Open AccessA study of formaldehyde chemistry above a forest canopy
Author(s) -
Sumner Ann Louise,
Shepson Paul B.,
Couch Tara L.,
Thornberry Troy,
Carroll Mary Anne,
Sillman Sandy,
Pippin Margaret,
Bertman Steven,
Tan David,
Faloona Ian,
Brune William,
Young Valerie,
Cooper Owen,
Moody Jennie,
Stockwell William
Publication year - 2001
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 - 10.1029/2000jd900761
Subject(s) - formaldehyde , isoprene , deposition (geology) , ozone , atmospheric chemistry , mixing ratio , environmental chemistry , tree canopy , daytime , chemistry , atmospheric sciences , canopy , environmental science , diel vertical migration , organic chemistry , geology , botany , biology , paleontology , oceanography , sediment , copolymer , polymer
Gas‐phase formaldehyde (HCHO) was measured at a mixed deciduous/coniferous forest site as a part of the PROPHET 1998 summer field intensive. For the measurement period of July 11 through August 20, 1998, formaldehyde mixing ratios ranged from 0.5 to 12 ppb at a height ∼10 m above the forest canopy, with the highest concentrations observed in southeasterly air masses. Concentrations varied on average from a mid‐afternoon maximum influenced by photochemical production of 4.0 ppb, to a late night minimum of 2.2 ppb, probably resulting from dry depositional loss. An analysis of local HCHO sources revealed that isoprene was the most important of the measured formaldehyde precursors, contributing, on average, 82% of the calculated midday HCHO production rate. We calculate that the nighttime HCHO dry deposition velocity is 2.6 times that of ozone, or approximately 0.65 cm/s. In the daytime, photolysis, dry deposition, and reaction with hydroxyl radical (OH) are roughly equally important as loss processes. Explicit calculations of HCHO chemical behavior highlighted the probable importance of transport and surface deposition to understanding the diel behavior of formaldehyde.