Terrestrial Condition Assessment (TCA) Ozone - Acute

Direct Download (Raster Data Gateway) Objective: Assess impacts to vegetation from acute exposure to ozone (O3) during the growing season (April to September). Data: Two exposure indices were calculated from hourly O3 data collected by the EPA to track effects from chronic O3 exposure (W126 index) and acute O3 exposure (N100). The N100 index is the sum of hours over 100 ppb in a given month and captures peak events of high or acute exposure. For both indices, hourly data was used to calculate monthly values. Monitoring sites were only included if at least 75% of the hourly observations were available, and monthly values were corrected to account for any missing data following the procedures of Lefohn, Knudsen, and Shadwick (2011). Corrected monthly values were totaled across the growing season to generate an annual value. Annual values were averaged over the most recently available 3 year period to generate a value for each site. Site values were then interpolated using inverse distance weighting to attribute values to landscapes within 40 km of a monitoring site. There is typically a 1 year lag between the TCA assessment year and the most recently available for instance, for the 2024 TCA Assessment, ozone data from 2021-2023 were used to compute the 3-year average. For the 2023 TCA Assessment, 2022 ozone source data was not available so the same data from the prior assessment was used. Source data ranges and assessment year in parentheses are: 2017-2019 (TCA Assessment 2020), 2018-2020 (TCA Assessment 2021), 2019-2021 (TCA Assessment 2022), 2019-2021 (TCA Assessment 2023), and 2021-2023 (TCA Assessment 2024). Data Format: Point (site data) interpolated through inverse distance weighting and filtered to areas only within 40 km of an O3 monitor. Units: N100 is expressed in hours Spatial Resolution: 1000m (1km) Source data: EPA Hourly Ozone data Additional Resources: Details on Method Changes and Source Data Versions Overview of the Terrestrial Condition Assessment: TCA Hubsite or Landfire Office Hour Presentation Explore the results of the most recent assessment: TCA Interactive Data Viewer Learn more about the TCA KPI: TCA Dashboard *if you have trouble viewing the Dashboard, please submit a Tableau Viewer Access Request直接下载（栅格数据网关） 研究目标：评估生长季（4月至9月）臭氧（O₃）急性暴露对植被的影响。 数据：本研究基于美国环境保护署（EPA）采集的逐小时臭氧数据，计算得到两类暴露指数，分别用于追踪慢性臭氧暴露（W126指数）与急性臭氧暴露（N100指数）的环境影响。其中N100指数指单月内臭氧浓度超过100ppb的小时数总和，可捕捉高浓度臭氧或急性臭氧暴露的峰值事件。两类指数均基于逐小时观测数据计算得到月度暴露数值。仅纳入逐小时观测数据有效率不低于75%的监测站点，且月度暴露数值按照Lefohn、Knudsen与Shadwick（2011）提出的标准化流程进行缺失数据校正。将校正后的月度数值在完整生长季内求和，得到年度暴露总值；随后以各站点最近连续3年的年度暴露总值的平均值作为该站点的最终表征值。随后采用反距离权重法（Inverse Distance Weighting）对站点级暴露值进行空间插值，将暴露值赋值至监测站点周边40公里范围内的陆地景观区域。 需注意，TCA（陆地状况评估，Terrestrial Condition Assessment）评估年份与所用最新源数据之间通常存在1年的滞后周期：例如2024年TCA评估采用2021-2023年的臭氧数据计算3年平均值；而2023年TCA评估因无法获取2022年的臭氧源数据，故沿用了上一次评估的同源数据集。 各评估年份对应的源数据范围及对应评估标识如下（括号内为评估年份）：2017-2019（2020年TCA评估）、2018-2020（2021年TCA评估）、2019-2021（2022年TCA评估）、2019-2021（2023年TCA评估）以及2021-2023（2024年TCA评估）。 数据格式：站点点位数据经反距离权重法空间插值后，仅保留臭氧监测站点周边40公里范围内的区域。 单位：N100指数以小时为计量单元。 空间分辨率：1000米（1千米）。 源数据：美国环境保护署（EPA）逐小时臭氧监测数据。 附加资源： 1. 方法变更与源数据版本详情：《陆地状况评估要点概述》或Landfire办公室线上汇报材料 2. 探索最新评估结果：TCA交互式数据查看器 3. 了解更多TCA关键绩效指标（KPI）相关信息：TCA仪表盘 *若无法正常访问仪表盘，请提交Tableau查看器访问申请