Abrupt Enhancement of Convective Activity and Low-Level Westerly Burst during the Onset Phase of the 1986-87 El Ni&amp;ntilde;o

Nitta, Tsuyoshi; Motoki, Toshihiro

doi:10.2151/jmsj1965.65.3_497

Cited by 48 publications

(40 citation statements)

References 11 publications

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“…Therefore, the study of convection has been conducted mainly by using GMS data focusing on the behavior of large-scale clouds which usually contained several cloud clusters. Nitta and Motoki (1987) noted an abrupt enhancement of convective activity in relation to the 1986/87 El Nino event. Nakazawa (1988) proposed a concept of `super cloud clusters' and stressed the hierarchic structure of the convective activity over the western tropical Pacific.…”

Section: Introductionmentioning

confidence: 98%

Internal Structure and Time Evolution of a Cloud Cluster in the Western Tropical Pacific Region Observed by Keifu Maru

Mori¹

1992

Journal of the Meteorological Society of Japan

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Internal structure and time evolution of a cloud cluster in the ITCZ of the western tropical Pacific which appeared on 8-9 June 1990 was analyzed by using meteorological radar data on board of the Keifu Maru, a research vessel of Japan Meteorological Agency. The radar observed the cloud cluster throughout almost all its life cycle. The horizontal size of the cloud cluster was about 500km in diameter and its life time was about 15 hours. The cloud cluster in the mature stage was shown to be composed of four sub-systems of echoes in different stages of development, with earlier stages on the windward side of the low-level wind. The life time of each sub-system was found to be about 8-10 hours. Development and motion of this cloud cluster was characterized by the succesive formation and development of these sub-systems on the windward side of the low level inflow. A schematic model of this cloud cluster is proposed.

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Section: Introductionmentioning

confidence: 98%

Internal Structure and Time Evolution of a Cloud Cluster in the Western Tropical Pacific Region Observed by Keifu Maru

Mori¹

1992

Journal of the Meteorological Society of Japan

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“…However, detailed features of these convective systems, their interaction and roles in ENSO development have not yet been well examined. Nitta and Motoki (1987; hereafter referred to as NM) analyzed the abrupt enhancement of SCC and WWB in November 1986 which were followed by the development of the 1986/87 El Nino. Nitta (1989; hereafter referred to as NT) further pointed to the importance of the development of a twin cyclone accompanied by a strong WWB in May 1986 for the eastward expansion of high sea surface temperature (SST) toward the central Pacific from the western Pacific.…”

Section: Introductionmentioning

confidence: 99%

“…A twin cyclone corresponds to cyclone pairs developed both in the equatorial northern and southern hemispheres symmetric to the equator (Keen, 1982;Nitta, 1989). We define WWB as a strong low-level westerly which has a time scale of several days or more and a spatial scale of several thousand kilometers (Keen, 1982;Nitta and Motoki, 1987;Sui and Lau, 1991).…”

Section: Introductionmentioning

confidence: 99%

Multi-Scale Convective Systems during the Initial Phase of the 1986/87 El Niño

Nitta¹,

Mizuno²,

Takahashi³

1992

Journal of the Meteorological Society of Japan

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“…With the appearance of anomalous southerlies, the convection over ICP enhanced notably (Figure 11(b)). The relationship between the convection development over the Indian Ocean and the formation of the cyclonic pair has been discussed by many investigators (Nitta and Motoki, 1987;Lau et al, 1989;Nitta et al, 1992). They also stressed the westerlies between the twin cyclones would intensify evidently during the convection flaring up, giving a 'westerly burst'.…”

Section: Composite Analysesmentioning

confidence: 99%

Role of the quasi‐biweekly oscillation in the onset of convection over the Indochina Peninsula

Wen

Zhang

2007

Quart J Royal Meteoro Soc

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ABSTRACT:The characteristics of convection onset over the Indochina Peninsula and its possible mechanism are investigated using the reanalysis of the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) and the black-body temperature at the top of the cloud (T BB ). Results show that the convection onset occurs before the systemic northward progression of the tropical convection and is earlier than the onset of the summer monsoon over this region. The prominent difference between the onset of convection and that of the summer monsoon appears in the westmost part of the western Pacific subtropical high. When the convection bursts, the Indochina Peninsula is under the control of the western Pacific subtropical high. However, the summer monsoon onset follows the splitting of the subtropical high belt and the eastward retreat of the western Pacific subtropical high out of the Indochina Peninsula.The climatological features of T BB over the Indochina Peninsula indicate that the convective activities have a close relationship with the quasi-biweekly oscillation (QBWO). Based on the onset dates determined by the T BB data, casestudies and composite analyses are implemented on exploring the possible mechanism of the convection onset. It is found that the onset of convection is mainly influenced by factors as follows. The wet phase of QBWO of the tropical convection propagates northward from Sumatra to the Indochina Peninsula. Over the southern Indochina Peninsula, anomalous southerlies (the Rossby wave response to the tropical convective QBWO) are beneficial to both the northward progression of the convective disturbances and the convergence of the low-level moisture flux. Furthermore, the Indochina Peninsula is easily affected by any cold surge invading southwards from higher latitudes, which intensifies the convective activities when merging with the wet/warm current.

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Abrupt Enhancement of Convective Activity and Low-Level Westerly Burst during the Onset Phase of the 1986-87 El Niño

Cited by 48 publications

References 11 publications

Internal Structure and Time Evolution of a Cloud Cluster in the Western Tropical Pacific Region Observed by Keifu Maru

Internal Structure and Time Evolution of a Cloud Cluster in the Western Tropical Pacific Region Observed by Keifu Maru

Multi-Scale Convective Systems during the Initial Phase of the 1986/87 El Niño

Role of the quasi‐biweekly oscillation in the onset of convection over the Indochina Peninsula

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Abrupt Enhancement of Convective Activity and Low-Level Westerly Burst during the Onset Phase of the 1986-87 El Ni&ntilde;o

Cited by 48 publications

References 11 publications

Internal Structure and Time Evolution of a Cloud Cluster in the Western Tropical Pacific Region Observed by Keifu Maru

Internal Structure and Time Evolution of a Cloud Cluster in the Western Tropical Pacific Region Observed by Keifu Maru

Multi-Scale Convective Systems during the Initial Phase of the 1986/87 El Ni&ntilde;o

Role of the quasi‐biweekly oscillation in the onset of convection over the Indochina Peninsula

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Abrupt Enhancement of Convective Activity and Low-Level Westerly Burst during the Onset Phase of the 1986-87 El Niño

Multi-Scale Convective Systems during the Initial Phase of the 1986/87 El Niño