Examination of Hurricane Sandy’s (2012) structure and intensity evolution from full-field and anomaly-field analyses

An anomaly-based field analysis approach and a set of simple beta-advection models (BAMs) have been used to examine the structure evolution and unusual left turn of Hurricane Sandy (2012) before it made the landfall and caused severe damage along the eastern US coast. Results show that the anomaly-based analysis approach can clearly reveal Sandy’s structure evolution, including its interaction with other synoptic-scale systems as well as the intensification and extratropical transition (ET) processes. During its lifetime, Sandy experienced two consecutive periods of intensification caused by the merging of anomalous vortices on 27 and 29 October. The unusual left turn and the ET process prior to the landfall are respectively influenced by an anomalous anticyclone to the northeast and an anomalous cold vortex at the 300–850 hPa layer to the northwest, which is confirmed by the experiments using the generalised BAM.