An investigation of methods for injecting emissions from boreal wildfires using WRF-Chem during ARCTAS 1Department of Meteorology, Florida State University, Tallahassee, Florida, USA
21 Jun 2011
2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
3NASA Goddard Space Flight Center, Hampton Virginia, USA
*present address: Naval Research Laboratory, Monterey, California, USA
Received: 18 Sep 2010 – Published in Atmos. Chem. Phys. Discuss.: 08 Nov 2010Abstract. The Weather Research and Forecasting Model (WRF) is considered a "next
generation" mesoscale meteorology model. The inclusion of a chemistry
module (WRF-Chem) allows transport simulations of chemical and aerosol
species such as those observed during NASA's Arctic Research of the
Composition of the Troposphere from Aircraft and Satellites (ARCTAS) in
2008. The ARCTAS summer deployment phase during June and July coincided with
large boreal wildfires in Saskatchewan and Eastern Russia.
Revised: 02 Jun 2011 – Accepted: 07 Jun 2011 – Published: 21 Jun 2011
One of the most important aspects of simulating wildfire plume transport is
the height at which emissions are injected. WRF-Chem contains an integrated
one-dimensional plume rise model to determine the appropriate injection
layer. The plume rise model accounts for thermal buoyancy associated with
fires and local atmospheric stability. This paper describes a case study of
a 10 day period during the Spring phase of ARCTAS. It compares results from
the plume model against those of two more traditional injection methods:
Injecting within the planetary boundary layer, and in a layer 3–5 km above
ground level. Fire locations are satellite derived from the GOES Wildfire
Automated Biomass Burning Algorithm (WF_ABBA) and the MODIS thermal
hotspot detection. Two methods for preprocessing these fire data are
compared: The prep_chem_sources method included with WRF-Chem, and the
Naval Research Laboratory's Fire Locating and Monitoring of Burning
Emissions (FLAMBE). Results from the simulations are compared with
satellite-derived products from the AIRS, MISR and CALIOP sensors.
When FLAMBE provides input to the 1-D plume rise model, the resulting
injection heights exhibit the best agreement with satellite-observed
injection heights. The FLAMBE-derived heights are more realistic than those
utilizing prep_chem_sources. Conversely, when the planetary boundary
layer or the 3–5 km a.g.l. layer were filled with emissions, the resulting
injection heights exhibit less agreement with observed plume heights.
Results indicate that differences in injection heights produce different
transport pathways. These differences are especially pronounced in area of
strong vertical wind shear and when the integration period is long.
Citation: Sessions, W. R., Fuelberg, H. E., Kahn, R. A., and Winker, D. M.: An investigation of methods for injecting emissions from boreal wildfires using WRF-Chem during ARCTAS, Atmos. Chem. Phys., 11, 5719-5744, doi:10.5194/acp-11-5719-2011, 2011.