Research/Terra/ 321268
Task evidence / native-population-snow

High-density population and 2023–24 snowfall

PassComputational taskUnpublished draft
Download evidence JSON ↓

The question

321268
Find areas in the USA where population density exceeds 1000 people per square kilometer and snow accumulation was over 15 inches in 2023-2024
Exact submitted task and declared adaptations
Find areas in the USA where population density exceeds 1000 people per square kilometer and snow accumulation was over 15 inches in 2023-2024

Task conventions: Use frozen WorldPop USA 2020 counts and NOAA 2023-09-30 to 2024-09-30 snow in inches, original band 1. WorldPop is people PER CELL; derive people/km2 by dividing scaled counts by the full original WGS84 ellipsoidal meridian/parallel cell area. To limit memory, a lossless population crop uses these EXACT native-grid edges around the whole snow footprint: [-127.52624950980558, 18.432916768446546, -64.51791642850557, 57.64124994494655], width 7561 height 4705. Retain that original population grid: do not resample or interpolate population. Sample original snow at each population cell centre by containing pixel (nearest on aligned pixel centres), no bilinear averages. A cell qualifies only if density STRICTLY >1000 people/km2 AND sampled snow STRICTLY >15 inches. Both must be observed. Source masks/nonfinite values or outside the snow grid are unknown, not a failed threshold. Unobserved USA outside the supplied snow footprint is also unknown, not proof of no qualifying areas. Valid nonqualifying cells are zero; qualifying are one; missing either input is NoData. This native-cell allocation is a spatial screening convention, not within-cell uniformity or simultaneous observation in 2020 and 2023–24.



Publish the full cropped 0/1/NoData result raster and add it to the map, showing selected cells and unknown coverage distinctly. End with fenced JSON {count:qualifying cells,unknown_count:missing-either-input cells within the specified crop,coverage_note:string,selection:{collectionId,itemId,assetKey},map_layer_id:string}. Explain 2020 population, 2023–24 snow, strict thresholds, and incomplete geographic coverage.

Delivery format: provide the answer object with all fields specified above as final_response on assess_result, alongside the inspected final artifact_refs. This replaces the JSON-code-block formatting requirement above. Blue attaches your explicit selection to the accepted final answer. Finish with a concise ordinary-language answer agreeing with that selected result; do not duplicate the JSON in chat.

Supplied immutable inputs:
[
  {
    "name": "USA population count, WorldPop 2020",
    "edition": "2020 UN-adjusted population counts aggregated to 1 km cells",
    "units": {
      "band1": "people per cell"
    },
    "collectionId": "blue-generated--[resource id withheld]",
    "itemId": "[resource id withheld]",
    "assetKey": "data"
  },
  {
    "name": "US snowfall, 2023\u201324 frozen season",
    "edition": "2023-09-30 to 2024-09-30",
    "units": {
      "band1": "inches"
    },
    "collectionId": "blue-generated--[resource id withheld]",
    "itemId": "[resource id withheld]",
    "assetKey": "data"
  }
]

Outcome & verification

Independent artifact and delivery checks passed.

Duration
38m 23s
Recorded Blue tool calls
48
Total tokens
4,121,564
Model cost
Not recorded
Application revision
d50497ea9084f29c91b05406688f87035df98d8a
Release
terra-geobenchx-v1

Recorded final answer

Done — I found 34,217 qualifying cells. The map now includes the published layer “Dense population + snow screen.” It uses 2020 WorldPop population and 2023–24 NOAA snow with strict thresholds of >1000 people/km² and >15 inches. Within the exact crop, 23,857,845 cells remain unknown because one input is missing or outside the observed snow footprint, so this is not complete USA coverage. ### Limitations - USA outside the supplied snow footprint remains unknown in this screening. - Population is from 2020, while snow is from 2023-09-30 to 2024-09-30. - Population is from WorldPop 2020, while snow is from NOAA 2023-09-30 to 2024-09-30. - Cells with missing population or snow, including USA outside the supplied snow footprint, remain NoData and therefore unknown. - This is a native-cell screening convention and does not imply within-cell uniformity or simultaneous observation. - Population evidence is fixed to WorldPop USA 2020 counts. - Snow evidence is limited to the supplied NOAA 2023-09-30 to 2024-09-30 footprint and band 1 values. - Missing population or snow stays NoData in the final raster.

Independent checks

These checks are separate from the agent's own assessment. A successful job or an assertion of success is not enough to pass.

Expected count
34217
Reported count
34217
Computation verified
Yes
Answer fulfilled
Yes
Full grading and rubric record
{
  "expectedCount": 34217,
  "actualCount": 34217,
  "expectedMetrics": null,
  "actualMetrics": null,
  "computationCorrect": true,
  "answerFulfilled": true,
  "adjudication": null,
  "qualification": null,
  "reasons": []
}

Recorded investigation findings

The agent's reported hypotheses and assessments, retained as evidence of its process—not independent proof that the answer is correct. Failed calls retain their requested verdict, not an accepted assessment.

run_trial · completed

Does the proposed native-cell method preserve the cropped WorldPop grid, apply strict >1000 people/km2 and >15 inch thresholds separately, and keep missing inputs as NoData when the two masks are combined?

assess_trial · completed · assessment: sufficient

The trial preserved one native WorldPop grid from clip through density, thresholding, and final combination. The aligned snow output matched that grid with nearest resampling from the original 0.04 degree snow raster. The threshold masks contained only 0, 1, and NoData values. The combined mask had validOutputWithMissingInputCount equal to 0, so missing population or missing snow did not turn into false zeros. The preview showed both qualifying and nonqualifying observed cells in the test area.

run_trial · completed

Can an area-bounded source selection produce the exact full requested crop on the native WorldPop grid without the full-source clip limit, while preserving the same density, nearest-snow, strict-threshold, and NoData behavior?

assess_trial · completed · assessment: insufficient

The area-bounded exact source selection did not crop the WorldPop raster. The population output remained at the full source extent with width 43072 and height 6298, and the aligned snow and final mask inherited that full grid. This method therefore does not satisfy the required exact crop extent or dimensions, even though the downstream thresholding and NoData behavior remained consistent.

run_trial · failed

Does a processor-based raster crop using pass-through map algebra honor the exact supplied native-grid crop and allow the full requested screening result to be produced at 7561 by 4705 cells?

run_trial · completed

Can raster-align crop the population raster to the exact requested native grid without changing aligned cell values, so the full screening result can be produced at 7561 by 4705 cells?

assess_trial · completed · assessment: sufficient

This full-scope trial produced the requested crop bounds [-127.52624950980558, 18.432916768446546, -64.51791642850557, 57.64124994494655] at width 7561 and height 4705 on EPSG:4326 with 0.0083333333 degree cells. The downstream density raster and the nearest-aligned snow raster shared that exact grid. The combined raster preserved missing inputs as NoData, with validOutputWithMissingInputCount equal to 0, and its exact statistics reported 34217 qualifying cells and 23857845 missing-either-input cells. The expected total cell count in the trial question was misstated: 7561 multiplied by 4705 equals 35574505, which matches the observed total_cells exactly.

assess_result · completed · assessment: sufficient

I published the requested cropped screening raster and exact count table. The final raster matches the requested crop bounds and 7561 by 4705 native-grid dimensions, uses 2020 WorldPop counts converted to people per square kilometre on the original grid, samples NOAA 2023-09-30 to 2024-09-30 snow band 1 by nearest onto that grid, applies strict >1000 people/km² and >15 inch thresholds, and preserves missing population or snow as NoData. The exact final counts are 34217 qualifying cells and 23857845 missing-either-input cells. The published raster is added to the map as layer [resource id withheld] with a classified-raster display.

Recorded workflow

  1. 01

    Combine the strict threshold masks

    Recorded raster-map-algebra · succeeded

  2. 02

    USA dense population and snow screening raster

    Recorded output · succeeded

  3. 03

    USA dense population and snow screening counts

    Recorded output · succeeded

  4. 04

    Summarize the finished cropped raster

    Recorded raster-statistics · succeeded

  5. 05

    Align population to the exact native crop grid

    Recorded raster-align · succeeded

  6. 06

    Convert cropped population counts to density

    Recorded raster-count-density · succeeded

  7. 07

    Apply the strict population threshold

    Recorded raster-reclassify · succeeded

  8. 08

    Align snow to the cropped population grid

    Recorded raster-align · succeeded

  9. 09

    Use snow band 1

    Recorded raster-extract-band · succeeded

  10. 10

    Apply the strict snow threshold

    Recorded raster-reclassify · succeeded

  11. 11

    blue-generated--[resource id withheld]

    Recorded source · succeeded

  12. 12

    blue-generated--[resource id withheld]

    Recorded source · succeeded

  13. 13

    Combine the strict threshold masks

    Recorded raster-map-algebra · succeeded

  14. 14

    Summarize the finished cropped raster

    Recorded raster-statistics · succeeded

  15. 15

    Align population to the exact native crop grid

    Recorded raster-align · succeeded

  16. 16

    Convert cropped population counts to density

    Recorded raster-count-density · succeeded

  17. 17

    Apply the strict population threshold

    Recorded raster-reclassify · succeeded

  18. 18

    Align snow to the cropped population grid

    Recorded raster-align · succeeded

  19. 19

    Use snow band 1

    Recorded raster-extract-band · succeeded

  20. 20

    Apply the strict snow threshold

    Recorded raster-reclassify · succeeded

  21. 21

    blue-generated--[resource id withheld]

    Recorded source · succeeded

  22. 22

    blue-generated--[resource id withheld]

    Recorded source · succeeded

  23. 23

    Align population to the exact native crop grid

    Recorded output · succeeded

  24. 24

    Convert cropped population counts to density

    Recorded output · succeeded

  25. 25

    Align snow to the cropped population grid

    Recorded output · succeeded

  26. 26

    Combine the strict threshold masks

    Recorded output · succeeded

  27. 27

    Summarize the finished cropped raster

    Recorded output · succeeded

  28. 28

    Combine the threshold masks

    Recorded raster-map-algebra · succeeded

  29. 29

    Summarize the finished full-crop raster

    Recorded raster-statistics · succeeded

  30. 30

    Convert bounded population counts to density

    Recorded raster-count-density · succeeded

  31. 31

    Apply the strict population threshold

    Recorded raster-reclassify · succeeded

  32. 32

    Population source cropped at selection

    Recorded source · succeeded

  33. 33

    Align snow to the bounded population grid

    Recorded raster-align · succeeded

  34. 34

    Use snow band 1

    Recorded raster-extract-band · succeeded

  35. 35

    Apply the strict snow threshold

    Recorded raster-reclassify · succeeded

  36. 36

    Snow source cropped at selection

    Recorded source · succeeded

  37. 37

    Population source cropped at selection

    Recorded output · succeeded

  38. 38

    Convert bounded population counts to density

    Recorded output · succeeded

  39. 39

    Align snow to the bounded population grid

    Recorded output · succeeded

  40. 40

    Combine the threshold masks

    Recorded output · succeeded

  41. 41

    Summarize the finished full-crop raster

    Recorded output · succeeded

  42. 42

    Combine strict threshold masks

    Recorded raster-map-algebra · succeeded

  43. 43

    Clip population to local test area

    Recorded spatial-clip · succeeded

  44. 44

    Convert counts to density

    Recorded raster-count-density · succeeded

  45. 45

    Apply population threshold

    Recorded raster-reclassify · succeeded

  46. 46

    Align snow to population grid

    Recorded raster-align · succeeded

  47. 47

    Use snow band 1

    Recorded raster-extract-band · succeeded

  48. 48

    Apply snow threshold

    Recorded raster-reclassify · succeeded

  49. 49

    blue-generated--[resource id withheld]

    Recorded source · succeeded

  50. 50

    blue-generated--[resource id withheld]

    Recorded source · succeeded

  51. 51

    Clip population to local test area

    Recorded output · succeeded

  52. 52

    Convert counts to density

    Recorded output · succeeded

  53. 53

    Align snow to population grid

    Recorded output · succeeded

  54. 54

    Apply population threshold

    Recorded output · succeeded

  55. 55

    Apply snow threshold

    Recorded output · succeeded

  56. 56

    Combine strict threshold masks

    Recorded output · succeeded

Activity

Recorded actions

Recorded observable actions only, not private reasoning. Raw payloads, geometry, private links and credentials are omitted; full evidence is retained privately. Activity/workflow lists bounded at 500 entries.

  1. Progress update

    I’ll confirm the saved context and inspect the supplied rasters so I can build the native-cell screening exactly as requested.

  2. Progress update

    I found the core Blue analysis tools. Next I’m checking the retained brief, then I’ll inspect the two supplied rasters and the available raster processors before testing the method on a small slice.

  3. get_analysis

    Recorded tool call · completed

  4. get_tool_help

    Recorded tool call · completed

  5. list_processors

    Recorded tool call · completed

  6. get_tool_help

    Recorded tool call · completed

  7. Progress update

    I have the trial and proposal schemas. Now I’m inspecting the exact input items and the processor contracts for density conversion, alignment, thresholding, and raster statistics so I can keep the grid and NoData rules exact.

  8. get_collection

    Recorded tool call · completed

  9. get_collection

    Recorded tool call · completed

  10. get_tool_help

    Recorded tool call · completed

  11. get_tool_help

    Recorded tool call · failed

  12. get_tool_help

    Recorded tool call · completed

  13. Progress update

    The two input collections are the exact supplied WorldPop and NOAA rasters. Next I’m checking their item metadata and exact grid properties so I can keep the crop, alignment, and NoData handling consistent with the benchmark rules.

  14. list_items

    Recorded tool call · completed

  15. list_items

    Recorded tool call · completed

  16. describe_processors

    Recorded tool call · completed

  17. describe_processors

    Recorded tool call · completed

  18. get_tool_help

    Recorded tool call · completed

  19. get_tool_help

    Recorded tool call · completed

  20. get_tool_help

    Recorded tool call · completed

  21. Progress update

    I found a safer way to preserve unknown cells: threshold each input into a 0/1/NoData mask first, then multiply the two masks. That should keep missing population or missing snow as NoData instead of falsely turning them into zero. I’m checking that contract now.

  22. get_tool_help

    Recorded tool call · completed

  23. get_tool_help

    Recorded tool call · completed

  24. get_tool_help

    Recorded tool call · completed

  25. describe_processors

    Recorded tool call · completed

  26. Progress update

    I’ve pinned down the method: crop the WorldPop raster to the exact supplied bbox, convert cropped counts to people/km² on that unchanged grid, nearest-sample snow onto that grid, threshold each input separately, then multiply the two 0/1 masks so missing stays missing. I’m recording that goal and the final checks now.

  27. Progress update

    The brief update just needed the required spatial scope field. I’m correcting that and then moving into a small trial that checks the exact native-grid logic before I scale it to the full crop.

  28. update_analysis_brief

    Recorded tool call · completed

  29. run_trial

    Recorded tool call · completed

  30. Progress update

    The trial finished successfully. It confirmed the local grid handling and, importantly, that multiplying the two threshold masks preserved missing snow or population as NoData instead of turning unknown cells into zero. I’m reading the visual report now, then I’ll save the full-country crop workflow.

  31. get_trial_report

    Recorded tool call · completed

  32. assess_trial

    Recorded tool call · completed

  33. Progress update

    I’ve got a tested method now, so I’m saving the full production workflow for the exact supplied crop and the exact strict-threshold rules. I’m also including a summary output so the final answer can use exact qualifying and unknown cell counts from the finished raster, not estimates.

  34. propose_workflow

    Recorded tool call · failed

  35. Progress update

    The workflow is almost valid. Blue just asked me to point the population criterion at its actual final-use branch instead of the crop grid it also helps define. I’m correcting that binding now, and I’ll do the same for snow to keep the contract explicit.

  36. propose_workflow

    Recorded tool call · completed

  37. Progress update

    The saved full workflow hit a real scaling limit in the clip step: it would read the entire WorldPop source before clipping, which is too large. I’m testing the needed fix now: bind the exact crop at the source step first, then run the same density, nearest-snow, threshold, and summary logic on that bounded crop. If that works, I can save the runnable production workflow without changing the requested method.

  38. run_trial

    Recorded tool call · completed

  39. get_trial_report

    Recorded tool call · completed

  40. Progress update

    The source-bounded trial finished, and it showed the area field on an exact source selection did not crop the raster. That means it is not the right production method. I’m reading that evidence now, then I’ll switch to a crop step that clips inside a raster processor instead of relying on source selection.

  41. Progress update

    The full-scope source-bound test did what I needed it to do: it ruled out that shortcut. The output stayed at the full WorldPop extent, so it cannot satisfy the exact crop requirement. I’m recording that and moving to a processor-based crop that should honor the requested grid edges inside the computation itself.

  42. assess_trial

    Recorded tool call · completed

  43. run_trial

    Recorded tool call · failed

  44. Progress update

    I’m testing the likely fix now: a pass-through raster algebra crop on the population raster itself, using the exact supplied native-grid edges. I expect that to produce the requested 7561×4705 crop, after which the already-tested density, nearest-snow, and 0/1/NoData logic can run unchanged.

  45. Progress update

    I found a stronger candidate: align the population raster to an explicit grid that exactly matches the requested native crop. Because the source and target grid are both EPSG:4326 with the same 0.0083333333° spacing and aligned edges, nearest sampling should act as an exact window rather than a real resample. I’m testing that full path now.

  46. run_trial

    Recorded tool call · completed

  47. Progress update

    The new full-scope trial looks promising: it hit the exact crop bounds and the exact 7561×4705 grid. I’m reading the trial report now so I can record that method as the tested production path, then I’ll save the runnable workflow from this exact full-scope trial.

  48. get_trial_report

    Recorded tool call · completed

  49. assess_trial

    Recorded tool call · completed

  50. Progress update

    I now have an exact full-scope tested computation. I’m saving that exact trial as the production workflow, with one final raster deliverable and one exact summary deliverable for the counts used in the accepted answer.

  51. propose_workflow

    Recorded tool call · completed

  52. Progress update

    The workflow is technically ready. The last remaining step before execution is a plan review note: I need to formally resolve the one rejected crop shortcut and show that the saved workflow uses the tested exact-crop method instead.

  53. get_analysis

    Recorded tool call · completed

  54. assess_plan

    Recorded tool call · completed

  55. Progress update

    The method is now fully supported. I’m starting the saved production workflow, then I’ll inspect the final raster and exact counts, add the raster to your map, and attach the verified answer object to the final result.

  56. execute_workflow

    Recorded tool call · completed

  57. Progress update

    The workflow has finished in the background. I’m checking the published outputs now so I can verify the raster and counts, then I’ll add the final raster to the map and record the selected answer.

  58. inspect_workflow_results

    Recorded tool call · completed

  59. Progress update

    I have a completed workflow run. Next I’m reading the exact published raster and summary outputs so I can verify the final counts and bind the correct layer on your map.

  60. inspect_workflow_results

    Recorded tool call · completed

  61. Progress update

    I have the published raster and the published summary table. I’m doing one final preview check on the raster and reading the exact counts row from the summary before I bind the raster to the map.

  62. inspect_artifact

    Recorded tool call · completed

  63. inspect_artifact

    Recorded tool call · completed

  64. Progress update

    The inspection jobs finished. I’m reading the final raster preview and the exact summary row now, then I’ll add the raster to the map and lock in the final answer object with the verified counts.

  65. inspect_artifact

    Recorded tool call · completed

  66. inspect_artifact

    Recorded tool call · completed

  67. add_catalog_layer

    Recorded tool call · completed

  68. get_tool_help

    Recorded tool call · completed

  69. Progress update

    I have the verified final counts. I’m adding the published raster to the map now and checking the accepted-result schema one last time so I can attach the exact answer object cleanly.

  70. Progress update

    The raster is on the map now as a classified layer. I’m confirming the layer binding, then I’ll record the final result with the exact qualifying and unknown counts from the published outputs.

  71. list_map_layers

    Recorded tool call · completed

  72. Progress update

    I’m pulling the remaining current-run receipts so the final assessment can point to the exact production snow-band and threshold steps, not just the earlier trial.

  73. inspect_workflow_results

    Recorded tool call · completed

  74. Progress update

    I’ve verified the published raster, the exact count table, and the live map layer. I’m recording the final result now with the selected raster artifact and the exact answer fields you requested.

  75. assess_result

    Recorded tool call · completed

|||

© 2026 Exia Labs, Inc.