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

Document Type

Article

Publication Date

12-16-2020

Publication Title

Geophysical Research Letters

Volume

47

Issue

23

First page number:

1

Last page number:

12

Abstract

© 2020. American Geophysical Union. All Rights Reserved. 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.

Keywords

Absorption aerosol optical depth; Arctic warming; Biomass burning; Brown carbon; Radiative effect; Whitening

Disciplines

Environmental Health | Radiochemistry

Language

English

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