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1. Introduction Continuous regions of north–south-oriented high terrain can modulate the movement of synoptic-scale cold air masses by contributing to terrain-channeled surges of this cold air into subtropical and tropical latitudes (e.g., Myers 1964 ; DiMego et al. 1976 ; Parmenter 1976 ; Garreaud 1999 , 2000 , 2001 ; Lupo et al. 2001 ). Preferred pathways for these cold surges have been identified to the lee of many mountain ranges worldwide ( Fig. 1 ) including the Rockies (e
1. Introduction Continuous regions of north–south-oriented high terrain can modulate the movement of synoptic-scale cold air masses by contributing to terrain-channeled surges of this cold air into subtropical and tropical latitudes (e.g., Myers 1964 ; DiMego et al. 1976 ; Parmenter 1976 ; Garreaud 1999 , 2000 , 2001 ; Lupo et al. 2001 ). Preferred pathways for these cold surges have been identified to the lee of many mountain ranges worldwide ( Fig. 1 ) including the Rockies (e
1. Introduction Cold air is frequently advected along the lee side of high terrain and channeled equatorward, creating a cold surge. Cold surges are shallow regions of cold, stable air that extend approximately 500–1000 km, or one Rossby radius of deformation away from high terrain ( Pierrehumbert and Wyman 1985 ). Cold surges typically have a coherent signature from two days up to an entire week and are often associated with strong low-level equatorward flow exceeding 20 m s −1 , decreases in
1. Introduction Cold air is frequently advected along the lee side of high terrain and channeled equatorward, creating a cold surge. Cold surges are shallow regions of cold, stable air that extend approximately 500–1000 km, or one Rossby radius of deformation away from high terrain ( Pierrehumbert and Wyman 1985 ). Cold surges typically have a coherent signature from two days up to an entire week and are often associated with strong low-level equatorward flow exceeding 20 m s −1 , decreases in
described above, some studies have suggested that some cold surges are distinctive from the wave train type. For example, Takaya and Nakamura (2005b) documented two different origins of the intraseasonal amplification of the Siberian high: a wave train from the Atlantic and a blocking from the Pacific. In fact, the two origins lead to different types of cold air outbreaks over East Asia. Park et al. (2008) reported that the expansions of the Siberian high and the subsequent cold surges are caused by
described above, some studies have suggested that some cold surges are distinctive from the wave train type. For example, Takaya and Nakamura (2005b) documented two different origins of the intraseasonal amplification of the Siberian high: a wave train from the Atlantic and a blocking from the Pacific. In fact, the two origins lead to different types of cold air outbreaks over East Asia. Park et al. (2008) reported that the expansions of the Siberian high and the subsequent cold surges are caused by
1. Introduction East Asian winter is intermittently intruded by the sudden release of cold airmasses (CAM) from the high latitudes, which affects weather variability across the Far East and the North Pacific. This so-called cold air outbreak or cold surge event typically leads to rapid temperature drops, high pressure, and strong winds for one to several days ( Chang et al. 1979 ; Ding and Krishnamurti 1987 ; Zhang et al. 1997 ; Shoji et al. 2014 ). Severe cold surges are well known for
1. Introduction East Asian winter is intermittently intruded by the sudden release of cold airmasses (CAM) from the high latitudes, which affects weather variability across the Far East and the North Pacific. This so-called cold air outbreak or cold surge event typically leads to rapid temperature drops, high pressure, and strong winds for one to several days ( Chang et al. 1979 ; Ding and Krishnamurti 1987 ; Zhang et al. 1997 ; Shoji et al. 2014 ). Severe cold surges are well known for
1. Introduction Cold-air incursions across South America can present particular characteristics due to the presence of the Andes Mountains, which contribute to the advancement of cold fronts to the southwest of the Amazon basin. Besides organizing the convection in northern Brazil ( Garreaud and Wallace 1998 ), the continental fronts are also known to cause impacts that are especially felt by agriculture because of freeze events, with significant losses in coffee production and consequent
1. Introduction Cold-air incursions across South America can present particular characteristics due to the presence of the Andes Mountains, which contribute to the advancement of cold fronts to the southwest of the Amazon basin. Besides organizing the convection in northern Brazil ( Garreaud and Wallace 1998 ), the continental fronts are also known to cause impacts that are especially felt by agriculture because of freeze events, with significant losses in coffee production and consequent
. J. Geophys. Res. , 114 , D02112 , https://doi.org/10.1029/2008JD010929 . Wang , Z. , and Y. Ding , 2006 : Climate change of the cold wave frequency of China in the last 53 years and the possible reasons (in Chinese). Chin. J. Atmos. Sci. , 30 , 1068 – 1076 . Woo , S.-H. , B. Kim , J.-H. Jeong , S. Kim , and G. Lim , 2012 : Decadal changes in surface air temperature variability and cold surge characteristics over northeast Asia and their relation with the Arctic
. J. Geophys. Res. , 114 , D02112 , https://doi.org/10.1029/2008JD010929 . Wang , Z. , and Y. Ding , 2006 : Climate change of the cold wave frequency of China in the last 53 years and the possible reasons (in Chinese). Chin. J. Atmos. Sci. , 30 , 1068 – 1076 . Woo , S.-H. , B. Kim , J.-H. Jeong , S. Kim , and G. Lim , 2012 : Decadal changes in surface air temperature variability and cold surge characteristics over northeast Asia and their relation with the Arctic
1. Introduction A cold surge over the South China Sea (SCS) features an abrupt outbreak of northerly or northeasterly winds and is a typical but severe weather phenomenon during the boreal winter ( Ramage 1971 ; Chang et al. 1983 ; Lau and Chang 1987 ; Chang et al. 2006 , 2011 ). As a form of southward propagation of northerlies from the midlatitudes, cold surges can result in a drop of air temperature (e.g., Boyle and Chen 1987 ; Lu and Chang 2009 ), an intensification of tropical
1. Introduction A cold surge over the South China Sea (SCS) features an abrupt outbreak of northerly or northeasterly winds and is a typical but severe weather phenomenon during the boreal winter ( Ramage 1971 ; Chang et al. 1983 ; Lau and Chang 1987 ; Chang et al. 2006 , 2011 ). As a form of southward propagation of northerlies from the midlatitudes, cold surges can result in a drop of air temperature (e.g., Boyle and Chen 1987 ; Lu and Chang 2009 ), an intensification of tropical
humidity ( Qu et al. 2015 ; S.-H. Wang et al. 2016 ). As cold surges propagate to the south, massive amounts of northern particulates are brought to the southeastern continental edge within a shallow layer approximately 1 km above the surface ( Hsu et al. 2010 ; Yan et al. 2015 ; S.-H. Wang et al. 2016 ) and have consequently degraded air quality in the southeastern coastal region. This is different from the haze events in the NCP, where high PM 2.5 concentrations have been suggested to be mainly
humidity ( Qu et al. 2015 ; S.-H. Wang et al. 2016 ). As cold surges propagate to the south, massive amounts of northern particulates are brought to the southeastern continental edge within a shallow layer approximately 1 km above the surface ( Hsu et al. 2010 ; Yan et al. 2015 ; S.-H. Wang et al. 2016 ) and have consequently degraded air quality in the southeastern coastal region. This is different from the haze events in the NCP, where high PM 2.5 concentrations have been suggested to be mainly
improve our interpretations of the suite of measurements made at this site, at other subtropical sites worldwide, and from remote sensing platforms. b. South American cold-air surges Synoptic-scale surges of cold, midlatitude air along major mountain ranges are common worldwide and have been recognized along the Andes ( Marengo et al. 1997 ; Krishnamurti et al. 1999 ), Rocky Mountains ( Colle and Mass 1995 ), the Himalaya ( Wu and Chan 1995 , 1997 ), and in Central America ( Schultz and Bracken 1998
improve our interpretations of the suite of measurements made at this site, at other subtropical sites worldwide, and from remote sensing platforms. b. South American cold-air surges Synoptic-scale surges of cold, midlatitude air along major mountain ranges are common worldwide and have been recognized along the Andes ( Marengo et al. 1997 ; Krishnamurti et al. 1999 ), Rocky Mountains ( Colle and Mass 1995 ), the Himalaya ( Wu and Chan 1995 , 1997 ), and in Central America ( Schultz and Bracken 1998
Cordillera, cold surges that propagate through eastern Brazil occur in the absence of both an intense surface anticyclone and highly amplified upper-tropospheric longwave pattern (not shown). These situations occur in the presence of a surface cyclone off the eastern coast of South America, allowing maritime polar air to flow equatorward west of the cyclone’s center ( Lupo et al. 2001 ). Fig . 1. Topographic map of South America with the synoptic climatology of cyclone (red) and anticyclone (blue) tracks
Cordillera, cold surges that propagate through eastern Brazil occur in the absence of both an intense surface anticyclone and highly amplified upper-tropospheric longwave pattern (not shown). These situations occur in the presence of a surface cyclone off the eastern coast of South America, allowing maritime polar air to flow equatorward west of the cyclone’s center ( Lupo et al. 2001 ). Fig . 1. Topographic map of South America with the synoptic climatology of cyclone (red) and anticyclone (blue) tracks
