When a local .hgt tile is missing, download it from the public AWS S3
skadi bucket, decompress with zlib, and write to the tiles directory
before retrying the lookup. Falls back to Open-Meteo/OpenTopo APIs if
the download fails.
Eliminates the external wgrib2 C tool dependency that blocked HRRR
processing. Implements Lambert Conformal projection, simple packing
(Template 5.0), complex packing with spatial differencing (Template 5.3),
and GRIB2 section parsing — enough to extract point values from HRRR
grid data using only Elixir.
Fetch elevation data along the path between two stations via the
Open-Meteo Elevation API (with Open-Topo-Data fallback), compute
Fresnel zone clearance, earth bulge, and knife-edge diffraction loss,
and store the results per QSO.
- terrain_profiles table with migration and TerrainProfile schema
- ElevationClient with batched API calls and fallback
- TerrainAnalysis with Fresnel/diffraction physics (ITU-R P.526-15)
- TerrainProfileWorker on Oban :terrain queue
- QsoWeatherEnqueueWorker enqueues terrain jobs automatically
- QSO show page displays verdict badge and collapsible elevation table
- Reorder show page: terrain, soundings, solar, HRRR, surface obs
- Fix Dockerfile wgrib2 build (add cmake dependency)
IEM was returning 503s under 10 concurrent workers. Three fixes:
- Req transient retry with exponential backoff on IEM requests
- WeatherFetchWorker Oban job retries failed ASOS/RAOB fetches 2-3h later
with random jitter to avoid thundering herd
- Import script concurrency reduced 10→5, weather queue capped at 3
