{
  "CPU_GPU_fine_indexing_validation": [
    {
      "dx_m": 1000.0,
      "CPU_GPU_pass": true,
      "max_absolute_error_kg": 2.2737367544323206e-13
    },
    {
      "dx_m": 500.0,
      "CPU_GPU_pass": true,
      "max_absolute_error_kg": 2.3447910280083306e-13
    }
  ],
  "physical_scheme_changes": [],
  "numerical_changes": [
    "horizontal estimation grid 2000 -> 1000 -> 500 m; domain edges unchanged",
    "particles per source step 2 -> 128 for every study grid; particle mass scaled inversely",
    "two shared-path seeds across all grid levels"
  ],
  "near_surface_height": "0-25 m AGL volume mean",
  "grid_metrics": [
    {
      "grid_m": 2000.0,
      "seed": 20261113,
      "particles_per_source_step": 128,
      "total_emitted_particles": 5529600,
      "shape": [
        15,
        13,
        92,
        130
      ],
      "GPU_seconds": 2.0668886000057682,
      "max_hourly_mass_error_kg": 9.413270163349807e-11,
      "common_2km_cell_mass_max_error_kg": 0.0,
      "median_nonzero_cell_day_particle_time_count": 19.0,
      "fraction_nonzero_cell_days_below20_samples": 0.5033384226237951,
      "native_0_25m_peak_ug_m3": 0.47373306555809824
    },
    {
      "grid_m": 1000.0,
      "seed": 20261113,
      "particles_per_source_step": 128,
      "total_emitted_particles": 5529600,
      "shape": [
        15,
        13,
        184,
        260
      ],
      "GPU_seconds": 2.073531899994123,
      "max_hourly_mass_error_kg": 9.57243173616007e-11,
      "common_2km_cell_mass_max_error_kg": 1.657007864253046e-14,
      "median_nonzero_cell_day_particle_time_count": 6.0,
      "fraction_nonzero_cell_days_below20_samples": 0.8146069615379595,
      "native_0_25m_peak_ug_m3": 0.639504794845273
    },
    {
      "grid_m": 500.0,
      "seed": 20261113,
      "particles_per_source_step": 128,
      "total_emitted_particles": 5529600,
      "shape": [
        15,
        13,
        368,
        520
      ],
      "GPU_seconds": 2.0584937000094214,
      "max_hourly_mass_error_kg": 1.1118572729174048e-10,
      "common_2km_cell_mass_max_error_kg": 1.5737411374061594e-14,
      "median_nonzero_cell_day_particle_time_count": 2.0,
      "fraction_nonzero_cell_days_below20_samples": 0.9291382558765476,
      "native_0_25m_peak_ug_m3": 0.8493551436326775
    },
    {
      "grid_m": 2000.0,
      "seed": 20261114,
      "particles_per_source_step": 128,
      "total_emitted_particles": 5529600,
      "shape": [
        15,
        13,
        92,
        130
      ],
      "GPU_seconds": 2.1969205000059446,
      "max_hourly_mass_error_kg": 9.072209650184959e-11,
      "common_2km_cell_mass_max_error_kg": 0.0,
      "median_nonzero_cell_day_particle_time_count": 19.0,
      "fraction_nonzero_cell_days_below20_samples": 0.5029577721150346,
      "native_0_25m_peak_ug_m3": 0.4522661096261642
    },
    {
      "grid_m": 1000.0,
      "seed": 20261114,
      "particles_per_source_step": 128,
      "total_emitted_particles": 5529600,
      "shape": [
        15,
        13,
        184,
        260
      ],
      "GPU_seconds": 2.074542599992128,
      "max_hourly_mass_error_kg": 1.0436451702844352e-10,
      "common_2km_cell_mass_max_error_kg": 1.5987211554602254e-14,
      "median_nonzero_cell_day_particle_time_count": 6.0,
      "fraction_nonzero_cell_days_below20_samples": 0.8143673511990188,
      "native_0_25m_peak_ug_m3": 0.602274371974334
    },
    {
      "grid_m": 500.0,
      "seed": 20261114,
      "particles_per_source_step": 128,
      "total_emitted_particles": 5529600,
      "shape": [
        15,
        13,
        368,
        520
      ],
      "GPU_seconds": 2.0781744999985676,
      "max_hourly_mass_error_kg": 9.208633855450898e-11,
      "common_2km_cell_mass_max_error_kg": 1.554312234475219e-14,
      "median_nonzero_cell_day_particle_time_count": 2.0,
      "fraction_nonzero_cell_days_below20_samples": 0.9294400620484506,
      "native_0_25m_peak_ug_m3": 0.9238100126106867
    }
  ],
  "grid_sensitivity": {
    "20261113": [
      {
        "coarse_m": 2000,
        "fine_m": 1000,
        "native_field_normalized_L1_difference": 0.3016670809770297
      },
      {
        "coarse_m": 1000,
        "fine_m": 500,
        "native_field_normalized_L1_difference": 0.41666630088442325
      }
    ],
    "20261114": [
      {
        "coarse_m": 2000,
        "fine_m": 1000,
        "native_field_normalized_L1_difference": 0.3022335020857571
      },
      {
        "coarse_m": 1000,
        "fine_m": 500,
        "native_field_normalized_L1_difference": 0.41961310484060677
      }
    ]
  },
  "same_grid_seed_sensitivity_L1": {
    "2000": 0.16982246096146783,
    "1000": 0.3267676849421575,
    "500": 0.6036963947008746
  },
  "native_receptor_sensitivity": [
    {
      "source_receptor": "LS12",
      "seed": 20261113,
      "2km_to_1km_normalized_L1_difference": 0.31507056290319774,
      "1km_to_500m_normalized_L1_difference": 0.19970080366432463
    },
    {
      "source_receptor": "LS12",
      "seed": 20261114,
      "2km_to_1km_normalized_L1_difference": 0.3032175933784341,
      "1km_to_500m_normalized_L1_difference": 0.18286884534053496
    },
    {
      "source_receptor": "LS13",
      "seed": 20261113,
      "2km_to_1km_normalized_L1_difference": 0.5740548453081886,
      "1km_to_500m_normalized_L1_difference": 0.25412409989757484
    },
    {
      "source_receptor": "LS13",
      "seed": 20261114,
      "2km_to_1km_normalized_L1_difference": 0.56805650990325,
      "1km_to_500m_normalized_L1_difference": 0.28483911214713603
    },
    {
      "source_receptor": "LS15",
      "seed": 20261113,
      "2km_to_1km_normalized_L1_difference": 0.31507056290319774,
      "1km_to_500m_normalized_L1_difference": 0.19970080366432463
    },
    {
      "source_receptor": "LS15",
      "seed": 20261114,
      "2km_to_1km_normalized_L1_difference": 0.3032175933784341,
      "1km_to_500m_normalized_L1_difference": 0.18286884534053496
    },
    {
      "source_receptor": "LJ01",
      "seed": 20261113,
      "2km_to_1km_normalized_L1_difference": 0.38313901425985686,
      "1km_to_500m_normalized_L1_difference": 0.31109613646225676
    },
    {
      "source_receptor": "LJ01",
      "seed": 20261114,
      "2km_to_1km_normalized_L1_difference": 0.3488280880667591,
      "1km_to_500m_normalized_L1_difference": 0.335589804533759
    }
  ],
  "declared_diagnostic_criteria": {
    "native_1km_to_500m_receptor_L1_max": 0.05,
    "native_1km_to_500m_field_L1_max": 0.1
  },
  "local_grid_convergence_demonstrated": false,
  "caution": "The grid is a particle-density estimator, not an Eulerian dynamics mesh. Conservative common-volume consistency is not a Richardson convergence-order result."
}