Variability of Ozone Deposition Velocity Over a Mixed Suburban Temperate Forest

Abstract

A 10-year long dataset of half-hourly ozone (O 3 ) fluxes was used to study the variability in deposition velocity (υ d ) over a mixed temperate suburban forest. Average (median) υ d amounted to 0.70 (0.46) cm s −1 , with day-and night-time average (median) of 0.98 (0.73) cm s −1 and 0.46 (0.30) cm s −1 , respectively. It was found that the precipitation form had a marked impact on υ d and the deposition efficiency (υ d/ υ dmax ), with highest values measured when the canopy was dew-wetted or covered with snow. The analysis further evidenced that traffic volume led to increased deposition due to the presence of chemical reactions between O 3 and nitric oxide (NO) above the canopy surface. During the working week, daytime values of υ d, υ d/ υ dmax and the O 3 fluxes (F) were found to be significantly higher than the weekend values, especially during the winter half-year. In a next step, half hourly deposition data were aggregated into day-and night-time monthly values, for a correlative study with measured environmental variables. Monthly average night-time/daytime υ d and υ d/ υ dmax were positively correlated with the relative humidity at the canopy surface (RH(z 0 ′ )) and negatively correlated with the water levels below the ground surface. During the daytime, monthly υ d and υ d/ υ dmax were additionally increased during the working-week when traffic volume was high. There existed, however, substantially different weather conditions, in which unaccounted covariates with a totally different meteorological signature controlled the υ d and F. It was speculated that, among other, biogenic volatile compounds (BVOCs) could have contributed to O 3 quenching in some (spring) months with severe drought stress.

Dry Deposition of Ozone Over Land: Processes, Measurement, and Modeling

“…Data included are laboratory studies (Aldaz, ; Galbally & Roy, ) and field studies from Mawson, Antarctica (Galbally & Allison, ), Mt. Buller, Australia (Galbally & Allison, ), Illinois (Wesely et al, ), Lancaster, England (Colbeck & Harrison, ), Camp Borden (Padro, ; Padro et al, ; Z. Wu et al, ), GLEES Brooklyn Lake (Zeller, ; Zeller & Hehn, , ), Central Plains Experimental Range (Stocker et al, ), Ice Camp Narwahl (Gong et al, ), Alert, Canada (Hopper et al, ), Arctic (Helmig, Bocquet, et al, ), Bruneck in the Southern Alps (Cieslik, ), Summit Greenland (Bocquet et al, ; Helmig, Cohen, et al, ), Flanders (Neirynck & Verstraeten, ), and Horsepool in the Uintah Basin (unpublished).…”

“…A range of approaches has been used to study ozone fluxes over snow, including observing ozone decay in chambers filled with snow (Aldaz, ; Galbally & Roy, ), the flux gradient technique (Bocquet et al, ; Colbeck & Harrison, ; Helmig, Cohen, et al, ; Neirynck & Verstraeten, ; Z. Wu et al, ), EC (Stocker et al, ; Zeller & Hehn, ; Zeller & Nikolov, ), and near‐surface vertical profiles measured with an automated elevator system (Van Dam et al, ).…”

“…Several field studies report increases in inferred nonstomatal uptake over vegetation with relative humidity, providing evidence that aqueous surface chemistry on leaves may be important at ecosystem scales (Altimir et al, 2006;Clifton et al, 2019;Lamaud et al, 2009;Q. Li, Gabay et al, 2018;Neirynck & Verstraeten, 2018;Rannik et al, 2012;L. Zhang et al, 2002).…”

“…Ozone deposition velocity over snow-covered surfaces also exhibits a diel cycle, with maximum values in the afternoon (Helmig, Cohen, et al, 2009;Neirynck & Verstraeten, 2018). The processes driving the diel cycle are uncertain.…”

“…A range of approaches has been used to study ozone fluxes over snow, including observing ozone decay in chambers filled with snow (Aldaz, 1969;Galbally & Roy, 1980), the flux gradient technique (Bocquet et al, 2011;Colbeck & Harrison, 1985;Helmig, Cohen, et al, 2009;Neirynck & Verstraeten, 2018;Z. Wu et al, 2016), EC (Stocker et al, 1995;Zeller & Hehn, 1996;Zeller & Nikolov, 2000), Data included are laboratory studies (Aldaz, 1969;Galbally & Roy, 1980) and field studies from Mawson, Antarctica (Galbally & Allison, 1972), Mt.…”