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Atmospheric Transport and Dispersion of the Mountain Pine Beetle in British Columbia

Atmospheric Transport and Dispersion of the Mountain Pine Beetle in British Columbia. Peter L. Jackson Yuanqiao Wen Brendan Murphy Brenda Moore University of Northern British Columbia Funded by: NRCan/CFS Mountain Pine Beetle Initiative. Mountain Pine Beetle (MPB) infestation

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Atmospheric Transport and Dispersion of the Mountain Pine Beetle in British Columbia

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  1. Atmospheric Transport and Dispersion of the Mountain Pine Beetle in British Columbia Peter L. Jackson Yuanqiao Wen Brendan Murphy Brenda Moore University of Northern British Columbia Funded by: NRCan/CFS Mountain Pine Beetle Initiative 12th AMS Mountain Meteorology Conference August 31, 2006

  2. Mountain Pine Beetle (MPB) infestation • has reached epidemic proportions in central BC affecting more than 7 million ha and 280 million m3 of timber (2004 red attack) a) d) • successful reproduction requires • mass attack to overwhelm tree b) c) Photo credits (clockwise from top): a) http://www.ecoforestry.ca/jrnl_artilces/images/17-1-Partridge-Reuters.jpg b&c) http://www.sparwood.bc.ca/forest/untreated.htm d) http://www.pfc.forestry.ca/entomology/mpb/management/ silviculture/images/valley_lrg.jpg 12th AMS Mountain Meteorology Conference August 31, 2006

  3. So, what do beetles have to do with mountain meteorology? Besides the name (Mountain Pine Beetle), meteorological issues are: • Do MPB utilize winds in the ABL to aid their movement?, and if so • Are they able make the “jump” across the Rockies from the beetle infested area in the BC central interior to the Jack Pine stands to the east? 12th AMS Mountain Meteorology Conference August 31, 2006

  4. MPB Behaviour • behaviour to a large extent is meteorologically controlled • Emergence and flight in summer after 3 days of Tmax > 18 ºC but < 30°C • Peak emergence for successful mass-attack occurs when Tmax > 25 ºC 12th AMS Mountain Meteorology Conference August 31, 2006

  5. Dispersion is • active by flight over short distances / light wind (local scale: within stand over a few km) • passive advection due to winds and turbulence above and within canopy (landscape scale: between stands perhaps 10-100 km) • Passive transport may allow epidemic to spread rapidly over great distances  little is known about passive transport and this is the focus of our work 12th AMS Mountain Meteorology Conference August 31, 2006

  6. MPB Spread in BC 1959-2002 • animation based on annual aerial survey of MPB “reds” (last year’s attack) 12th AMS Mountain Meteorology Conference August 31, 2006

  7. MPB Infestation 2005 • eastward movement of the “front” • spread of MPB limited by the -40 ºC annual minimum isotherm • climate change moves -40 ºC northeastward • concern over MPB crossing the Rocky Mountains and affecting the Jack Pine stands of Northern Canada 12th AMS Mountain Meteorology Conference August 31, 2006

  8. Methods • Assume that passive transport of MPB is similar to transport and dispersion of air pollutants • CSU Regional Atmospheric Modeling System (RAMS) to simulate the conditions during MPB flight • The meteorological fields from RAMS are used to calculate trajectories 12th AMS Mountain Meteorology Conference August 31, 2006

  9. The Synoptic weather pattern determines the atmospheric background conditions in which MPB emerge and move. • Average weather pattern(s) associated with MPB flight are found using compositing • This leads to an understanding of regional wind patterns during flight 12th AMS Mountain Meteorology Conference August 31, 2006

  10. Synoptic Climatology • It is likely that passive transport will be most important when peak emergence is occurring • Peak emergence is associated with higher temperatures • Define HC2 as days with Tmax > 25 C, but < 30 C 12th AMS Mountain Meteorology Conference August 31, 2006

  11. composite 2002 Evolution of HC2 composite 500 hPa and Lifted Index (shaded) based on NCEP Reanalysis data: as upper ridge passes atmosphere becomes moderately unstable (Lifted index negative) resulting in “thermals” convecting MPB into the ABL 12th AMS Mountain Meteorology Conference August 31, 2006

  12. Realistic event Simulation Prince George Infestation East of Rockies – initiated in 2002: Hourly output from RAMS simulation at model level 2 (~40 m AGL), from grid 4 at 3 km horizontal resolution (only every 2nd wind vector shown) 12th AMS Mountain Meteorology Conference August 31, 2006

  13. Back Trajectories ending at 00Z 24 July 2002 (17:00 PDT) • issue is: how high do they fly? • entomologists don’t know • weather radar offers promise… 105m 1100m 12th AMS Mountain Meteorology Conference August 31, 2006

  14. July 25/26 2005 event similar to synoptic climatology • Warm • MSLP falling • Preceded by passage of upper ridge 12th AMS Mountain Meteorology Conference August 31, 2006

  15. MPB flux in ABL = 42 million beetles per hour crossing a 1 km line 12th AMS Mountain Meteorology Conference August 31, 2006

  16. Conclusions and Future Work • MPB emergence, flight, mortality determined by weather • Potential for long-range transport in ABL seen on radar and verified by in-situ capture • Trajectory analysis indicates movement across Rockies likely explanation for start of infestation to the east • We have simulated over 60 MPB flight days and will be producing “ensemble” trajectory estimates of MPB long-range movement for input into Decision Support models used by forest managers 12th AMS Mountain Meteorology Conference August 31, 2006

  17. The End 12th AMS Mountain Meteorology Conference August 31, 2006

  18. Future Work • Continue idealized simulations in relation to terrain • “rules of thumb” for beetle spread on the landscape • Continue simulation / validation of case studies to predict where beetles go from one year to the next. • used in real time for planning beetle control strategies • Ensemble trajectories created for each grid point in the landscape, based on a runs of a large number of past peak emergence heating cycle events. • used as input to beetle spread scenarios models for forest managers to assess the impact of silvicultural and management practices 12th AMS Mountain Meteorology Conference August 31, 2006

  19. Idealized Simulations • goal is to understand how atmospheric flows in complex terrain might affect MPB transport • Idealized (sinusoidal) terrain inserted into RAMS • Under light synoptic conditions generate anabatic (upslope) flows by day • Intent is to insert “particles” into the flow field and see how they are dispersed • N-S vertical cross section with ridges running W-E in afternoon • Contours = Temperature 12th AMS Mountain Meteorology Conference August 31, 2006

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