Ionospheric effects over the five Middle Asian ionospheric stations to the major space weather event of the May 25–26, 1967 geomagnetic storm with the Dst-index of −387 nT are studied based on ionosonde measurements that were not previously considered: Alma-Ata (43.25N, 76.92E), Karaganda (49.82N, 73.08E), Novokazalinsk (45.76N, 62.12E), Tashkent (41.33N, 69.62E), Ashkhabad (37.90N, 58.30E). The study presents a description of the geomagnetic storm effects on the ionosphere electron concentration from F-region down to the lower ionosphere, points out the storm effects in different ionospheric layers for the time period 22–31 May 1967. The observations indicate a major (≥50%) and long lasting (>28 h) negative ionospheric disturbance appeared during night- and daytime simultaneously at all five stations. The daytime foF2 values on 26 May were practically at the nighttime foF2 level on this day and well below the background daytime foF2 level. A rapid increase in h’F associated with reductions in foF2 occurred over all stations during the development of the main phase of the magnetic storm. Large changes in the critical frequencies foE, foEs, and fmin that is possible linked to the enhanced X-ray flux, increased intensity in solar cosmic rays, and precipitation of energetic neutral atoms at the respective latitudes were observed during 23–26 May 1967.

基于电离层探空仪测量结果，研究了 1967 年 5 月 25 日至 26 日 Dst 指数为 -387 nT 的地磁风暴对五个中亚电离层站的电离层影响：阿拉木图 (Alma-Ata)北纬 43.25，东经 76.92)、卡拉干达 (北纬 49.82，东经 73.08)、新卡扎林斯克 (北纬 45.76，东经 62.12)、塔什干 (北纬 41.33，东经 69.62)、阿什哈巴德 (北纬 37.90，东经 58.30)。该研究描述了地磁风暴对从 F 区到电离层下部的电离层电子浓度的影响，指出了 1967 年 5 月 22 日至 31 日期间不同电离层的风暴影响。观测表明主要（5个台站夜间和白天同时出现≥50%）且持续时间长（>28小时）的负电离层扰动。5 月 26 日的白天 foF2 值实际上处于当天夜间 foF2 水平，远低于背景白天 foF2 水平。在磁暴主阶段发展期间，所有台站都出现了与 foF2 减少相关的 h'F 快速增加。1967 年 5 月 23 日至 26 日期间，观察到临界频率 foE、foEs 和 fmin 发生了巨大变化，这可能与 X 射线通量增强、太阳宇宙射线强度增加以及各纬度高能中性原子的沉淀有关。