DOAS related techniques and application in photochemical measurement in Changjiang-Huaihe region

Correspondence: Pinhua Xie(phxie@aiofm.ac.cn)

The understanding of the causes of photochemical pollution in Changjiang-Huaihe (Jianghuai) region, China, is limited due to the lack of investigation on the spatial-temporal distribution of secondary pollutants and its precursors, meteorological data and atmospheric oxidation. Aiming at this need, an integrated three-dimensional detection system for the key atmospheric components has been established by combining the in-situ and ground based telemetry. To meet the needs of the three-dimensional distribution detection of key atmospheric trace components (precursors - intermediates - secondary pollutants), a trace gas profile inversion algorithm of 50 m vertical resolution based on Monte Carlo method, named McPrA (Monte carlo Profile retrieval algorithm by AIOFM), and a machine learning algorithm based on MAX-DOAS observation were established, respectively. And the Open-path BroadBand Cavity Enhanced Absorption Spectroscopy (OP-BBCEAS) based on ball platform was established to carry out comparative verification and prior optimization for MAX-DOAS inversion algorithm. Long-term spatial-temporal distribution observations of key atmospheric trace components were carried out over the Jianghuai region, China. Aerosol profiles mainly showed the Gaussian shape with the high value concentrated in the range of 0.5-1.5 km. And the key gases profiles showed the exponential shape and concentrated within 1 km of the surface. The potential sources of trace gases at different heights of Hefei City were studied. It was found that aerosol transport from northern Anhui and northern Jiangsu was significant, and its transport layer was concentrated at the altitude of 500 m. For the polluted gases (NO₂, SO₂ and HCHO), the junction of eastern Anhui and Jiangsu was the main source area for the altitude below 500 m, especially the transport of NO₂ was the most significant. With the increase of the altitude, the influence of northern Anhui on Hefei City was gradually enhanced. The result of an integrated analysis of the meteorological factors affecting ozone pollution in Hefei was shown that the highest ozone concentration was mainly under the control of peripheral subsidence of typhoon. Additionally, a typical site for Jianghuai region, named Science Island in Hefei, was set up as a super observatory for photochemical pollution. The characteristics of the ozone control regime in the Jianghuai region were analyzed, and the quantitative response relationship between ozone generation and precursors were revealed.

This work was supported by the National Natural Science Foundation of China (Nos. U19A2044, 42105132, 42030609) and the National Key Research and Development Program of China (No. 2022YFC3700303).