Study of Neptune dayside magnetosheath fluctuations during Voyager-2 flyby

Turbulence in the outer planetary magnetospheres has been relatively less studied than in the Earth's magnetosphere, especially for the ice giants which have been visited only by the Voyager-2 spacecraft so far. The aim of this work is to study the turbulence in Nep-tune's dayside magnetosheath. Voyager-2 magnetometer 3-s averaged magnetic field data were analyzed with several data analysis tech-niques. It was found that most of the magnetosheath magnetic field is aligned in the BT direction. The BR-component spectrum showed the predominance of short-period (5 minutes) oscillations, while the BT- and BN- components showed the occurrence of longer-period (20-50 minutes) oscillations. The Fourier spectrum of the magnetic field showed a breakpoint near 0.00165 Hz. The lower frequency por-tion showed index (absolute values) smaller than 1.0. The higher frequency portion showed a much steeper spectrum, with power law values varying from about 2.0 to 2.4. The statistical kurtosis parameters for BR and BN are higher than 3 in almost all scales, while the BT component (main field direction) has a more Gaussian or sub-Gaussian behavior, specially in scales higher than 20 minutes. The kurtosis is very high at the low frequency spectral power of 40 minutes for the BN-component, indicating asymmetric or non -Gaussian magnetic field distribution in the magnetosheath. The multifractal spectrum is well spread in the magnetosheath revealing a rich and dynamic activity in this region. Overall, the Neptune's magnetosheath is found to have a strong turbulence activity that is com-parable to that of other planetary magnetosheaths.(c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.