Abstract The climate, topography, high population and associated emissions of California pose unique challenges in attaining the ozone (O3) National Ambient Air Quality Standard. California's Sierra Nevada Mountains are situated east, and downwind of, the San Joaquin Valley (SJV), which has some of the worst air quality in the US. This work reports surface and vertical O3 observations over the Sierra Nevada Mountains and the SJV from 1998 to 2018. Over this period, the O3 concentrations observed on highly polluted days (95th percentile) decreased, primarily because of summertime emission reductions. Analysis of surface site diurnal data highlights the impacts that the SJV has on the Sierra Nevada Mountains, particularly at lower elevations. O3 typically remains higher overnight at mountain sites, compared to SJV sites, and as a result mountain sites can have high cumulative exposure to O3. Evidence of local and transport effects on O3 trends across the Sierra Nevada Mountains is presented through examining of the timing of O3 exceedances and correlations with different surface sites and with O3 aloft. The data indicate a strong regional influence of emissions from the SJV over the Sierra Nevada Mountains and aloft up to 3 km.

中文翻译：

---

上风未达标区对加利福尼亚内华达山脉臭氧的影响

摘要 加利福尼亚的气候、地形、人口众多和相关的排放对达到臭氧 (O3) 国家环境空气质量标准提出了独特的挑战。加利福尼亚的内华达山脉位于圣华金山谷 (SJV) 的东风和下风处，那里的空气质量是美国最差的。这项工作报告了 1998 年至 2018 年在内华达山脉和 SJV 上的表面和垂直 O3 观测。在此期间，在高污染天（第 95 个百分位数）观测到的 O3 浓度下降，主要是因为夏季排放量减少。地表站点昼夜数据分析突出了 SJV 对内华达山脉的影响，尤其是在低海拔地区。与 SJV 站点相比，山区站点的 O3 通常在夜间保持较高水平，因此，山区可能有很高的 O3 累积暴露量。通过检查 O3 超标的时间以及与不同地表地点和高空 O3 的相关性，提供了本地和运输对内华达山脉 O3 趋势的影响的证据。数据表明，SJV 的排放对内华达山脉和高达 3 公里的高空产生了强烈的区域影响。