The transport of tropospheric ozone, ozone precursors, carbon monoxide, etc from Asia to North America is an active area of research (see J.L. Ambrose, et al., 2011) These types of events occur rather dramatically in the springtime, apparently due to meteorological conditions when westerly winds are strong, which carries polluted air across the Pacific. Stratospheric ozone events can be differentiated because they have low moisture and no associated increase in carbon monoxide.

What meteorological factors contribute to the increased transport of Asia-generated air pollution to North America? What occurs meteorologically in the springtime that leads to more westerly transport than any other season? The analyses I've seen say that transport can occur anywhere from 2.5 km to 8 km above sea level.

Are there factors that could cause temporal or spatial shifts in how these types of pollution transport events are recepted in North America?

M. Lin et al., 2011 image

Image from M. Lin et al., 2011 publication showing carbon monoxide crossing the Pacific Ocean caught by Aqua/AIRS, (1018 molecules / cm2)

  • $\begingroup$ Flow is from west (Asia) to east (America). $\endgroup$
    – f.thorpe
    Oct 7, 2015 at 15:28
  • $\begingroup$ so that would be the westerlies then. In your question you have mentioned easterlies. $\endgroup$
    – user1066
    Oct 8, 2015 at 0:02
  • $\begingroup$ how is the transport of pollutants from Asia during the rest of the year ? $\endgroup$
    – user1066
    Oct 8, 2015 at 12:54
  • $\begingroup$ @gansub there are still events that occur other times of the year... but my understanding is that late spring is when the transport is strongest due to meteorological conditions. I can find some other references if you think that would help. $\endgroup$
    – f.thorpe
    Oct 8, 2015 at 18:02
  • $\begingroup$ these westerly winds that move these pollutants - what geopotential height are they ? $\endgroup$
    – user1066
    Oct 9, 2015 at 0:11


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