Microburst Wind Shear Models from the Joint Airport Weather Studies (JAWS)

摘要

Multiple Doppler radar data collected during the Joint Airport Weather Studies (JAWS) Project is used to synthesize the three-dimensional wind in the region of a microburst. A six-degree-of-freedom numerical aircraft model having characteristics similar to Boeing 727 series aircraft is used to investigate jet transport aircraft response to microburst winds during simulated approaches and departures. Simple pilot control laws are used to adjust thrust, pitch, roll, and yaw so as to maintain given approach or departure parameters. Generally, when horizontal wind shear along the approach or departure path is .0001/s or greater, the model is unable to maintain the desired approach path and suffers a significant reduction in climb performance during a go-around or departure. Although the mean wind shear along a path gives a good qualitative measure of the wind shear threat to a jet transport, different paths with similar mean shears can yield markedly different results, as do the same paths with similar mean shears can yield markedly different results, as do the same paths through the microburst at different times, emphasizing the fine temporal and spatial scale of microburst winds. Finally, during the approximate 30 s period required for the aircraft to traverse the region of highest horizontal shear, time variations in the microburst wind field are shown to insignificantly affect the modelled flight path because the traverse period is a short time compared to the life time of a microburst.