An assessment of HOx chemistry in the tropical pacific boundary layer: Comparison of model simulations with observations recorded during PEM tropics A

Authors

G. Chen, Georgia Institute of Technology
D. Davis, Georgia Institute of Technology
J. Crawford, NASA Langley Research Center
B. Heikes, University of Rhode Island
D. O'Sullivan, US Naval Academy
M. Lee, Korea Institute Of Ocean Science & Technology
F. Eisele, National Center for Atmospheric Research
L. Mauldin, National Center for Atmospheric Research
D. Tanner, Georgia Institute of Technology
J. Collins, NASA Langley Research Center
J. Barrick, NASA Langley Research Center
B. Anderson, NASA Langley Research Center
D. Blake, University of California, Irvine
J. Bradshaw, Georgia Institute of Technology
S. Sandholm, Georgia Institute of Technology
M. Carroll, University of Michigan, Ann Arbor
G. Albercook, University of Michigan, Ann Arbor
A. Clarke, University of Hawaiʻi at Mānoa

Document Type

Article

Date of Original Version

4-17-2001

Abstract

Reported are the results from a comparison of OH, H2O2CH3OOH, and O3 observations with model predictions based on current HOx-CH4 reaction mechanisms. The field observations are those recorded during the NASA GTE field program, PEM-Tropics A. The major focus of this paper is on those data generated on the NASA P-3B aircraft during a mission flown in the marine boundary layer (MBL) near Christmas Island, a site located in the centra l equatorial Pacific (i.e., 2°N, 157°W). Taking advantage of the stability of the southeastern trade-winds, an air parcel was sampled in a Lagrangian mode over a significant fraction of a solar day. Analyses of these data revealed excellent agreement between model simulated and observed OH. In addition, the model simulations reproduced the major features in the observed diurnal profiles of H2O2 and CH3OOH. In the case of O3, the model captured the key observational feature which involved an early morning maximum. An examination of the MBL HOx budget indicated that the O(1D) + H2O reaction is the major source of HOx while the major sinks involve both physical and chemical processes involving the peroxide species, H2O2 and CH3OOH. Overall, the generally good agreement between model and observations suggests that our current understanding of HOx-CH4 chemistry in the tropical MBL is quite good; however, there remains a need to critically examine this chemistry when both CH2O and HO2 are added to the species measured.

Publication Title, e.g., Journal

Journal of Atmospheric Chemistry

Volume

38

Issue

3

Citation/Publisher Attribution

Chen, G., D. Davis, J. Crawford, B. Heikes, D. O'Sullivan, M. Lee, F. Eisele, L. Mauldin, D. Tanner, J. Collins, J. Barrick, B. Anderson, D. Blake, J. Bradshaw, S. Sandholm, M. Carroll, G. Albercook, and A. Clarke. "An assessment of HOx chemistry in the tropical pacific boundary layer: Comparison of model simulations with observations recorded during PEM tropics A." Journal of Atmospheric Chemistry 38, 3 (2001). doi: 10.1023/A:1006402626288.