Northwestward Propagation of the Intraseasonal Oscillation in the Western North Pacific during the Boreal Summer: Structure and Mechanism

Hsu, Huang‐Hsiung; Weng, Chun-Hsiung

doi:10.1175/1520-0442(2001)014<3834:npotio>2.0.co;2

Cited by 153 publications

(132 citation statements)

References 25 publications

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“…This phase difference is similar to that as in Hsu and Weng (2001) in the northward propagating intraseasonal oscillation and in a model simulation by tropical heating as in Hoskins and Karoly (1981). Kosaka and Nakamura (2010) simulate the PJ pattern initiated by tropical heating and found a similar phase relationship between the convection and circulation.…”

Section: Circulation Features and Moisture Supplysupporting

confidence: 84%

Characteristics of Summertime Circulation Patterns for Southern Taiwan’s Monsoon Rainfall from July to September

Ko¹,

Tzeng²

2013

Terr. Atmos. Ocean. Sci.

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This study documents the circulation features associated with summer monsoon rainfall over southern Taiwan from July through September over the period 1974 -2001. Four types of monsoon systems, Monsoon I, I-TC, II and II-TC, are identified based on the daily rainfall data of 4 observational stations over southern Taiwan and the daily wind direction data of Lanyu. The total rainfall amount of Monsoon I and I-TC is much greater than that for Monsoon II and II-TC because the former two have more moisture. Monsoon I is characterized by a strong southwesterly flow over southern Taiwan due to the tightening of the pressure gradient between the monsoon trough and subtropical high over the western North Pacific. The Monsoon I-TC pattern exhibits a deep monsoon trough along with an anomalous cyclone near the East China Sea; this pattern drives a large volume of moisture that causes heavy rainfall over southern Taiwan. The circulation patterns of Monsoon I and I-TC resemble the flow pattern during the Mei-Yu or "Plum Rain" season from May through mid-July. The Monsoon II pattern reveals a trough south of Taiwan and accompanied by a strong ridge north to it. The convection is located near the southern flank of the monsoon trough. The circulation pattern of Monsoon II-TC yields a deep trough south of the westward protruding subtropical ridge. Additionally, the Monsoon II-TC is less significant because of the wide variety of the TC locations. The Monsoon II and II-TC patterns are similar to the Pacific-Japan (PJ) pattern that can affect weather in the East Asian summer monsoon area.

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Section: Circulation Features and Moisture Supplysupporting

confidence: 84%

Characteristics of Summertime Circulation Patterns for Southern Taiwan’s Monsoon Rainfall from July to September

Ko¹,

Tzeng²

2013

Terr. Atmos. Ocean. Sci.

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“…Alternatively, anomalous heating appears to the immediate north of the YRV and the northern Philippines, where experienced anomalous cooling during PEPEs. It is widely agreed that a moist Rossby wave in the lower troposphere may account for the northwestward propagation of the convective heating in the western North Pacific Xie and Wang 1996;Kemball-Cook and Wang 2001;Hsu and Weng 2001). Moisture flux vorticity at 850-hPa (contours) is used to delineate the low-level moist Rossby wave.…”

Section: Apparent Heat Source Evolution and Its Influences On The Wpsmentioning

confidence: 99%

“…The anomalous behavior of the WPSH has been largely attributed to a northwestward propagating convection-circulation pair, which originates from the equatorial centralwestern Pacific Hsu and Weng 2001). Such northwestward-progressive pair features by a quasibiweekly mode (Fukutomi and Yasunari 1999;Kikuchi and Wang 2009;Yang et al 2010;Cao et al 2012;Jin et al 2013).…”

Section: Introductionmentioning

confidence: 99%

“…The eastward extension of the SAH seems closely associated with a mid-latitude wave train (Yang et al 2010;Ren et al 2015). Coincidently, interaction between diabatic heating and circulations plays significant roles in modulating both the WPSH and the SAH, because varied spatial distribution of the anomalous diabatic heating can induce vorticity variations in both the lower and upper levels (Hong et al 2015;Ren et al 2015;Hsu and Weng 2001). Though phenomena concerning the anomalous WPSH and SAH were descriptively presented individually or simultaneously in some previous studies based on specific cases or composited results (Wang et al 2000;Wu and Liu 2003;Qian et al 2004;Ren et al 2007;Mao et al 2010;Yang et al 2010;Zhai 2014b, 2015), detailed mechanisms for the approach, maintenance, and departure of these two dominant systems related to PEPEs have hitherto been rarely systematically reported.…”

Section: Introductionmentioning

confidence: 99%

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Mechanisms for concurrent low-latitude circulation anomalies responsible for persistent extreme precipitation in the Yangtze River Valley

Chen

Zhai

2015

Clim Dyn

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“…This filter is the same as that used in Hsu and Weng (2001), and has been proved to be useful in isolating the signals in the chosen frequency band. Details of these spectral and filtering techniques will be discussed in the following section.…”

Section: Data and Analysis Proceduresmentioning

confidence: 99%

Sub-Monthly Circulation Features Associated with Tropical Cyclone Tracks over the East Asian Monsoon Area during July-August Season

Hsu

2006

Journal of the Meteorological Society of Japan

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This study explores sub-monthly variation for the circulation and convection in the western North Pacific during July and August. The sub-monthly variability is dominated by a wave-like pattern that propagates north-northwestward from the northeast of Papua New Guinea, to the East China Sea. The wavelength and phase speed are about 4000 km and 5 m s À1 , respectively. This feature fluctuates in a 7-30 day timescale, with the spectral peak at 12.5 days. The vertical structure exhibits a barotropic structure below 500 hPa, which gradually tilts northwestward in upper levels near Taiwan and southern Japan. For more than 70% of cases which reveal the wave-like fluctuation, recurving tropical cyclones are found to occur concurrently with the wave-like pattern. These recurving tropical cyclones are likely part of the wave-like pattern, and may not be regarded as isolated vortices. The wave-like pattern occurs in a large-scale flow, which is characterized by an enhanced monsoon trough extending eastward into the Philippine Sea, and a strong ridge protruding westward from the subtropical high. It is suggested that the cyclonic phase of the wave-like pattern provides a favorable environment for the genesis, growth, and movement of the recurving tropical cyclones. The monsoon trough/subtropical ridge fluctuation, the wave-like pattern, and tropical cyclones, which represent phenomena in three different time and spatial scales, form a multi-scale system that affects the sub-monthly variability of the circulation, and convection, in the western North Pacific during the boreal summer.

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Northwestward Propagation of the Intraseasonal Oscillation in the Western North Pacific during the Boreal Summer: Structure and Mechanism

Cited by 153 publications

References 25 publications

Characteristics of Summertime Circulation Patterns for Southern Taiwan’s Monsoon Rainfall from July to September

Characteristics of Summertime Circulation Patterns for Southern Taiwan’s Monsoon Rainfall from July to September

Mechanisms for concurrent low-latitude circulation anomalies responsible for persistent extreme precipitation in the Yangtze River Valley

Sub-Monthly Circulation Features Associated with Tropical Cyclone Tracks over the East Asian Monsoon Area during July-August Season

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