A deep stratospheric intrusion associated with an intense cut-off low event over East Asia

European Centre for Medium-Range Weather Forecasts Re-Analysis Interim (ERA-Interim) reanalysis data and satellite data, and trajectory model were applied to analyze the dynamical, thermo-dynamical, and chemical structure in the upper troposphere and lower stratosphere (UTLS) of an intense cut-off low (COL) event occurring over East Asia during June 19-23, 2010, and to characterize the process and transport pathway of deep stratospheric intrusion. The Atmospheric Infrared Sounder (AIRS) ozone data and the Global Positioning System Ozone (GPSO3) sonde data showed that the air mass originating from the polar formed a region with relatively high values of potential vorticity (PV) and ozone in the center of COL, and a secondary ozone peak appeared in the upper troposphere during mature stage of the COL. Forward trajectory simulation suggested that during the first stage of COL, deep stratospheric intrusion associated with strong northerly wind jet on the west side of the upper-level trough transported ozone-rich air from the polar lower stratosphere into the middle and lower troposphere in the mid-latitude, and increased the ozone concentration there. During the mature stage of the COL, stratospheric air was transported counterclockwise into the troposphere. Backward trajectory model was used to find the source regions of air mass within the COL during its mature stage. Model results show that air masses with high ozone concentration in the center of the COL have two source regions: one is the subpolar vortex which lies in northern part of Center Siberia, where ozone-rich air plays a major role in increasing the ozone concentrations, and the other is the strong shear region which is near by the cyclonic side of the extratropical jet axis (west of 90A degrees E, near 50A degrees N). The air masses with low ozone concentration around the COL also have two source regions: one is the anticyclonic side of the extratropical jet axis, where the air mass with the relatively low ozone concentration at the bottom of the COL is mainly controlled by horizontal movement, and the other is the warm area of the south side of COL, where the air mass on the east and west side of the COL is mainly dominated by upward motion.