TY - JOUR
T1 - Investigating Solar Wind-Driven Electric Field Influence on Long-Term Dynamics of Jovian Synchrotron Radiation
AU - Han, S.
AU - Murakami, G.
AU - Kita, H.
AU - Tsuchiya, F.
AU - Tao, C.
AU - Misawa, H.
AU - Yamazaki, A.
AU - Nakamura, M.
N1 - Funding Information:
The authors wish to thank all group members who contributed to the HISAKI project. We would greatly appreciate M. Sekido and E. Kawai of Kashima Space Technology Center, National Institute of Information and Communications Technology, Japan for supporting the observation of JSR flux densities. Also, we would like to thank D. Santos-Costa for active discussions to compose this paper. HISAKI/EXCEED data are available in the Data Archives and Transmission System (DARTS) of ISAS/JAXA (http://darts.isas.jaxa.jp). Propagated solar wind data are available from C. AMDA database (http://amda.cdpp.eu). The OMNI data used for the solar wind model were taken from the NASA Coordinated Data Analysis Web (CAWeb). Kashima Space Technology Center data are provided as Table S1 in the supporting information.
Publisher Copyright:
©2018. American Geophysical Union. All Rights Reserved.
PY - 2018/11
Y1 - 2018/11
N2 - Since the first discovery of Jovian Synchrotron Radiation (JSR) from Jovian radiation belt in late 1950s, origin of its time variations has been one of the main subjects of the Jovian radiation belt study. JSR is reported to be strongly correlated with solar wind ram pressure with a possible time lag, which remains an unsolved issue. In our study, the influence of dawn-to-dusk electric field modulated with solar wind ram pressure on JSR variations is investigated. Alongside the original diffusion coefficient (DLL(UV)), a new diffusion coefficient (DLL(Elec)) which is dependent on solar wind conditions is applied to a one-dimensional lossy radial diffusion model, and we reproduce long-term variations of JSR between 1971 and early 2018. For the specific choice of DLL(UV) = 3.0 × 10−10L3[s−1], the correlation coefficient is found to be 0.6 between the simulated JSR and the ground observation data prior to 2005, and the intermittent observation after 2005 supports our simulation as well. We suggest that while DLL(UV) is the primary mode of diffusion that determines the steady profile of electron population and JSR, DLL(Elec) serves as a secondary mode, which controls long-term variations of JSR.
AB - Since the first discovery of Jovian Synchrotron Radiation (JSR) from Jovian radiation belt in late 1950s, origin of its time variations has been one of the main subjects of the Jovian radiation belt study. JSR is reported to be strongly correlated with solar wind ram pressure with a possible time lag, which remains an unsolved issue. In our study, the influence of dawn-to-dusk electric field modulated with solar wind ram pressure on JSR variations is investigated. Alongside the original diffusion coefficient (DLL(UV)), a new diffusion coefficient (DLL(Elec)) which is dependent on solar wind conditions is applied to a one-dimensional lossy radial diffusion model, and we reproduce long-term variations of JSR between 1971 and early 2018. For the specific choice of DLL(UV) = 3.0 × 10−10L3[s−1], the correlation coefficient is found to be 0.6 between the simulated JSR and the ground observation data prior to 2005, and the intermittent observation after 2005 supports our simulation as well. We suggest that while DLL(UV) is the primary mode of diffusion that determines the steady profile of electron population and JSR, DLL(Elec) serves as a secondary mode, which controls long-term variations of JSR.
KW - HISAKI
KW - Jupiter
KW - radiation belt
KW - solar wind
KW - synchrotron radiation
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U2 - 10.1029/2018JA025849
DO - 10.1029/2018JA025849
M3 - Article
AN - SCOPUS:85057475022
SN - 2169-9380
VL - 123
SP - 9508
EP - 9516
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 11
ER -