Naimark Jacob G, Fiore Arlene M, Jin Xiaomeng, Wang Yuxuan, Klovenski Elizabeth, Braneon Christian
Department of Earth and Environmental Sciences, Columbia College Columbia University New York NY USA.
Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory Columbia University Palisades NY USA.
Geophys Res Lett. 2021 Apr 16;48(7):e2020GL091520. doi: 10.1029/2020GL091520. Epub 2021 Apr 1.
Prior work suggests drought exacerbates US air quality by increasing surface ozone concentrations. We analyze 2005-2015 tropospheric column concentrations of two trace gases that serve as proxies for surface ozone precursors retrieved from the OMI/Aura satellite: Nitrogen dioxide (ΩNO NO proxy) and formaldehyde (ΩHCHO; VOC proxy). We find 3.5% and 7.7% summer drought enhancements (classified by SPEI) for ΩNO and ΩHCHO, respectively, corroborating signals previously extracted from ground-level observations. When we subset by land cover type, the strongest ΩHCHO drought enhancement (10%) occurs in the woody savannas of the Southeast US. By isolating the influences of precipitation and temperature, we infer that enhanced biogenic VOC emissions in this region increase ΩHCHO independently with both high temperature and low precipitation during drought. The strongest ΩNO drought enhancement (6.0%) occurs over Midwest US croplands and grasslands, which we infer to reflect the sensitivity of soil NO emissions to temperature.
先前的研究表明，干旱会通过增加地表臭氧浓度来加剧美国的空气质量问题。我们分析了2005年至2015年期间对流层柱状两种痕量气体的浓度，这两种痕量气体可作为从OMI/Aura卫星获取的地表臭氧前体的替代物：二氧化氮（ΩNO；NO替代物）和甲醛（ΩHCHO；挥发性有机化合物替代物）。我们发现，ΩNO和ΩHCHO在夏季干旱期间（根据标准化降水蒸散指数分类）分别增加了3.5%和7.7%，这证实了先前从地面观测中提取的信号。当我们按土地覆盖类型进行子集分析时，ΩHCHO在干旱期间增强最为显著的区域（10%）出现在美国东南部的木质稀树草原。通过分离降水和温度的影响，我们推断该地区生物源挥发性有机化合物排放的增加在干旱期间与高温和低降水均独立地增加了ΩHCHO。ΩNO在干旱期间增强最为显著的区域（6.0%）出现在美国中西部的农田和草原，我们推断这反映了土壤一氧化氮排放对温度的敏感性。
