An index to link scientific productivity with visibility

I here propose an index that links the number of papers a researcher has published with impact factors (IFs) of the journals that publish these papers. A researcher is said to have an index z if totally z of his/her papers are published in journals with IFs of at least z/2. The z-index, not meant to evaluate, compare and rank scientists, is a number that hopefully conveniently summarizes the number of publications in journals with high IFs.