This paper investigates the broadband shock-associated noise (BBSAN) radiated from supersonic jets at the root source level. The sources are modeled according to an acoustic analogy. The acoustic-analogy model is informed by high-spatial-resolution two-dimensional two-component particle image velocimetry (PIV) data and solutions to the Reynolds-averaged Navier-Stokes (RANS) equations for the reconstruction of the equivalent BBSAN sources. The measurements are of screeching underexpanded jets issuing from a purely converging nozzle at ideally expanded Mach numbers of 1.45 and 1.59. The jet conditions are simulated using a RANS solver with a k − ω shear-stress-transport turbulence model. The RANS scales are modeled using formulations of a two-timescale model based on the turbulence dissipation and large-eddy-convection time. The large-eddy-convection-based scale is recommended as a replacement for the standard turbulence-dissipation scale in low-order BBSAN models. The equivalent BBSAN sources are reconstructed from the PIV measurements and RANS solutions at the peak Strouhal number. The equivalent BBSAN sources extracted from the PIV and RANS data are shown to have a favorable agreement.