{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T21:47:58Z","timestamp":1772142478732,"version":"3.50.1"},"reference-count":61,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2023,3,20]],"date-time":"2023-03-20T00:00:00Z","timestamp":1679270400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"State Key Laboratory of Applied Optics","award":["SKLAO2021001A02"],"award-info":[{"award-number":["SKLAO2021001A02"]}]},{"name":"State Key Laboratory of Applied Optics","award":["2020KJ003"],"award-info":[{"award-number":["2020KJ003"]}]},{"name":"S&amp;T Development Fund of CAMS","award":["SKLAO2021001A02"],"award-info":[{"award-number":["SKLAO2021001A02"]}]},{"name":"S&amp;T Development Fund of CAMS","award":["2020KJ003"],"award-info":[{"award-number":["2020KJ003"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The vertical profiles of nitrogen dioxide (NO2) and formaldehyde (HCHO) in the troposphere at the Longfengshan (LFS) regional atmospheric background station (127\u00b036\u2032 E, 44\u00b044\u2032 N, 330.5 m above sea level) from 24 October 2020 to 13 October 2021 were retrieved from solar scattering spectra by multi-axis differential optical absorption spectroscopy (MAX-DOAS). We analyzed the temporal variations of NO2 and HCHO as well as the sensitivity of ozone (O3) production to the concentration ratio of HCHO to NO2. The largest NO2 volume mixing ratios (VMRs) occur in the near-surface layer for each month, with high values concentrated in the morning and evening. HCHO has an elevated layer around the altitude of 1.4 km consistently. The means \u00b1 standard deviations of vertical column densities (VCDs) and near-surface VMRs were 4.69 \u00b1 3.72 \u00d71015 molecule\u00b7cm\u22122 and 1.22 \u00b1 1.09 ppb for NO2, and they were 1.19 \u00b1 8.35 \u00d7 1016 molecule\u00b7cm\u22122 and 2.41 \u00b1 3.26 ppb for HCHO. The VCDs and near-surface VMRs for NO2 were high in the cold months and low in the warm months, while HCHO presented the opposite. The larger near-surface NO2 VMRs appeared in the condition associated with lower temperature and higher humidity, but this relationship was not found between HCHO and temperature. We also found the O3 production at the Longfengshan station was mainly in the NOx-limited regime. This is the first study presenting the vertical distributions of NO2 and HCHO in the regional background atmosphere of northeastern China, which are significant to enhancing the understanding of background atmospheric chemistry and regional ozone pollution processes.<\/jats:p>","DOI":"10.3390\/s23063269","type":"journal-article","created":{"date-parts":[[2023,3,20]],"date-time":"2023-03-20T06:48:35Z","timestamp":1679294915000},"page":"3269","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["MAX-DOAS Measurements of Tropospheric NO2 and HCHO Vertical Profiles at the Longfengshan Regional Background Station in Northeastern China"],"prefix":"10.3390","volume":"23","author":[{"given":"Shuyin","family":"Liu","sequence":"first","affiliation":[{"name":"State Key Laboratory of Severe Weather & Institute of Tibetan Plateau Meteorology, Chinese Academy of Meteorological Sciences, Beijing 100081, China"}]},{"given":"Siyang","family":"Cheng","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Severe Weather & Institute of Tibetan Plateau Meteorology, Chinese Academy of Meteorological Sciences, Beijing 100081, China"},{"name":"State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China"}]},{"given":"Jianzhong","family":"Ma","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Severe Weather & Institute of Tibetan Plateau Meteorology, Chinese Academy of Meteorological Sciences, Beijing 100081, China"}]},{"given":"Xiaobin","family":"Xu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Severe Weather & Institute of Tibetan Plateau Meteorology, Chinese Academy of Meteorological Sciences, Beijing 100081, China"}]},{"given":"Jinguang","family":"Lv","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China"}]},{"given":"Junli","family":"Jin","sequence":"additional","affiliation":[{"name":"Meteorological Observation Center of China Meteorological Administration, Beijing 100081, China"}]},{"given":"Junrang","family":"Guo","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Severe Weather & Institute of Tibetan Plateau Meteorology, Chinese Academy of Meteorological Sciences, Beijing 100081, China"}]},{"given":"Dajiang","family":"Yu","sequence":"additional","affiliation":[{"name":"Longfengshan Regional Background Station, Heilongjiang Meteorological Bureau, Wuchang 150200, China"}]},{"given":"Xin","family":"Dai","sequence":"additional","affiliation":[{"name":"Longfengshan Regional Background Station, Heilongjiang Meteorological Bureau, Wuchang 150200, China"}]}],"member":"1968","published-online":{"date-parts":[[2023,3,20]]},"reference":[{"key":"ref_1","unstructured":"Seinfeld, J.H., and Pandis, S.N. 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