Polar cap blobs: enhanced density structures different from polar cap patches in the polar cap ionosphere

Friday, 14 July 2017: 13:50
Furong Room (Cynn Hotel)
Qing-He Zhang1, Yu-Zhang Ma1, Periyadan T Jayachandran2, Joran Moen3, Michael M Lockwood4, Yongliang Zhang5, Y. Wang1, David Themens2, Beichen Zhang6 and Zan-Yang Xing1, (1)Institute of Space Sciences, Shandong University, Weihai, China, (2)University of New Brunswick, Fredericton, NB, Canada, (3)University of Oslo, Oslo, Norway, (4)University of Reading, Reading, Berkshire, United Kingdom, (5)Johns Hopkins University, Baltimore, MD, United States, (6)Polar Research Institute of China, Shanghai, China
Abstract:
A new nomenclature of “polar cap blobs” has been introduced to differentiate another type of enhanced density structure from patches in the polar cap ionosphere. This is based on in situ and ground-based observations, by learning from the terminology of auroral blobs, a plasma structure within the nightside auroral oval on the closed field lines. Comparing with the polar cap patches, which are transported from the dayside sunlit region with dense and cold plasma, the polar cap blobs are associated with particle precipitations and aurora arcs in the polar cap with dense, hot plasma, strong field-aligned currents and flow shears. This indicates multi-instrument observations are necessary in identifying polar cap blobs and patches. Notably, the polar cap blobs may lead much stronger ionospheric scintillations to Global Navigation Satellite System (GNSS) signals in the polar cap region than patches, which will be very useful to grade the importance of space weather phenomena in the polar cap.
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