{
  "status": "PIPELINE VALIDATED ON STAND-IN GEOMETRY — NOT the BedMachine science result",
  "blocker": "The requested dataset could not be downloaded; a synthetic substitute was used.",
  "physics": {
    "rho_ice_kgm3": 917.0,
    "rho_rock_kgm3": 2670.0,
    "contrast_gcc": -1.753,
    "units_note": "SimPEG gravity takes g/cc and returns mGal; validated against an analytic sphere to 0.003%",
    "sign_note": "z-up: a mass deficit yields POSITIVE gz"
  },
  "survey": {
    "station_spacing_m": 2500.0,
    "drape_m": 450.0,
    "component": "gz",
    "nD": 529,
    "noise_floor_mGal": 1.0,
    "noise_source": "Operation IceBridge AIRGrav crossover accuracy",
    "seed": 42,
    "relative_error": 0.0
  },
  "meshes": {
    "forward_m": [
      500.0,
      500.0,
      100.0
    ],
    "inversion_m": [
      1000.0,
      1000.0,
      200.0
    ],
    "inversion_active_cells": 49376,
    "note": "inversion mesh deliberately coarser than the forward mesh to avoid an inverse crime"
  },
  "regularization": {
    "type": "WeightedLeastSquares",
    "alpha_s": 0.0001,
    "alpha_x": 1.0,
    "alpha_y": 1.0,
    "alpha_z": 1.0,
    "sensitivity_weighting": "UpdateSensitivityWeights(every_iteration=False)",
    "bounds_gcc": [
      -1.753,
      0.3
    ],
    "optimizer": "ProjectedGNCG",
    "tolerance_note": "tolG/tolX/tolF set to 1e-8 as attributes; SimPEG defaults stop after 1 iteration and exit 0 while unconverged"
  },
  "beta_selection": {
    "method": "fixed-beta bracketing of the target misfit, interpolated on the trade-off curve",
    "chosen_beta": 0.0004764,
    "chi": 1.0118070948275015,
    "phi_d": 535.2459531637483,
    "phi_d_target": 529,
    "iterations": 8,
    "why_not_cooling": "BetaSchedule overshot the target between iterations at this problem scale (chi 0.47), and a gentler schedule hit maxIter under-fit (chi 28.5)"
  },
  "recovery": {
    "beta": 0.0004764,
    "chi": 1.0118070948275015,
    "phi_d": 535.2459531637483,
    "phi_d_target": 529,
    "iters": 8,
    "nC": 49376,
    "trough_axis_true_m": -336.41553831157756,
    "trough_axis_rec_m": -250.25214647540398,
    "axis_error_m": 86.16339183617359,
    "trough_width_true_m": 53415.299549723444,
    "trough_width_rec_m": 55073.879251847466,
    "width_error_pct": 3.1050648711238176,
    "peak_eq_thickness_true_m": 2363.9992487226573,
    "peak_eq_thickness_rec_m": 2369.0677080672485,
    "peak_thickness_error_pct": 0.21440190166430442,
    "recovered_mass_kg": -6504842699379811.0,
    "true_mass_kg": -6193806476341420.0,
    "mass_ratio": 1.0502172975901751,
    "min_recovered_contrast_gcc": -1.753,
    "true_contrast_gcc": -1.753,
    "frac_cells_at_lower_bound": 0.009073233959818535
  },
  "caveats": [
    "Residual mean 0.827 and std 0.572 rather than the ideal (0,1): the fit is systematically biased and the recovered model under-predicts the anomaly. Reported, not corrected.",
    "Absolute bed depth is NOT resolved; the recovered contrast is smeared through the column with no sharp ice-rock interface.",
    "Recovered density contrast is a lower bound because smooth regularization underestimates amplitude.",
    "The solution is non-unique and depends on the regularization; a different alpha_s or beta gives a different image that fits the data equally well."
  ],
  "_public_copy_note": "Public copy: internal compute identifiers and local environment paths were removed or generalized. Scientific values are retained. Paths may need adapting and some original run inputs are not included."
}