Ionospheric climatology and model from long-term databases of worldwide incoherent scatter radars Shun-Rong Zhang and John Holt MIT Haystack Observatory Tony van Eyken EISCAT Association Mary McCready SRI International Christine Amory-Mazaudier Centre for the Study of Earth and Planets Environments, CNRS Shoichiro Fukao Research Institute for Sustainable Humanosphere, Kyoto University Michael Sulzer Arecibo Observatory, National Astronomy & Ionosphere Center Long-term databases of worldwide incoherent scatter radars are utilized to study ionospheric climatology and create empirical models for electron density, ion and electron temperatures, and ion drifts. These radars, including, from magnetic north to south and east to west, EISCAT Svalbard Radar (Norway), Sondrestrom Radar (Greenland), EISCAT Tromso Radars (Norway), Millstone Hill Radar (USA), St. Santin Radar (France), Shigaraki Middle and Upper atmosphere (MU) Radar (Japan) and Arecibo Radar (Puerto Rico), are able to characterize diurnal, seasonal, and solar cycle variations of height dependent ionospheric strctures in a broad latitude and longitude area. In these huge databases, available through the MADRIGAL system (http://www.openmadrigal.org), the data cover generally 1-2 solar cycles, and for Millstone Hill and Arecibo they span nearly 3 solar cycles. Based on these data, our systematical analyses result in a comprehensive overview of various features of the ionosphere and series of web-based empirical models (http://www.haystack.mit.edu/madrigal/Models/). This presentation will review local models for each site and discuss the ionospheric climatology, with emphasis on the development of annual/semiannual electron density variations with latitudes and longitudes, and on ionospheric thermal status at midlatitudes. This presentation will also explore the long-term trend of ionospheric electron density and ion temperature variations from Millstone Hill observations.