edu.ucar.opensky::articles:6928 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T15:36:30.051952 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d77m086h Summertime influence of Asian pollution in the free troposphere over North America 2007-05-11T00:00:00Z publication https://n2t.org/ark:/85065/d77m086h https://doi.org/10.1029/2006JD007919 Liang, Q. author Jaegle, L. author Hudman, Rynda C. author Turquety, S. author Jacob, D. author Avery, M. author Browell, E. author Sachse, G. author Blake, D. author Brune, W. author Ren, X. author Cohen, R. author Dibb, J. author Fried, Alan author Fuelberg, H. author Porter, M. author Heikes, B. author Huey, G. author Singh, H. author Wennberg, P. author UCAR/NCAR - Library publisher We analyze aircraft observations obtained during INTEX-A (1 July to 14 August 2004) to examine the summertime influence of Asian pollution in the free troposphere over North America. By applying correlation analysis and principal component analysis (PCA) to the observations between 6 and 12 km, we find dominant influences from recent convection and lightning (13% of observations), Asia (7%), the lower stratosphere (7%), and boreal forest fires (2%), with the remaining 71% assigned to background. Asian air masses are marked by high levels of CO, O&#x2083, HCN, PAN, C&#x2082H&#x2082, C&#x2086H&#x2086, methanol, and SO&#x2084 ^2-. The partitioning of NO_y species in the Asian plumes is dominated by PAN (∼600 pptv), with varying NO_x/HNO&#x2083 ratios in individual plumes, consistent with individual transit times of 3–9 days. Export of Asian pollution occurred in warm conveyor belts of midlatitude cyclones, deep convection, and in typhoons. Compared to Asian outflow measurements during spring, INTEX-A observations display lower levels of anthropogenic pollutants (CO, C&#x2083H&#x2088, C&#x2082H6, C&#x2086H&#x2086) due to shorter summer lifetimes; higher levels of biogenic tracers (methanol and acetone) because of a more active biosphere; and higher levels of PAN, NO_x, HNO&#x2083, and O&#x2083 reflecting active photochemistry, possibly enhanced by efficient NO_y export and lightning. The high ΔO&#x2083/ΔCO ratio (0.76 mol/mol) in Asian plumes during INTEX-A is due to strong photochemical production and, in some cases, mixing with stratospheric air along isentropic surfaces. The GEOS-Chem global model captures the timing and location of the Asian plumes. However, it significantly underestimates the magnitude of observed enhancements in CO, O&#x2083, PAN and NO_x. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright 2007 American Geophysical Union. None eng geoscientificInformation