A VLF Beacon Transmitter at South Pole

[0093381]这项工作是一项为期三年的工作，目的是在南极建立和运行一个甚低频（VLF）信标发射机，用于连续测量太阳对地球中间层和较低电离层的影响。具体来说，发射机将产生太阳质子事件、地球外辐射带的相对论性（300 keV）电子沉淀、高纬度/极帽磁层-电离层耦合过程的高能电子沉淀和焦耳加热分量的数据。在地球同步轨道上测量的相对论性电子居群显示出与亚暴和太阳活动相关的显著波动。在一个事件中，这些高能量的电子可以穿透到低至30-40公里的高度，产生电离，x射线，并可能影响涉及臭氧产生的化学反应。相对论性电子沉降的程度将通过在南极各站点接收到的南极VLF信号的振幅和相位变化来观测。南极信标将协同加强其他南极高层大气研究工作，如自动地球物理观测计划和南半球相干高频雷达网络（SUPERDARN）。拟议的计划还有力地补充了正在进行的低空（SAMPEX）和高空（POLAR）捕获和沉淀高能电子的卫星测量。信标将以大约20千赫的频率发射，辐射1千瓦的总功率，使用6.25公里（尖端到尖端长度）长的水平偶极子天线。它将在计算机控制下运行，每15分钟运行约1分钟

0093381InanThe proposed work is a three year effort to establish and operate a very low frequency (VLF) beacon transmitter at South Pole, for the continuous measurement of solar effects on the Earth's mesosphere and lower ionosphere. Specifically the transmitter will produce data on solar proton events, relativistic (300 keV) electron precipitation from the Earth's outer radiation belts, and energetic electron precipitation and Joule heating components of high latitude/polar cap magnetosphere-ionosphere coupling processes. The relativistic electron population as measured at geosynchronous orbit exhibits pronounced fluctuations in association with substorm and solar activity. During an event, these highly energetic electrons can penetrate to altitudes as low as 30-40 km, producing ionization, x-rays and possibly affecting chemical reactions involving ozone production. The extent of relativistic electron precipitation will be observed by means of amplitude and phase variations of the South Pole VLF signal as received at various Antarctic stations. The South Pole beacon will synergistically enhance other antarctic upper atmospheric research efforts, such as the Automatic Geophysical Observatory programs and the southern hemisphere coherent HF radar network (SUPERDARN). The proposed program also strongly complements ongoing satellite based measurements of trapped and precipitating high energy electrons both at low altitudes (SAMPEX) and high altitudes (POLAR). The beacon will transmit at approximately 20 kHz, radiating 1 kW of total power with a ~6.25 km (tip-to-tip length) long horizontal dipole antenna. It will be operating under computer control with a synoptic schedule of about 1 min out of every 15 minutes.***