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First MAX‐DOAS Observations of Formaldehyde and Glyoxal in Phimai, Thailand
Author(s) -
Hoque H. M. S.,
Irie H.,
Damiani A.
Publication year - 2018
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2018jd028480
Subject(s) - differential optical absorption spectroscopy , glyoxal , formaldehyde , biomass burning , chemistry , biomass (ecology) , tracer , environmental science , dry season , environmental chemistry , nitrogen , nitrogen dioxide , aerosol , atmospheric sciences , absorption (acoustics) , agronomy , geography , materials science , geology , physics , cartography , organic chemistry , nuclear physics , biology , composite material
Multiaxis differential optical absorption spectroscopy (MAX‐DOAS) observations were performed for the first time in Thailand at the rural site of Phimai (15.18°N, 102.56°E). Vertical profiles of eight components were retrieved separately using the Japanese MAX‐DOAS profile retrieval algorithm, version 2. Here we focused on formaldehyde (HCHO) and glyoxal (CHOCHO) and evaluated their volume mixing ratios in the lowest layer (0–1 km) of the retrieved vertical profiles. We estimated the ratio of CHOCHO to HCHO concentrations ( R GF ), which has been suggested to be an important tracer indicative of changes in volatile organic compound emissions. Higher HCHO and CHOCHO concentrations were observed during the dry season, reflecting the influence of biomass burning. The mean R GF for the Phimai site was estimated to be 0.032 ± 0.005. The estimated R GF for the dry season (0.028 ± 0.002) was lower than that during the wet season (0.040 ± 0.003), when biogenic emissions were dominated. While Phimai can be characterized as an environment with low nitrogen dioxide (NO 2 ) concentrations (<1 ppbv), the potential impact of biomass burning on the lower R GF during the dry season was investigated by the occasional enhancement of NO 2 concentrations as a tracer of biomass burning.