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Abstract:
GNSS radio occultation measurements are used to observe the occurrence and the intensity of sporadic E layers on a global scale. We analysed data acquired by several satellite missions. Our data set currently comprises more than 17.7 million of globally distributed radio occultation profiles. For our study, we use ionosonde data at midlatitude and low latitude stations as well as Signal-to-Noise Ratio (SNR) GNSSS L1 radio occultation profiles. The SNR is sensitive to vertical changes in the electron density which is reflected in large fluctuations in the according altitude range of the profile. Therefore, vertically thin ionospheric phenomena like sporadic E layers (Es) can easily be identified using numerical filtering techniques.In this study, we are focusing on sporadic E layers that appear in the northern polar region (60°N – 90°N). We will present a climatology of the polar Es events and will discuss their temporal and spatial occurrence. Generally, polar Es layers show a different local time distribution compared to midlatitude sporadic E events which might be caused by electric fields influencing the sporadic E formation process.
