WNA-FLEXPART-BackTraj-2011: Western North America Air Mass Back Trajectories

NASA's WNA-FLEXPART-BackTraj-2011 dataset provides 15-day backward air mass trajectory simulations for Western North America using the FLEXPART Lagrangian dispersion model driven by ERA5 reanalysis. The model output, at hourly temporal and 1° x 1° spatial resolution from the surface to 20 km, is designed to match gridded ozone observations from ozonesonde, lidar, and aircraft campaigns spanning 1994-2021. This product enables the analysis of source-receptor relationships to identify contributions to tropospheric ozone and other atmospheric components across diurnal to decadal scales.

Use Cases

• Identifying source regions contributing to high ozone episodes in Western North America based on backward trajectory calculations.
• Analyzing seasonal or decadal changes in atmospheric transport patterns using the 1994-2021 temporal coverage.
• Estimating source contributions from different atmospheric layers (surface to 20 km) to downwind receptor observations.
• Supporting source apportionment studies for other atmospheric components co-located with the defined ozone receptor sites.

Strengths

• Provides high-resolution global simulations with hourly temporal and 1° x 1° spatial granularity.
• Covers a long observational period, matching ozone data from 1994 to 2021.
• Includes detailed vertical information, modeling trajectories from the surface up to 20 km altitude.
• Generated with NASA program support and high-performance computing resources, indicating institutional backing.

Limitations

• Critical metadata conflicts exist: the 'last updated' date differs significantly between Data.gov (2026) and NASA Earthdata (2011).
• Column names and exact data structure are unknown across all platform descriptions.
• Dataset size and row counts are not provided, limiting assessment of data volume.

Provenance

Source

National Aeronautics and Space Administration (NASA)

Collection Method

Simulations from the FLEXPART Lagrangian Particle Dispersion Model, driven by ERA5 reanalysis meteorological data.

Time Range

1994-2021 (matching the period of gridded ozone observations used for receptor selection).

Freshness

Last updated dates conflict: Data.gov lists 2026-04-09, while NASA Earthdata lists 2011-12-31.

Geography

Western North America, with global simulation capability for backward trajectories.