Abstract
Ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements were performed during the summer (13 June–20 August) of 2014 at a rural site in North China Plain. The vertical profiles of aerosol extinction (AE) in the lower troposphere were retrieved to analyze the temporal variations of AE profiles, near-surface AE, and aerosol optical depth (AOD). The average AOD and near-surface AE over the period of study were 0.51 ± 0.26 and 0.33 ± 0.18 km−1 during the effective observation period, respectively. High AE events and elevated AE layers were identified based on the time series of hourly AE profiles, near-surface AEs and AODs. It is found that in addition to the planetary boundary layer height (PBLH) and relative humidity (RH), the variations in the wind field have large impacts on the near-surface AE, AOD, and AE profile. Among 16 wind sectors, higher AOD or AE occur mostly in the directions of the cities upstream. The diurnal variations of the AE profiles, AODs and near-surface AEs are significant and influenced mainly by the source emissions, PBLH, and RH. The AE profile shape from MAX-DOAS measurement is generally in agreement with that from light detection and ranging (lidar) observations, although the AE absolute levels are different. Overall, ground-based MAX-DOAS can serve as a supplement to measure the AE vertical profiles in the lower troposphere.
Highlights
Along with the rapid development of economy and society, aerosol loading levels across China sharply increased over the past several decades [1]
The average aerosol optical depth (AOD) and near-surface aerosol extinction (AE), i.e. 0.51 ± 0.26 and 0.33 ± 0.18 km−1, over the campaign period are slightly smaller than the levels at the nearby suburban site of Xingtai (AOD: 0.65, AE: 0.43 km−1 in May and June 2016) [50]
Based on the correlation of hourly AE profiles between MAX-DOAS and lidar, we found that higher correlation appears when the AOD from MAX-DOAS and relative humidity (RH) are higher (Figure 7c,d)
Summary
Along with the rapid development of economy and society, aerosol loading levels across China sharply increased over the past several decades [1]. Related measurements above are insufficient to observe profiles of aerosol optical properties in the troposphere with no blind region and high time resolution. We made MAX-DOAS measurements during the field campaign of the Vertical Observations of trace Gases and Aerosols (VOGA) at Raoyang, a rural site of NCP, in summer 2014. The primary objective of this study is to retrieve the AE profiles from the MAX-DOAS measurement data, investigate the characteristics and temporal evolution of the AE vertical distribution over this. 3 ofthe polluted 2020, rural11,area, observational site, MAX-DOAS, and lidar instruments, process of spectral analysis, and the retrieval of AE vertical profiles. The characteristics and temporal evolution of the AE vertical distribution over this polluted rural It is surrounded by a cluster of industrial and populated cites, such as Hengshui, area, and compare MAX-DOAS results with lidar AE profiles. More descriptions about the same type of instrument are available in
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