Open AccessVertical distribution of mercury, CO, ozone, and aerosol scattering coefficient in the Pacific Northwest during the spring 2006 INTEX‐B campaign
Author(s) -
Swartzendruber P. C.,
Chand D.,
Jaffe D. A.,
Smith J.,
Reidmiller D.,
Gratz L.,
Keeler J.,
Strode S.,
Jaeglé L.,
Talbot R.
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 - 10.1029/2007jd009579
Subject(s) - troposphere , aerosol , ozone , atmospheric sciences , environmental science , boundary layer , planetary boundary layer , chemical transport model , meteorology , climatology , geology , physics , thermodynamics
In the spring of 2006, we measured the vertical distribution of gaseous elemental mercury (GEM), CO, ozone, and aerosol scattering coefficient in the Pacific Northwest concurrent with NASA's INTEX‐B campaign. Seven profiles from the surface to 6 km were conducted from 12 April to 8 May along with one flight in the Seattle‐Tacoma boundary layer. Ozone had a bimodal distribution with the lower mode occurring primarily in the mixed layer and the higher mode occurring in the free troposphere. In the free troposphere, the mixing ratios (1 − σ ) of GEM, CO, ozone, and aerosol scattering coefficient were 1.52 (0.165) ng/m 3 , 142 (14.9) ppbv, 78 (7.7) ppbv, and 3.0 (1.8) Mm −1 , respectively. GEM and CO were correlated in the high ozone mode (r 2 = 0.30) but were uncorrelated in the lower mode (r 2 = 0.05). Three flights observed enhancements of GEM and CO with good correlations and with regression slopes (0.0067 (±0.0027) ng/m 3 /ppbv by ordinary least squares regression and 0.0097 (±0.0018) ng/m 3 /ppbv by reduced major axis regression) slightly higher than previous observations of enhancements due to Asian industrial long‐range transport (LRT). The influence of Asian LRT is supported by back trajectories and a global chemical transport model. In the Seattle‐Tacoma boundary layer flight, CO was uncorrelated with GEM, which reflects relatively weaker local GEM sources. On three flights, pockets of air were observed with strong inverse GEM‐ozone and ozone‐CO correlations (in contrast to all data), which is evidence of upper tropospheric/lower stratospheric (UTLS) influence. An extrapolation of the GEM‐CO and GEM‐ozone slopes suggests the UTLS can be depleted of GEM.