Measuring the Vertical Profiles of Aerosol Extinction in the Lower Troposphere by MAX-DOAS at a Rural Site in the North China Plain

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.

Temporal Variation of NO2 and HCHO Vertical Profiles Derived from MAX-DOAS Observation in Summer at a Rural Site of the North China Plain and Ozone Production in Relation to HCHO/NO2 Ratio

“…The Yanshan and Taihang Mountains are distributed in the north and west of Raoyang, respectively. A cluster of industrial and populated cites surrounding Raoyang observatory are approximately 50-200 km away (Figure 1b) [25]. More details of geographical conditions and atmospheric environment concerning Raoyang station can be found in previous studies [26][27][28][29].…”

“…The settings of fitting parameters for NO2 a HCHO spectral analysis can be taken from previous studies [16,31], listed in Table S1. the post-processing of data quality control, NO2 and HCHO dSCDs were rejected wh the root mean square (RMS) of spectral fitting residuals was larger than 0.003 [25]. Figu 2 shows an example of spectral fitting for NO2 and HCHO dSCDs from spectrum me ured at the elevation angle of 10° at 12:05 Beijing time (BJ, UTC + 8 h) on 13 June 2014.…”

“…A computer with professional software was used for operational control and data collection. More descriptions about the Mini MAX-DOAS instrument are available in our previous work [25,[30][31][32][33].…”

“…The AE vertical profiles at 360 nm have been successfully retrieved from the oxygen dimer (O 4 ) delta dSCDs during the field campaign. The specific results and inversion parameters (for example, surface albedo, single scattering albedo and asymmetry factor of aerosol, temperature and pressure profiles) for AE profiles can be referred to previous studies [25]. The AE profiles were used as the input parameters for NO 2 and HCHO profile inversion in the second step.…”

MAX-DOAS Measurements of Tropospheric NO2 and HCHO Vertical Profiles at the Longfengshan Regional Background Station in Northeastern China

“…The spectra of dark current and electron offset were also measured at specific operating temperatures, which were used to correct the measured spectra in the daytime and then reduce the influence of the spectrograph's photoelectric noise [32]. More information about the instrumentation parameters can be found in the previous studies [31,43,44]. We used a mini MAX-DOAS instrument from the Hoffmann Messtechnik GmbH, Germany, which was also used in our previous studies [24,36].…”