Empirical regional models for the short-term forecast of <i>M3000F2</i> during not quiet geomagnetic conditions over Europe

• Main Author: M. Pietrella
• Format: Article
• Language: English
• Published: Copernicus Publications 2013-10-01
• Series: Annales Geophysicae
• Online Access: https://www.ann-geophys.net/31/1653/2013/angeo-31-1653-2013.pdf

Twelve empirical local models have been developed for the long-term prediction of the ionospheric characteristic <i>M3000F2</i>, and then used as starting point for the development of a short-term forecasting empirical regional model of <i>M3000F2</i> under not quiet geomagnetic conditions. Under the assumption that the monthly median measurements of <i>M3000F2</i> are linearly correlated to the solar activity, a set of regression coefficients were calculated over 12 months and 24 h for each of 12 ionospheric observatories located in the European area, and then used for the long-term prediction of <i>M3000F2</i> at each station under consideration. <br><br> Based on the 12 long-term prediction empirical local models of <i>M3000F2</i>, an empirical regional model for the prediction of the monthly median field of <i>M3000F2</i> over Europe (indicated as <i>RM_M3000F2</i>) was developed. <br><br> Thanks to the <i>IFELM_foF2</i> models, which are able to provide short-term forecasts of the critical frequency of the F2 layer (<i>fo</i>F2_STF) up to three hours in advance, it was possible to considerer the Brudley–Dudeney algorithm as a function of <i>fo</i>F2_STF to correct <i>RM_M3000F2</i> and thus obtain an empirical regional model for the short-term forecasting of <i>M3000F2</i> (indicated as <i>RM_M3000F2_BD</i>) up to three hours in advance under not quiet geomagnetic conditions. <br><br> From the long-term predictions of <i>M3000F2</i> provided by the IRI model, an empirical regional model for the forecast of the monthly median field of <i>M3000F2</i> over Europe (indicated as <i>IRI_RM_M3000F2</i>) was derived. <br><br> <i>IRI_RM_M3000F2</i> predictions were modified with the Bradley–Dudeney correction factor, and another empirical regional model for the short-term forecasting of <i>M3000F2</i> (indicated as <i>IRI_RM_M3000F2_BD</i>) up to three hours ahead under not quiet geomagnetic conditions was obtained. <br><br> The main results achieved comparing the performance of <i>RM_M3000F2</i>, <i>RM_M3000F2_BD</i>, <i>IRI_RM_M3000F2</i>, and <i>IRI_RM_M3000F2_BD</i> are (1) in the case of moderate geomagnetic activity, the Bradley–Dudeney correction factor does not improve significantly the predictions; (2) under disturbed geomagnetic conditions, the Bradley–Dudeney formula improves the predictions of <i>RM_M3000F2</i> in the entire European area; (3) in the case of very disturbed geomagnetic conditions, the Bradley–Dudeney algorithm is very effective in improving the performance of <i>IRI_RM_M3000F2</i>; (4) under moderate geomagnetic conditions, the long-term prediction maps of <i>M3000F2</i> generated by <i>RM_M3000F2</i> can be considered as short-term forecasting maps providing very satisfactory results because quiet geomagnetic conditions are not so diverse from moderate geomagnetic conditions; (5) the forecasting maps originated by <i>RM_M3000F2</i>, <i>RM_M3000F2_BD</i>, and <i>IRI_RM_M3000F2_BD</i> show some regions where the forecasts are not satisfactory, but also wide sectors where the <i>M3000F2</i> forecasts quite faithfully match the <i>M3000F2</i> observations, and therefore <i>RM_M3000F2</i>, <i>RM_M3000F2_BD</i>, and <i>IRI_RM_M3000F2_BD</i> could be exploited to produce short-term forecasting maps of <i>M3000F2</i> over Europe up to 3 h in advance.