Large Scale Coronal Magnetic Field and Coronal Holes in the Declining Phase of Solar Cycles

The variation of the solar wind speed with the Carrington longitude in the declining phase of solar cycles 18 and 19 are deduced by using geomagnetic data. Referring to the sector structure of the IPM inferred from the geomagnetic observations in the polar cap, the polarity of the coronal magnetic field and the heliospheric colatitude and the Carrington longitude of the dipole-like poles are inferred in the same periods. The average results are compared with that of the solar cycle 20.