Compressive fluctuations in solar wind have been extensively studied in the past using data from spacecraft on the ecliptic plane. In present analysis, based on Ulysses data, for the first time the nature of polar wind compressive fluctuations is investigated. Data are from the first out-of-ecliptic orbit of Ulysses, when solar activity is low. In such conditions, as well known, the high-latitude wind appears as a fast and relatively steady plasma flow. Correlation coefficients at hourly scale for several pairs of solar wind parameters like velocity, density, temperature, magnetic field magnitude, thermal pressure, magnetic pressure, and total plasma pressure are used to characterize the wind compressive state. Results appear to confirm the view that compressive fluctuations in solar wind are a complex superposition of MHD compressive modes and pressure-balanced structures.

Compressive Fluctuations in High-Latitude Solar Wind

PIETROPAOLO, Ermanno;
2002-01-01

Abstract

Compressive fluctuations in solar wind have been extensively studied in the past using data from spacecraft on the ecliptic plane. In present analysis, based on Ulysses data, for the first time the nature of polar wind compressive fluctuations is investigated. Data are from the first out-of-ecliptic orbit of Ulysses, when solar activity is low. In such conditions, as well known, the high-latitude wind appears as a fast and relatively steady plasma flow. Correlation coefficients at hourly scale for several pairs of solar wind parameters like velocity, density, temperature, magnetic field magnitude, thermal pressure, magnetic pressure, and total plasma pressure are used to characterize the wind compressive state. Results appear to confirm the view that compressive fluctuations in solar wind are a complex superposition of MHD compressive modes and pressure-balanced structures.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11697/30780
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