Continuous measurements of electron temperatures, electron concentrations, and vertical plasma drift were made at Jicamarca during the September 11, 1969, solar eclipse. Control measurements were made on September 13, 1969. Synthesis of the observed electron concentrations was made, using a model that solved the time‐dependent electron‐ion continuity equations. Ions O+, NO+, O2+, and N2+ were treated. Physical and chemical processes pertinent to the F region were considered in a realistic way. At noon, 300 km above Jicamarca, we obtained the values q = 290−3 sec−1 for the O+ production rate, β = 1.94 × 10−4 sec−1 for the loss coefficient, and H = 59 km for the atomic oxygen scale height. All large‐scale features observed in the F2 region were synthesized by the model. This synthesis was not sensitive to a simultaneous 30% reduction of q and β Copyright 1972 by the American Geophysical Union.