Figure 8: Schematic profile of geopotential height change with time (geopotential tendency (Φ/t); m day−1) at 500 hPa level (approximately 5.5 km height) and atmospheric boundary layer (ABL), modified from Choi et al. [28]. Negative geopotential tendency (Φ/t) means the decrease of geopotential height for 24 hours (i.e., shrunken atmospheric layer) and vice versa. Positive vorticity ( ) at the 500 hPa level, which implies the downward motion of air toward the ground corresponds to negative geopotential tendency area and vice versa.