This proposal will study Earth's magnetosheath and its interaction with the magnetosphere by (1) analysis of all the magnetosheath data collected by the IMP-8 plasma instrument over the past 20 years, using a revised analysis routine optimized for magnetosheath data to produce a data set of the magnetosheath plasma density, velocity, and temperature; (2) production of synoptic maps of plasma parameters in the magnetosheath for various upstream solar conditions; (3) use of these maps to attempt to delineate the boundary of the plasma mantle for different solar wind conditions; and (4) comparison of the magnetosheath data with model results. Data will be analyzed to look for variations in the magnetosheath configuration due to differing upstream magnetic field and plasma conditions. The results will be compared with the best models available, and will test theoretical understanding of magnetosheath processes and identify regions which deviate from the model expectations.***
