Energy Spectrum Analysis With Wind Profile Radar Measurements

Wind profile radar is a new detecting instrument, atmospheric wind field and some other meteorological elements can be detected continuously. Using wind profile radar measurements, which is continuous, high resolution, for spectral analysis is helpful to realize the distribution of energy at high altitude. A new way is provided for the weather analysis.Spectral analysis for further study of atmospheric properties uses frequency or wave number as a parameter to define the function. A series of observations are decomposed into frequency or wavelength component to find the role vortex of different space and time scales plays in the whole atmospheric. Study of wind energy spectrum and turbulence spectrum focused more on atmospheric boundary layer and less on high-altitude. Using FFT to calculate the wind energy spectrum density and turbulent spectrum density at high-altitude with wind profiling radar measurements, and the distribution characteristics were analyzed.Based on the wind profile radar spectral analysis algorithm, calculates the spectrum density. The data used to spectral analysis is from the troposphere wind profile radar located in Beijing and boundary layer wind profile radar located in Yichun. The article has discussed the characteristics of spectrum in stable weather and several different weather conditions; analysis of upper wind spectrum in April,2012in Yichun has been preceded as well.Turbulence spectrum analysis at lkm-5km in stable weather conditions shows that the spectral density expresses in power at a frequency range2×10-5-1031/s. The function can be defined as S(f)=afb, the slop b is between0.82and1.04, indicates that turbulence is on the transition zone from energetic area to inertial subrange. Wind shear and convective activity may enhance the turbulence.The spectrum in different weather condition shows different characteristics. The peaks seeing in turbulence spectrum shows the period of weather system. Cold windy appears1.5days time period in the turbulence spectrum, the amplitude at5km is the largest. Wide range rainstorm exhibit2or3peaks in spectrum, the period is15-20h and in the severe convective weather conditions there occurs two peaks at the period of13h and9h. Compared with stable weather, the turbulence spectrum density accounted for the proportion of wind energy spectrum density is increases rapidly, especially in peak areas.The wind energy spectrum density and turbulent spectrum density are calculated with the data of wind profiling radar during precipitation event in April,2012at Yichun. Spectral analysis is carried out combined with surface precipitation. Two synoptic systems in different time scale are discovered. The period appeared in wind energy spectrum and turbulent spectrum are5-7days and2-3days. Wind energy spectrum density in5-7days period is4times higher than2-3days, as well as wind speed. Wind energy spectrum reduces obviously at2020m. It is possible because of cold air activity. While the system about2-3days is weaker, the wind spectrum density is dense at low altitude.