An analysis of explosive cyclone cases was produced by comparing the reanalysis of MERRA-2 (high spatial resolution) and NCEP2 (low spatial resolution) to South Atlantic in the 2014-2015 period. A total of 51 cases were found, of which 49 were detected by the first reanalysis and 33 by the second (2 cases identified by NCEP2 were not identified by MERRA-2). Spring was the dominant season in the formation of the cases in both reanalyses. It was observed that most systems are formed preferentially eastward of a preexisting trough at higher levels, while others are formed under an almost zonal upper airstream. This difference is more evident in the NCEP2. It was also diagnosed that the MERRA-2 shows more clearly the diffluence in the 250 hPa flow.The analysis of the composite fields revealed a negative horizontal tilt of the trough in 500 hPa, influenced by intense convection as the system develops. Besides, it pointed to a more pronounced jet stream in intense explosive cyclones and more prominent diffluence in non-intense cases. Since the NCEP2 reanalysis detected fewer cases (and only 2 intense) than MERRA-2, it was considered that the former is less suited to the analysis of this type of event.
The coastal region of South America is known for the high frequency of extratropical cyclones. From 2010 to 2020, there was an exceptional case regarding intensity, reaching 2.73 Bergeron, between January 02 and 03, 2019. To better understand the characteristics of this type of explosive cyclone, this work sought to investigate the synoptic conditions in this phenomenon. To this end, a visual inspection method of the sea level pressure charts was applied, allied with the functions available in the Grid Analysis and Display software. The cyclone began by transitioning from the continental low to the extratropical cyclone, associated with a trough at higher levels in a zone of weak temperature advection. As the system developed, there was a fracture in the upper air trough, acquiring negative horizontal inclination and the transition of the cyclone from the tropical to the polar side of the jet streak. Sea heat fluxes become relevant only 6 hours after cyclogenesis and enhance as the surface wind increases in the cold sector of the cyclone. In addition, a robust stratospheric ozone intrusion arose close to 700 hPa in the cyclone region, related to the dynamic tropopause folding.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.