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Lukas Papritz and Harald Sodemann

are accompanied by intense precipitation as the air masses ascend in the so-called warm conveyor belt (e.g., Browning 1990 ; Madonna et al. 2014 ) or are steered toward the steep orographic rise along the western Norwegian coast ( Stohl et al. 2008 ; Azad and Sorteberg 2017 ). These warm conditions are subsequently followed by the advection of cold and dry Arctic air masses behind the cyclone’s cold front. The Arctic air masses are typically colder than the underlying sea surface, and are

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Tsing-Chang Chen, Ming-Cheng Yen, Wan-Ru Huang, and William A. Gallus Jr.

surge is generally characterized by a steep rise of surface pressure ( p s ), a sharp drop of surface temperature ( T s ), and a strengthening of northerly surface winds ( υ s ). Through further analysis of surface synoptic conditions, Chang et al. (1983) observed that the surge arrival may consist of two steps: the edge passage of the high-density cold-air current reflected by a drastic increase in p s , and the thermal frontal passage indicated by a sharp drop in dewpoint ( T d ). The

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Zhiwei Wu, Hai Lin, Yun Li, and Youmin Tang

-shifted Hawaiian high pressure system and favors cold air from the north. Fig . 4. The AM (a) climatology in SLP (contours in hectopascals), surface air temperature (Ts; color shadings in degrees Celsius), and 925-hPa winds (vectors in meters per second), and their anomalies regressed to the (b) KFF(DC) and (c) KFF(IA), as defined in Fig. 3 . Only wind speed anomalies above 1 m s −1 are plotted. For a high KFF(IA) year ( Fig. 4c ), the surface circulation pattern is similar to that of a high KFF(DC), except

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Dehai Luo, Yiqing Xiao, Yina Diao, Aiguo Dai, Christian L. E. Franzke, and Ian Simmonds

accumulation and extension of cold air of event 1 into event 2 that appeared rapidly after the decay of event 1. The time-mean 850-hPa horizontal wind vector (arrows in Figs. 1c,d ) and its anomaly vector (the nature of which can be estimated from Figs. 1a,b ) show that the cold air from northern China can reach southern China for event 2 through cold temperature advection induced by northerlies ( Figs. 1b,d ). The intensified southern branch trough of the plateau trough near 85°E as seen in the total

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Jared A. Rackley and John A. Knox

1. Introduction Topography is known to affect synoptic and mesoscale weather patterns throughout the world. One such effect, cold-air damming (CAD), occurs when a shallow, surface-based layer of relatively cold air becomes entrenched against the windward side of a mountain range ( Richwien 1980 ). The shallow dome of cold and stable air that becomes established during a CAD event is often identified by the characteristic “U”- or “wedge”- shaped inverted ridge that appears in the sea level

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Richard Grotjahn and Rui Zhang

1. Introduction Extreme cold air outbreaks (CAOs) have created multibillion dollar losses in the state of California. Especially hard hit have been agricultural operations in the California Central Valley (CCV). The large societal and economic consequences of CAOs in the CCV and elsewhere motivate investigations of CAOs in different regions of the world. Extreme CAOs advect strongly cold air into a region that lengthens the time of excessive cold during the day; longer duration is linked to

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Binhe Luo, Dehai Luo, Aiguo Dai, I. Simmonds, and Lixin Wu

; Lin 2015 ; Yu et al. 2016 ; Yu and Lin 2019 ). During the 2013/14 winter, intense cold extreme events occurred over most of North America ( Wang et al. 2015 ; Yu and Zhang 2015 ; Singh et al. 2016 ; Peng et al. 2018 , 2019 ). This winter was also characterized by a zonal dipole pattern with a warm surface air temperature (SAT) anomaly in western North America and a cold anomaly in eastern North America, which is often referred to as a warm west/cold east (WWCE) dipole pattern ( Wang et al

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Annick Terpstra, Ian A. Renfrew, and Denis E. Sergeev

1. Introduction In the North Atlantic region heat, moisture, and momentum exchange between the ocean and atmosphere modulates the global oceanic heat transport ( Buckley and Marshall 2016 ; Renfrew et al. 2019 ). Atmospheric forcing is the main driver for this local air–sea exchange and intermittent excursions of cold polar air masses over the open ocean, that is, maritime cold-air outbreak (CAO) events, account for 60%–80% of the wintertime ocean heat loss ( Papritz and Spengler 2017 ). In

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Jennifer K. Fletcher, Shannon Mason, and Christian Jakob

: those embedded within marine cold air outbreaks (MCAOs). Individual cold air outbreaks over mid- and high-latitude oceans have been well documented for their distinctive cloud features, including striking mesoscale organization ( Atkinson and Zhang 1996 ; Brümmer and Pohlmann 2000 , and references therein). These include cloud streets—long roll clouds typically oriented along the mean wind—as well as cellular convection. Different mesoscale shallow convective organization patterns are associated

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Niklas Boers, Henrique M. J. Barbosa, Bodo Bookhagen, José A. Marengo, Norbert Marwan, and Jürgen Kurths

fronts on large-scale circulation and associated precipitation anomalies has been thoroughly studied (e.g., Kousky 1979 ; Kiladis and Weickmann 1992 ; Liebmann et al. 1999 ; Siqueira and Machado 2004 ; Siqueira et al. 2005 ). In particular, northward migrating convective disturbances over SESA have been associated with southerly incursions of cold air from midlatitudes ( Garreaud and Wallace 1998 ; Garreaud 2000 ). These authors showed that the convective bands add an important contribution to

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