IUFRO 2005 July 12, 2005

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

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

c)
b)
Photo credits (clockwise from top) a)
http//www.ecoforestry.ca/jrnl_artilces/images/17-
1-Partridge-Reuters.jpg bc) http//www.sparwood.b
c.ca/forest/untreated.htm d) http//www.pfc.fores
try.ca/entomology/mpb/management/
silviculture/images/valley_lrg.jpg
3
MPB Behaviour

• behaviour to a large extent is meteorologically
  controlled
• Emergence and flight in summer after 3 days of
  Tmax gt 18 ºC but lt 30C
• Peak emergence for successful mass-attack occurs
  when Tmax gt 25 ºC

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

5
MPB Spread in BC 1959-2002

• animation based on annual aerial survey of MPB
  reds (last years attack)

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

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

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

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 gt 25 C, but lt 30 C

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)

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

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)
13
Back Trajectories ending at 00Z 24 July 2002
(1700 PDT)

• issue is how high do they fly?
• entomologists dont know
• weather radar offers promise

105m
1100m
14
July 14-15, 2004 Peak emergence event
15
0.5 degree PPI radar scan from 00Z 15 July 2004
(1700 PDT 14 July 2004) Reflectivity lt 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
16
The End
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