A reassessment of HOx South Pole chemistry based on observations recorded during ISCAT 2000

Reported here are modeling results based on ISCAT (Investigation of Sulfur Chemistry of Antarctic Troposphere) 2000 observations recorded at the South Pole (SP) during the Austral Summer of 2000. The observations included a comprehensive set of photochemical parameters, e.g., NO, O3, and CO. It is w...

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Bibliographic Details
Published in:Atmospheric Environment
Main Authors: Chen, G, Davis, D D, Crawford, J, Hutterli, Manuel, Huey, L Gregory, Slusher, D, Mauldin, Lee, Eisele, Fred, Tanner, D, Dibb, Jack E., Buhr, Martin, McConnell, J R, Lefer, Barry, Shetter, R E, Blake, D R, Song, C H, Lombardi, K, Arnoldy, J
Format: Text
Language:unknown
Published: University of New Hampshire Scholars' Repository 2004
Subjects:
Antarctica
South Pole
Photochemistry
HOx
Snow emissions
ISCAT
Atmospheric Sciences
Arctic
Antarctic
Austral
Antarc*
South pole
Online Access:https://scholars.unh.edu/earthsci_facpub/28
https://doi.org/10.1016/j.atmosenv.2003.07.018
Description
Summary:Reported here are modeling results based on ISCAT (Investigation of Sulfur Chemistry of Antarctic Troposphere) 2000 observations recorded at the South Pole (SP) during the Austral Summer of 2000. The observations included a comprehensive set of photochemical parameters, e.g., NO, O3, and CO. It is worthy to note that not only were OH and HO2 observed, but also HOx precursor species CH2O, H2O2, and HONO were measured. Previous studies have suggested that HONO is the major source of OH/HOx in the Arctic; however, observed HONO levels at SPinduced dramatic model overprediction of both HOx and NOx when used to constrain the model calculations. In contrast, model predictions constrained by observed values of CH2O and H2O2 are consistent with the observations of OH and HO2 (i.e., within 20%) for more than half of the data. Significant model overpredictions of OH, however, were seen at the NO levels lower than 50 pptv or higher than 150 pptv. An analysis of HOx budget at the median NO level suggests that snow emissions of H2O2 and CH2O are the single most important primary source of SPHOx, contributing 46% to the total source. Major sinks for HOx are found to be dry deposition of HO2NO2 and HNO3 as well as their reactions with OH. Although ISCAT 2000 led to a major progress in our understanding of SPHOx chemistry, critical aspects of this chemistry are still in need of further investigation.

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