caa a22 4500 605472742 CHVBK 20210128100339.0 cr unu---uuuuu 210128e20151101xx s 000 0 eng 10.1007/s00382-015-2483-7 doi (NATIONALLICENCE)springer-10.1007/s00382-015-2483-7 A new dynamical index for classification of cold surge types over East Asia [Elektronische Daten] [Tae-Won Park, Chang-Hoi Ho, Jee-Hoon Jeong, Jin-Woo Heo, Yi Deng] The cold surges over East Asia can be classified into wave-train type and blocking type according to their dynamic origins. In the present study, two dynamic indices are proposed to objectively identify cold surge types using potential temperature (θ) on the dynamic tropopause at 2-potential vorticity units (2-PVU) surface. The two indices are designed to represent primary characteristics of the two types of cold surge. The wave-train index (WI) is defined as a difference of anomalous θ on the 2-PVU surface between the western North Pacific and northeast China, which captures a southward (northward) intrusion of cold (warm) air mass related to the trough-ridge pattern. The blocking index (BI) is defined as a difference of anomalous θ between the subarctic region and northeast China, which indicates air mass overturning related to a reversal of the usual meridional θ gradient commonly observed in the occurrence of blocking type cold surge. Composite analyses based on the distribution of the WI and BI clearly demonstrate the dynamic evolutions of corresponding cold surge types. The wave-train cold surge is associated with a southeastward expansion of the Siberian High and northerly wind near surface, which is caused by growing baroclinic waves. During the blocking cold surge, a geopotential height dipole indicating the subarctic blocking and deepening of East Asian coastal trough induces a southward expansion of the Siberian High and northeasterly wind. Compared to the wave-train type, the blocking cold surge exhibits a longer duration and stronger intensity. In the new framework of these dynamic indices, we can detect a third type of cold surge when both the wave-train and the blocking occur together. In addition, we can exclude the events that do not have the essential features of the upper tropospheric disturbances or the subarctic anticyclonic circulation, which are responsible for cold surge occurrence, using the new indices. Springer-Verlag Berlin Heidelberg, 2015 Park Tae-Won School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA aut Ho Chang-Hoi School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea aut Jeong Jee-Hoon Department of Oceanography, Chonnam National University, Gwangju, South Korea aut Heo Jin-Woo School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea aut Deng Yi School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA aut Climate Dynamics Springer Berlin Heidelberg 45/9-10(2015-11-01), 2469-2484 0930-7575 45:9-10<2469 2015 45 382 https://doi.org/10.1007/s00382-015-2483-7 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-015-2483-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Park Tae-Won School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA aut NATIONALLICENCE 700 1- Ho Chang-Hoi School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea aut NATIONALLICENCE 700 1- Jeong Jee-Hoon Department of Oceanography, Chonnam National University, Gwangju, South Korea aut NATIONALLICENCE 700 1- Heo Jin-Woo School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea aut NATIONALLICENCE 700 1- Deng Yi School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 45/9-10(2015-11-01), 2469-2484 0930-7575 45:9-10<2469 2015 45 382