@Article{SarkhelMRSCGJKKRSWMR:2015:CaStOc,
author = "Sarkhel, S. and Mathews, J. D. and Raizada, S. and Sekar, R. and
Chakrabarty, D. and Guharay, Amitava and Jee, G. and Kim, J-H. and
Kerr, R. B. and Ramkumar, G. and Sridharan, S. and Wu, Q. and
Mlynczak, M. G. and Russell, J. M.",
affiliation = "{Pennsylvania State University} and {Pennsylvania State
University} and SRI International, Arecibo and {Physical Research
Laboratory} and {Physical Research Laboratory} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Korea Polar Research
Institute} and {Korea Polar Research Institute} and SRI
International, Arecibo and {Vikram Sarabhai Space Centre} and
National Atmospheric Research Laboratory, India and {National
Center for Atmospheric Research} and {NASA Langley Research
Center} and {Hampton University}",
title = "A case study on occurrence of an unusual structure in the sodium
layer over Gadanki, India",
journal = "Earth, Planets and Space",
year = "2015",
volume = "67",
number = "1",
abstract = "The height-time-concentration map of neutral sodium (Na) atoms
measured by a Na lidar during the night of 18 to 19 March 2007
over Gadanki, India (13.5° N, 79.2° E) reveals an unusual
structure in the Na layer for around 30 min in the altitude range
of 92 to 98 km which is similar to the usual 'C' type structures
observed at other locations. In order to understand the physical
mechanism behind the generation of this unusual event, an
investigation is carried out combining the data from multiple
instruments that include the meteor wind radar over
Thiruvananthapuram, India (8.5° N, 77° E) and the SABER instrument
onboard the TIMED satellite. The temperature and wind profiles
from the data set provided by these instruments allow us to infer
the Richardson number which is found to be noticeably less than
the canonical threshold of 0.25 above 92 km over
Thiruvananthapuram suggesting the plausible generation of
Kelvin-Helmholtz (KH) billows over southwestern part of the Indian
subcontinent. Based on the average wind speed and direction over
Thiruvananthapuram, it is proposed that the KH-billow structure
was modified due to the background wind and was advected with it
in nearly 'frozen-in' condition (without significant decay) in the
northeastward direction reaching the Na lidar location (Gadanki).
This case study, therefore, presents a scenario wherein the
initially deformed KH-billow structure survived for a few hours
(instead of a few minutes or tens of minutes as reported in
earlier works) in an apparently 'frozen-in' condition under
favorable background conditions. In this communication, we suggest
a hypothesis where this deformed KH-billow structure plays crucial
role in creating the abovementioned unusual structure observed in
the Na layer over Gadanki.",
doi = "10.1186/s40623-015-0183-5",
url = "http://dx.doi.org/10.1186/s40623-015-0183-5",
issn = "1343-8832",
language = "en",
targetfile = "Sarkhel_case.pdf",
urlaccessdate = "27 abr. 2024"
}