Research On Characteristics And Causes Of Aircraft Turbulence On Plateau Based On Aircraft Detection Data

China is the country with the most higher plateau airport in the world,and aircraft turbulence is an important factor that threatens the safety and efficiency of flights in plateau.Revealing the temporal and spatial distribution characteristics of aircraft turbulence and the source of turbulence in this area has important guiding significance for the research and forecast of aircraft turbulence in plateau routes.Based on the aircraft’s airborne detection data,this research uses the vertical overload increment method to quantitatively identify aircraft turbulence of different intensities.The aircraft turbulence data,terrain data,reanalysis data and lightning data are used to objectively classify the aircraft turbulence of Lhasa route,Jiuzhai route,Daocheng route and Linzhi route into three types:convection-induced,tropopause/jet and mountain wave.The temporal and spatial characteristics of different types of turbulence are statistically analyzed,and the environmental field characteristics of typical convection-induced and mountain wave turbulence are analyzed in detail.The results show that Chinese plateau routes are more severely affected by aircraft turbulence,and Lhasa route is most affected by turbulence,with an average turbulence frequency of 78%.Convection-induced turbulence is dominant in summer,and Daocheng route is most seriously affected by it,with a frequency of 30.60%.Tropopause/jet-induced clear air turbulence is dominant during spring and winter,and Lhasa route is most affected by it,with a frequency of 42.82%.Mountain wave induced clear air turbulence is dominant during spring and winter,and it seriously affects the flight safety of the four routes.The frequency of approach and departure turbulence is higher than that of the cruise,with an average of 86.93%higher per route.During the cruise,there are many areas that are affected by various types of turbulence throughout the year.Among them,the east side of Lhasa airport is most affected by the three types of turbulence;the flight level where the turbulence occurs of four routes are concentrated at the altitude below 10,100 meters.Convection-induced turbulence in Lhasa and Daocheng routes mainly occurs in the north side of lightnings and Jiuzhai route is in the south-to-east side of lightnings,mostly caused by developing convective clouds.Lightning activity is a good indicator of convection-induced aircraft turbulence.The analysis of the mountain-wave-induced clear air turbulence shows that,compared without turbulence,the stability and wind speed at high levels are bigger when the turbulence occurs,while the stability at low levels is similar.The analysis of the mountain-wave-induced clear air turbulence shows that the turbulence occurs at the maximum wind speed at high levels and the scorer parameter indicates mountain wave.Vertical propagation and breaking of gravity-wave with height at low levels causes the turbulence.In addition,the three-dimensional wind speed and temperature power spectral density of both convection-induced turbulence and mountain-wave-induced clear air turbulence show k^-5/3 wave number dependence at range of 10^-4～10^-3m^-1 consistent with the Kolmogorov inertial subrange turbulence spectrum.