@Article{RibeiroBosa:2018:ElMiLa,
author = "Ribeiro, Bruno Zanetti and Bosart, L. F.",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {University
at Albany}",
title = "Elevated mixed layers and associated severe thunderstorm
environments in South and North America",
journal = "Monthly Weather Review",
year = "2018",
volume = "146",
number = "1",
pages = "3--28",
month = "jan.",
keywords = "Orographic effects, Reanalysis data, Severe storms, Synoptic
climatology.",
abstract = "This 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 Andes.
The synoptic conditions associated with EMLs in South and North
America are characterized by an upper-level trough upstream and
low-level moisture flux convergence due to poleward-directed flow,
favoring synoptic-scale ascent poleward of the EML location, where
the convective inhibition is relatively low. When EMLs occur,
higher surface-based convective available potential energy and
low-level storm-relative helicity, in association with lower
lifting condensation level heights observed in North America,
indicate that surface-based supercell storms and tornadoes are
more likely to occur on this continent in comparison with South
America, corroborating observations.",
doi = "10.1175/MWR-D-17-0121.1",
url = "http://dx.doi.org/10.1175/MWR-D-17-0121.1",
issn = "0027-0644",
language = "en",
urlaccessdate = "27 abr. 2024"
}