edu.ucar.opensky::articles:24217 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-25T06:32:19.476447 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d71v5j9m Wintertime formaldehyde: Airborne observations and source apportionment over the eastern United States 2021-03-16T00:00:00Z publication https://n2t.org/ark:/85065/d71v5j9m https://doi.org/10.1029/2020JD033518 Green, J. R. author Fiddler, M. N. author Fibiger, D. L. author McDuffie, E. E. author Aquino, Janine A. author Campos, Teresa author Shah, V. author Jaeglé, L. author Thornton, J. A. author DiGangi, J. P. author Wolfe, G. M. author Bililign, S. author Brown, S. S. author UCAR/NCAR - Library publisher Formaldehyde (HCHO) is generated from direct urban emission sources and secondary production from the photochemical reactions of urban smog. HCHO is linked to tropospheric ozone formation, and contributes to the photochemical reactions of other components of urban smog. In this study, pollution plume intercepts during the Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign were used to investigate and characterize the formation of HCHO in relation to several anthropogenic tracers. Analysis of aircraft intercepts combined with detailed chemical box modeling downwind of several cities suggests that the most important contribution to observed HCHO was primary emission. A box model analysis of a single plume suggested that secondary sources contribute to 21 +/- 10% of the observed HCHO. Ratios of HCHO/CO observed in the northeast US, from Ohio to New York, ranging from 0.2% to 0.6%, are consistent with direct emissions combined with at most modest photochemical production. Analysis of the nocturnal boundary layer and residual layer from repeated vertical profiling over urban influenced areas indicate a direct HCHO emission flux of 1.3 x 10(14) molecules cm(-2) h(-1). In a case study in Atlanta, GA, nighttime HCHO exhibited a ratio to CO (0.6%-1.8%) and was anti-correlated with O-3. Observations were consistent with mixing between direct HCHO emissions in urban air masses with those influenced by more rapid HCHO photochemical production. The HCHO/CO emissions ratios determined from the measured data are 2.3-15 times greater than the NEI 2017 emissions database. The largest observed HCHO/CO was 1.7%-1.8%, located near co-generating power stations. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright author(s). This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. None eng geoscientificInformation