NSWP: Equatorial Investigations in the Pacific Sector

该项目将解决国家空间天气计划的一个优先目标，即需要对夜间赤道F区（称为赤道扩散F，或ESF）等离子体密度的强烈电离层不规则性进行短期预报。目前，ESF无法在日常基础上进行预测，甚至在预计ESF首次出现前不到一小时也无法预测。越来越多的证据表明，在F层底部形成的大规模波浪结构（LSWS）可能是一个关键因素，尽管没有被注意到，而许多先前的研究都集中在日落后黄昏时F区域的上升上。最近的研究表明，对日落后上升速度的测量可能受到大规模波浪结构的污染，这可能有助于解释为什么日落后上升对ESF的控制在气候学上是有效的，但在日常基础上却失效了。本项目将研究大尺度波浪结构、日落后升和ESF之间的关系。大尺度波浪结构的探测和表征需要使用具有可操纵波束的雷达或在经度上紧密间隔的传感器。目前，这类传感器只有位于波纳佩岛和圣诞岛的多波束雷达，以及位于瓜贾林岛的可操纵非相干散射雷达ALTAIR。该项目将利用这些数据集完成以下任务：(1)利用波纳佩7年的三波束雷达数据和圣诞岛4年的两波束雷达数据，确定大尺度波浪结构的存在，提取日落后的真实上升速度；(2)操作波纳佩最近重新配置的五波束雷达，以便获得能够确定大尺度波结构水平波长的数据；(3)利用两个雷达收集的所有数据，每个雷达都跨越一个完整的太阳周期，确定大尺度波浪结构、日落后上升和ESF之间的短期和长期关系。这项工作有望产生第一个包含大尺度波浪结构、日落后上升和ESF信息的数据库，该数据库包含太平洋中部两个地点跨越一个完整太阳周期的连续测量数据。该数据库可用于从一分钟到一个完整太阳周期的各种时间尺度的调查，并将适合支持CHAMP、ROCSAT、DMSP、TIMED、Formosat和C/NOFS等卫星项目。

This project will address a priority goal of the National Space Weather Program, the need for able short-term forecasts of intense ionospheric irregularities in plasma density that develop in the nighttime equatorial F region (referred to as equatorial spread F, or ESF). Currently, ESF cannot be predicted on a day-to-day basis, even up to less than an hour before the expected first appearance of ESF. There is growing evidence that a key, though unheralded, player may be large-scale wave structure (LSWS) that develops in the bottomside F layer, whereas many previous efforts focused on the post-sunset rise of the F region at dusk. Recent research suggests that measurements of the velocity of the post-sunset rise may be contaminated by the large-scale wave structure, which may help explain why the control of ESF by the post-sunset rise, which holds climatologically, breaks down on a day-to-day basis. This project will investigate the relationships among the large scale wave structure, the post sunset rise, and ESF. The detection and characterization of the large scale wave structures require use of a radar with a steerable beam or sensors spaced closely in longitude. Currently, the only sensors of this kind are the multi-beam radars on the island of Pohnpei and Christmas Island as well as the steerable incoherent-scatter radar ALTAIR located in Kwajalein. The project will use the datasets to perform the following tasks: (1) Use three-beam radar data collected over seven years at Pohnpei, and two-beam radar data collected over four years at Christmas Island, to determine the presence of large scale wave structure and to extract the true post-sunset rise velocity; (2) Operate the recently reconfigured five-beam radar at Pohnpei in order to acquire data which will enable determination of the horizontal wavelength of the large scale wave structure; (3 ) Use all data collected by both radars, each spanning a full solar cycle, to determine short-term and long-term relationships among large scale wave structure, the post-sunset rise, and ESF. The proposed effort is expected to yield the first database with information on large scale waves structure, the post sunset rise, and ESF containing continuous measurements from two locations in the central Pacific sector that span a single, full solar cycle This database can be used for various investigations on time scales from a minute to a full single solar cycle and will be suitable for support of satellite programs such as CHAMP, ROCSAT, DMSP, TIMED, Formosat, and C/NOFS.