Role of Daily and Inter Annual Variability in Boundary Conditions on surface air quality in the WUS Dan Jaffe, University of Washington

Transcription

1 Role of Daily and Inter Annual Variability in Boundary Conditions on surface air quality in the WUS Dan Jaffe, University of Washington

2 Inter annual Variations in MDA8>X at at 10 sites in Inter Mountain West IAV due to variations in both spring and summer. Nearly all sites in Rocky Mtn region show similar IAV. Spring variations in boundary conditions. Summer variations in wildfires. Jaffe (2011)

3 Mt. Bachelor, Oregon, 2.8 km above sea level The only high elevation/free trop research site on west coast of U.S. Continuous observations of CO, O 3, aerosols and Hg since 2004; Frequent detection of Asian pollution and biomass burning plumes; More than 2 dozen papers since 2004 on O 3, PM. Hg, LRT, wildfires, etc. Key goal: Identify importance of global sources on US air quality.

4 Transport of Free Trop O 3 to surface sites: Wigder et al 2013

5 Modeled FT O 3 tracer for 4/6/2010 (high O 3 day) using CMAQ w/12 km grid (collab with WSU) Vertical crosssection Surface mixing ratio MBO Boise MBO Boise Wigder et al 2013

6 Springtime O 3 trend at MBO: Gratz et al, 2014

7 Changes in Spring O 3 at MBO 95 th percentile 50 th percentile 5 th percentile This is likely due to the build up of Asian emissions (Gratz et al 2014).

8 Changes in Spring O 3 at MBO 95 th percentile Spring th percentile 5 th percentile This is likely due to the build up of Asian emissions (Gratz et al 2014).

9 MBO O 3 MDA8s May Use measured tracers to id source. 9

10 MBO MDA8s May O 3 5/29 Asian LRT 5/ /9 UTLS 10

11 Western US Ozone sites SJV

12 Inter Annual Variations for May in Nevada Monthly average MDA8 Number of Exceedance days

13 Location May 2012 Relative to May (MDA8, ppbv) Great Basin NV (2.1 km) Mt Bachelor OR (2.8 km) Boise ID MSA (0.8 km) Reno Sparks, NV (1.5 km) Salt Lake City, UT (1.4 km) +7.0 Tehama Cty CA (0.6 km) Portland OR MSA (0.2 km) Lassen N.P. CA (1.8 km) Siskiyou Cty CA (0.8 km) San Joaquin Cty (0.1 km) Higher elevation sites shows greater enhancement.

14 May MDA for Salt Lake City and MBO SLC 2010, 2011, MBO 2010, 2011, 2013, , 2014 SLC 2012 MBO 2012

15 Number of Days MDA8> X at SLC for May only

16 MDA8 at Four High Elevation Sites in WUS in Spring 2012

17 MDA8 at Four High Elevation Sites in WUS in Spring Large scale coherence across WUS 2. Boundary Conditions matter!

18 Spring 2015 O 3 data at Mt. Bachelor 5 year April May Average = 51.1 ppbv 2013 Average to date = 56.6 ppbv

19 Spring 2015 O 3 data at Mt. Bachelor 5 year April May Average = 51.1 ppbv 2013 Average to date = 56.6 ppbv

20 Siberian Fires, Mid April 2015

21 Changes in Spring O 3 at MBO 95 th percentile 50 th percentile 5 th percentile 2015 I predict many more days with elevated O 3 across the WUS in spring 2015.

22 Summary MBO observations show that high MDA8 days can occur due to UTLS, Asian pollution or wildfires. We see a pos trend in spring O 3 at MBO for Modest variations in BC (3 6 ppbv) can have substantial impact on the number of exceedance days, especially if NAAQS is lowered. Observations at MBO can give information on IAV in BC. May 2012 was highest May in last decade in WUS (+2 6 ppbv), due to enhanced UTLS, and this enhanced O 3 by a similar amount at many urban sites in the Western US (Reno, SLC, Boise). Spring 2015 is likely to be even higher than Highest spring O 3 in past 12 years at MBO due to Siberian fires. I predict significantly enhanced O 3 across the WUS in spring 2015.

23 The Boundary Condition Challenge! 1.How do we evaluate inter annual and daily variations in BCs for Western NA? Mountain top observations. Ozonesondes too few observations. Satellites inadequate precision. Lidar? 1.How sensitive is urban air to BC? Does this sensitivity increase at lower mixing ratios? 2.How well can we model variations in BCs? How do we evaluate modeled BCs?

24 SPARES

25 Causes of high O 3 days at MBO: UTLS, Asian pollution and wildfires Ambrose et al 2011 Baylon et al 2014

26 iurnal cycle of Water vapor and O 3 in spring at MBO ight average WV is similar to free trop data from balloons. aytime, WV levels indicate a mix of FT and BL air. WV to help identify FT air

27 mary of ΔO 3 / ΔCO from >100 published studies al/ Temperate: Age cs/ Subtropics: Mean ΔO 3 /ΔCO (ppbv/ppbv) (# plumes) Range of ΔO 3 /ΔCO ays (n=55) s 0.15 (n=39) s 0.22 (n=29) Age Mean ΔO 3 /ΔCO (ppbv/ppbv) (# plumes) ays 0.14 (n=59) s 0.35 (n=13) s 0.63 (n=18) Range of ΔO 3 /ΔCO.A. and Wigder, N.L., Ozone production from wildfires: A critical Atmos. Envir., doi: /j.atmosenv , 2012.

28 Diurnal circulation pattern at Mt. Bachelor h Day: upslope flow brings modified BLairtosummit. Thisairiswetand usually low in O 3. Night: downslope flows brings Free Tropospheric (FT) air to the summit. This air is dry and usually high in O 3. f FT Air of day. r vapor mixing ratio rlift soundings, observations of NOx (Weiss, 2007; Fischer 2009; 2010; Reidmiller )

29 MDA8 O 3 at Mt. Bachelor Proposed new U.S. standard between ppbv Current U.S. O 3 standard Max daily 8 hour avg O 3 at Mt. Bachelor for How does MBO O 3 influence surface AQ?

30 MBO Avg MDA8 vs Month

31 MBO May CO 5/29 5/ /9

32 MBO May WV 5/29 5/ /9

33 May MBO MDA vs 2012

34 The Team

35 know that MBO can experience high O 3 days... ow does FT O 3 influence surface/urban AQ? Mt.Bachelor Boise 48 hour forward air trajectories starting from Mt. Bachelor

36 Use of CMAQ to model FT BL exchange for 4/6/2010 using WSU AIRPACT group (Lamb, Vaughan, Thorpe) Wigder et al 2013