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John M. Peters and Russ S. Schumacher

–1-km layer; (c),(d) the 1–2-km layer; and (g),(h) the 1.5–2.5-km layer. c. Influence of dynamical quantities on the MCS evolution The magnitude of the southerly component of southwesterly inflow into the western end of the MCS briefly abated during both southward cold pool surge events, which disrupted the supply of high CAPE air to the upstream end of the MCS, and resulted in a temporary cessation of the training of convection (as illustrated in section 4a ). In this subsection, we analyze the

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William W. Hobbs

. The central region is sharply delimited on all its margins, which are marked by an abruptrise of air temperature and by a fall of daily temperature range.3. The zone surrounding the cold central area of Greenland and extending beyond the glacial marginhas at all times outblowing winds supplied from the central area.4. The winds centrifugal to Greenland vary in force from near-calms to surges with velocities of 100and more miles per hour.5. Variations of wind velocity occur with little change in

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Chiu-Wai Yuen

15 JANUARY 1985 CHIU-WAI YUEN 135Simulations of Cold Surges over Oceans with Application to AMTEX '75 CHIU-WAI YUENDepartment of Meteorology, University of Wisconsin, Madison, WI 53706(Manuscript received 21 May 1984, in final form 3 October 1984) ABSTRACT Comparative numerical experiments and observational verifications for cold surges over the ocean areconducted using a primitive

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Shellie M. Rowe and Matthew H. Hitchman

versus latitude) and the evolution of wind speed along this trajectory in the UWNMS. For plotting purposes, angular momentum divided by (m s −1 ) is shown. 4. Case study 1 (5–6 February 2008) a. Poleward surges and jet intensification The evolution of winds, angular momentum, and indicators of inertial instability in meridional section for case 1 is shown in Fig. 1 . The sequence begins before the jet interacts with inertially unstable air and ends during the time of the farthest poleward extent

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Brant Liebmann, George N. Kiladis, Leila M. V. Carvalho, Charles Jones, Carolina S. Vera, Ileana Bladé, and Dave Allured

from South America into the Atlantic. We will show that, indeed, a substantial fraction of the Kelvin waves observed over South America appear to be triggered by cold-air outbreaks or “cold surges” reminiscent of the events documented by Garreaud and Wallace (1998) and Garreaud (2000) . After describing the data and how they are filtered in section 2 , the results are presented in section 3 . This section includes a description of different ways that Kelvin waves come to be over South America

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Yonghong Yao, Hai Lin, and Qigang Wu

1. Introduction Wintertime precipitation over the China mainland is mainly associated with the East Asian winter monsoon system, which is characterized by strong northwesterly and northeasterly winds in the lower troposphere originating from Siberian-high surges of cold and dry air. (In this paper, winter refers to the November–March boreal “extended winter.”) Although precipitation is limited in winter compared to summer (and provides beneficial moisture), the most costly and disruptive winter

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Paul J. Neiman, F. Martin Ralph, Robert L. Weber, Taneil Uttal, Louisa B. Nance, and David H. Levinson

eastern Colorado is the interaction of leeside frontal surges with downslope windstorms. Depending on the orientation, propagation direction, and depth of the leeside front relative to the mountains, the front and mountain waves can interact in a variety of ways. For example, Lee et al. (1989) used two-dimensional, geostrophic, numerical simulations to show that downslope windstorms induced by large-amplitude mountain waves are significantly affected by the presence, depth, and intensity of cold air

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Mong-Ming Lu and Chih-Pei Chang

most prominent patterns is the atmospheric blocking or the persistent anticyclonic flow anomaly that can modulate the climatic leading modes ( Croci-Maspoli et al. 2007 ) and upper-level jet streams. In this paper we will investigate the possible causes for these unusual late-winter strong cold surges. Ding and Ma (2007) and Ma et al. (2008) focused their studies on the synoptic developments associated with two major cold-air outbreaks (“cold waves”) over mainland China—one in late December

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Tsing-Chang Chen, Jenq-Dar Tsay, Jun Matsumoto, and Jordan Alpert

of synoptic systems for SCS TS/TY genesis during May: easterlies originated from the northeast Asian cold-surge-like flow and easterlies fed by the western North Pacific cold-air outbreak. Of the 17 identified geneses for TSs/TYs in the SCS, 12 belong to type 1 cyclonic shear flow and 4 belong to type 2 cyclonic shear flow. The genesis for TY Cecil unusually occurred in an SCS cyclonic shear flow formed by the monsoon westerlies and the wake low of TY Brenda. TS/TY geneses occurred in May in 14

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Ngar-Cheung Lau and Ka-Ming Lau

al. (1979) has providedobservational evidence on the extensive air-sea interaction and organized convective activity which occcurover the near-equatorial South China Sea followingnortheasterly cold surges over that region. Subsequentstudies by Chang and Lau (1980, 1982) demonstratedthat the active surge periods are accompanied by astrengthening of the local, thermally direct meridionalcirculation over East Asia, and by noticeable fluctuations in the intensity of Walker-type circulations inthe

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