嘉宾(Presenter)：Prof. Larry Lyons (UCLA)
时间（Date & Time）：November 12, 2018, 14:30-16:00
地点(Venue):闻天楼南楼208, Wentian Building, South 208
题目(Title)：Earth’s Aurora: A Two-Dimensional Monitor of Near-Earth Space Environment Dynamics
Earth’s aurora not only brings amazement and wonder to all who view it, but by itself is a remarkable scientific instrument that uniquely offers two-dimensional monitoring of the dynamic near-Earth space environment. To take advantage, it is necessary to understand how to “read” the patterns of the aurora and the physical message imparted to us by the different patterns. The aurora reflects flows in the ionosphere, flows that result from the dynamics of the magnetosphere-ionosphere system. Combining auroral measurements with measurement of the ionospheric flows has allowed us to learn how to read the auroral patterns, allowing the evolution of the aurora to be used to identify the various types of disturbances within this system and the flows that lead to these disturbances. Ground-based measurements of currents in the ionosphere were used nearly 60 years ago to discover that the solar wind drives large scale flows within, and energy transfer to, the magnetosphere-ionosphere system. Now, with modern auroral and flow measurements, we have learned that meso-scale flows are as intense as large -scale flows and control the different variety of types of disturbance, such as poleward boundary intensifications, streamers, substorms, and omega bands. We now need to learn what controls when and where a specific type of disturbance will occur and how it will develop with time, and auroral measurements are pointing to the directions that we need to consider.
Professor L. Lyons received his PhD with a Space Physics specialty at the University of California, Los Angeles (UCLA). After spending time at three other institutions, he returned to UCLA, becoming a Distinguished Professor in the Department of Atmospheric and Oceanic Sciences. His primary research interests involve the interaction of solar-wind energy with the Earth's environment. This includes the transfer of energy to the Earth’s magnetosphere, manifestations of this energy within the magnetosphere and ionosphere, and effects of the energy when it is deposited within the ionosphere and upper atmosphere. Emphasis is placed on observations and modeling of geomagnetic disturbances within the magnetosphere-ionosphere system that result from solar-wind energy. The observational aspects of the research focus on combining observations of ionospheric flows, currents, and the aurora from ground-based observing platforms with in-situ measurements of magnetospheric plasma populations and fields from spacecraft. Different types of disturbances are being identified and characterized, and the processes responsible for the storage, transfer, and release of plasma and field energy within the magnetosphere-ionosphere system during the various disturbances are analyzed.