Vertical profile of aerosol extinction based on the measurement of O₄of multi-elevation angles with MAX-DOAS*

Abstract

A method for aerosol extinction profile retrieval using ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) is studied, which is based on a look-up table algorithm. The algorithm uses parametric method to represent aerosol extinction profiles and simulate different atmospheric aerosol states through atmospheric radiation transfer model. Based on the method, aerosol extinction profile was obtained during six cloud-free days. The O4 differential air mass factor (dAMF) measured by MAX-DOAS is compared with the corresponding model results under different atmospheric conditions ( R 2 = 0.78 ). The aerosol optical thickness, aerosol weight factor in boundary layer, and the height of the boundary layer are obtained after the process of minimization and look-up table method. The retrieved aerosol extinction in boundary layer is compared with PM2.5 data measured by ground point instrument. The diurnal variation trends of the two methods are in good agreement. The correlation coefficients of the two methods are 0.71 when the aerosol optical thickness is smaller than 0.5. The results show that the look-up table method can obtain the aerosol state of the troposphere and provide validation for other instrument data.

Research of NO2 vertical profiles with look-up table method based on MAX-DOAS

“…In order to decreased the error caused by spectral analysis and atmospheric instability, the hourly average of the measurements are measured out at each elevation angle. [8] It can be seen from Fig. 4(b) that the NO 2 concentration is basically high in the morning and evening, but low in the afternoon.…”

“…In the course of wavelength fitting, small wavelength drift or squeezing is allowed to compensate for the error caused by the instability of the spectrometer. [8] The fitting band of O 4 and NO 2 is 337 nm-370 nm, and the reference spectrum is set as a fixed reference spectrum. The gas cross sections involved in the fitting are NO 2 , and the fitted residual is 1.49 × 10 −3 , which is mainly originated from unknown structure and system noise.…”

“…In 2013, Wu et al [7] have employed the look-up table method of MAX-DOAS to retrieve aerosol extinction profiles, but just with the focus on the noon period (09:00-13:00). In 2019, Mou et al [8] used the look-up table method to retrieve the aerosol extinction profiles from 08:00-16:00, but they did not retrieve the trace gas profiles. In this article, the groundbased MAX-DOAS was applied to carry out continuous observation experiments in Huaibei area.…”

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

“…For example, a new method, deducing aerosol scattering and absorption properties, has recently been developed based on the oxygen dimer (O 4 ) absorptions [38]. The MAX-DOAS technique, as a widely used technique and an additional option, can bridge the observation gap of AE vertical profile in the lower troposphere left by aircraft or light-detection and ranging (lidar) [39][40][41][42][43][44]. However, there have been relatively few studies on the characteristics of AE profiles retrieved by MAX-DOAS, especially in comparison with independent observations, such as the lidar AE profile [37,[45][46][47][48].…”