Form the end of substorm growth phase till the first 1-2 minutes of onset: Evidence of a transitional stage in optical auroral and in-situ observations

Jun Liang, University of Calgary, Physics and Astronomy, Calgary, AB, Canada, Ping Zhu, University of Science and Technology of China, Key Laboratory of Geospace Environment, Chinese Academy of Sciences, Hefei, China; Univ Wisconsin-Madison, Madison, United States, Eric Donovan, University of Calgary, Calgary, AB, Canada and Miho Saito, Tokyo Institute of Technology, Earth and Planetary Sciences, Tokyo, Japan