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Perspectives on Long Range Transport – Jeff Lundgren and Ian McKendry Geog/ATSC UBC. Emerging interest on West Coast and elsewhere in Chemical Weather :
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Perspectives on Long Range Transport – Jeff Lundgren and Ian McKendry Geog/ATSC UBC
Emerging interest on West Coast and elsewhere in Chemical Weather: “ local, regional and global distributions of important trace gases and aerosols and their variabilities on time scales of minutes to hours to days, particularly in light of their various impacts, such as on human health, ecosystems, and the meteorological weather and climate”. - Lawrence et al. 2005 http://www.iaff1286.com/kelowna.html
Outline • History – a West Coast Perspective • Trans-Pacific Transport – what we know • Defining “Background” and “chemical weather” - importance to Canada Wide Standards • Outstanding scientific issues
Chernobyl 1986 alerted us to potential impacts of Long Range Transport
Evidence from West of LRT – Siberian Fires etc. McKendry and Lundgren 2000 Climatology of Layer Structures
1998 Asian Dust Event was the catalyst for research a. GOES 10 geostationary satellite image of the dust taken on the evening of April 27. The dust cloud, marked by the brighter reflectance covers the entire northwestern US and adjacent portions of Canada. A dust stream is also seen crossing the Rocky Mountains toward the east. b. Contour map of the PM10 concentration on April 29, 1998. Note the coincidence of high PM10 and satellite reflectance over Washington c. Regional average daily PM10 concentration over the West Coast. The sharp peak on April 27-30 is due to the Asian dust.
On Heels of 1998 Event came April 12-16 2001: “The Perfect Asian Dust Storm” http://www.lakepowell.net/asiandust.htm
Jaffe et. al. ongoing Aircraft and monitoring in Western North America highlights diversity and frequency of events Jaffe et al. 2003
Dust Veils streaming off North Africa 1 March 2005 (this image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite). Available online at the NASA Earth Observatory: tp://earthobservatory.nasa.gov/NaturalHazards/ 2005: A New Pathway identified for Dust – Sahara Eastward to North America
GEOS-CHEM Model Note lack of dust activity near surface Over Eurasia and No precipitation En route ~19,000km
B A Cloud Saharan Dust Layer Lidar Backscatter NRL Aerosol Forecast for Saturna Is.
B A Subsidence Lidar Backscatter NRL Aerosol Forecast for Saturna Is.
From Sunling Gong’s work we know a lot now about the Inter-annual variability and pathways of Asian LRT Spring Zonal fluxes mgm-2s-1 at 140oW Gong et al. 2006
A novel approach to investigating transport – tremendous potential Mean Asian transit time 8 days in mid-trop And 14 days at surface
Scales and Processes affecting intercontinental transport SOURCE SINK Subsidence Synoptic systems Local winds Boundary layer Processes Chemistry TRANSPORT Convection Synoptic systems Boundary Layer Warm Conveyer Belts Planetary waves Deposition Processes Chemistry Synoptic “handover” Minutes - days Minutes-days ~10-15 days
Objectives of Ongoing Research • Identify global pathways • Climatology of transport pathways • Estimate burden • Identify trends • Estimate contribution to local air quality
Estimating contribution to local air quality:With the move to Canada Wide Standards for PM2.5 and O3 there is a need to define background concentrations that not amenable to control strategies and may violate standards background concentration (level) is formally defined as: “ The concentration of a given species in a pristine air mass in which anthropogenic impurities of a relatively short lifetime are not present. The background concentrations of relatively long-lived molecules, methane, carbon dioxide, halocarbons (CF3Cl, CF2Cl2, etc.) and some other species continue to rise due to anthropogenic input, so the composition of background air is undergoing continual change. Background concentration of a given species is sometimes considered to be the concentration of that impurity in a given air mass when the contribution from anthropogenic sources under study is absent. Synonymous with baseline concentration.” 1990, 62, 2175 IUPAC Compendium of Chemical Terminology 2nd Edition (1997)
GFDL Modelling http://www.gfdl.noaa.gov/aboutus/milestones/asian_emissions.html
(Combined Marine Asian Air) NOTE: Proposed CWS PM2.5: 30 mgm-3, 24-hour (midnight to midnight) averaging time - 98th percentile ambient measurement annually, averaged over three consecutive years.
Impact of Episodic events (“Chemical Weather”) on PM2.5 Background 1 McKendry et al, 2001; Husar et al. 2001 2 EPA (2002) suggest an increase of 8.7± 2.3 µgm-3during dust events, with mean maximum dust contributions of 19.7± 8.4 µgm-3
Scientific Issues • Multiple phenomena occurring across a range of spatial and temporal scales • Events singular (spring maximum) • Observations are difficult and interpretation involves multiple lines of evidence • Chemistry likely complex • Urgent need for continuous lidar measurements on west Coast to complement Whistler High Altitude measurements
Publications • McKendry, I. G. and J. Lundgren, 2000. "Tropospheric layering of ozone in regions of urbanised complex and/or coastal terrain - a review," Progress in Physical Geography, 24, p. 359-384. • McKendry, I. G., J. P. Hacker, R. Stull, S. Sakiyama, D. Mignacca and K. Reid, 2001. "Long range transport of Asian dust to the Lower Fraser Valley, British Columbia, Canada," Journal of Geophysical Research, 106(D16), p. 18361-18370. • Husar, R. B., D. M. Tratt, B. A. Schichtel, S. R. Falke, F. Li, D. Jaffe, S. Gassó, T. Gill, N. S. Laulainen, F. Lu, M. C. Reheis, Y. Chun, D. Westphal, B. N. Holben, C. Gueymard, I. McKendry, N. Kuring, G. C. Feldman, C. McClain, R. J. Frouin, J. Merrill, D. DuBois, F. Vignola, T. Murayama, S. Nickovic, W. E. Wilson, K. Sassen, N. Sugimoto and W. C. Malm, 2001. "The Asian dust events of April 1998," Journal of Geophysical Research, 106(D16), p. 18371-18380. • Hacker, J. P., I. G. McKendry and R. B. Stull, 2001. "Modeled downward transport of Asian dust over Western North America during April 1998," Journal of Applied Meteorology, 40, p. 1617-1628. • D. Jaffe, I. G. McKendry and H. Price. 2003 "Six Case Studies of Trans-Pacific Transport of Air Pollutants," Atmospheric Environment, 37, 391-404 • S. L. Gong, X. Y. Zhang, T. L. Zhao, I. G. McKendry and D. Jaffe. 2003 “Characterization of soil dust aerosol in China and its transport/distribution Journal Geophysical Research. 108(D9) • T.L. Zhao, S.L. Gong, X.Y. Zhang, I.G. McKendry 2003, “Modelled size-segregated budgets of soil dust aerosol during ACE-Asia, 2001: Implications for Trans-Pacific transport” - Journal of Geophysical Research, 108, D23, 8665. • H. Price, D. Jaffe, P. Doskey, I. McKendry and T. Anderson. 2003: “Vertical Profiles of O3, aerosols, CO and NMHCs in the Northeast Pacific during the ACE-ASIA and TRACE-P experiments” J. Geophys. Res.Vol. 108, No. D20, 8799 • M. Holzer, I. G. McKendry and D. Jaffe, 2003 "Springtime trans-Pacific atmospheric transport from East Asia: A transit-time-PDF approach" Journal of Geophysical Research, 108 D22, 4708. • Zhao, T.L., S. L. Gong, X. Y. Zhang, I. G. McKendry, and Z. J. Zhou 2006 “A Simulated Climatology of Asian Dust Aerosol and its Trans-Pacific Transport 1. Mean climate and validation” J. Climate 19(1): 88-103 • Gong, S.L., X.Y. Zhang , T.L. Zhao, X. Zhang, I.G. McKendry and C.S. Zhao. 2006: “A Simulated Climatology of Asian Dust Aerosol and its Trans-Pacific Transport 2. Interannual Variability and Climate Connections”, J. Climate 19(1): 104-122 • Bennett C.M., I.G. McKendry, S. Kelly, K. Denike and T. Koch “Impact of the 1998 Gobi Dust Event on Hospital Admissions in the Lower Fraser Valley, British Columbia”, Science of the Total Environ. (in Press) • McKendry, Strawbridge, O’Neill, McDonald, Liu, P. Jaegle, Jaffe, Fairlie, A Case of Trans-Pacific Transport of Saharan Dust to Western North America, JGR