Preparing Fire Emissions for CMAQ

October 7, 2014

Objective

Provide options for preparing the PMDETAIL fire inventories for CMAQ 2011 modeling.

Description

Task 1 of the 3SAQS 2015 Work Plan calls for the development of a year 2011 CMAQ modeling platform. Fires (wild, agricultural, and prescribed) are significant air pollution sources that require special treatment in the air quality modeling system due to their unique physical and chemical characteristics. The PMDETAIL fire inventory includes information on specific fire events, including the size of the fires (daily area burned and pollution fluxes), timing, spatial (horizontal and vertical extent), and chemical parameters of the fires. These parameters are read in by software that translates the fire inventories into a format and terms that can be used by an air quality model for simulating the air quality impacts of the fires. ENVIRON both developed software for preprocessing the PMDETAIL inventories for input to CAMx and modified CAMx for modeling these data. Similar software and modifications are needed before the PMDETAIL fires can be simulated in CMAQ.

The two parameters of the PMDETAIL fire inventories that are require special treatment include the horizontal spatial allocation (gridding) and vertical plume distribution (plume rise).

Gridding the fire inventories

The PMDETAIL fire inventory provides coordinates for daily fire event centroids. When allocating the fire emissions to modeling grid cells, care must be taken to consider the ratio between the fire size (acres) and the grid cell area. The reason for this consideration is that as grid resolutions increase, the fire emissions become concentrated in one grid cell which may misrepresent the spatial extent of the fire impacts.

Grid Resolution	km^2	Acres
36	1296	320,249
12	144	35,583
4	16	3,953