Estimation of the rate of ozone formation in the atmospheric boundary layer of Western Siberia derived from the airborne measurements

Ozone in the troposphere has a negative effect on vegetation and human health. Ozone is the result of local photochemical production, surface deposition, and horizontal (advection) and vertical transport (stratosphere-to-troposphere intrusion). The paper presents the result of calculating the rate of ozone formation in the atmospheric boundary layer. The calculations performed with the airborne measurement data obtained in the background region of Western Siberia (56.1-56.4°N and 84.2-84.8°E). Measurements have been carried out from 2011 to 2013, a total of 10 measurement campaigns were performed. The ozone concentration was measured by the OPTEC 3.02P gas analyzer. Each of the measurement campaigns was conducted in one day for each season. One campaign included four-time airborne measurements (in winter - three-time): first - 2 hours after sunrise, second - 11:30 a.m., third - 2: 30 p.m., fourth - 2 hours before sunset, according to local time GMT+7). Ozone concentration profiles were obtained up to a height of 3000m (2000m in winter). The rate of ozone formation was calculated in two ways. The first approach was based on differences between two vertical profiles that were measured in adjacent time intervals. The obtained profiles of vertical rates were averaged for the boundary layer and free atmosphere. The boundary layer height was determined using the vertical profile of the potential temperature. The second approach was based on solving an inverse problem for a two-dimensional (time-height) convection-diffusion model. The task included an optimization algorithm with the additional stabilizer in the functional. The vertical diffusion coefficients which were required for the calculations were obtained from the WRF-Chem v.3.8.1 model. It was shown that the rate of ozone formation in the atmospheric boundary layer is from 2.8 to 9.9 μg / m³. In the free troposphere - from 0.5 to 2.1 μg / m³. Hence the ozone formation rate in the atmospheric boundary layer is 2-8 times higher than in the free troposphere.

This work was supported by grants RFBR № 17-05-00374, RFBR № 18-45-700020, the Ministry of Education and Science of the Russian Federation (IAO SB RAS State Task No. AAAA-A17-117021310142-5) and ICMMG SB RAS State task no. 0315- 2016-0004