Study On Reflection To Radar Wave Through The Polar Summer Mesosphere

PMSE are strong radar echoes commonly observed by VHF MST radars from thin layers in the 80-90 km altitude interval at high latitudes during summer. This kind of phenomenon was first discovered by Ecklund and Balsley in the late 1970s. The PMSE phenomenon has caused extensive concern of the medium high atmosphere physicist and carry on a great deal of research., but still have no complete comprehend the actual physical mechanism of PMSE up to now.To the research which produces the physical mechanism of the PMSE, the theories of current mainly have: Classical turbulence t, Turbulence aided by enhanced Schmidt Number, Dusty plasma scattering, Dust hole scattering (Electron density holes). Among them the most popular theories assumption is that the electron structures that cause the scattering are driven by neutral turbulence. A requirement at VHF frequencies and up is that the dust size/charge-number be large enough to extend sufficiently the convective-diffusive subrange of the electron turbulence via an enhancement of the Schmidt number. However measure result enunciation at UHF frequencies (e.g. the EISCAT 930 MHz radar): this requirement implies large dust charge numbers incompatible with reliable models and indirect measurements. Generally accepted there is no doubt that charged dust/aerosols in the mesosphere play a decisive role in creating PMSE, however the actual mechanism is far from clear.On the above-mentioned cognitive foundation, we try to study the electromagnetic reflectance of polar mesosphere in summer based on the theory of wave propagation in layered medium and under the precondition of ignoring the impact of anisotropy, The results of sounding rocket campaigns indicate that the electron density and the dust charge density of polar mesosphere in summer have layered structure. Based on the data of sounding rocket campaigns, we calculated the reflectance and SNR each layer of polar mesosphere in summer according to theory of traditional plasma and dust plasma respectively. Results indicates: 1) the density of the radar echo reflected by layered structure of electron density can interpret the density of PMSE sufficiently; 2) the reflectance and SNR calculated with traditional theory of plasma has little difference with that calculated with theory of dust plasma.