{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,23]],"date-time":"2025-12-23T10:41:37Z","timestamp":1766486497647,"version":"build-2065373602"},"reference-count":43,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2019,6,27]],"date-time":"2019-06-27T00:00:00Z","timestamp":1561593600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Glyoxal (CHOCHO) and formaldehyde (HCHO) trace gases were successfully retrieved from a multi-axis differential optical absorption spectroscopy (MAX-DOAS) system in Beijing (39.95\u00b0N, 116.32\u00b0E) and Baoding (39.15\u00b0N, 115.40\u00b0E), China. The measurements of these trace gases span the period from May 2017 to April 2018. Higher levels of trace gases were observed in Beijing most likely due to increased transport and industrial activities compared to Baoding. Different time scales were analyzed from seasonal to daily levels. Seasonal variation categorized by wintertime maximum and summertime minimum was observed for CHOCHO, while for HCHO maximum values were recorded during summer at both observation points. Variations in the diurnal cycle of trace gases were examined. The results are consistent with strong links to photo-oxidations of VOCs for HCHO production, whereas the CHOCHO diurnal variation can be related to anthropogenic effects in the evening. Weekends didn\u2019t have any significant effect on both HCHO and CHOCHO. We investigated the temperature dependency of HCHO and CHOCHO. HCHO shows positive correlation with air temperature, which strengthened the argument that HCHO production is linked to photo-oxidation of VOCs. CHOCHO is anti-correlated with air temperature. This suggests that photolysis is a major sink for CHOCHO in Beijing and Baoding. We also investigated the relationship between CHOCHO and HCHO VCDs with enhanced vegetation index (EVI) data obtained from MODIS, which represents a direct relation with biogenic emissions. The positive correlations were observed among monthly mean HCHO VCDs and monthly mean EVI at both monitoring stations. The strong correlation of HCHO with EVI found, suggests that oxidation of isoprene and HCHO production is strongly related, while negative correlation was observed among CHOCHO VCDs and EVI.<\/jats:p>","DOI":"10.3390\/rs11131524","type":"journal-article","created":{"date-parts":[[2019,6,27]],"date-time":"2019-06-27T08:19:13Z","timestamp":1561623553000},"page":"1524","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":31,"title":["Ground-Based MAX-DOAS Observations of CHOCHO and HCHO in Beijing and Baoding, China"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0684-1970","authenticated-orcid":false,"given":"Zeeshan","family":"Javed","sequence":"first","affiliation":[{"name":"School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China"}]},{"given":"Cheng","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China"},{"name":"Key Lab of Environmental Optics &amp; Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China"},{"name":"Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China"},{"name":"Anhui Province Key Laboratory of Polar Environment and Global Change, USTC, Hefei 230026, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4489-6593","authenticated-orcid":false,"given":"Muhammad","family":"Khokhar","sequence":"additional","affiliation":[{"name":"Institute of Environmental Sciences and Engineering, National University of Sciences and Technology, Islamabad 44000, Pakistan"}]},{"given":"Wei","family":"Tan","sequence":"additional","affiliation":[{"name":"Key Lab of Environmental Optics &amp; Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China"}]},{"given":"Haoran","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China"}]},{"given":"Chengzhi","family":"Xing","sequence":"additional","affiliation":[{"name":"School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China"}]},{"given":"Xiangguang","family":"Ji","sequence":"additional","affiliation":[{"name":"Key Lab of Environmental Optics &amp; Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China"},{"name":"School of Environmental science and Optoelectronic Technology, University of Science and Technology of China, Hefei 230026, China"}]},{"given":"Aimon","family":"Tanvir","sequence":"additional","affiliation":[{"name":"Institute of Environmental Sciences and Engineering, National University of Sciences and Technology, Islamabad 44000, Pakistan"}]},{"given":"Qianqian","family":"Hong","sequence":"additional","affiliation":[{"name":"School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China"},{"name":"Key Lab of Environmental Optics &amp; Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0015-3395","authenticated-orcid":false,"given":"Osama","family":"Sandhu","sequence":"additional","affiliation":[{"name":"Institute of Environmental Sciences and Engineering, National University of Sciences and Technology, Islamabad 44000, Pakistan"}]},{"given":"Abdul","family":"Rehman","sequence":"additional","affiliation":[{"name":"School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China"}]}],"member":"1968","published-online":{"date-parts":[[2019,6,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Luo, Y., Chen, H., Peng, C., Yang, G., Yang, Y., and Zhang, Y. 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