Panel (a) represents the surface density distribution of the Kwon et al. (2011) model (see the solid line, see also Equation (2)) and the minimum surface density of gas (﹩{{\rm{\Sigma }}}_{g,\mathrm{min}}﹩) that is required to trigger the GIs (see the dashed curve). Panel (b) shows the radial temperature distribution given by a power law function in the Kwon et al. (2011) model (see the solid line) and the minimum disk temperature (T_min) that is required to satisfy the cooling condition of the GI (see the dashed line). The shaded area in both of the panels represents the region where the GI can be invoked.