TY - JOUR
T1 - Seasonal variation of levoglucosan in aerosols over the western North Pacific and its assessment as a biomass-burning tracer
AU - Mochida, Michihiro
AU - Kawamura, Kimitaka
AU - Fu, Pingqing
AU - Takemura, Toshihiko
N1 - Funding Information:
N. Umemoto and A. Kurokawa are gratefully acknowledged for their help with chemical analysis. We thank JAXA/Tokyo Bika Co. Ltd. for the use of the sampling site and help with sample collection, and Tokyo Dylec Corp. for help with the OC/EC determination of the filter samples. We also thank the people who contributed to the development of SPRINTARS. The SPRINTARS simulation in this study was performed on the NIES supercomputer system (NEC SX-8R). We gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for providing the HYSPLIT transport model. This work was supported in part by Grants-in-Aid for Scientific Research 14204055 and 17340166 and the Program for Improvement of Research Environment for Young Researchers from Special Coordination Funds for Promoting Science and Technology commissioned by MEXT , Japan.
PY - 2010/9
Y1 - 2010/9
N2 - Levoglucosan is considered as a useful molecular tracer of biomass-burning aerosols in the atmosphere. To characterize the seasonal variation of its concentrations over the Pacific Ocean and to assess its usefulness as a tracer after long-range transport, we investigated long-term variations of levoglucosan over Chichi-jima in the western North Pacific, from 2001 to 2004. Organic carbon (OC), elemental carbon (EC) and d-glucose were analyzed for comparison. The seasonal variation of levoglucosan concentrations showed a maximum in the winter, which is consistent with the enhanced Asian outflow to the Pacific indicated by backward air-mass trajectories. The concentration levels of levoglucosan estimated from global aerosol model outputs in the winter are, on average, comparable to the observed levels, suggesting that a considerable fraction of levoglucosan did not decompose during long-range transport from the Asian continent by westerly/northwesterly winds. This result is supported by comparable ratios of levoglucosan to EC in Chichi-jima and the East Asian coastal region. Conversely, the measured concentrations of levoglucosan in the summer were significantly lower than the modeled one. This implies a degradation of levoglucosan in the air masses that stagnated over the Pacific, although uncertainties in the model estimate may also be partly responsible for this discrepancy. One possible degradation pathway is oxidation by OH radicals; the contribution of acid-catalyzed reactions needs further investigation.
AB - Levoglucosan is considered as a useful molecular tracer of biomass-burning aerosols in the atmosphere. To characterize the seasonal variation of its concentrations over the Pacific Ocean and to assess its usefulness as a tracer after long-range transport, we investigated long-term variations of levoglucosan over Chichi-jima in the western North Pacific, from 2001 to 2004. Organic carbon (OC), elemental carbon (EC) and d-glucose were analyzed for comparison. The seasonal variation of levoglucosan concentrations showed a maximum in the winter, which is consistent with the enhanced Asian outflow to the Pacific indicated by backward air-mass trajectories. The concentration levels of levoglucosan estimated from global aerosol model outputs in the winter are, on average, comparable to the observed levels, suggesting that a considerable fraction of levoglucosan did not decompose during long-range transport from the Asian continent by westerly/northwesterly winds. This result is supported by comparable ratios of levoglucosan to EC in Chichi-jima and the East Asian coastal region. Conversely, the measured concentrations of levoglucosan in the summer were significantly lower than the modeled one. This implies a degradation of levoglucosan in the air masses that stagnated over the Pacific, although uncertainties in the model estimate may also be partly responsible for this discrepancy. One possible degradation pathway is oxidation by OH radicals; the contribution of acid-catalyzed reactions needs further investigation.
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U2 - 10.1016/j.atmosenv.2010.06.017
DO - 10.1016/j.atmosenv.2010.06.017
M3 - Article
AN - SCOPUS:77955282613
VL - 44
SP - 3511
EP - 3518
JO - Atmospheric Environment
JF - Atmospheric Environment
SN - 1352-2310
IS - 29
ER -