12 th AMS Mountain Meteorology Conference August 31, 2006 1 Atmospheric Transport and Dispersion of the Mountain Pine Beetle in British Columbia Peter

12th AMS Mountain Meteorology Conference August 31, 2006

1

Atmospheric Transport and Dispersion of the Mountain Pine

Beetle in British Columbia

Peter L. Jackson

Yuanqiao Wen

Brendan Murphy

Brenda MooreUniversity of Northern British Columbia

Funded by: NRCan/CFS Mountain Pine Beetle Initiative


2

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

a)

c)b)

d)

• successful reproduction requires mass attack to overwhelm tree

•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)

http://www.ecoforestry.ca/jrnl_artilces/images/17-1-Partridge-Reuters.jpg

http://www.sparwood.bc.ca/forest/untreated.htm

http://www.pfc.forestry.ca/entomology/mpb/management/

http://www.pfc.forestry.ca/entomology/mpb/management/silviculture/images/valley_lrg.jpg

http://www.pfc.forestry.ca/entomology/mpb/management/silviculture/images/valley_lrg.jpg


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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?


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


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


6

MPB Spread in BC 1959-2002• animation based on annual aerial survey of MPB “reds” (last year’s attack)


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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


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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


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• 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


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


11

570

576

582

-1

-0.5

0

0.5

1

1.5

He

ight

(d

m)

Te

mp

era

ture

Ind

ex

(oC

)

Day-3 Day-2 Day-1 Day 0 Day+1 Day+2 Day+3

H(500hPa)

LFTX

558

564

570

576

582

-4

-2

0

2

4

6

He

ight

(d

m)

Te

mp

era

ture

Ind

ex

(oC

)

Jul 21 Jul 22 Jul 23 Jul 24 Jul 25 Jul 26 Jul 27

H(500hPa)

LFTX

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


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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)

Prince George

Realistic event Simulation


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Back Trajectories ending at 00Z 24 July 2002 (17:00 PDT)

105m

1100m

• issue is: how high do they fly?• entomologists don’t know• weather radar offers promise…


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• July 25/26 2005 event similar to synoptic climatology– Warm– MSLP falling– Preceded by

passage of upper ridge


15

500

1000

1500

2000

2500

0 3000 6000

Elev

atio

n AS

L (m

)

# MPB / gigaliter

(b) July 26, 2005

MPB density

0 5 10

NNWWSWSSEENE

Wind Speed (m/s)

Wind Direction

WspdWdir

5 10 15 20 25 30 500

1000

1500

2000

2500

90%

70%

50%

30%

10%

Elev

atio

n AS

L (m

)

Temperature (C)

Relative Humidity

T 3mRH 3m

• MPB flux in ABL = 42 million beetles per hour crossing a 1 km line


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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


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The End


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Future Work1. Continue idealized simulations in relation to terrain

– “rules of thumb” for beetle spread on the landscape

2. 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

3. 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


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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

Documents

12 th AMS Mountain Meteorology Conference August 31, 2006 1 Atmospheric Transport and Dispersion of the Mountain Pine Beetle in British Columbia Peter