LAUSR

AbstractThis study presents a climatological and composite analysis of elevated mixed layers (EMLs) in South and North America derived from the NCEP Climate Forecast System Reanalysis. The EMLs are identified based on objective criteria applied to the reanalysis data. Composite analyses of synoptic-scale conditions and severe weather parameters associated with spring EML cases are presented. EMLs are more frequent immediately to the east of the Andes and the Rockies. The North American EMLs form by surface heating over the higher terrain of the Rockies, with peak frequency occurring in spring and summer. EMLs in South America are generated by differential temperature advection due to ageostrophic circulations east of the Andes, as indicated by the temperature lapse rate tendency equation, which relates to the higher frequency of EMLs during the cold season in South America. EMLs over North America are about 100 hPa lower than over South America due to the lower height of the Rockies in comparison to the A...