TY - JOUR
T1 - Global model simulation of summertime U.S. ozone diurnal cycle and its sensitivity to PBL mixing, spatial resolution, and emissions
AU - Lin, Jin Tai
AU - Youn, Daeok
AU - Liang, Xin Zhong
AU - Wuebbles, Donald J.
N1 - Funding Information:
The research was supported in part by the United States Environmental Protection Agency Science to Achieve Results (STAR) Program under award number EPA RD-83337301-0 and the National Oceanic and Atmospheric Administration Education Partnership Program (EPP) COM Howard 631017. The authors acknowledge NCAR for the ECMWF ERA-40 data; GEIA/POET for the POET emission data; and NCSA/UIUC for the supercomputing support. We thank Peter Hess, Jean-Francois Lamarque and Larry Horowitz for discussions on the model performance and uncertainties. The views expressed are those of the authors and do not necessarily reflect those of the sponsoring agencies and other organizations including the Illinois State Water Survey.
PY - 2008/11
Y1 - 2008/11
N2 - Simulation of summertime U.S. surface ozone diurnal cycle is influenced by the model representation of planetary boundary layer (PBL) mixing, spatial resolution, and precursor emissions. These factors are investigated here for five major regions (Northeast, Midwest, Southeast, California, and Southwest) by using the Model for Ozone And Related chemical Tracers version 2.4 (MOZART-2.4), with important modifications, to conduct sensitivity experiments for summer 1999 with three PBL mixing schemes, two horizontal resolutions and two emissions datasets. Among these factors, the PBL mixing is dominant. The default non-local scheme well reproduces the observed ozone diurnal variation, where the timing for the afternoon maximum and the morning minimum is within 1 h of the observed; biases for the minimum are less than 5 ppb except over the Southeast; and the ozone maximum-minimum contrast (OMMC) is within 10 ppb of observations except for the overprediction by 18.9 ppb over the Northeast. In contrast, the local scheme significantly overestimates the OMMC by 10-34 ppb over all regions as ozone and precursors are trapped too close to the ground. On the other hand, the full-mixing assumption underestimates the OMMC by 0-25 ppb, except over the Northeast, as the nighttime ozone decline is greatly underpredicted. As compared to PBL mixing, the effects of horizontal resolutions and precursor emissions being used are smaller but non-negligible. Overall, with the non-local mixing scheme, relatively high horizontal resolution (∼1.1°) and updated emissions data, the modified MOZART is capable of simulating the main features of the observed ozone diurnal cycle.
AB - Simulation of summertime U.S. surface ozone diurnal cycle is influenced by the model representation of planetary boundary layer (PBL) mixing, spatial resolution, and precursor emissions. These factors are investigated here for five major regions (Northeast, Midwest, Southeast, California, and Southwest) by using the Model for Ozone And Related chemical Tracers version 2.4 (MOZART-2.4), with important modifications, to conduct sensitivity experiments for summer 1999 with three PBL mixing schemes, two horizontal resolutions and two emissions datasets. Among these factors, the PBL mixing is dominant. The default non-local scheme well reproduces the observed ozone diurnal variation, where the timing for the afternoon maximum and the morning minimum is within 1 h of the observed; biases for the minimum are less than 5 ppb except over the Southeast; and the ozone maximum-minimum contrast (OMMC) is within 10 ppb of observations except for the overprediction by 18.9 ppb over the Northeast. In contrast, the local scheme significantly overestimates the OMMC by 10-34 ppb over all regions as ozone and precursors are trapped too close to the ground. On the other hand, the full-mixing assumption underestimates the OMMC by 0-25 ppb, except over the Northeast, as the nighttime ozone decline is greatly underpredicted. As compared to PBL mixing, the effects of horizontal resolutions and precursor emissions being used are smaller but non-negligible. Overall, with the non-local mixing scheme, relatively high horizontal resolution (∼1.1°) and updated emissions data, the modified MOZART is capable of simulating the main features of the observed ozone diurnal cycle.
KW - Emissions
KW - Ozone diurnal cycle
KW - PBL mixing
KW - Resolution
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U2 - 10.1016/j.atmosenv.2008.08.012
DO - 10.1016/j.atmosenv.2008.08.012
M3 - Article
AN - SCOPUS:54349095576
SN - 1352-2310
VL - 42
SP - 8470
EP - 8483
JO - Atmospheric Environment
JF - Atmospheric Environment
IS - 36
ER -