Summertime observations of HONO, HCHO, and O₃ at the summit of Whiteface Mountain, New York

Abstract

[1] HONO, HCHO, and O 3 concentrations were measured at the summit of Whiteface Mountain, New York, during the summer of 1999. Concentrations were in the range of 5-400 pptv with a median of 27 pptv and a mean of 46 pptv for HONO, in the range of 30-6170 pptv with a median of 1260 pptv and a mean of 1340 pptv for HCHO, and in the range of 20-105 ppbv with a median of 51 ppbv and a mean of 49 ppbv for O 3 . The daily HO x productions from the photolysis of O 3 , HONO, and HCHO were 6.1, 2.8, and 1.9 ppbv d À1, respectively, contributing 57, 26, and 17% to the overall daily radical budget from these precursors. Significant diurnal variation of average HONO concentrations was observed, with a late morning maximum and a late afternoon/early evening minimum. HNO 3 photolysis on the mountain slope surfaces is proposed as the major daytime source for HONO, sustaining the majority of the observed daytime HONO concentrations against its photolytic loss. The daytime HONO/NO x ratio was also found to be high, $0.33 between 0800 and 1600 LT, suggesting that the transport of HONO from the ground surface to the observation height should be short, perhaps limited to the top portion of the mountain slope. The late afternoon HONO concentrations ($27 pptv) may be considered as typical daytime HONO concentration in the aloft air mass not influenced by surface processes. While particulate nitrate photolysis may contribute significantly as a HONO source, more HONO formation/transport mechanisms are still required to account for the majority of the observed HONO concentration. HCHO concentrations exhibited only a small diurnal variation, with daytime concentrations slightly higher than nighttime concentration. HCHO was mainly transported to the site rather than produced locally from the biogenic photooxidation. O 3 concentrations exhibited a diurnal variation that was similar to but more pronounced than HCHO, suggesting that the daytime in situ O 3 photochemical production was small compared to its loss through photolysis and dry deposition.

Exploring the atmospheric chemistry of nitrous acid (HONO) at a rural site in Southern China

“…The gas phase HNO 3 concentrations are in the range of 100 ppt to 3 ppb with an average of 700 ppt, which are comparable with those observed at other rural sites (e.g. Zhou et al, 2007). Similar variations can be found between HNO 3 and HONO.…”

“…2) are among the highest ever recorded at a site outside of big cities (cf. Alicke et al, 2003;Kleffmann et al, 2005;Cheng et al, 2007;Shon et al, 2007;Zhou et al, 2007). However, when we refer to campaign averages and relate them to measurements which were done in or in the vicinity of big cities ( Table 2) we see that the BG data are at the low end for nighttime and almost average for daytime observations.…”

“…The HONO/NO 2 observed in many field studies range from 2 % to 10 % with lower values in the fresh air masses (Febo et al, 1996;Lammel and Cape, 1996;Alicke et al, 2002Alicke et al, , 2003Stutz et al, 2004;Zhou et al, 2007;Su et al, 2008b;Sörgel et al, 2011b). The measured HONO/NO 2 during the PRIDE-PRD2006 campaign ranged from <1.1 % (1 % quantile) to >35 % (99 % quantile) with mean value of 7.1 ± 6.1 %.…”

“…These measurements revealed concentrations from several ppts in remote and clean areas (e.g. Zhou et al, 2002Zhou et al, , 2007Beine et al, 2006;Ren et al, 2010) up to several ppbs in more polluted environments (e.g. Febo et al, 1996;Stutz et al, 2002;Kanaya et al, 2007;Su et al, 2008a;Yu et al, 2009).…”

Observations of high rates of NO&lt;sub&gt;2&lt;/sub&gt;-HONO conversion in the nocturnal atmospheric boundary layer in Kathmandu, Nepal

“…The water uptake processes can take place on the ground surface (major HONO formation source in this paper) as well as aerosol surfaces. As many earlier papers reported, water droplets (on ground or aerosol) at a RH of over 96% play a role in the HONO sink, leading to lower [HONO]/[NO 2 ] values, which is in agreement with our observation (Lammel and Perner, 1988;Zhou et al, 2007;He et al, 2006;Acker et al, 2005Acker et al, , 2001Lammel, 1999).…”