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Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/14193
Title: On the Long Lasting “C-Type” Structures in the Sodium Lidargram: The Lifetime of Kelvin-Helmholtz Billows in the Mesosphere and Lower Thermosphere Region
Authors: Mondal S.
Sarkhel, Sumanta
Agarwal J.
Chakrabarty D.
Sekar R.
Yuan T.
Cai X.
Liu A.Z.
Nozawa S.
Saito N.
Kawahara T.D.
Mlynczak M.G.
Russell J.M.
III
Published in: Journal of Geophysical Research: Space Physics
Abstract: In order to understand the characteristics of long-lasting “C-type” structure in the Sodium (Na) lidargram, six cases from different observational locations have been analyzed. The Na lidargram, collected from low-, middle-, and high-latitude sites, show long lifetime of the C-type structures which is believed to be the manifestation of Kelvin-Helmholtz (KH) billows in the Mesosphere and Lower Thermosphere (MLT) region. In order to explore the characteristics of the long-lasting C-type structures, the altitude profile of square of Brunt-Väisälä frequency in the MLT region has been derived using the temperature profile collected from the Na lidar instruments and the SABER instrument onboard TIMED satellite. It is found to be positive in the C-type structure region for all the six cases which indicates that the regions are convectively stable. Simultaneous wind measurements, which allowed us to calculate the Richardson numbers and Reynolds numbers for three cases, suggest that the regions where the C-type structure appeared were dynamically stable and nonturbulent. This paper brings out a hypothesis wherein the low temperature can increase the magnitude of the Prandtl number and convectively stable atmospheric region can cause the magnitude of Reynolds number to decrease. As a consequence, the remnant of previously generated KH billows in nearly “frozen-in” condition can be advected through this conducive region to a different location by the background wind where they can sustain for a long time without much deformation. These long-lived KH billows in the MLT region will eventually manifest the long-lasting C-type structures in the Na lidargram. ©2019. American Geophysical Union. All Rights Reserved.
Citation: Journal of Geophysical Research: Space Physics (2019), 124(4): 3110-3124
URI: https://doi.org/10.1029/2019JA026630
http://repository.iitr.ac.in/handle/123456789/14193
Issue Date: 2019
Publisher: Blackwell Publishing Ltd
Keywords: C-type structure
Kelvin-Helmholtz billows
Prandtl number
Reynolds number
sodium lidar
ISSN: 21699380
Author Scopus IDs: 24166877100
22981859800
57208578287
36573323400
7006643447
55708368700
56332930600
7402583785
55654598300
56967492900
7202414605
7003854810
55947319900
Author Affiliations: Mondal, S., Department of Physics, Indian Institute of Technology Roorkee, Roorkee, India
Sarkhel, S., Department of Physics, Indian Institute of Technology Roorkee, Roorkee, India
Agarwal, J., Department of Physics, Indian Institute of Technology Roorkee, Roorkee, India
Chakrabarty, D., Space and Atmospheric Sciences Division, Physical Research Laboratory, Ahmedabad, India
Sekar, R., Space and Atmospheric Sciences Division, Physical Research Laboratory, Ahmedabad, India
Yuan, T., Physics Department, Utah State University, Logan, UT, United States
Cai, X., Physics Department, Utah State University, Logan, UT, United States
Liu, A.Z., Center for Space and Atmospheric Research & Department of Physical Sciences, Embry-Riddle Aeronautical University, Daytona Beach, FL, United States
Nozawa, S., Institute for Space-Earth Environmental Research (ISEE), Nagoya University, Nagoya, Japan
Saito, N., Photonics Control Technology Team, RIKEN Center for Advanced Photonics, Wako, Japan
Kawahara, T.D., Faculty of Engineering, Shinshu University, Nagano, Japan
Mlynczak, M.G., Atmospheric Sciences Division, NASA Langley Research Center, Hampton, VA, United States
Russell, J.M., III, Center for Atmospheric Sciences, Hampton University, Hampton, VA, United States
Corresponding Author: Sarkhel, S.; Department of Physics, Indian Institute of Technology RoorkeeIndia; email: sarkhel.fph@iitr.ac.in
Appears in Collections:Journal Publications [PH]

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