Open AccessSteady state free radical budgets and ozone photochemistry during TOPSE
Author(s) -
Cantrell Christopher A.,
Mauldin L.,
Zondlo M.,
Eisele F.,
Kosciuch E.,
Shetter R.,
Lefer B.,
Hall S.,
Campos T.,
Ridley B.,
Walega J.,
Fried A.,
Wert B.,
Flocke F.,
Weinheimer A.,
Hannigan J.,
Coffey M.,
Atlas E.,
Stephens S.,
Heikes B.,
Snow J.,
Blake D.,
Blake N.,
Katzenstein A.,
Lopez J.,
Browell E. V.,
Dibb J.,
Scheuer E.,
Seid G.,
Talbot R.
Publication year - 2003
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 - 10.1029/2002jd002198
Subject(s) - ozone , latitude , middle latitudes , atmospheric sciences , troposphere , environmental science , sink (geography) , steady state (chemistry) , photochemistry , atmospheric chemistry , chemistry , climatology , meteorology , physics , geology , cartography , astronomy , geography
A steady state model, constrained by a number of measured quantities, was used to derive peroxy radical levels for the conditions of the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign. The analysis is made using data collected aboard the NCAR/NSF C‐130 aircraft from February through May 2000 at latitudes from 40° to 85°N, and at altitudes from the surface to 7.6 km. HO 2 + RO 2 radical concentrations were measured during the experiment, which are compared with model results over the domain of the study showing good agreement on the average. Average measurement/model ratios are 1.04 (σ = 0.73) and 0.96 (σ = 0.52) for the MLB and HLB, respectively. Budgets of total peroxy radical levels as well as of individual free radical members were constructed, which reveal interesting differences compared to studies at lower latitudes. The midlatitude part of the study region is a significant net source of ozone, while the high latitudes constitute a small net sink leading to the hypothesis that transport from the middle latitudes can explain the observed increase in ozone in the high latitudes. Radical reservoir species concentrations are modeled and compared with the observations. For most conditions, the model does a good job of reproducing the formaldehyde observations, but the peroxide observations are significantly less than steady state for this study. Photostationary state (PSS) derived total peroxy radical levels and NO/NO 2 ratios are compared with the measurements and the model; PSS‐derived results are higher than observations or the steady state model at low NO concentrations.