A model is developed for estimating the Pedersen currents driven in the conjugate ionosphere by an oscillatory ionospheric dynamo associated with acoustic in the upper atmosphere. The model is electrostatic within each ionosphere but uses Alfv¿n waves in the intervening geomagnetic flux tube. The acoustic frequency range (f~101--102 mHz) considered here allows for coupling to the geomagnetic micropulsation spectrum. Exercises of the model show that the conjugate coupling could be both efficient and observable (by HF sounding). During the daytime the preferred observational model would be of plasma compression in the upper E region. During the nighttime, only observations of F-region plasma convection would be possible. Daytime and nighttime coupling efficiencies differ markedly because of a variation in ionospheric boundary condition at the foot of the flux tube.