As we know, the Sporadic-E layer (Es layer) is a globally common phenomenon, which is comprehensively and unceasingly studied by using the observation measurements and numerical simulations in decades. At middle latitudes, the remarkable agreements on the characteristics and generation mechanisms of Es layer have then been generally achieved. However, over the polar region, it is still poorly understood due to sparse measurements and the difficulty of conventional mechanisms to operate. In this study, two interesting events of polar cap Es layer are firstly reported by using the twin radars of RISR-N and RISR-C, CADI, and Magnetometer simultaneously. Through comprehensively studies, the recognize of polar cap Es layer is clearly extended, not only on the characteristics but also on the mechanism processes. The polar cap Es layer is horizontally greater than 350km. Moreover, a new process on the generation mechanism is provoked including the functions of particle precipitation and gravity wave. Furthermore, the TEC variations associated with the polar cap Es layer are pulse-like enhancements with a general strength of ~0.5 TECu and are followed by smaller but rapid TEC perturbations. In the near future, the investigation of the effect of Sporadic-E layer on the radio wave propagation over the polar region will be extended, which is aiming to preliminarily establish the propagation model to service the various applications much better.
As a consequence, we present peculiar evidences for the first time to greatly enrich our knowledge on the polar cap Es layer, showing us a new insight on it.

偶发E层,物理特征,形成机理,影响效应,高纬极区