Measurement report: Photochemical production and loss rates of formaldehyde and ozone across Europe
oleh: C. M. Nussbaumer, J. N. Crowley, J. Schuladen, J. Williams, J. Williams, S. Hafermann, A. Reiffs, R. Axinte, H. Harder, C. Ernest, C. Ernest, A. Novelli, A. Novelli, K. Sala, M. Martinez, C. Mallik, C. Mallik, L. Tomsche, L. Tomsche, C. Plass-Dülmer, B. Bohn, J. Lelieveld, J. Lelieveld, H. Fischer
| Format: | Article |
|---|---|
| Diterbitkan: | Copernicus Publications 2021-12-01 |
Deskripsi
<p>Various atmospheric sources and sinks regulate the abundance of tropospheric formaldehyde (HCHO), which is an important trace gas impacting the <span class="inline-formula">HO<sub><i>x</i></sub></span> (<span class="inline-formula">≡</span> <span class="inline-formula">HO<sub>2</sub></span> <span class="inline-formula">+</span> OH) budget and the concentration of ozone (<span class="inline-formula">O<sub>3</sub></span>). In this study, we present the formation and destruction terms of ambient HCHO and <span class="inline-formula">O<sub>3</sub></span> calculated from in situ observations of various atmospheric trace gases measured at three different sites across Europe during summertime. These include a coastal site in Cyprus, in the scope of the Cyprus Photochemistry Experiment (CYPHEX) in 2014, a mountain site in southern Germany, as part of the Hohenpeißenberg Photochemistry Experiment (HOPE) in 2012, and a forested site in Finland, where measurements were performed during the Hyytiälä United Measurements of Photochemistry and Particles (HUMPPA) campaign in 2010. We show that, at all three sites, formaldehyde production from the OH oxidation of methane (<span class="inline-formula">CH<sub>4</sub></span>), acetaldehyde (<span class="inline-formula">CH<sub>3</sub>CHO</span>), isoprene (<span class="inline-formula">C<sub>5</sub>H<sub>8</sub></span>) and methanol (<span class="inline-formula">CH<sub>3</sub>OH</span>) can almost completely balance the observed loss via photolysis, OH oxidation and dry deposition. Ozone chemistry is clearly controlled by nitrogen oxides (<span class="inline-formula">NO<sub><i>x</i></sub></span> <span class="inline-formula">≡</span> NO <span class="inline-formula">+</span> <span class="inline-formula">NO<sub>2</sub></span>) that include <span class="inline-formula">O<sub>3</sub></span> production from <span class="inline-formula">NO<sub>2</sub></span> photolysis and <span class="inline-formula">O<sub>3</sub></span> loss via the reaction with NO. Finally, we use the HCHO budget calculations to determine whether net ozone production is limited by the availability of VOCs (volatile organic compounds; VOC-limited regime) or <span class="inline-formula">NO<sub><i>x</i></sub></span> (<span class="inline-formula">NO<sub><i>x</i></sub></span>-limited regime). At the mountain site in Germany, <span class="inline-formula">O<sub>3</sub></span> production is VOC limited, whereas it is <span class="inline-formula">NO<sub><i>x</i></sub></span> limited at the coastal site in Cyprus. The forested site in Finland is in the transition regime.</p>