Formaldehyde over North America and the North Atlantic during the summer 2004 INTEX campaign: Methods, observed distributions, and measurement‐model comparisons

Authors

Alan Fried
James G. Walega
Jennifer R. Olson
Jim H. Crawford
Gao Chen
Petter Weibring
Dirk Richter
Chad Roller
Frank K. Tittel
Brian G. Heikes, University of Rhode IslandFollow
Julie A. Snow
Haiwei Shen, University of Rhode Island
Daniel W. O'Sullivan
Michael Porter
Henry Fuelberg
Jeremy Halland
Dylan B. Millet

Document Type

Article

Date of Original Version

2008

Department

Oceanography

Abstract

A tunable diode laser absorption spectrometer (TDLAS) was operated on the NASA DC‐8 aircraft during the summer INTEX‐NA study to acquire ambient formaldehyde (CH₂O) measurements over North America and the North Atlantic Ocean from ∼0.2 km to ∼12.5 km altitude spanning 17 science flights. Measurements of CH₂O in the boundary layer and upper troposphere over the southeastern United States were anomalously low compared to studies in other years, and this was attributed to the record low temperatures over this region during the summer of 2004. Formaldehyde is primarily formed over the southeast from isoprene, and isoprene emissions are strongly temperature‐dependent. Despite this effect, the median upper tropospheric (UT) CH₂O mixing ratio of 159 pptv from the TDLAS over continental North America is about a factor of 4 times higher than the median UT value of 40 pptv observed over remote regions during TRACE‐P. These observations together with the higher variability observed in this study all point to the fact that continental CH₂O levels in the upper troposphere were significantly perturbed during the summer of 2004 relative to more typical background levels in the upper troposphere over more remote regions. The TDLAS measurements discussed in this paper are employed together with box model results in the companion paper by Fried et al. to further examine enhanced CH₂O distributions in the upper troposphere due to convection. Measurements of CH₂O on the DC‐8 were also acquired by a coil enzyme fluorometric system and compared with measurements from the TDLAS system.

Citation/Publisher Attribution

Fried, A., et al. (2008), Formaldehyde over North America and the North Atlantic during the summer 2004 INTEX campaign: Methods, observed distributions, and measurement‐model comparisons, J. Geophys. Res., 113, D10302, doi: 10.1029/2007JD009185.

Available at: https://doi.org/10.1029/2007JD009185