Aircraft measurements reveal vertical distribution of atmospheric ammonia over the North China Plain in early autumn
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ORIGINAL PAPER
Aircraft measurements reveal vertical distribution of atmospheric ammonia over the North China Plain in early autumn Weiwei Pu1,2 · Heng Guo1,2 · Zhiqiang Ma1,2,3 · Yulu Qiu1,2 · Yixi Tang1,2 · Quan Liu4 · Fei Wang4 · Jiujiang Sheng4 Received: 6 April 2020 / Accepted: 5 July 2020 © Springer Nature Switzerland AG 2020
Abstract Ammonia (NH3) is an atmospheric contaminant contributing to the formation of fine particles, e.g., particulate matter ( PM2.5), which induces respiratory diseases. In the atmosphere, horizontal NH3 levels in the stratosphere, middle-upper troposphere, and planetary boundary layer have been studied using surface monitoring and satellite data, yet N H3 vertical distribution above the planetary boundary layer within the lower troposphere is poorly known. In particular, vertical N H3 data would provide information on the role of N H3 in secondary aerosol formation in the lower troposphere. Here, two N H3 profiles on September 2 and 3, 2017, were obtained by in situ aircraft measurement, plus temperature, dew point temperature, and relative humidity over the North China Plain. We also used synoptic analysis and WRF-CHEM modeling. We observed one pollution layer from 2800 to 3500 m on September 2, and two pollution layers, 1750–2250 m and 2500–3450 m, on September 3. Results show that the highest NH3 concentration above the planetary boundary layer was 28.0 ppb at 2500–3450 m over Baoding, comparable to that observed in the planetary boundary layer, of 33.1 ppb, on September 3, 2017. The transport of clean air masses from the northwest of China led to a sharp decrease in N H3 concentration between 2300 and 2800 m and highlighted a relatively high N H3 concentration of 20.0 ppb at approximately 3000 m, which led to the formation of an elevated pollution layer on September 2. The highest pollution layer of 28.0 ppb at 2500–3450 m on September 3, 2017, appears to be driven by the westerly wind, whereas the lower pollution layer of 20.1 ppb at 1750–2250 m was influenced by both local pollutants of the North China Plain and a vertical entrainment effect. Keywords Vertical profile · Ammonia · Elevated pollution layer · North China Plain · Aircraft measurement
Introduction Weiwei Pu and Heng Guo have contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10311-020-01051-4) contains supplementary material, which is available to authorized users. * Zhiqiang Ma [email protected] * Quan Liu [email protected] 1
Institute of Urban Meteorology, China Meteorological Administration, Beijing 100089, China
2
Environmental Meteorological Forecast Center of Beijing‑Tianjin‑Hebei, China Meteorological Administration, Beijing 100089, China
3
Beijing Shangdianzi Regional Atmosphere Watch Station, Beijing 101507, China
4
Beijing Weather Modification Office, Beijing Meteorological Service, Beijing 100089, China
As the most important gas-phase alkaline species, ammonia (NH3) contributes considerabl
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