Distribution of modeled integrated intensities (top 4 panels) and line opacities (bottom 4 panels) as a function of the K number. Each panel presents the results for a different (J + 1 → J) K-ladder. The 3 different gray levels corresponds to 3 different uncertainty intervals, i.e., 68% (1σ), 95% (2σ), and 99.9% (3σ) from dark to light gray. For the 4 top panels, the observed line intensities with their 1σ uncertainty intervals are plotted as red segments The dashed horizontal black line displays the 2σ upper limits for the undetected lines.