## 1 Introduction
In addition, the edges of the ionization patches may generate some irregularities, resulting in serious ionospheric scintillation that may interrupt satellite communication and navigation systems [20; 21]. The aforementioned phenomena have been vastly observed [7; 12; 21; 22; 23; 24]. [PERSON] and [PERSON] [25] first found the WSA in 1957 using the ionosonde measurements. The WSA may originate in the South Pacific region and has an important relationship with the ionospheric equatorial anomalies [20; 23]. With the developments of satellite technologies, the GNSS measurements [12], altimetry satellite [26], and occultation observation [27] provide abundant data to study the WSA and its impact on polar ionosphere. [PERSON] et al. [7] tested the performances of different ionospheric models under WSA conditions. In addition, it is of great significance to study the formation and evolution of ionization patches [28]. [PERSON] and [PERSON] [22] compared the differences in the ionization patches' variations with seasons, time, and interplanetary magnetic field in the Arctic and Antarctic. [PERSON] et al. [29] detected their evolution and dissipation in the aurora zone at night based on multisource data. [PERSON] et al. [30] utilized the Super Dual Auroral Radar Network (SuperDARN) to track the generation and evolution of such patches in the Arctic during a magnetic storm on September 24 in 2011, while [PERSON] et al. [12] verified their evolution on that particular day by using global positioning system (GPS) ground observations. At present, the research on the polar ionosphere is mostly based on ground radar and occultation observation. Although these observations can obtain detailed ionospheric information, they are expensive, weakly time effective, and cannot cover the entire polar regions. GNSS measurements have also been applied to the research of polar ionosphere, but most of the existing studies are based on short-term observations, and there are no long-term analyses. Moreover, the polar regions are highly variable environments, which are affected by solar activity, the polar days and nights, the WSA, and the presence of geomagnetic storms. Few studies have investigated the variations of the polar ionospheric TEC under such complicated influences. Lastly, most of the previous studies only focus on one polar region, either Arctic or Antarctic, and few studies analyze and compare the variation of the polar TEC in both these regions and the coupling relationship between them. In this paper, we mainly focus on the spatiotemporal distributions and variations of the polar ionospheric TEC under disturbed conditions, including different periods of solar activity, the polar day/night alternation, the WSA as well as the presence of geomagnetic storms, in both the Arctic and the Antarctic for about 13 years. As a first step, the GNSS measurements are adopted to map the polar ionospheric TEC for about one solar cycle using four models (the POLY model, the GTSF model, the SH model, and the SCH model), comparing their performances in mapping the polar TEC. Next, the spatial characteristics of the polar ionospheric TEC are analyzed under comprehensive disturbed conditions. Then, the temporal variations of the polar TEC and their correlations with GIM and solar activity index of F10.7 are investigated. Finally, we track the generation and evolution of the ionization patches during a magnetic storm in the Antarctic on day of year (DOY) 076 in 2015.