• Atmosphere
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• v.34 no.4
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• pp.397-415
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• 2024

Reported tornado event occurred in Dangjin, Chungcheongnam-do at 0650~0730 UTC on 15 March 2019 was examined using Weather Research and Forecasting model with four nested domains (dx = 5, 1, 0.2, and 0.05 km). From synoptic analysis in ERA5 reanalysis data, eastward moving upper-level trough was developed rapidly in the Yellow Sea. Strong tropopause folding with Potential Vorticity Unit (PVU) higher than 1.5 PVU moved downward to 600-hPa level in mid troposphere following the trough over the location of tornado event. Under this large-scale background condition, surface front developed very intensively in the west coast of Korea along with strong low-level jet and moisture band at 850-hPa level. In domain 2, the maximum Bulk wind shear at Dorido point was 12.86 m s^-1. Cold front evolved to be a comma cloud with upper-level trough and strong bulk vertical shear near Dangjin, which include eastward moving gust front revealed as a strong horizontal temperature gradient and convergence near the surface. In domains 3 and 4, the local maximum value of the simulated vertical vorticity (24 × 10^-2 s^-1) with strong updraft (8.18 m s^-1) near the observed tornado event along with the surface gust front was found to be a possible area for tornadogenesis from the x-z and time-z cross-sections near the simulated tornado event. In the vorticity budget analysis, the local maximum of vertical vorticity during this event was generated significantly by tilting and stretching forcings.

• Journal of Environmental Science International
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• v.11 no.3
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• pp.155-160
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• 2002

Using measured data at Daegu by tethersonde for the period of 1984∼1987, we have investigated the lower atmospheric boundary layer structure including relationships between inversion layer and meteorological factors(wind and temperature), and the inversion strength and inversion height. The inversion layer was defined from the vertical temperature profile and its strength was analyzed with the wind shear as well as the vertical temperature gradient. From October to January, measured inversion layer isn't destroyed, however, in June, after sun rise, it is destroyed by surface heating and mixed layer is developed from surface. According to Pasquill stability classes, the moderately stable cases dominated. It's the larger vertical temperature gradient the lower SBL height. We have introduced B(bulk turbulence scale) which indicated SBL height. It's larger B, the higher SBL height and vice versa. It was noted that the bulk turbulence scale (B) is appropriate to determine the stable boundary layer height.

• Atmosphere
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• v.25 no.4
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• pp.611-622
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• 2015

Heavy rainfall ($>30mm\;hr^{-1}$) over the Korean Peninsula is examined in order to understand thermo-dynamic characteristics of the atmosphere, using radiosonde observational data from seven upper-air observation stations during the last 17 years (1997~2013). A total of 82 heavy rainfall cases during the summer season (June-August) were selected for this study. The average values of thermo-dynamic indices of heavy rainfall events are Total Precipitable Water (TPW) = 60 mm, Convective Available Potential Energy (CAPE) = $850J\;kg^{-1}$, Convective Inhibition (CIN) = $15J\;kg^{-1}$, Storm Relative Helicity (SRH) = $160m^2s^{-2}$, and 0~3 km bulk wind shear = $5s^{-1}$. About 34% of the cases were associated with a Changma front; this pattern is more significant than other synoptic pressure patterns such as troughs (22%), migratory cyclones (15%), edges of high-pressure (12%), typhoons (11%), and low-pressure originating from Changma fronts (6%). The spatial distribution of thermo-dynamic conditions (CAPE and SRH) is similar to the range of thunderstorms over the United States, but extreme conditions (supercell thunderstorms and tornadoes) did not appear in the Korean Peninsula. Synoptic conditions, vertical buoyancy (CAPE, CIN), and wind parameters (SRH, shear) are shown to discriminate among the environments of the three types. The first type occurred with high CAPE and low wind shear by the edge of the high pressure pattern, but Second type is related to Changma front and typhoon, exhibiting low CAPE and high wind shear. The last type exhibited characteristics intermediate between the first and second types, such as moderate CAPE and wind shear near the migratory cyclone and trough.