maritime_aggregate_track_tortuosity
Aggregate and compare tortuosity of historical ship tracks to test whether marine chronometers reduced meandering or if wind changes improved routes.
Instructions
Aggregate route tortuosity across CLIWOC tracks with optional comparison.
Tests the chronometer hypothesis: if marine chronometers improved navigation, tortuosity should decrease over time. If tortuosity stays constant while speed DiD shows asymmetric gains, that confirms wind change rather than better routing.
Args: group_by: "decade", "year", "direction", "nationality" lat_min/lat_max/lon_min/lon_max: Bounding box nationality: Filter by nationality code year_start/year_end: Filter by year range direction: Filter by "eastbound" or "westbound" month_start/month_end: Month filter (supports wrap-around) min_speed_km_day: Minimum speed filter (default: 5.0) max_speed_km_day: Maximum speed filter (default: 400.0) min_positions: Minimum positions in bbox (default: 5) r_min: Minimum tortuosity R to include (e.g. 1.0 excludes artifacts) r_max: Maximum tortuosity R to include (e.g. 5.0 excludes loiterers) period1_years: First period as "YYYY/YYYY" range or "YYYY,YYYY,..." list period2_years: Second period as "YYYY/YYYY" range or "YYYY,YYYY,..." list n_bootstrap: Bootstrap iterations (default: 10000) output_mode: Response format - "json" (default) or "text"
Returns: JSON or text with per-group tortuosity stats, optional comparison
Tips for LLMs: - group_by="decade" to see tortuosity trends over time - Use direction="eastbound" vs "westbound" separately - r_min=1.0, r_max=5.0 focuses on normal transit voyages - period1_years/period2_years for formal comparison with CI - Periods accept "YYYY/YYYY" ranges or "YYYY,YYYY,..." year lists - Combine with maritime_did_speed_test for complete decomposition - min_positions=5 filters out short transits
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| group_by | No | decade | |
| lat_min | No | ||
| lat_max | No | ||
| lon_min | No | ||
| lon_max | No | ||
| nationality | No | ||
| year_start | No | ||
| year_end | No | ||
| direction | No | ||
| month_start | No | ||
| month_end | No | ||
| min_speed_km_day | No | ||
| max_speed_km_day | No | ||
| min_positions | No | ||
| r_min | No | ||
| r_max | No | ||
| period1_years | No | ||
| period2_years | No | ||
| n_bootstrap | No | ||
| output_mode | No | json |