Evidence for modulation at the solar rotation period of the convection electric field, plasmaspheric density, ULF wave power, and energetic particles over the Van Allen Probes Mission

Thaller, Scott

Evidence for modulation at the solar rotation period of the convection electric field, plasmaspheric density, ULF wave power, and energetic particles over the Van Allen Probes Mission

Monday, 5 March 2018: 16:45

Longshot and Bogey (Hotel Quinta da Marinha)

Scott A Thaller¹, John R Wygant¹, Cynthia A Cattell¹, Aaron W Breneman², Evan Tyler³, Sheng Tian⁴, Sebastian De Pascuale⁵, William S Kurth⁵, Craig Kletzing⁶, Harlan E. Spence⁷, Geoffrey D Reeves⁸, Daniel N Baker⁹, J Bernard Blake¹⁰, Joseph F. Fennell¹⁰ and Seth G Claudepierre¹⁰, (1)University of Minnesota, School of Physics and Astronomy, Minneapolis, MN, United States, (2)The University of Minnesota, Minneapolis, MN, United States, (3)University of Minnesota Twin Cities, Minneapolis, MN, United States, (4)University of Minnesota Twin Cities, School of Physics and Astronomy, Minneapolis, MN, United States, (5)Univ. of Iowa, Iowa City, IA, United States, (6)University of Iowa, Department of Physics and Astronomy, Iowa City, IA, United States, (7)Solar System Exploration Research Virtual Institute, NASA Ames Research Center, Moffett Field, CA, United States, (8)Los Alamos National Laboratory, Los Alamos, NM, United States, (9)LASP, University of Colorado at Boulder, Boulder, CO, United States, (10)Aerospace Corporation, Los Angeles, CA, United States

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Abstract:

Using Van Allen Probes data, we present the first in situ observations of the convection electric field and ExB drift related phenomena in the inner magnetosphere being driven at the solar rotation period (~27 days) and harmonics. We examine their relation to multi-day variations of ULF wave intensity, and the effects of such modulations on energetic electrons and protons in the inner magnetosphere. Our analysis of the cold plasma density and electric fields in the inner magnetosphere shows intervals of strong ~27-day modulation of the plasmapause location (~0.7 R_E peak-to-peak), cold plasma density (~250 cm^-3 peak-to-peak), and large scale electric field (~0.3 mV/m peak-to-peak) at L = 2.5 – 5.0. This periodicity is due to geoeffective conditions in the solar wind passing over Earth as shown by the fact that the variations in the plasmapause location anti-correlate with the solar wind electric field, magnetospheric electric field, and Kp index. This effect becomes more prominent in the declining phase of the solar cycle. Preliminary observations show that the ULF wave power with periods ~1 – 6 minutes may also be modulated at the solar rotation period. Preliminary observations also show 1.8 and 3.4 MeV electrons at L = 5, which have drift periods comparable to the ULF wave periods, are also being modulated in number flux at near the solar rotation period. In this presentation, we will examine the relation between the solar rotation modulation of the convection electric field, ULF wave power, energetic electron flux, and energetic/ring current ions.