We report some ionospheric phenomena that occurred on September 23, 2019 observed by an airglow imager installed at University of Kashmir, Srinagar, India (34.08°N, 74.79°E, and 25.91°N magnetic latitude). The various phenomena observed on this night are as follows: (1) The wave-like structures near the dusk time having phase fronts aligned along Northwest to Southeast direction and moving southwestward, classified as nighttime medium-scale traveling ionospheric disturbance. (2) Simultaneous observation of northwestward-moving nighttime medium-scale traveling ionospheric disturbances and eastward-drifting plasma irregularity and (3) The westward reversal of field-aligned plasma irregularity and K-shaped depletion structure formation post-midnight. We analyze their characteristics and evolution processes in detail. The plasma irregularity seems to be the signature of locally generated plasma irregularities at low-mid-latitude transition region as the radar observations from a geomagnetic low-latitude station (Gadanki, India; 13.5°N, 79.2°E, Magnetic latitude ~ 6.5°N) do not show any signatures of equatorial plasma bubbles during this night. It is interesting to note that the westward reversal of plasma irregularity occurred even when the geomagnetic conditions were at quiet levels (Kp ~ 0 to 1+). Though the observed nighttime MSTIDs and plasma irregularity bands are two different events, yet the structures appear to interact with each other, the apparent mechanism leading to the quiet time westward reversal of plasma irregularity structures at midnight and the development of complex K-shaped depletion structure. Interaction between these phenomena and their observed characteristic features is also discussed.

我们报告了由印度斯利那加克什米尔大学安装的气辉成像仪在2019年9月23日发生的电离层现象（北纬34.08°，北纬74.79°和北纬25.91°）。今晚观察到的各种现象如下：（1）黄昏时间附近的波状结构，其相前沿西北向东南方向排列并向西南移动，被分类为夜间中程电离层扰动。（2）同时观测西北移动的夜间中尺度电离层扰动和向东漂移的等离子体不规则性；（3）午夜后场向排列的等离子体不规则性和K形耗尽结构形成的向西反转。我们将详细分析其特征和演变过程。从地磁低纬度站（印度加丹基；印度13.5°N，79.2°E，磁性纬度〜6.5°）的雷达观测结果看，等离子体不规则性似乎是低中纬度过渡区局部产生的等离子体不规则性的标志。 N）在今晚没有赤道等离子气泡的迹象。有趣的是，即使地磁条件处于安静水平（Kp〜0至1+），也发生了等离子体不规则性的向西逆转。尽管夜间观测到的MSTIDs和血浆不规则带是两个不同的事件，但结构似乎相互作用，这种明显的机理导致午夜血浆不规则结构向西安静的逆转以及复杂的K形耗尽结构的发展。 。