Contribution functions and retrieved TPs for trailing hemisphere datasets: M22-T (top row) and J21-T (bottom row). Columns show the 3T, 2T, and 1T parameterizations. Colored curves are the normalized line center, ν₀, contribution functions for the SO₂ transitions listed in the legend (frequencies in GHz); larger contribution function values indicate layers that contribute most to the emergent flux. The thicker, solid line is the best-fit TP. Left axes give pressure; right axes show the corresponding altitude. The dashed horizontal black line indicates the modeled surface pressure, quoted with uncertainties calculated from the upper and lower bounds of the SO₂ column density.