Articles | Volume 35, issue 2
Ann. Geophys., 35, 227–237, 2017
https://doi.org/10.5194/angeo-35-227-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Special issue: The 14th International Symposium on Equatorial Aeronomy
Regular paper 21 Feb 2017
Regular paper | 21 Feb 2017
Large- and small-scale periodicities in the mesosphere as obtained from variations in O2 and OH nightglow emissions
Ravindra P. Singh and Duggirala Pallamraju
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Fazlul I. Laskar, Gunter Stober, Jens Fiedler, Meers M. Oppenheim, Jorge L. Chau, Duggirala Pallamraju, Nicholas M. Pedatella, Masaki Tsutsumi, and Toralf Renkwitz
Atmos. Chem. Phys., 19, 5259–5267, https://doi.org/10.5194/acp-19-5259-2019, https://doi.org/10.5194/acp-19-5259-2019, 2019
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Meteor radars are used to track and estimate the fading time of meteor trails. In this investigation, it is observed that the diffusion time estimated from such trail fading time is anomalously higher during noctilucent clouds (NLC) than that in its absence. We propose that NLC particles absorb background electrons and thus modify the background electrodynamics, leading to such an anomaly.
Deepak K. Karan, Duggirala Pallamraju, Kedar A. Phadke, Tatiparti Vijayalakshmi, Tarun K. Pant, and Shyamoli Mukherjee
Ann. Geophys., 34, 1019–1030, https://doi.org/10.5194/angeo-34-1019-2016, https://doi.org/10.5194/angeo-34-1019-2016, 2016
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Dayglow emission variability is expected to show a symmetric solar zenith-angle-dependent diurnal pattern as the production mechanisms are dominated by solar flux; however, this is not always the case. Our investigation reveals an imprint of equatorial electrodynamics on the neutral dayglow emission variability, as opposed to that of the solar zenith angle. This has implications in gaining a comprehensive understanding of the coupled nature of the ion-neutral behaviour in the upper atmosphere.
M. Pramitha, M. Venkat Ratnam, A. Taori, B. V. Krishna Murthy, D. Pallamraju, and S. Vijaya Bhaskar Rao
Atmos. Chem. Phys., 15, 2709–2721, https://doi.org/10.5194/acp-15-2709-2015, https://doi.org/10.5194/acp-15-2709-2015, 2015
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Sources and propagation characteristics of high-frequency gravity waves observed in the mesosphere using airglow emissions from Gadanki and Hyderabad, India, are investigated using reverse ray tracing. Wave amplitudes are also traced back, including both radiative and diffusive damping. Interestingly, large vertical shears in the horizontal wind are noticed near the ray terminal points (at 10-12km altitude) and are thus identified to be the source for generating the observed gravity waves.
Special issue
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A near-infrared imaging spectrograph (NIRIS) has been developed in-house and is being operated from a low-latitude location, Gurushikhar, Mount Abu (24.6° N, 72.8° E), in India. The results presented in this study provide us with a comprehensive picture of mesospheric wave dynamics in terms of characterizing their response to various sources (solar and atmospheric) that give rise to the variability in the mesospheric intensities and temperatures.
A near-infrared imaging spectrograph (NIRIS) has been developed in-house and is being operated...