Wildfire Plume Injection Heights Over North America: An Analysis
of MISR Observations
Maria Val Martin and Jennifer A. Logan (Harvard Univ., USA)
Fok-Yan Leung (Washington State Univ., USA)
David L. Nelson, Ralph A. Kahn and David J. Diner (NASA)
Saulo Freitas (INPE, Brazil)
Research funded by NSF and EPA
Wildfire Plume Injection Heights Over North America: An Analysis
of MISR Observations
Outline: An statistical analysis of aerosol injection heights
over North America The use of a 1-D plume-rise model to develop a
parameterization of the injection heights of North American wildfire emissions
Multi-angle Imaging SpectroRadiometer- MISR
9 view angles at Earth surface: nadir to 70.5º forward and backward
4 bands at each angle:446, 558, 672, 866 nm
Continuous pole-to-pole coverage on orbit dayside
400-km swath9 day coverage at equator2 day coverage at poles
Overpass around local noon time in high and mid- latitudes
275 m - 1.1 km sampling
In polar orbit aboard Terra since December 1999
Analysis of Fire Plumes: MISR INteractive eXplorer (MINX)
(http://www.openchannelsoftware.org)
Cross-section of heights as a function of distance from the source
Histogram of heights retrieved by MINX
Plume over central Alaska on June 2002
About 3000 plumes digitalized over North America
http://www-misr2.jpl.nasa.gov/EPA-Plumes/
2002N = 480
2005N = 980
2006N = 463
2007N = 580
2004N = 690
Plume Distribution and Atmospheric Conditions
pcR
dz
d/
PT where,Stability
P0
Meteorological fields
from GEOS-4 and GEOS-5 2x2.5
Histogram of Plume Height Retrievals Atmospheric Stability Profile
Stable Layer
Boundary Layer (BL)
Max
Avg Median
Mode
Plume Height?
Each individual height
5-30% smoke emissions are injected above the boundary layer
Kahn et al, [2008]
Distribution of MISR heights-PBL for smoke plumes
200210–25%
20054–15%
20069–28%
20079–18%
2004
Percentage of smoke above BL varies with vegetation type and fire season
2002
2004200520062007
Vegetation classification based on MODIS IGBP land cover (1x1 km)
% Height retrievals with [Height-PBL] > 0.5 km
(http://modis-land.gsfc.nasa.gov/landcover.htm)
Trop Forest
Cropland
Extra-Trop Forest
Boreal Forest
Boreal Shrub
Non-Bor Shrub
Boreal Grass
Non-Bor Grass
Kahn et al, [2007] Leung et al, [in prep]
11% 13% 7% 24%13%
Smoke emissions tend to get confined within stable layers in the atmosphere, when they exist
Distribution of all individual heights in the FT – Stable Layer
MISR Heights – Stable Layer ≈ 0 km
1-D Plume-resolving Model
Detailed information in Freitas et al, [2007]
Key input parameters:•Instant fire size: MODIS fire counts (scaled by max FRP observed over vegetation type [Charles Ichoku, personal communication])
(> 80% fires <25 Ha)
•Total heat flux: Max MODIS FRP observed over vegetation type x 10 [Wooster et al, 2005](~9000-18000 W/m2)•RH, T, P, wind speed and direction: from GEOS-4 meteo fields 2x2.5
• Fuel moisture content: from Canadian Fire Weather Model
Simulation of a boreal fire plume in Alaska and a grassland fire plume in Mexico
Fire Size= 300 HaHeat Flux= 18 kW/m2
Fire Size= 3.8 HaHeat Flux= 9 kW/m2
MISR Retrieved HeightsMISR Smoke Plume 1D Plume-rise Model
Boreal Forest Fire
Trop. Grassland Fire
Simulation of a boreal fire plume in Alaska and a grassland fire plume over Mexico
Fire Size= 300 HaHeat Flux= 18 kW/m2
Fire Size= 3.8 HaHeat Flux= 9 kW/m2
MISR Retrieved HeightsMISR Smoke Plume 1D Plume-rise Model
Boreal Forest Fire
Trop. Grassland Fire
6200 m 6500 m
600 m555 m
The 1-D Plume-resolving Model simulates fairly well the observed MISR heights
Correlation between simulated plume heights and MISR observed heights over North America
5-30% of smoke emissions are injected above the BL.
The percentage of smoke that reaches the FT varies with vegetation type and fire season.
When smoke emissions reach the free troposphere, they tend to get trapped in stable layers, if they are present.
1-D plume-resolving model simulates fairly well the observed MISR plume heights.
In the future, we plan to embed the 1-D plume-resolving model with GEOS-Chem to simulate vertical transport of North American wildfire emissions.
Concluding Remarks
Extra Slides
The 1D plume-resolving model: Governing equations
dynamics
thermodynamics
water vapor conservation
bulk microphysics
cloud water conservation
rain/ice conservation
The 1D plume-resolving model: The lower boundary conditions
