strong interannual variability of intraseasonal convection exists in the west Pacific (WP), in the form of years with strong eastward propagation (i.e., associated with the MJO) and years with strong westward propagation. Years with strong westward propagation on intraseasonal timescales are dominated by a westward propagating intraseasonal mode (WPIM), which is the second leading intraseasonal mode after the MJO over the tropical WP. Initiated over the central Pacific, the WPIM exhibits slow equatorial westward propagation (5 m/s) with a period of 25 days and a spatial scale of zonal wave number 3–4. Unlike the MJO, the WPIM lacks a significant tilt with height in specific humidity and vertical velocity. A strong anticorrelation is found between MJO and WPIM activity on interannual timescales over the WP. Budget analyses of the moist static energy suggest that both modes are driven by horizontal moist static energy advection and that substantial differences in winter mean large‐scale moisture and zonal winds largely define their distinct propagation behaviors. The WPIM is favored, while the MJO is suppressed when mean equatorial low‐level easterlies between 150°E and 160°W are enhanced and equatorial mean low‐level moisture is reduced near the Dateline and enhanced in the off‐equatorial WP (110°–150°E). While the WPIM bears resemblance to low‐frequency equatorial Rossby waves, a more detailed analysis must be conducted to affirm if they are the same phenomenon.

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Barrier Effect of the Indo-Pacific Maritime Continent on the MJO: Perspectives from Tracking MJO Precipitation

Cited by 188 publications

References 83 publications

Atmospheric Mechanisms for MJO Decay Over the Maritime Continent

Atmospheric Mechanisms for MJO Decay Over the Maritime Continent

Maritime continent coastlines controlling Earth’s climate

Distinct Propagation Characteristics of Intraseasonal Variability Over the Tropical West Pacific

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