Equatorial coronal holes and their relation to high-speed solar wind streams

Using together SUMER, EIT and MDI onboard SOHO, we examine plasma properties and magnetic fields at the base of three equatorial coronal holes (ECHs) occurring during August and October 1996 near solar minimum. We estimate the electron density, flow speed deduced from UV/EUV lines as well as the average magnetic field of the photosphere. These ECHs produced distinct high-speed streams in the ecliptic plane with average flow speeds of larger than 500 kms(-1). With SWE and MFI both onboard the WIND satellite, we also determine the parameter values of the plasma and magnetic field of these high-speed streams at 1 AU in the Earth's orbit. We discuss the relationships between observations of high-speed streams at 1 AU and coronal holes at the coronal base.