Large enhancements in PAN, ozone, and other chemical species (not shown) were observed during a large pollution event on April 23rd (Day 113). Also shown in this plot is "Hours in the Asian Box," a trajectory-derived parameter that provides an estimate of the probability that air has been influenced by the continental boundary layer of central East Asia. |
Home Contact Information Group Members Research Projects Publications C.V. Department of Atmospheric Sciences |
OVERVIEW![]()
Mount Bachelor Observatory (MBO) is located on the summit of Mount
Bachelor, a dormant volcano in the Cascades of central Oregon. The site
is maintained primarily by the Jaffe group
at UW Bothell and Mt. Bachelor,
Inc. ski area. At 2.7 km (9000 ft) above sea level, the research
station regularly receives free tropospheric air, making it an ideal
location for studying a number of intriguing chemical/meteorological
phenomena, particularly long range transport of asian pollution.
Recent research efforts by groups at Mount Bachelor and other sites, in addition to several airplane-based field campaigns and extensive satellite ![]() 2006 MBO FIELD INTENSIVE RECENT DATA ![]() The above figure shows time traces of peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), the ratio of PPN to PAN and ozone measured from April 11 to May 14, 2006 (for reference, day 100 is April 10th). APN mixing ratios varied by orders of magnitude throughout the month and are highly event-driven. PPN/PAN, often used as an indicator for anthropogenic influence, shows that much of the air reaching MBO has been influenced to some degree by anthropogenic hydrocarbons but is also photochemically well-aged. Changes in ozone are often correlated with changes in PAN, especially during pollution episodes (c.f. days 129 and 132). Combining this data with other available measurements and back trajectory analysis, we have been able to gain insight into the origin of these air masses and their effects on ozone production chemistry. The figures below illustrate some of our preliminary findings. ![]() ![]() |
HYSPLIT back trajectories for the
pollution episode shown at the left indicate that a strong Asian
transport event was observed at this time. ~5 days prior to arriving at
MBO, air from the Asian continent was rapidly lofted to the free
troposphere, where westerly winds carried it to North America.
Subsidence-induced warming may have led to thermal decomposition of PAN
and subsequent NOx-catalyzed ozone production. |
The NCAR C-130 during a fly-by of Mount Bachelor. |
Springtime transport of pollution from Asia, as predicted by the GMAO/GEOS-Chem chemical transport model. |