Abstract
We propose a method for Global Ionospheric Maps of Total Electron
Content forecasting using the Nearest Neighbour method. The assumption
is that in a database of global ionosphere maps spanning more than two
solar cycles, one can select a set of past observations that have
similar geomagnetic conditions to those of the current map. The
assumption is that the current ionospheric condition can be expressed by
a linear combination of conditions seen in the past. The average these
maps leads to common geomagnetic components being preserved and those
not shared by several maps being reduced. The method is based on
searching the historical database for the dates of the maps closest to
the current map and using as a prediction the maps in the database that
correspond to time shifts on the prediction horizons. In contrast to
other methods of machine learning, the implementation only requires a
distance computation and does not need a previous step of model training
and adjustment for each prediction horizon. Also provides confidence
intervals for the forecast. The method has been analyzed for two full
years (2015 and 2018), for selected days of 2015 and 2018, i.e., two
storm days and two non-storm days and the performance of the system has
been compared with CODE (24- and 48-hour forecast horizons).