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The morning glory wave of southern California

Tsai, Victor C. and Kanamori, Hiroo and Artru, Juliette (2004) The morning glory wave of southern California. Journal of Geophysical Research B, 109 (B2). Art. No. B02307. ISSN 0148-0227. doi:10.1029/2003JB002596.

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A pulse-like disturbance traveling across the Los Angeles basin was observed on 12 October 2001 with seismographs of the TriNet network. This wave had a period of about 1000 s and a propagation speed of about 10 m/s, much slower than seismic waves. The seismograph data were compared with barograph data, and a good correlation was found so the wave was determined to be atmospheric in origin. It had amplitude of about 1 mbar, but it was not known what process could produce such a wave. Since the initial finding, we have inspected all the TriNet barograph and seismograph data for a period of two and a half years (from January 2000 to August 2002) and found four more similar events. Each of the events has amplitude between 0.8 and 1.3 mbar, a period between 700 and 1400 s, and a propagation speed between 5 and 25 m/s. We conclude that these waves are internal gravity waves trapped in a stable layer formed by a temperature inversion. Some of these waves have large amplitudes and develop into solitary waves (nonlinear internal gravity waves) similar to the spectacular “morning glory” wave observed in Australia. We call these waves the LA morning glory waves. The LA morning glory wave is probably excited by either stormy weather, winds such as the Santa Ana winds, or large teleseismic events. The morning glory wave could contribute to the recently reported excitation of the background free oscillations of the Earth. Additionally, because of its large amplitude it could have important implications for aviation safety, as was suggested earlier for the morning glory waves in Australia.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Tsai, Victor C.0000-0003-1809-6672
Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 2004 by the American Geophysical Union. Received 21 May 2003; revised 26 September 2003; accepted 14 November 2003; published 13 February 2004. This research was supported by the SURF program at Caltech as well as generous funding from Marcella Bonsall. We thank Sharon Kedar for bringing our attention to the long-period seismic signal observed on 12 October 2001. We would also like to thank Doug Christie, Andy Ingersoll, Don Anderson, and Toshiro Tanimoto for their critique and suggestions. The seismic and barograph data used in this study were downloaded from the IRIS Data Management Center and the Data Center of the Southern California Earthquake Center.
Group:Seismological Laboratory
Funding AgencyGrant Number
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Marcella BonsallUNSPECIFIED
Issue or Number:B2
Record Number:CaltechAUTHORS:20140611-131841863
Persistent URL:
Official Citation:Tsai, V. C., H. Kanamori, and J. Artru (2004), The morning glory wave of southern California, J. Geophys. Res., 109, B02307, doi:10.1029/2003JB002596
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46208
Deposited By: Tony Diaz
Deposited On:11 Jun 2014 20:48
Last Modified:10 Nov 2021 17:22

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