Heliolatitude and time variations of solar wind structure from in situ measurements and interplanetary scintillation observations

TL;DR

This paper develops a comprehensive 3D model of solar wind structure in heliolatitude and time by integrating remote sensing and in situ measurements over 1.5 solar cycles, enhancing heliospheric understanding.

Contribution

It introduces a novel method combining multiple data sources to reconstruct the 3D solar wind structure in both latitude and time.

Findings

Reconstructed solar wind speed and density variations over 1.5 solar cycles.

Derived correlation formulas between solar wind speed and density.

Calculated variations in solar wind flux, pressure, and charge exchange rates.

Abstract

The 3D structure of solar wind and its evolution in time is needed for heliospheric modeling and interpretation of energetic neutral atoms observations. We present a model to retrieve the solar wind structure in heliolatitude and time using all available and complementary data sources. We determine the heliolatitude structure of solar wind speed on a yearly time grid over the past 1.5 solar cycles based on remote-sensing observations of interplanetary scintillations, in situ out-of-ecliptic measurements from Ulysses, and in situ in-ecliptic measurements from the OMNI-2 database. Since the in situ information on the solar wind density structure out of ecliptic is not available apart from the Ulysses data, we derive correlation formulae between solar wind speed and density and use the information on the solar wind speed from interplanetary scintillation observations to retrieve the 3D structure of solar wind density. With the variations of solar wind density and speed in time and heliolatitude available we calculate variations in solar wind flux, dynamic pressure and charge exchange rate in the approximation of stationary H atoms.