The anomalous component of cosmic rays: Oxygen latitudinal gradient

Abstract

We have studied the latitudinal evolution of the anomalous cosmic ray oxygen component at ULYSSES during its journey to the south pole of the sun. Observations from the COSPIN Low Energy Telescope at ULYSSES are compared with observations in the vicinity of the Earth, provided by the HILT sensor on the SAMPEX spacecraft. We present results in two oxygen energy ranges from 8 to 12 MeV/n and from 12 to 16 MeV/n over a period from August 1992 until end of May 1994. Only quiet time periods which contain no solar energetic particles are taken into account. The data set covers a latitudinal range of about 50° and show for both energy channels a decrease of the SAMPEX to ULYSSES flux ratio equivalent to a positive latitudinal gradient of ∼ 2%/degree.