FREddyPro (version 1.0)

Calculate: Kormann and Meixner 2001 flux footprint model

Description

Performs the footprint calculation for a single set of inputs

Usage

Calculate(fetch = 500, height = 3, grid = 200, speed, direction, uStar,
zol, sigmaV)

Arguments

fetch

The upwind distance over which you want the calculation domain to extend Note that the footprint will be normalized to that domain so footprints that extend well beyond the domain will be overrepresented in

height

The z-d height of the flux system

grid

The total calculation grid size. The default is 200 which would mean the footprint would be represented in a 200x200 array corresponding to dimensions of two times the fetch on each side of the grid.

speed

Single values of wind speed at the flux system

direction

Single values of the direction wind is coming from at the flux system

uStar

Single values of friction velocity

zol

Single values of Monin Ohbukov stability parameter

sigmaV

Single values of the standard deviation of the cross-stream wind component

Value

Output is a list object with a 3 elements including:footprint: the array holding the footprint probabilities FPn: the array holding the grid point distance north of the flux system FPe the array holding the grid point distance east of the flux system

References

Kormann, R., and Meixner, F.X. (2001). An analytical footprint model for non-neutral stratification, Boundary-Layer Meteorology. 99, 207-224.

Examples

## Load the data
data(fluxes)

## Clean fluxes
fluxes=cleanFluxes(fluxes,sdCor=TRUE,sdTimes=3,timesList=3,distCor=TRUE,
                   thresholdList=list(H=c(-100,1000),LE=c(-100,1000)))	

## Use data without NA values
fluxes_noNA<-fluxes[which(!is.na(fluxes$L)),]

## Displacement height
d=17.42

## Calculate z
fluxes_noNA$z=(fluxes_noNA$X.z.d..L*fluxes_noNA$L)+d

## Calculate zol
fluxes_noNA$zol=fluxes_noNA$z/fluxes_noNA$L

## Calculate the footprint
footprint=Calculate(fetch=500,height=33,grid=200,fluxes_noNA$wind_speed[853],
fluxes_noNA$wind_dir[853],fluxes_noNA$u.[853],fluxes_noNA$zol[853],
sqrt(fluxes_noNA$u_var[853]))

## You can also use the plot.footprint function of FREddyPro to plot the result
plotFootprint(footprint)