TGO Ramfjordmoen Ionosonde Data April 1987

About this dataset: This dataset contains ionograms in PNG format and covers data from April 01-30, 1987.About the Tromsø Ionosonde (1984-1992): During the period 1984-1992 the Ionosonde was situated at 69° 35' N, 19° 13' E at Ramfjordmoen near Tromsø, Norway and operated by the Auroral Observatory of the University of Tromsø. The instrument operated at this location prior to 1984, and still operates there (as of 2018); see the related publication for details. The instrument was fully digitized and based on a Hewlett Packard 21MX computer. The combination of a low power transmitter and complementary code transmission made the Tromsø ionosonde equivalent to a conventional ionosonde (at the time) with 20 µs pulses and 16 kW peak power. Routine operation was one ionogram every 20 min with a frequency sweep from 1 MHz to 12 MHz lasting between 2 and 3 min. For the 100 km altitude region the precision of determining the height of a sporadic E layer is ± 3 km. The ionograms were stored on magnetic tape. A noise discrimination routine in the computer program reduced the stored data to less than 10% of the raw data. In this way one 2400' tape held about 1300 ionograms, equivalent to 18 days' data. The tapes were 4-11 years old when they were read, resulting in around 20% data-loss during the process of transferring to other media. Today, storage is on online disk and with offline an archive on a variety of media.本数据集说明：本数据集收录PNG格式的电离层探测图（ionogram），涵盖1987年4月1日至30日的探测数据。关于特罗姆瑟电离层探测仪（1984-1992年）：1984年至1992年间，该电离层探测仪部署于挪威特罗姆瑟市附近的拉姆峡湾莫恩，地理坐标为北纬69°35′、东经19°13′，由特罗姆瑟大学极光观测台负责运营维护。该仪器早在1984年之前便已在此处投入运行，截至2018年仍保持正常工作；详细技术参数可参阅相关研究文献。该仪器为全数字化探测系统，搭载惠普（Hewlett Packard）21MX计算机。其低功率发射机与互补码传输技术的组合，使得该特罗姆瑟电离层探测仪的性能等效于当时采用20微秒脉冲、16千瓦峰值功率的常规电离层探测仪。常规运行模式为每20分钟获取一张电离层探测图，频率扫描范围为1兆赫至12兆赫，单次扫描持续2至3分钟。在100千米高度区间内，偶发E层（sporadic E layer）的高度测定精度可达±3千米。早期探测数据以磁带为存储介质，计算机程序内置的噪声判别程序可将存储数据压缩至原始数据的10%以内。按此压缩比例，一盘2400英尺长的磁带可存储约1300张电离层探测图，相当于18天的探测总量。这批磁带在读取时已有4至11年的存储时长，因此在介质迁移过程中约产生20%的数据丢失。目前，该数据集已迁移至在线磁盘存储，并通过多种介质实现离线归档。