Earth’s Aurora: A Two-Dimensional Monitor of Near-Earth Space Environment Dynamics
Tid: On 2018-09-05 kl 13.15 - 14.00
Föreläsare: Dr Larry Lyons, Professor at the Dept. of Atmospheric and Ocean Sciences, U. California
Plats: Hall F3, Lindstedtsvägen 26, KTH campus
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 2-D 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 ionospheric flows that result from magnetosphere-ionosphere dynamics. Combining the auroral and ionospheric flow measurements 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 different types of large-scale auroral forms. We now need to learn what controls when and where a specific type of disturbance will occur and develop with time. Auroral measurements point to the directions that we need to consider.
The lecture is part of a series of annual lectures in memory of KTH-professor Hannes Alfvén,who received of the Nobel Prize in Physics, 1970. The lecture is supported economically by the Royal Swedish Academy of Sciences, through its Nobel committee for physics.
Professor Lyons received his PhD with a Space Physics specialty at the University of California, Los Angeles. 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 space 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 resulting from the solar wind energy input.
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 plasma populations and fields in the magnetosphere. 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.