Tunable diode laser measurements of formaldehyde during the TOPSe 2000 study: Distributions, trends, and model comparisons

Alan Fried, Yuhang Wang, Chris Cantrell, Bryan Wert, James Walega, Brian Ridley, Elliot Atlas, Rick Shetter, Barry Lefer, M. T. Coffey, Jim Hannigan, Donald Blake, Nicola Blake, Simone Meinardi, Bob Talbot, Jack Dibb, Eric Scheuer, Oliver Wingenter, Julie Snow, Brian HeikesDieter Ehhalt

Research output: Contribution to journalArticle

40 Scopus citations

Abstract

Airborne measurements of formaldehyde (CH2O) were acquired employing tunable diode laser absorption spectroscopy (TDLAS) during the 2000 Tropospheric Ozone Production About the Spring Equinox (TOPSE) study. This study consisted of seven deployments spanning the time period from 4 February to 23 May 2000 and covered a wide latitudinal band from 40°N to 85°N. The median measured CH2O concentrations, with a few exceptions, did not show any clear temporal trends from February to May in each of five altitude and three latitude bins examined. Detailed measurement-model comparisons were carried out using a variety of approaches employing two different steady state models. Because recent emissions of CH2O and/or its precursors often result in model underpredictions, background conditions were identified using a number of chemical tracers. For background conditions at temperatures warmer than -45°C, the measurement-model agreement on average ranged between -13% and +5% (measurement- model/measurement), which corresponded to mean and median (measurement- model) differences of 3 ± 69 and -6 parts per trillion by volume (pptv), respectively. At very low temperatures starting at around -45°C, significant and persistent (measurement-model) differences were observed from February to early April from southern Canada to the Arctic Ocean in the 6-8 km altitude range. In such cases, measured CH2O was as much as 392 pptv higher than modeled, and the median difference was 132 pptv (83%). Low light conditions as well as cold temperatures may be important in this effect. A number of possible mechanisms involving the reaction of CH3O2 with HO2 to produce CH2O directly were investigated, but in each case the discrepancy was only minimally reduced. Other possibilities were also considered but in each case there was no compelling evidence to support any of the hypotheses. Whatever the cause, the elevated CH2O concentrations significantly impact upper tropospheric HOx levels at high latitudes (>57°N ) in the February-April time frame.

Original languageEnglish (US)
Pages (from-to)13-1 - 13-22
JournalJournal of Geophysical Research: Atmospheres
Volume108
Issue number4
DOIs
StatePublished - Feb 27 2003

Keywords

  • Airborne formaldehyde measurements
  • Formaldehyde during TOPSE
  • Formaldehyde measurements at high latitudes
  • Tunable diode laser measurements

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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    Fried, A., Wang, Y., Cantrell, C., Wert, B., Walega, J., Ridley, B., Atlas, E., Shetter, R., Lefer, B., Coffey, M. T., Hannigan, J., Blake, D., Blake, N., Meinardi, S., Talbot, B., Dibb, J., Scheuer, E., Wingenter, O., Snow, J., ... Ehhalt, D. (2003). Tunable diode laser measurements of formaldehyde during the TOPSe 2000 study: Distributions, trends, and model comparisons. Journal of Geophysical Research: Atmospheres, 108(4), 13-1 - 13-22. https://doi.org/10.1029/2002jd002208