## 2.24.2. Agricultural fires[¶](#agricultural-fires "Permalink to this headline")
-------------------------------------------------------------------------------

The burned area of cropland (km2 s\-1) is taken as \\({A}\_{b}\\):

(2.24.30)[¶](#equation-23-30 "Permalink to this equation")\\\[A\_{b} =a\_{1} f\_{se} f\_{t} f\_{crop} A\_{g}\\\]

where \\(a\_{1}\\) (s\-1) is a constant; \\(f\_{se}\\) represents the socioeconomic effect on fires; \\(f\_{t}\\) determines the seasonality of agricultural fires; \\(f\_{crop}\\) is the fractional coverage of cropland. \\(a\_{1}\\) = 1.6x10\-4 hr\-1is estimated using an inverse method, by matching 1997-2004 simulations to the analysis of [van der Werf et al. (2010)](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#vanderwerfetal2010) that shows the 2001-2009 average contribution of cropland fires is 4.7% of the total global burned area.

The socioeconomic factor \\(f\_{se}\\) is given as follows:

(2.24.31)[¶](#equation-23-31 "Permalink to this equation")\\\[f\_{se} =f\_{d} f\_{e} .\\\]

Here

(2.24.32)[¶](#equation-23-32 "Permalink to this equation")\\\[f\_{d} =0.04+0.96\\times \\exp \[-\\pi (\\frac{D\_{p} }{350} )^{0.5} \]\\\]

and

(2.24.33)[¶](#equation-23-33 "Permalink to this equation")\\\[f\_{e} =0.01+0.99\\times \\exp (-\\pi \\frac{GDP}{10} )\\\]

are the effects of population density and GDP on burned area, derived in a similar way to equation [(2.24.32)](#equation-23-32) and [(2.24.33)](#equation-23-33). \\(f\_{t}\\) is set to 1 at the first time step during the climatological peak month for agricultural fires ([van der Werf et al. 2010](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#vanderwerfetal2010)); \\({f}\_{t}\\) is set to 0 otherwise. Peak month in this dataset correlates with the month after harvesting or the month before planting. In CLM we use this dataset the same way whether the CROP option is active or not, without regard to the CROP option’s simulated planting and harvesting dates.

In the post-fire region, fire impact is parameterized similar to section [2.24.1.3](#fire-impact) but with combustion completeness factors and tissue mortality factors for crop PFTs ([Table 2.24.1](#table-pft-specific-combustion-completeness-and-fire-mortality-factors)).

