Effects of topography upon mountain pine beetle (Dendroctonus ponderosae) transport and dispersion as indicated by mesoscale meteorological models. Brenda L. Moore

1
Effects of topography upon mountain pine beetle
(Dendroctonus ponderosae) transport and
dispersion as indicated by mesoscale
meteorological models.Brenda L. Moore P. L.
JacksonEnvironmental Science and Engineering
Program, University of Northern British Columbia,
Prince George, B.C. V2N 4Z9______________________
__________________________________________________
_________________________________________

• Results
• Figures 3 and 4 show a sampling of RAMS model
  output for artificial topography simulations
• 22 UTC (300 pm PST) used to illustrate
  convective meteorological conditions
• At this time, wind direction is highly variable,
  but speeds generally low (fair-weather
  conditions) (Figure 3b and 4b)
• High temperatures in valley bottoms, with a
  gradient of approx. 15 degrees Celsius from
  valley to peak (Figures 3a and 4a)

• Model Initialization
• 2 atmospheric models used RAMS (preliminary
  results shown) and HYPACT (to be used later)
• RAMS initialized horizontally homogeneously at 12
  UTC
• Representative soundings from Prince George (ZXS)
  upper-air station were found based upon a
  synoptic climatology of MPB emergence days (see
  Murphy and Jackson P1.12)
• RMSE (Root Mean Square Error) and RMSVE (Root
  Mean Square Vector Error) used to rank and
  determine the most representative soundings

• Introduction
• The mountain pine beetle (MPB, Dendroctonus
  ponderosae) is a natural part of western North
  American forested ecosystems at low population
  levels
• The current epidemic has been reached due to
• Recent weather conditions (warmer and drier)
• Abundance of mature lodgepole pine (Pinus
  contorta) (fire suppression and forestry
  practices
• Within B.C., the current outbreak stretches 4.2
  million hectares
• MPB spread is currently documented through
• Aerial surveys (to assess the extent of the
  previous years population)
• Ground data collection beetle probing (to
  assess the spatial extent of newly infested
  stands)

Figure 1 Landscape-level MPB infestation near
Tweedsmuir, B.C. (http//www.mountainpinebeetle.c
om/images/photos/MPB-1-1.jpg)

• Discussion
• Model output shows anabatic/katabatic flows
  dominating local wind circulations
• Night-time down-slope (katabatic) winds cause
  pooling of cool air and subsequent inversion
  conditions
• In the mid-morning, inversion breaks down and
  differential heating of slopes brings up-slope
  (anabatic) winds
• Afternoon brings convective conditions (Figure 3b
  and 4b) with variable wind directions and
  substantial mixing
• Anabatic flows during the day may act to advect
  MPB up slopes and aloft along ridge lines
• Subsidence in mid-valleys may act as fallout
  regions for MPB

a
b

• Artificial Topography
• 3 landscapes used flat (control), E-W sinusoidal
  terrain (Figure 2a), N-S sinusoidal terrain
  (Figure 2b)
• Grids centered at Prince George upper-air station
  (53.9 lat., -122.0 long., 601 masl)
• Wavelength and amplitude for sine wave obtained
  by averaging measurements from Tweedsmuir Park
  (large MPB infestation) (Figure 1)

• Rationale
• Production of a predictive MPB dispersion model
  has the potential to direct ground surveys and
  therefore reduce costs
• Current MPB modeling endeavors focus on the
  single tree to stand level and rarely include
  meteorological variables, although they are noted
  as important to MPB ecology
• Use of atmospheric models to determine extent of
  MPB dispersal over longer distances (between
  stands) should provide a regional visualization
  of spatial infestation extent which could be used
  by resource managers
• As a preliminary step in the full MPB dispersal
  model, this research seeks to validate the models
  used and explore fundamental relationships
  between MPB dispersal and local topography

Figure 3 Sample RAMS output for E-W topography
simulation temperature (a) and wind speed and
direction (b)
a
b
a
b

• Future Work
• Realistic simulations of Prince George SO2
  concentrations will be used to validate
  RAMS/HYPACT at simulating real-life situations
• Further qualitative study of RAMS output
  (comparison to published literature)
• Use HYPACT (Lagrangian particle dispersion model)
  to insert, advect and disperse MPB using RAMS
  meteorological output
• Quantitative comparison between control (flat)
  and variable (sinusoidal) topographies to
  determine if an effect is present and/or which
  landscapes offer the greatest forcing on MPB
  dispersal

Figure 2 Artificial topography contours for N-S
simulation (a) and E-W simulation (b)
Figure 4 Sample RAMS output for E-W topography
simulation temperature (a) and wind speed and
direction (b)
Acknowledgements Funding for this work is
provided by the Natural Resources Canada /
Canadian Forest Service Mountain Pine Beetle
Initiative.
Background photograph from http//www.pfc.forestr
y.ca/entomology/mpb/outbreak/outbreak-cycle_e.html