@Article{AndrioliBaXuYaChZh:2017:StTeGr,
author = "Andrioli, V{\^a}nia F{\'a}tima and Batista, Paulo Prado and Xu,
Jiyao and Yang, Guotao and Chi, Wang and Zhengkuan, Liu",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Chinese Academy of
Sciences} and {Chinese Academy of Sciences} and {Chinese Academy
of Sciences} and {Chinese Academy of Sciences}",
title = "Strong temperature gradients and vertical wind shear on MLT region
associated to instability source at 23°S",
journal = "Journal of Geophysical Research: Space Physics",
year = "2017",
volume = "122",
number = "4",
pages = "4500--4511",
month = "Apr.",
keywords = "convective instability, dynamical instability, mesopause
instabilities, meteor radar wind, Na lidar temperature.",
abstract = "Na lidar temperature measurements were taken successfully from
2007 to 2009 in the mesopause region over S{\~a}o Jos{\'e} dos
Campos (23.1°S, 45.9°W). Strong gradients on these vertical
temperature profiles are often observed. A simple theoretical
study has shown that temperature gradient of at least \−8
K/km is required concurrently with the typical tidal wind shear in
order to generate dynamical instability in the MLT region. We have
studied vertical shear in horizontal wind related to atmospheric
tides, inferred by meteor radar, with the aim of analyzing
instability occurrence. These wind measurements were taken from an
all-sky meteor radar at Cachoeira Paulista (22.7°S, 45°W). Two
years of simultaneous data, wind and temperature, were used in
this analysis which represent 79 days, totalizing 589 h of
simultaneous observations. We realize that the condition for the
local Richardson number (Ri) dropping below the critical value of
instability (Ri < 0.25) is often reached in 98% of the analyzed
cases. The mean probabilities for occurrence of convective and
dynamical instabilities, in the altitude region between 82 and 98
km, were observed to be about 3% and 17.5%, respectively.
Additionally, vertical distribution of these probabilities has
revealed a weak occurrence of dynamical instability around 90 km,
and this fact can be related to the double mesopause typically
observed in this site.",
doi = "10.1002/2016JA023638",
url = "http://dx.doi.org/10.1002/2016JA023638",
issn = "2169-9402",
language = "en",
targetfile = "andrioli_strong.pdf",
urlaccessdate = "19 abr. 2024"
}