Updated Millstone Hill and Sondrestrom Incoherent Scatter Radars Convection Model Shun-Rong Zhang, John M. Holt, and William C. Rideout MIT Haystack Observatory, Westford, MA, USA Mary McCready SRI International, Menlo Park, CA, USA High latitude convection electric fields play a central role in linking the solar wind and magnetosphere with ionosphere and thermosphere processes. The characteristics of the convection has been extensively studied, and empirical or statistical models of the convection have been created and are under steady revision over the years with new data and novel analysis techniques becoming available. These models include those based on OGO-6, DE-2 and DMSP low altitude satellite measurements of electric fields. Assimilation of various types of data (e.g., AMIE) provides also a global mapping of the convection pattern. Ground based instruments such as incoherent scatter radar (ISR) and SuperDARN measure the line of sight velocity and their long-term observations make important contributions to the modeling effort. Holt et al. (1987) described the technique and model using Millstone Hill ISR data, and the technique was then applied to combining Millstone Hill and Sondrestrom ISR data to form a single model (Foster et al., 1987), MHS. The earlier Millstone Hill model provides potentials and velocities at 3 levels of Kp (or 9 levels of Power Precipitation index) for IMF "away" and "from" directions. MHS is however, for 4 combinations of By and Bz signs. Since MHS was published more than 1 decade ago, additional data from both sites have been collected, and it is now the right time to update them with more data and finer By and Bz dependence. This paper will describe the updated model, and compare it to the old version as well as to models from other techniques.