edu.ucar.opensky::articles:6548 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T15:15:38.761665 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7bc3zq5 Role of convection in redistributing formaldehyde to the upper troposphere over North America and the North Atlantic during the summer 2004 INTEX campaign 2008-09-05T00:00:00Z publication https://n2t.org/ark:/85065/d7bc3zq5 https://doi.org/10.1029/2007JD009760 Fried, Alan author Olson, J. author Walega, James G. author Crawford, J. author Chen, G. author Weibring, Petter author Richter, Dirk author Roller, Chad B. author Tittel, F. author Porter, M. author Fuelberg, H. author Halland, J. author Bertram, T. author Cohen, R. author Pickering, K. author Heikes, B. author Snow, J. author Shen, H. author O'Sullivan, D. author Brune, W. author Ren, X. author Blake, D. author Blake, N. author Sachse, G. author Diskin, G. author Podolske, J. author Vay, S. author Shetter, Richard E. author Hall, Samuel R. author Anderson, B. author Thornhill, L. author Clarke, A. author McNaughton, C. author Singh, H. author Avery, M. author Huey, G. author Kim, S. author Millet, D. author UCAR/NCAR - Library publisher Measurements of formaldehyde (CH₂O) from a tunable diode laser absorption spectrometer (TDLAS) were acquired onboard the NASA DC-8 aircraft during the summer 2004 INTEX-NA campaign to test our understanding of convection and CH₂O production mechanisms in the upper troposphere (UT, 6 - 12 km) over continental North America and the North Atlantic Ocean. The present study utilizes these TDLAS measurements and results from a box model to (1) establish sets of conditions by which to distinguish "background" UT CH₂O levels from those perturbed by convection and other causes; (2) quantify the CH₂O precursor budgets for both air mass types; (3) quantify the fraction of time that the UT CH₂O measurements over North America and North Atlantic are perturbed during the summer of 2004; (4) provide estimates for the fraction of time that such perturbed CH₂O levels are caused by direct convection of boundary layer CH₂O and/or convection of CH₂O precursors; (5) assess the ability of box models to reproduce the CH₂O measurements; and (6) examine CH₂O and HO₂ relationships in the presence of enhanced NO. Multiple tracers were used to arrive at a set of UT CH₂O background and perturbed air mass periods, and 46% of the TDLAS measurements fell within the latter category. In general, production of CH₂O from CH₄ was found to be the dominant source term, even in perturbed air masses. This was followed by production from methyl hydroperoxide, methanol, PAN-type compounds, and ketones, in descending order of their contribution. At least 70% to 73% of the elevated UT observations were caused by enhanced production from CH₂O precursors rather than direct transport of CH₂O from the boundary layer. In the presence of elevated NO, there was a definite trend in the CH₂O measurement - model discrepancy, and this was highly correlated with HO₂ measurement - model discrepancies in the UT. 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 An edited version of this paper was published by AGU. Copyright 2008 American Geophysical Union. None eng geoscientificInformation