Fig. 16From: Comparison between IRI and preliminary Swarm Langmuir probe measurements during the St. Patrick storm periodVery low values of electron density measured by Swarm A for the evening sector. Swarm A electron density values (in red) lower than 2 × 104 cm−3, for periods P1 (top panel), M2 (middle panel), and R1 (bottom panel), for the evening sector. Coordinates are geographical, and bold lines represent magnetic parallels drawn with a 30° stepBack to article page