A new methodology for the estimation of smoke-injection height fromwild-land fires is proposed and evaluated. It is demonstrated that theapproaches developed for estimating the plume rise from stacks, such as theformulas of G. Briggs, can be formally written in terms characterising thewild-land fires: fire energy, size and temperature. However, thesesemi-empirical methods still perform quite poorly because the physicalprocesses controlling the uplift of the wildfire plumes differ from thosecontrolling the plume rise from stacks. The proposed new methodologyconsiders wildfire plumes in a way similar to Convective Available PotentialEnergy (CAPE) computations. The new formulations are applied to a datasetcollected within the MISR Plume Height Project for about 2000 fire plumes inNorth America and Siberia. The estimates of the new method are compared withremote-sensing observations of the plume top by the MISR instrument, withtwo versions of the Briggs' plume-rise formulas, with the 1-D plume-risemodel BUOYANT, and with the prescribed plume-top position (the approachwidely used in dispersion modelling). The new method has performedsignificantly better than all these approaches. For two-thirds of the cases,its predictions deviated from the MISR observations by less than 500 m, whichis the uncertainty of the observations themselves. It is shown that thefraction of "good" predictions is much higher (>80%) for the plumesreaching the free troposphere.
展开▼
