TGO Ramfjordmoen Ionosonde Data June 1989

About this dataset: This dataset contains ionograms in PNG format and covers data from June 01-30, 1989.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：本数据集包含PNG格式的电离图（ionogram），涵盖1989年6月1日至30日的观测数据。
特罗姆瑟电离测高仪（Tromsø Ionosonde，1984-1992年）概况：1984年至1992年间，该电离测高仪部署于挪威特罗姆瑟附近的拉姆峡湾莫恩（Ramfjordmoen），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行维护。该仪器在1984年之前便已在此处运行，且截至2018年仍持续部署于此；详细信息可参阅相关学术出版物。
该仪器实现全数字化，基于惠普（Hewlett Packard，HP）21MX计算机搭建。其低功率发射机与互补编码传输技术的组合，使得特罗姆瑟电离测高仪的性能等效于当时采用20微秒脉冲、峰值功率16千瓦的传统电离测高仪。常规运行模式为每20分钟采集一幅电离图，扫描频率范围为1兆赫至12兆赫，单次扫描时长为2至3分钟。针对100千米高度区域的偶发E层（sporadic E layer）高度测定精度可达±3千米。
此前电离图均存储于磁带之上，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。以此方式，一盘长度为2400英尺的磁带可存储约1300幅电离图，对应18天的观测数据。这批磁带在被读取时已有4至11年的存放时长，因此在转换至其他存储介质的过程中出现了约20%的数据丢失。目前，该数据集已在线存储于磁盘，并通过多种介质实现离线归档。