报告人：Jiajia Liu，Research Associate

               School of Mathematics and Statistics， The University of Sheffield

时间：2019年3月12日（周二）下午4:00

地点：教学行政楼1514会议室

报告摘要：

Swirling motions in the solar atmosphere have been widely observed in recent years and suggested to play a key role in channeling energy from the photosphere into the corona. In this talk, we will present a newly-developed Automated Swirl Detection Algorithm (ASDA) and discuss its applications. ASDA is found to be very proficient at detecting swirls in a variety of synthetic data with various levels of noise, implying our subsequent scientific results are astute. Applying ASDA to photospheric observations with a spatial resolution of 39.2 km sampled by the Solar Optical Telescope (SOT) on-board Hinode, suggests a total number of 1.62×10⁵ swirls in the photosphere, with an average radius and rotating speed of ~290 km and < 1.0 km/s, respectively. Comparisons between swirls detected in Bifrost numerical MHD simulations and both ground-based and space-borne observations have also been performed. 

Moreover, applying ASDA to simultaneous photospheric and chromospheric observations provides us new evidence that ubiquitous Alfvén pulse are excited by prevalent intensity swirls in the solar photosphere. Correlation analysis between swirls detected at different heights in the solar atmosphere and realistic numerical simulation show that, these prevalent Alfvén pulses propagate upwards through the solar atmosphere and reach the chromospheric layers. They are found to be able to potentially carry the energy needed to sustain the temperatures of quiet regions in the upper chromosphere.