Investigation of NOx emissions and NOx-related chemistry in East Asia using CMAQ-predicted and GOME-derived NO2 columns
Item
Title (Dublin Core)
Investigation of NOx emissions and NOx-related chemistry in East Asia using CMAQ-predicted and GOME-derived NO2 columns
Description (Dublin Core)
In this study, NO<sub>2</sub> columns from the US EPA Models-3/CMAQ model simulations carried out using the 2001 ACE-ASIA (Asia Pacific Regional Aerosol Characterization Experiment) emission inventory over East Asia were compared with the GOME-derived NO<sub>2</sub> columns. There were large discrepancies between the CMAQ-predicted and GOME-derived NO<sub>2</sub> columns in the fall and winter seasons. In particular, while the CMAQ-predicted NO<sub>2</sub> columns produced larger values than the GOME-derived NO<sub>2</sub> columns over South Korea for all four seasons, the CMAQ-predicted NO<sub>2</sub> columns produced smaller values than the GOME-derived NO<sub>2</sub> columns over North China for all seasons with the exception of summer (summer anomaly). It is believed that there might be some error in the NO<sub>x</sub> emission estimates as well as uncertainty in the NO<sub>x</sub> chemical loss rates over North China and South Korea. Regarding the latter, this study further focused on the biogenic VOC (BVOC) emissions that were strongly coupled with NO<sub>x</sub> chemistry during summer in East Asia. This study also investigated whether the CMAQ-modeled NO<sub>2</sub>/NO<sub>x</sub> ratios with the possibly overestimated isoprene emissions were higher than those with reduced isoprene emissions. Although changes in both the NO<sub>x</sub> chemical loss rates and NO<sub>2</sub>/NO<sub>x</sub> ratios from CMAQ-modeling with the different isoprene emissions affected the CMAQ-modeled NO<sub>2</sub> levels, the effects were found to be limited, mainly due to the low absolute levels of NO<sub>2</sub> in summer. Seasonal variations of the NO<sub>x</sub> emission fluxes over East Asia were further investigated by a set of sensitivity runs of the CMAQ model. Although the results still exhibited the summer anomaly possibly due to the uncertainties in both NO<sub>x</sub>-related chemistry in the CMAQ model and the GOME measurements, it is believed that consideration of both the seasonal variations in NO<sub>x</sub> emissions and the correct BVOC emissions in East Asia are critical. Overall, it is estimated that the NO<sub>x</sub> emissions are underestimated by ~57.3% in North China and overestimated by ~46.1% in South Korea over an entire year. In order to confirm the uncertainty in NO<sub>x</sub> emissions, the NO<sub>x</sub> emissions over South Korea and China were further investigated using the ACE-ASIA, REAS (Regional Emission inventory in ASia), and CAPSS (Clean Air Policy Support System) emission inventories. The comparison between the CMAQ-calculated and GOME-derived NO<sub>2</sub> columns indicated that both the ACE-ASIA and REAS inventories have some uncertainty in NO<sub>x</sub> emissions over North China and South Korea, which can also lead to some errors in modeling the formation of ozone and secondary aerosols in South Korea and North China.
Creator (Dublin Core)
Han, K. M.
Song, C. H.
Ahn, H. J.
Park, R. S.
Woo, J. H.
Lee, C. K.
Richter, A.
Burrows, J. P.
Kim, J. Y.
Hong, J. H.
Date (Dublin Core)
2018-01-15
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-9-1017-2009
https://acp.copernicus.org/articles/9/1017/2009/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
