Eighth Symposium on Integrated Observing and Assimilation Systems for Atmosphere, Oceans, and Land Surface


Source modeling of microbaroms in the Pacific

Mark C. Willis, University of Hawaii, Honolulu, HI; and M. Garces, C. Hetzer, and S. Businger

Marine weather indirectly generates infrasonic signals in the 0.1-0.5 Hz frequency band that are able to propagate thousands of kilometers. It has been suggested that the generation mechanism for microbaroms is nonlinear interactions of ocean surface waves, which is the same as the theoretical source for microseisms. Theory predicts that a wave spectrum at any given point is only able to radiate infrasonic acoustic waves if the spectrum contains swell components that are almost opposite in direction and of a near identical frequency. Global ocean wave spectra provided by the National Oceanic and Atmospheric Administration’s (NOAA’s) Wavewatch 3 (WW3) model are used to estimate the acoustic source pressure spectra induced by nonlinear ocean wave interactions. Microbarom signals detected at International Monitoring System (IMS) station I59US, Hawaii show a clear relationship with marine storms and regions of high ocean surface waves. Predicted acoustic source pressure spectra also show a relationship with low pressure centers and the associated high significant wave heights. However, our predictions also show a large number of obscure source locations that greatly increase the complexity of the problem as presented by past research.

extended abstract  Extended Abstract (756K)

Supplementary URL: http://www.soest.hawaii.edu/MET/Faculty/businger/personnel/mwillis

Poster Session 2, Atmospheric, Oceanic and Land Observations
Wednesday, 14 January 2004, 2:30 PM-4:00 PM, Hall AB

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