Characteristics of Asian Pollution at Mt. Bachelor Observatory during Spring

2004

Peter Weiss-Penzias

UWB Data Workshop, Oct. 14, 2004

Acknowledgements:

Dan Jaffe, Isaac Bertschi, and James Dennison

Phil Swartzendruber and Eric Prestbo

Carol Higginbotham

Mt. Bachelor Ski Area Staff

Research ObjectiveCharacterize long-range transport (LRT) of pollution to the

West Coast in the free troposphere (FT) by making continuous measurements of O3, CO, particulates,

mercury and other tracers.

Hypotheses• Springtime LRT events should be stronger and more frequent at

MBO in the FT compared to those seen at Cheeka Peak (CPO), which is in the marine boundary layer (MBL).

• Ozone should be more strongly correlated to CO during events at MBO compared to CPO.

• Background levels of pollutants during spring should be higher at MBO compared to CPO.

• Total gaseous mercury (TGM) should be well correlated with CO in pollution originating from Asia, due to large TGM emissions in that region.

Observed Asian Pollution Events at CPO

CO ppbv O3/CO (r)9-Mar-97 24 -3.2 -0.3029-Mar-97 19 1.2 0.4211-Mar-01 28 4.5 0.597-Apr-01 16 -0.8 -0.4829-Apr-01 4 9.3 0.492-May-01 19 1.2 -0.1012-Jul-01 5 -2.4 -0.2316-Jul-01 7 -1.7 -0.0928-Sep-01 18 2.2 -0.1921-Nov-01 10 1.6 -0.055-Dec-01 16 -2.9 0.559-Jan-02 3 6.2 0.8820-Jan-02 28 2.6 -0.1327-Mar-02 24 2.1 -0.044-May-02 16 1.7 0.0515-May-02 8 -6.4 -0.46All Events 16 0.4 0.06

O3 ppbvEvent Date

From Weiss-Penzias et al., JGR, 2004

Hg0 Measurements at CPO during Asian Pollution Events

From Weiss-Penzias et al., ES&T, 2003

Note: Events were defined slightly differently between two projects.

Mt. Bachelor Observatory (MBO)Hemispheric Perspective

MBO

MBORegional Perspective

MBO Site Information

• 44.0oN, 121.7oW, 2763 meters asl

• Free-standing dormant volcanic cone in the Oregon Cascade Mountains.

• Summit reached by high-speed ski-lift.

• Large, multi-story building at summit.

• No combustion sources at summit, except for daily snow-grooming during ski season.

Instrumentation

• Carbon monoxide – Reduction gas analyzer (Trace Analytical) and non-dispersive infrared instruments (Thermo Electron)

• Ozone – Dasibi UV photometric analyzer.• Particulate Scattering – Single wavelength nephelometer

(Radiance Research), 1 mm size cut.• Total Airborne Mercury – Cold vapor atomic

fluorescence (Tekran 2537A).• Nitrogen Oxides (NO, NO2, PAN) – Chemiluminescence

(API 200 AU).• Temperature and Relative Humidity – Campbell

Scientific HMP 45C.

Spring 2004 Data – LRT Events Highlighted

Could these events be from local or regional pollution?

• Periods of high NOy (> 2 ppbv, spiky) were removed due to snow grooming equipment.

• During event periods, NOy shows very little (< 0.5 ppbv) enhancements.

• Hysplit trajectories for each event show air masses that are of Asian or European origin and are > 3 km above North America before arrival.

• Most events were accompanied by high pressure and low water vapor, indicating free tropospheric air.

Net Enhancements, by Event

N (hrs)

CO (ppbv)

O3 (ppbv)

Tsg (Mm-1)

TGM (ng/m3)

28-Mar 10 84 10.8 13.5 ND1-Apr 18 46 7.0 20.1 0.159-Apr 19 48 11.3 8.6 0.2210-Apr 11 57 27.3 23.5 0.2425-Apr 44 146 36.3 46.9 0.7627-Apr 18 32 9.0 10.1 0.121-May 15 17 10.7 6.6 0.084-May 29 31 15.6 4.8 0.277-May 17 33 13.4 10.4 0.1313-May 26 66 35.1 29.8 0.35

Average 21 56 17.6 17.4 0.26Stdev 10 37 11.0 13.1 0.21

defined as max-min during event, which is defined as CO minimum to minimum.

Enhancement Ratios(Slope of linear least squares fit)

O3/CO (ppbv/ppbv)

Tsg/CO (Mm-1/ppbv)

TGM/CO (ng/m3/100

ppbv)

TGM/O3 (ng/m3/10

ppbv)28-Mar 0.07 0.16 ND ND1-Apr 0.07 0.24 0.25 0.219-Apr -0.09 0.16 0.27 -0.0710-Apr -0.05 0.15 0.37 -0.0425-Apr 0.22 0.33 0.49 0.1227-Apr 0.05 0.20 0.21 0.031-May 0.52 0.25 -0.16 -0.024-May 0.33 0.05 0.65 0.067-May 1.31 0.32 0.20 -0.0313-May 0.37 0.36 0.27 0.08Average 0.28 0.22 0.28 0.04Stdev 0.41 0.10 0.22 0.09

Apr. 25th Event – Industrial Pollution

O3/COr2 = 0.87

Tsg/COr2 = 0.92

TGM/COr2 = 0.92

H2O/O3

r2 = 0.57

Hysplit Trajectory for Apr. 25th

4-5 dayscrossing time

Not clear fromtrajectory when pollutants were picked up

Apr. 9-10 Events – Stratospheric Influence

TGM/COr2 = 0.36

Tsg/COr2 = 0.48

O3/COr2 = 0.03

H2O/O3

r2 = 0.39

Time of O3 peak (strat. infl.)?

Large CO/Tsg peak

Apr. 9-10

May 13 Event – Industrial, High O3

TGM/COr2 = 0.20

Tsg/COr2 = 0.67

O3/COr2 = 0.40

H2O/O3

r2 = 0.67

Asian Poll. MBL Infl.

May 13-14

Comparisons Between Major Events

delCO delO3 delTsg del Hg min H2O10-Apr 57 27.3 27.7 0.31 0.0825-Apr 146 36.3 46.9 0.76 0.2013-May 66 35.1 29.8 0.35 0.22

N (hrs) r 2̂ slope r 2̂ slope r 2̂ slopex10010-Apr 30 0.03 -0.07 0.48 0.25 0.36 0.2925-Apr 44 0.87 0.22 0.92 0.33 0.92 0.4913-May 26 0.40 0.37 0.67 0.36 0.20 0.27

H2O/O3r 2̂ slopex10 slopex100

10-Apr 0.12 -0.43 -0.9925-Apr 0.89 0.12 -0.49

13-May 0.62 0.08 -0.65

O3/CO Tsg/CO TGM/CO

TGM/O3

ConcentrationEnhancements

Correlation with CO

Correlation with O3

Event Scatter Plots of O3, Tsg, TGM, and H2O vs. CO

Event Scatter Plots of TGM, and H2O vs. O3

Comparing CPO and MBO

CO (ppbv) O3 (ppbv) Tsg (Mm-1)Hg0

(ng/m3)2001 CPO 147 47.7 1.692002 CPO 142 43.3 2.2 1.432004 MBO 167 44.4 5.6 1.77

March 28 – May 19CPO data is “marine” periods only.

Conclusions

• Events are stronger (~50 vs. ~15 ppbv) and more numerous (~3 vs. ~10) at MBO vs. CPO.

• O3 moderately well correlated, -- Tsg and TGM well correlated with CO at MBO.

• Background CO 15% elevated at MBO vs. CPO.

• Background O3 not significantly higher at MBO.

Conclusions cont.

• TGM may have sink in stratospheric air and MBL.

• O3/CO relationship often complicated by intrusions of stratospheric air.

• Apr. 25th is largest, most coherent event seen, TGM/CO = ~0.5!