Ozone Overpass
Since October 2004 the OMI instrument on NASA's Aura satellite has measured the total ozone column — how much ozone sits in the whole slice of atmosphere above a point — on every orbit. NASA extracts these retrievals at the exact moments the satellite passes over each of 767 ground stations worldwide and publishes one running record per station. TerraPulse organizes those stations into a dex: one slot per station, carrying every overpass measurement made above it. A retrieval is a measurement, not a model — and the ozone hole shows up in the raw numbers: the South Pole station's 59,229 overpasses average 229 DU against an Arctic ~335 DU.
The dex
| Dex | Holds | Records |
|---|---|---|
overpass_station | Fixed ground stations, one slot per station, with the satellite-measured ozone column overhead | 767 |
Each slot is a place — a named station with coordinates and altitude — and its measured series: 2004-10-01 through the latest pass, roughly one to two retrievals per day per station (more near the poles, where orbits converge).
Provenance
The dex traces to NASA's Aura Validation Data Center (AVDC) overpass files for the OMI OMTO3 total-ozone product (Collection 4): satellite retrievals subset to station locations by NASA, quality-screened by NASA's published criteria, and ingested by TerraPulse without further filtering or adjustment.
What's in a record
- Station identity — name, country, AVDC overpass ID
- Location — latitude, longitude, altitude
- Total ozone column — in Dobson Units (DU), one value per satellite pass
- Pass context — orbit, distance from the station, solar zenith angle, cloud fraction and pressure, surface reflectivity, aerosol index
The station roster is built to carry more than ozone: the same slots are designed to take NASA's other overpass products (NO₂, SO₂, formaldehyde, aerosols, UV) as further cited series.