Open AccessFormaldehyde over North America and the North Atlantic during the summer 2004 INTEX campaign: Methods, observed distributions, and measurement‐model comparisons
Author(s) -
Fried Alan,
Walega James G.,
Olson Jennifer R.,
Crawford Jim H.,
Chen Gao,
Weibring Petter,
Richter Dirk,
Roller Chad,
Tittel Frank K.,
Heikes Brian G.,
Snow Julie A.,
Shen Haiwei,
O'Sullivan Daniel W.,
Porter Michael,
Fuelberg Henry,
Halland Jeremy,
Millet Dylan B.
Publication year - 2008
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007jd009185
Subject(s) - troposphere , atmospheric sciences , box model , environmental science , mixing ratio , isoprene , formaldehyde , altitude (triangle) , climatology , flux (metallurgy) , meteorology , geology , physics , chemistry , geometry , mathematics , organic chemistry , copolymer , polymer , nuclear magnetic resonance
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 (CH 2 O) measurements over North America and the North Atlantic Ocean from ∼0.2 km to ∼12.5 km altitude spanning 17 science flights. Measurements of CH 2 O 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) CH 2 O 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 CH 2 O 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 CH 2 O distributions in the upper troposphere due to convection. Measurements of CH 2 O on the DC‐8 were also acquired by a coil enzyme fluorometric system and compared with measurements from the TDLAS system.