Paleofire frequencies

Posted on February 9, 2012February 9, 2014 by Olivier |

KDffreq.m function calculates palaeo-fire frequency using a Gaussian kernel and computes bootstrapped confidence intervals arround fire frequency. Require the date of fire events as input variable. Associated with this function analyst may use cvKD.mfunction to estimate optimal kernel bandwidth by max log likelihood. Here’s an example:

Generate some fire dates for the last 8000 years:

x=randi(8000,40,1);
plot(x,1,'+','col','red')
set(gca,'xdir','reverse')
xlabel('Time (cal yrs. BP)')

Use the cvKD.m function to calculate the optimal bandwidth for the kernel:

cvKD(x)
ans = 724.3434

Then we estimate the long term fire frequency using the Gaussian kernel density procedure:

 [ffreq]=KDffreq(x,'up',0,'lo',8000,'bandwidth',700,'nbboot',100,'alpha',0.05 );