Non-linear Error Compensation Technique with Associative Restoration (NECTAR) is a novel approach to the assimilation of fragmentary sensor data to produce a global nowcast of the near-Earth space weather. NECTAR restores missing information by iteratively transforming (“morphing”) an underlying global climatology model into agreement with currently available sensor data. The morphing procedure benefits from analysis of the inherent multiscale diurnal periodicity of the geosystems by processing 24-hr time histories of the differences between measured and climate-expected values at each sensor site. The 24-hr deviation time series are used to compute and then globally interpolate the diurnal deviation harmonics. NECTAR therefore views the geosystem in terms of its periodic planetary-scale basis to associate observed fragments of the activity with the grand-scale weather processes of t...

The current study aims at investigating and identifying the ionospheric effects of the geomagnetic storm that occurred during 17–19 March 2015. Incidentally, with SYM‐H hitting a minimum of −232 nT, this was the strongest storm of the current solar cycle 24. The study investigates how the storm has affected the equatorial, low‐latitude, and midlatitude ionosphere in the American and the European sectors using available ground‐based ionosonde and GPS TEC (total electron content) data. The possible effects of prompt electric field penetration is observed in both sectors during the main phase of the storm. In the American sector, the coexistence of both positive and negative ionospheric storm phases are observed at low latitudes and midlatitudes to high latitudes, respectively. The positive storm phase is mainly due to the prompt penetration electric fields. The negative storm pha...