Fig. 6: Zonal cross-section of potential vorticity (PV), potential temperature (θ), vertical pressure velocity (ω), and meridionally averaged magnitude of integrated vapor transport (IVT).

Panels a-g correspond to the 202108 event, h-n to the 202007 event, and o-u to the 201009 event. The first row (a, h, o) represents the observational data. The second to fourth rows show the model experimental results. In the model panels, the left column (b, d, f, i, k, m, p, r, t) presents results from simulations with spectral nudging, whereas the right column (c, e, g, j, l, n, q, s, u) presents results without spectral nudging. In each panel, the top plot shows a zonal-vertical cross-section of PV, θ, and ω. The shading represents PV, black contours indicate θ, and pink contours denote negative ω, with a contour interval of 0.25 Pa s⁻¹. The bottom plot illustrates the meridionally averaged magnitude of IVT. All panels correspond to the time of maximum observed hourly precipitation at the surface stations for each event. The meridional averaging range for both the cross-section and IVT magnitude plots extended by ±2° in latitude from the ETC center.