PRELIMINARY RETRIEVAL OF SOLAR-WIND LATITUDE DISTRIBUTION FROM SOLAR-WIND ANISOTROPIES SOHO OBSERVATIONS/

The Solar Wind Anisotropies (SWAN) instrument on board the SOHO spacec raft measures Lyman alpha radiation emanating mainly from neutral hydr ogen gas in the solar neighborhood. This gas is part of the local inte rstellar cloud in which the Sun and the heliosphere are immersed. Meas urements of Lyman alpha can be used to infer the local cloud character istics like the velocity and the direction of the flow, gas temperatur e, and density. The strong interaction between the Sun and the neutral hydrogen gas also makes possible investigations of solar characterist ics by Lyman alpha measurements. In this work we will concentrate on d eriving the latitudinal distribution of solar-induced ionization from SWAN Lyman alpha maps measured in 1996 at a time of the solar minimum. From the ionization we derive the distribution of the solar wind mass flux SWAN Lyman alpha data show that the ionization and the mass flux are nearly flat for all solar latitudes except the narrow belt from - 20 degrees to 20 degrees around the solar equator. In this region, ion ization and the solar wind mass flux show a definite increase, which c an be seen as an intensity depression in the Lyman alpha data from dir ections near the ecliptic. These results confirm earlier in situ measu rements by Ulysses during the present minimum and Lyman alpha measurem ents by Prognoz satellites 20 years ago.