GIM-TEC adaptive ionospheric weather assessment and forecast system. 1 2 T.L. Gulyaeva 1 , F. Arikan 2 , M. Hernandez-Pajares 3 , I. Stanislawska 4 3 4 1 IZMIRAN, Kaluzskoe Sh. 4, Troitsk, Moscow 142190, Russia gulyaeva@izmiran.ru 5 2 Department of EEE, Hacettepe University, Beytepe, Ankara 06800, Turkey arikan@hacettepe.edu.tr 6 3 Universitat Politecnica de Catalunya (UPC) Barcelona, Spain manuel@ma4.upc.edu 7 4 Space Research Center, PAS, Warsaw, Poland stanis@cbk.waw.pl 8 9 Abstract 10 11 The Ionospheric Weather Assessment and Forecast (IWAF) system is a computer software package 12 designed to assess and predict the world-wide representation of 3-D electron density profiles from the 13 Global Ionospheric Maps of Total Electron Content (GIM-TEC). The unique system products include 14 daily-hourly numerical global maps of the F2 layer critical frequency (foF2) and the peak height 15 (hmF2) generated with the International Reference Ionosphere extended to the plasmasphere, IRI-Plas, 16 upgraded importing the daily-hourly GIM-TEC as a new model driving parameter. Since GIM-TEC 17 maps are provided with one- or two-days latency, the global maps forecast for one day and two days 18 ahead is envisaged using the harmonic analysis applied to the temporal changes of TEC, foF2 and 19 hmF2 at 5112 grid points of a map encapsulated in IONEX format (-87.5º:2.5º:87.5ºN in latitude, - 20 180º:5º:180ºE in longitude). The system provides online the ionospheric disturbance warnings in the 21 global W-index map establishing categories of the ionospheric weather from the quiet state (W=±1) to 22 intense storm (W=±4) according to the thresholds sets for instant TEC perturbations regarding quiet 23 reference median for the preceding 7 days. The accuracy of IWAF system predictions of TEC, foF2 24 and hmF2 maps is superior than the standard persistence model with prediction equal to the most 25 recent ‘true’ map. The paper presents outcome of the new service expressed by the global ionospheric 26