Title Contrasting atmospheric boundary layer chemistry of methylhydroperoxide (CH3OOH) and hydrogen peroxide (H2O2) above polar snow
Author Frey, M.M.; Hutterli, M.A.; Chen, G.; Sjostedt, S.J.; Burkhart, J.F.; Friel, D.K.; Bales, R.C.
Author Affil Frey, M.M., Natural Environment Research Council, British Antarctic Survey, Cambridge, United Kingdom. Other: NASA, Langley Research Center; University of Toronto, Canada; University of California, Merced; Boston College
Source Atmospheric Chemistry and Physics, 9(10), p.3261-3276, . Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1680- 7316
Publication Date 2009
Notes In English. Published in Atmospheric Chemistry and Physics Discussions: 14 January 2009, http://www.atmos-chem-phys- discuss.net/9/1235/2009/acpd-9-1235-2009.html ; accessed in Apr., 2011. 44 refs. Ant. Acc. No: 91571. GeoRef Acc. No: 310578
Index Terms atmospheric boundary layer; boundary layer; diurnal variations; firn; geochemistry; polar regions; polar atmospheres; pollution; snow; temperature; polar regions; Antarctica--South Pole; Greenland--Summit; Antarctica; Arctic region; atmosphere; atmospheric transport; deposition; formaldehyde; Greenland; hydrogen peroxide; ice cores; methyl hydroperoxide; methylhydroperoxide; nitrous oxide; oxidation; photochemistry; photolysis; pollutants; seasonal variations; sinks; snowpack; South Pole; Summit Greenland; transport; troposphere
Abstract Atmospheric hydroperoxides (ROOH) were measured at Summit, Greenland (72.97N, 38.77W) in summer 2003 (SUM03) and spring 2004 (SUM04) and South Pole in December 2003 (SP03). The two dominant hydroperoxides were H2O2 and CH3OOH (from here on MHP) with average (1sigma ) mixing ratios of 1448 (688) pptv, 204 (162) and 278 (67) for H2O2 and 578 (377) pptv, 139 (101) pptv and 138 (89) pptv for MHP, respectively. In early spring, MHP dominated the ROOH budget and showed night time maxima and daytime minima, out of phase with the diurnal cycle of H2O2, suggesting that the organic peroxide is controlled by photochemistry, while H2O2 is largely influenced by temperature driven exchange between the atmosphere and snow. Highly constrained photochemical box model runs yielded median ratios between modeled and observed MHP of 52%, 148% and 3% for SUM03, SUM04 and SP03, respectively. At Summit firn air measurements and model calculations suggest a daytime sink of MHP in the upper snow pack, which decreases in strength through the spring season into the summer. Up to 50% of the estimated sink rates of 1-51011 molecules m-3 s-1 equivalent to 24-96 pptv h-1 can be explained by photolysis and reaction with the OH radical in firn air and in the quasi-liquid layer on snow grains. Rapid processing of MHP in surface snow is expected to contribute significantly to a photochemical snow pack source of formaldehyde (CH2O). Conversely, summer levels of MHP at South Pole are inconsistent with the prevailing high NO concentrations, and cannot be explained currently by known photochemical precursors or transport, thus suggesting a missing source. Simultaneous measurements of H2O2, MHP and CH2O allow to constrain the NO background today and potentially also in the past using ice cores, although it seems less likely that MHP is preserved in firn and ice.
URL http://www.atmos-chem-phys.net/9/3261/2009/acp-9-3261-2009.pdf
Publication Type journal article
Record ID 65007023