Charged Aerosol Effects on the Scattering of Radar Waves from the D-Region
Charged Aerosol Effects on the Scattering of Radar Waves from the D-Region
复制标题
带电气溶胶对 D 区雷达波散射的影响
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
G. Teiser
中科院分区：
文献类型：
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作者：
M. Rapp;I. Strelnikova;Qiang Li;N. Engler;G. Teiser
带电气溶胶粒子是D区电荷平衡的重要贡献者，并影响雷达波的散射。这些粒子包括在所有D区高度和所有季节出现的流星烟粒子（MSP），以及在夏季出现在极地纬度80-90公里高度的中间层冰粒。我们认为，这是修改电子扩散的重带电气溶胶粒子，这是主要的效果，导致清楚地检测到的签名在非相干和相干雷达后向散射。在非相干散射的情况下，它表明，带电气溶胶粒子的存在下修改的非相干散射光谱。相应的观测与EISCAT超高频雷达和阿雷西博雷达已被用来检测MSP和冰粒在D-区域的高度，并确定其半径和数量密度。在相干散射的情况下，有人认为，修改后的D-区域电子的扩散特性导致在雷达布拉格波长的小尺度结构，由于湍流混合结合一个大的施密特数。为了检验这一理论，在特罗姆瑟（69°N）和斯瓦尔巴德（78°N）的EISCAT雷达和并置的53 MHz雷达上测量了极地中层夏季回波的校准回波强度，因此覆盖了53 MHz、224 MHz、500 MHz和933 MHz的频率。重要的是，这些观测结果中的绝大多数与相应的理论预测非常一致，从而为这一理论提供了强有力的支持。这一理论随后被应用于相同的数据集，以得出冰粒半径。相应的结果是在良好的协议与独立的数据集从卫星和地面光学观测。最后，对今后的研究提出了一些建议。
Charged aerosol particles are an important contributor to the D-region charge balance and affect the scattering of radar waves. Among these particles are meteoric smoke particles (MSP) which occur at all D-region altitudes and all seasons, and mesospheric ice particles whose occurrence is confined to altitudes of ∼80–90 km at polar latitudes during summer. We argue that it is the modification of electron diffusion by the heavy charged aerosol particles which is the prime effect leading to clearly detectable signatures in both incoherent and coherent radar backscatter. In the case of incoherent scatter, it is shown that the presence of charged aerosol particles modifies the incoherent scatter spectrum. Corresponding observations with the EISCAT UHF radar and the Arecibo radar have been used to detect both MSP and ice particles at D-region altitudes and characterize their radii and number densities. In the case of coherent scatter, it is argued that the modified diffusion properties of the D-region electrons lead to small scale structures at the radar Bragg wavelength due to turbulent mixing in combination with a large Schmidt number. To test this theory, calibrated echo strengths of polar mesosphere summer echoes have been measured with the EISCAT radars at Tromso (69°N) and Svalbard (78°N) and collocated 53 MHz radars, thus covering frequencies of 53 MHz, 224 MHz, 500 MHz, and 933 MHz. Importantly, the vast majority of these observations show excellent agreement with the corresponding theoretical predictions thus providing strong support for this theory. This theory was subsequently applied to the same data sets in order to derive ice particle radii. Corresponding results are in excellent agreement with independent data sets from satellite-borne and ground-based optical observations. Finally, some suggestions for future investigations are given.