Iri Task Force Activity at Ictp: Proposed Ments for the Iri Region below the F Peak Improve-

The Aeronomy and Radiopropagation Laboratory of the International Center for Theoretical Physics (ICTP) in Trieste, Italy has hosted special IRI Task Force Activities (‘IFAs) annually since 1994. This article reviews the format and results of the 1994, 1995, and 1996 TFAs. The prime focus of these TFAs has been the Fl region and the bottomside F2 region. Each meeting has tackled a specific subset of modeling problems using morning round-table discussions and afternoon computer sessions to solve the ‘problem of the day’. Data, models and related software were provided by the participants on electronic media or were retrieved over the intemet. As a result of this effort several improvements have been proposed for the IRI description of the region below the F2 peak: (1) A more accurate description of the probability of the existence of the Fl layer, (2) A more realistic description of the bottomside thickness parameters, (3) A set of new anchor points to define the intermediate region between the E valley top and the bottomside F2 region. INTRODUCTION