Terrestrial Condition Assessment Ozone: Acute Exposure Index at 1km Resolution

N100 index data quantifies acute ozone exposure for vegetation during the growing season, expressed in hours above 100 parts per billion. The U.S. Forest Service generated this raster dataset by interpolating EPA monitoring data using inverse distance weighting within a 40km radius. The 2024 assessment uses a three-year average of source data from 2021-2023.

Use Cases

• Modeling vegetation health impacts based on acute ozone exposure indices.
• Assessing regional air pollution risks for ecosystems using the N100 metric.
• Creating spatial risk maps for land management using the 1km resolution raster.
• Analyzing trends in peak ozone events during the April-September growing season.

Strengths

• Spatial resolution is explicitly defined as 1000 meters (1km).
• Data processing includes quality control, using only monitoring sites with at least 75% hourly data availability.
• Methodology is documented with references to specific procedures (Lefohn, Knudsen, and Shadwick, 2011).
• Clear temporal linkage is provided, showing source data ranges for each assessment year from 2020 to 2024.

Limitations

• Data coverage is limited to areas within 40 kilometers of an EPA ozone monitoring site.
• Column-level documentation is absent; field semantics must be inferred after download.
• There is typically a one-year lag between the assessment year and the most recent source data.

Provenance

Source

U.S. Environmental Protection Agency (EPA) Hourly Ozone data.

Collection Method

Hourly data from EPA monitors was processed into monthly N100 indices, corrected for missing data, summed for the growing season, and averaged over a three-year period. Site values were interpolated using inverse distance weighting.

Time Range

Source data ranges used in assessments: 2017-2019 (2020), 2018-2020 (2021), 2019-2021 (2022 & 2023), 2021-2023 (2024).

Freshness

Last updated 2026-03-13 22:50:25.831690; freshness should be verified.

Geography

Landscapes within 40 km of an EPA ozone monitoring site in the United States.