Tracing Acoustic-Gravity Waves from the Ocean into the Ionosphere: ONR BRC Project
 2013 - 2016
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Project Participants

Terence W. Bullett
Oleg A. Godin
Catalin Negrea
Nikolay A. Zabotin

Project Summary

Theory predicts strong coupling between waves in the atmosphere and the ocean at low frequencies where mechanical waves in both fluids should be treated as acoustic gravity waves (AGWs). It has been shown recently that for an underwater source, the power transmitted into the atmosphere through air-water interface can exceed the total power emitted by the same source in unbounded water by an order of magnitude or more, depending on wave frequency. Under somewhat idealized conditions, particularly strong transmission of AGWs from a compact underwater source into atmosphere has been predicted to occur in two narrow frequency bands with central frequencies of several mHz. Exact values of the central frequencies depend on the ocean depth and atmospheric conditions. These frequency bands can be called Transparency Windows. At a similar frequency, a transition in behavior of oceanic infragravity waves occurs; at higher frequencies the infragravity waves penetrate into the atmosphere only up to heights of the order of their wavelength, but below the transition frequency, the energy and momentum of infragravity waves are radiated into the atmosphere and are expected to reach the upper atmosphere, including thermosphere and ionosphere. This second effect may be called Wideband Transparency of the air-sea interface.

Experiment Idea

The project aims to confirm the two effects of transparency and will investigate their global consequences with theoretical and experimental means. Innovative passive techniques of noise interferometry will be applied to an unprecedented combination of ocean and ionosphere sensors. Data obtained with Deep-ocean Assessment and Reporting of Tsunami probes and with the Comprehensive Nuclear-Test-Ban Treaty Organization’s International Monitoring System’s hydroacoustic probes will be analyzed together with the data of precision ionospheric radio sounding performed with Dynasonde systems. Spectra of infragravity wave motions in the ocean will be compared with the spectra of AGWs measured over coastal regions at ionospheric altitudes to reveal peculiarities caused by the two effects of transparency mentioned above. Correlation and coherence calculations will be performed with the data of marine-based instruments and nearby Dynasondes. This will allow one to trace waves of oceanic origin and to quantify related transport of energy and momentum to thermospheric altitudes.

ONR BRC

Web site of the program.


Motivation

Godin O. A. Sound transmission through water-air interfaces: New insights into an old problem, Contemporary Physics, 49, p. 105–123 (2008). DOI: 10.1080/00107510802090415. link

Oleg A. Godin and Iosif M. Fuks (2012). Transmission of acoustic-gravity waves through gas–liquid interfaces. Journal of Fluid Mechanics, 709, pp 313-340. doi:10.1017/jfm.2012.336. link

Zabotin, N.A., J.W. Wright, and G.A. Zhbankov (2006), NeXtYZ: Three-dimensional electron density inversion for dynasonde ionograms, Radio Sci., 41, RS6S32, doi:10.1029/2005RS003352. link

Dynasonde Database

This link leads to a web interface to data storage and data analysis tools for Dynasondes participating in the project.

Station Map

Participating Stations:
WI937 75°28'42.14" W 37°56'11.04" N          Real Time
SJJ18 66° 8' 57.29" W 18° 6' 42.55" N           Real Time
BD840 105°16'8.51" W 39°59'32.88" N          Real Time


Marine Sensors

DART Stations
CTBTO Monitoring System

Publications

Oleg A. Godin, Nonlinear progressive acoustic-gravity waves: Exact solutions, Geophysical Research Abstracts, Vol. 15, EGU2013-1820, 2013, (EGU General Assembly, Vienna, Austria, 8-12 April 2013). Image

Godin O. A., N. A. Zabotin, A. F. Sheehan, Z. Yang, and J. A. Collins (2013), Power spectra of infragravity waves in a deep ocean, Geophys. Res. Lett., 40, 2159–2165, doi:10.1002/grl.50418. Abstract

Nikolay A. Zabotin and Oleg A. Godin, Infragravity waves in the ocean as a source of acoustic-gravity waves in the atmosphere, Geophysical Research Abstracts, Vol. 15, EGU2013-2118, 2013, (EGU General Assembly, Vienna, Austria, 8-12 April 2013). Image

Nikolay A. Zabotin, Oleg A. Godin and Anne Sheehan, Interferometry of background acoustic-gravity waves, Geophysical Research Abstracts, Vol. 15, EGU2013-2117, 2013, (EGU General Assembly, Vienna, Austria, 8-12 April 2013). Image

Catalin Negrea, Nikolay A. Zabotin, and Terence Bullett, Spectral Characteristics of Ionospheric Plasma Density and Tilt Variations from the Dynasonde Data, Vol. 15, EGU2013-954, 2013, (EGU General Assembly, Vienna, Austria, 8-12 April 2013). Image

Catalin Negrea, Nikolay A. Zabotin, and Terence Bullett, Wave activity in the Thermosphere-Ionosphere system as determined from Dynasonde data, CEDAR Meeting, Boulder, Colorado, 22-28 June 2013, IT Poster ITTI-13. Image