Spatial and Temporal Variability of Brown Carbon in the United States: Implications for Direct Radiative Effects

A newly developed data set from the Interagency Monitoring of PROtected Visual Environments (IMPROVE) observation network, combined with a 3‐D chemical transport model, is used to evaluate the spatial and temporal variability of brown carbon (BrC) in the United States. The model with BrC emitted fro...

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Bibliographic Details
Published in:Geophysical research letters 2020-12, Vol.47 (23), p.n/a
Main Authors: June, Nicole A., Wang, Xuan, Chen, L.‐W. Antony, Chow, Judith C., Watson, John G., Wang, Xiaoliang, Henderson, Barron H., Zheng, Yiqi, Mao, Jingqiu
Format: Article
Language:English
Subjects:
absorption aerosol optical depth
Arctic warming
biomass burning
brown carbon
radiative effect
whitening
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Summary:A newly developed data set from the Interagency Monitoring of PROtected Visual Environments (IMPROVE) observation network, combined with a 3‐D chemical transport model, is used to evaluate the spatial and temporal variability of brown carbon (BrC) in the United States. The model with BrC emitted from biomass burning and biofuel emissions agrees with the seasonal and spatial variability of BrC planetary boundary layer (PBL) absorption aerosol optical depth (AAOD) observations within a factor of 2. The model without whitening, the tendency for absorption to decrease with aerosol aging, overestimates the observed BrC PBL AAOD and does not reflect the measured BrC PBL AAOD spatial variability. The model shows higher absorption direct radiative effects (DRE) from BrC at northern high latitudes than at midlatitudes in spring and summer, due to boreal fire emissions, long whitening lifetimes, and high surface albedos. These findings highlight the need to study BrC over the Arctic region. Key Points Model with whitening can largely reproduce spatial and temporal variability of brown carbon in US. Biogenic SOA appears to be of minor importance to BrC. BrC absorption direct radiative effects appear to be most significant over Arctic region during spring and summer.
ISSN:0094-8276
1944-8007
DOI:10.1029/2020GL090332