An Examination of Photochemistry Based on INTEX-NA Observations
Abstract
Measurements made from the NASA DC8 aircraft over the North American continent and just off its east coast during the summertime 2004 INTEX-NA campaign provide an unprecedented array of photochemical observations for evaluation. This presents the opportunity for detailed analysis of photochemistry over a region that is influenced by significant urban and industrial pollution. The upper tropospheric environment is further influenced by convection and lightning production of NOx. A photochemical box model constrained by INTEX-NA observations of long-lived gases is used to predict radical concentrations. Radical predictions are then compared to measurements to test the fidelity of current photochemical theory, subject to the assumption that concentrations are controlled by local photochemistry. Analysis of the INTEX-NA data shows that discrepancies in the model-to-measurement comparison exist for several trace gases, including HO2 and other species that are dependent on HOx (e.g., peroxides, pernitric acid, aldehydes). While in some cases, discrepancies in the form of model underprediction can be explained by the neglect of convective transport, in many cases, discrepancies are contradictory between the species. Further, for some species such as peroxyacetic acid (PAA) and acetaldehyde, both photochemistry and convective transport fall well short of explaining observed upper tropospheric concentrations.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFM.A51C0063O
- Keywords:
-
- 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0345 Pollution: urban and regional (0305;
- 0478;
- 4251);
- 0365 Troposphere: composition and chemistry;
- 0368 Troposphere: constituent transport and chemistry