Atmospheric Modelling of Mountain Pine Beetle Transport

1. Atmospheric Modelling of Mountain Pine Beetle Transport Peter L. Jackson Brendan Murphy Brenda Moore University of Northern British Columbia Environmental Science & Engineering With assistance from: Ben Burkholder, Vera Lindsay Funded by: NRCan/CFS Mountain Pine Beetle Initiative IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

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 IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

3. 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 IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

4. 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 allows epidemic to spread rapidly over great distances  little is known about passive transport and this is the focus of our work IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

5. MPB Spread in BC 1959-2002 • animation based on annual aerial survey of MPB “reds” (last year’s attack) IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

6. 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 IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

7. Methods • Passive transport of MPB is similar to transport and dispersion of air pollutants • CSU Regional Atmospheric Modeling System (RAMS) to simulate the atmosphere (wind, temperature, humidity, pressure, etc. on a nested 3D grid) for both realistic and idealized simulations • The meteorological fields from RAMS are used to calculate trajectories IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

8. 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 IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

9. 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 IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

10. 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” (see poster) IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

11. 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 IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

12. Realistic 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) IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

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 IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

14. July 14-15, 2004 Peak emergence event IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

15. 0.5 degree PPI radar scan from 00Z 15 July 2004 (1700 PDT 14 July 2004) Reflectivity < 0 DBZ Echo tops 800 – 1500 m AGL Doppler radar image “clear air” returns are some type of insect  timing of appearance is consistent with peak emergence of MPB – click here for animation IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

16. The End IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson

17. Conclusions & Future Work • RAMS seems capable of representing the conditions during MPB emergence and flight • Approaches to future atmospheric modelling: • 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 IUFRO 2005 July 12, 2005 Paper 15 - Peter L. Jackson